JP2000313253A - Control device at restart of engine for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a vehicle from running out or retreating at the restart of an engine in a device holding braking force during automatic stop of the engine by reducing the braking force in accordance with the restored condition of driving force of the vehicle. SOLUTION: When a vehicle during running is braked, vehicle speed is lowered, the vehicle becomes in the perfect stop condition, and the automatic stop condition is realized, automatic stop control of an engine is begun. At this time, for insuring brake oil pressure, a linear valve 228 is made into the full closed condition, and the brake oil pressure is confined in a wheel cylinder 240. Thereafter when for example a brake off signal is generated within engine restarting conditions, the engine is restarted, but creep force is gradually generated together with start of the engine accompanying engagement of a forward clutch. Then the restoring condition of the creep force is detected, and it is controlled so as to reduce the braking force in accordance with the restored condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle engine which automatically stops an engine when a predetermined stop condition is satisfied and restarts the automatically stopped engine when a predetermined restart condition is satisfied. It relates to a control device at the time of starting.

[0002]

2. Description of the Related Art Conventionally, a vehicle is stopped during traveling, and when a predetermined stop condition is satisfied, an engine is automatically stopped to save fuel, reduce exhaust emissions, reduce noise, and the like. Vehicles have been proposed and are already in practical use (for example, JP-A-8-14076 and JP-A-9-222035).

More specifically, the engine is automatically stopped when it is determined that predetermined stop conditions such as vehicle speed zero, accelerator off, brake pedal on, and the like are satisfied.

When the condition for restarting the engine is satisfied, for example, when the driver indicates the intention of running such as depressing an accelerator pedal (accelerator on), the engine is restarted immediately. Further, when the charge capacity of the battery is insufficient, the engine is restarted even when the driver does not express his intention to travel. This is to prevent the battery from running down and to avoid a situation where the engine cannot be restarted.

[0005] In a vehicle equipped with an automatic transmission, if the shift position is set to a forward traveling position such as a "D (drive)" position, even if the vehicle speed is substantially zero, the automatic transmission is changed. The gear transmission of the machine is not set in the neutral state, but is set to the first speed. Accordingly, the output of the internal combustion engine is always transmitted to the output shaft via the torque converter and the forward clutch of the gear transmission, so that so-called creep occurs. This creep enables extremely low-speed running without the driver turning on the accelerator, and often works effectively for the driver in running the vehicle.

However, when the engine is automatically stopped, this creep force is not generated. Therefore, when the vehicle is stopped on a slope, there is a possibility that the vehicle will retreat. In view of such circumstances, there has been proposed a method of performing a control (so-called hill hold control) for holding a braking force so that a vehicle does not move by locking wheels when the engine is stopped.

When the engine is automatically stopped, the oil pump for the automatic transmission is also stopped, so that the clutch for forming the forward gear is also disengaged. Therefore, a technique has been proposed in which when the engine is restarted in the state where the shift position is the drive position, the clutch is simultaneously engaged in order to form the forward gear.

Further, if the forward clutch is engaged after the engine is restarted, the startability is impaired.
Even when the engine is automatically stopped, there is a technology that keeps the forward clutch engaged by turning the electric oil pump by a power source such as a motor generator or by providing a large accumulator. Proposed.

[0009]

However, no matter which control mode is adopted, when the engine is restarted, the creep force (driving force) is recovered and the brake operation (hill hold) is performed. If the timing of the release is shifted, a feeling of the vehicle jumping out may occur, or conversely, if the vehicle is on a steep slope, the vehicle may retreat.

In particular, in a vehicle employing a control mode in which the forward clutch is engaged together with the restart of the engine, the timing of generation of the driving force of the engine due to the restart, the engagement timing of the forward clutch, and the brake operation are determined. There is a situation in which the possibility of occurrence of a malfunction is likely to increase as a result of the combination of the cancellation timing and the three parties.

Further, after the engine is started, there is a state where the engine speed temporarily becomes higher than the idle speed (maximum speed) before the engine speed reaches the idle speed.

FIG. 1 shows the maximum rotational speed NEmax.
2 will be described.

FIG. 12 shows the vehicle speed V, the engine speed NE, the ON / OFF signal of the brake pedal, and the back-and-forth vibration of the vehicle (hereinafter referred to as the front-back G of the vehicle) when the hill hold control is not executed. Things.

In FIG. 12, a signal indicating that the brake pedal is on is detected at time t21, and the vehicle is stopped (vehicle speed is zero) at time t22.

When a predetermined engine automatic stop condition is satisfied, the engine starts automatic stop (time t23).

At time t24, for example, if there is a brake pedal off signal which is one of the engine restart conditions, the engine executes a restart process, and the engine speed NE starts to increase.

As described above, the engine rotational speed NE temporarily becomes higher than the idle rotational speed around time t25 before settling at the idle rotational speed NEi. This is the maximum rotation speed NEmax. This maximum rotation speed NEmax
As shown in the figure, the vehicle has largely shaken back and forth near the point where the vehicle reaches.

This is because the engine rotational speed NE has not yet completely settled down, because the engine has just started to start, and in addition to the state of engagement of the predetermined clutch, the vehicle is not operating properly. It is considered that this is a stable state.

At this time, since the brake pedal is in a released (released) state, the vehicle further shakes more.

The front and rear G occurring in the vehicle as described above may give the driver discomfort.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and it is possible to prevent the occurrence of a feeling of popping out of a vehicle or a retreat of a vehicle upon restarting an engine. It is another object of the present invention to provide a control device at the time of restarting the engine of a vehicle, which can ensure good startability.

[0022]

According to a first aspect of the present invention, an engine is automatically stopped when a predetermined stop condition is satisfied, and the engine automatically stopped when a predetermined restart condition is satisfied. In a control device for restarting an engine of a vehicle to be restarted, means for holding a braking force of the vehicle during automatic stop of the engine and detecting a recovery state of a driving force of the vehicle when the engine is restarted. Means,
When the automatically stopped engine restarts,
The object has been achieved by reducing the braking force of the vehicle in accordance with the recovery of the driving force of the vehicle.

As described above, by controlling (reducing) the braking force in accordance with the recovery of the driving force, the timing of the recovery of the driving force and the release of the brake operation can be optimized, and the feeling of the vehicle jumping out can be suppressed. In addition, it is possible to prevent the vehicle from moving backward. In addition, good startability can be secured.

Here, the "vehicle driving force" means
Specifically, it refers to the creep force generated as a result of restarting the engine, and the present invention does not necessarily require that this be directly detected.

For example, the driving force may be estimated from the engine speed.

In the first aspect, "the braking force of the vehicle is reduced in accordance with the recovery of the driving force of the vehicle."
The concept of determining the "start timing" of the brake force reduction in accordance with the recovery state of the driving force,
It includes both the concept of determining the "decrease method" of the braking force in accordance with the state of recovery of the driving force, and the point is that "depending on the result of monitoring the state of recovery of the driving force" Is determined as long as it is determined.

For example, when the present invention adopts a configuration in which the "start timing" of the reduction of the braking force is determined in accordance with the recovery state of the driving force, it depends on the recovery of the driving force until the "how to reduce". Is not required.

As a specific example of setting the "start timing" of the braking force reduction, for example, the braking force reduction may be started from a point in time when it is determined that even a small amount of driving force has been generated. The reduction of the braking force may be started from a point in time when it is determined that the driving force has reached a predetermined value.

Further, as described above, the driving force may be derived from the engine rotation speed. Therefore, when it is determined that the engine rotation speed has reached the predetermined engine rotation speed, a trigger is generated. The reduction of the braking force may be started.

On the other hand, as a specific example of setting the “decreasing method” of the braking force, for example, the braking force is reduced in an inversely proportional relationship with the driving force, or the braking force is set in advance by experimental data. You may make it decrease based on the map of "driving force"-"braking force".

As a method for reducing the braking force, for example, a linear valve capable of finely controlling the braking oil pressure may be used.

According to a second aspect of the present invention, there is provided an engine for a vehicle which automatically stops an engine when a predetermined stop condition is satisfied and restarts the automatically stopped engine when a predetermined restart condition is satisfied. In the control device at the time of restart, a means for maintaining the braking force of the vehicle during the automatic stop of the engine, and that when the engine is restarted, the engine speed reaches the maximum speed before the engine speed reaches the idle speed. Means for determining when the automatically stopped engine restarts, from the time when it is determined that the engine rotation speed has reached the maximum rotation speed before settling to the idle rotation speed, the braking force of the vehicle The above problem has been solved by reducing the amount.

Claim 2 shows an example of the "start timing" of the braking force decrease.

When the engine is warm and when it is cold, the timing at the start of the engine may vary as a real problem. However, according to the invention of claim 2, even if the timing of the engine start varies. That is, even if the generation of the driving force varies,
The start timing of the decrease in the braking force can always be kept constant.

According to the second aspect of the present invention, since the braking force is maintained until the unstable state at the beginning of the start of the engine starts (until the driving force is stabilized), the vehicle swings back and forth. Can be greatly suppressed.

As described above, for example, when the "start timing" of the braking force reduction is determined in accordance with the recovery state of the driving force, the "decrease method" does not necessarily need to depend on the driving force. Instead, for example, the “how to decrease” described in claims 3 and 4 may be adopted.

"Start timing" of braking force reduction
For this purpose, a so-called guard may be set so that the reduction of the braking force does not start at an erroneous timing even when the restart of the engine fails, for example.

[0038]

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

In this embodiment, in a vehicle drive system as shown in FIG. 6, the engine is automatically stopped when a predetermined stop condition is satisfied, and the automatic stop is performed when a predetermined restart condition is satisfied. The restarted engine is restarted.

In FIG. 6, reference numeral 1 denotes an engine mounted on the aforementioned vehicle, and 2 denotes an automatic transmission. The engine 1 has a motor generator (MG) 3 functioning as a motor and a generator for restarting the engine 1.
Is provided on the crankshaft 1a of the engine 1 with a clutch 26,
It is connected via a chain 27, a clutch 28 and a speed reduction mechanism R. Note that the engine starter may be provided separately from the motor generator 3, and the starter and the motor generator 3 may be used together when starting the engine, or the starter may be used exclusively at extremely low temperatures.

The reduction mechanism R is of a planetary gear type and has a sun gear 3
3, including a carrier 34, a ring gear 35, and a brake 3
1. It is incorporated between the motor generator 3 and the clutch 28 via the one-way clutch 32.

The oil pump 19 for the automatic transmission 2 is directly connected to the crankshaft 1a of the engine 1 via clutches 26 and 28. The automatic transmission 2 is provided with a known forward clutch C1 that is engaged during forward travel, a reverse clutch C2 (not shown) that is engaged during reverse travel, and the like. Reference numeral 4 denotes an inverter electrically connected to the motor generator 3. The inverter 4 varies the supply of electric energy from the battery 5 as a power source to the motor generator 3 by switching, thereby varying the rotation speed of the motor generator 3. Further, switching is performed so that electric energy is charged from motor generator 3 to battery 5.

Reference numeral 7 denotes a controller for controlling the connection and disconnection of the clutches 26 and 28 and the switching control of the inverter 4.

The arrow lines in the figure indicate each signal line.

The controller 7 has an ECU (electronic control unit) 80 for controlling an engine, an automatic transmission, and the like.
Is linked to. The controller 7 and the ECU 80 include various sensor groups 90 (an engine rotation speed sensor 9 for detecting the engine rotation speed NE) as indicated by an arrow line in the drawing.
1. A vehicle speed sensor 92 for detecting a vehicle speed Ve, an idle contact sensor for detecting on / off of an accelerator, a throttle opening sensor 93 for detecting a throttle opening corresponding to an accelerator opening, and a shift lever A shift position sensor 94 for detecting a shift position,
A brake signal sensor 95 for detecting a brake-on signal,
A sensor 96 for detecting the position of the ignition for detecting on / off of the ignition switch, an eco-run switch sensor 97 for detecting the eco-run mode, a turbine speed sensor 98 for detecting the turbine speed, a battery charge for detecting the charge of the battery Detection sensor 99, etc.)
Signal is input / output. The shift position sensor 94 is a sensor similar to the conventional one, and is arranged at each position.

The control 7 is linked to an engine ECU (electronic control unit) 80 for controlling the engine and the automatic transmission and the like, and a brake ECU 82 for controlling the braking force.

Next, a configuration for engaging the forward clutch C1 in the automatic transmission 2 will be described.

FIG. 7 is a hydraulic circuit diagram showing a main portion of a configuration for engaging the forward clutch C1 in the hydraulic control device of the automatic transmission. The case of the reverse clutch C2 is basically the same, and the description is omitted here.

The primary regulator valve 50 is controlled by a line pressure control solenoid 52,
The original pressure generated by the oil pump 19 is
Adjust to L. This line pressure PL is guided to the manual valve 54. The manual valve 54 is mechanically connected to the shift lever 44, and here, is in a forward position, for example, a D position, or a manual 1s.
When t (L), 2nd, or the like is selected, the line pressure PL is communicated with the forward clutch C1.

Manual valve 54 and forward clutch C1
A large orifice 56 and a switching valve 58 are interposed therebetween. The switching valve 58 is controlled by a solenoid 60,
The oil that has passed through the large orifice 56 is selectively guided to or cut off from the forward clutch C1.

The check ball 62 and the small orifice 64 are incorporated in parallel so as to bypass the switching valve 58. When the switching valve 58 is shut off by the solenoid 60, the oil passing through the large orifice 56 is further reduced to the small orifice. The clutch C1 reaches the forward clutch C1 via the second clutch 64. The check ball 62 functions so that when the hydraulic pressure of the forward clutch C1 is drained, the drain is smoothly performed.

An accumulator 70 is disposed in an oil passage 66 between the switching valve 58 and the forward clutch C1 via an orifice 68. The accumulator 70 includes a piston 72 and a spring 74, and includes a forward clutch C
When the oil is supplied to the clutch 1, it functions so as to be maintained at a predetermined oil pressure determined by the spring 74 for a while, and reduces a shock generated when the forward clutch C <b> 1 is engaged.

Next, the structure of a brake for keeping the vehicle stopped will be described with reference to FIG.

In FIG. 8, reference numeral 200 indicates a brake pedal as a brake operating member. The brake pedal 200 operates a master cylinder 208 via a hydraulic booster 206. A reservoir 210 is mounted on the upper part of the master cylinder 208. A pump 214 pumps up the brake fluid from the reservoir 210 and stores the brake fluid at a high pressure in an accumulator 216. The booster 206 is provided in the accumulator 216 with the fluid passage 218. Connected by

A pressurizing chamber (not shown) inside master cylinder 208 is connected to a wheel cylinder of a brake for braking front wheel 238 by a main liquid passage including liquid passages 212 and 244. On the other hand, the pressurizing chamber (not shown) is connected to a wheel cylinder of a brake for braking the rear wheel. However, since the configuration of the rear wheel system is the same as the configuration of the front wheel system, illustration and description are omitted. Hereinafter, only the front wheel system will be described.

The liquid passage 212 is provided with a check valve 222 and an electromagnetic pressure increasing / reducing valve 232. The electromagnetic pressure reducing valve 232 is always connected to the liquid passages 212 and 244, that is, the master cylinder 20.
8 and the wheel cylinder 240 are in a pressure increasing allowable state, but the intermediate pressure is supplied to the solenoid 230 to switch to a pressure-holding state in which the communication between the master cylinder 208 and the wheel cylinder 240 is interrupted.
Further, the three-position solenoid valve is switched to a pressure reduction allowable state in which the wheel cylinder 240 communicates with the reservoir 210 by supplying a large current to the solenoid 230.

A check valve 222 is provided in a bypass passage 224 that bypasses the electromagnetic pressure reducing valve 232.
The brake fluid in the wheel cylinder 240 can be returned to the master cylinder 208 via the bypass passage 224.

The bypass valve 224 between the master cylinder 208 and the wheel cylinder 240 is provided with a linear valve 2 having a function of keeping the brake fluid in the wheel cylinder 240 when the brake is applied.
28 are provided. The linear valve 228 is not limited to two types of control, ie, simple ON / OFF control. The linear valve 228 has a function that can control the opening and closing of the valve to an arbitrary position and can be linearly changed.

As will be described later, the presence of the linear valve 228 enables control to gradually release the brake oil pressure even when the brake pedal 200 is released at a stretch.

Further, in this embodiment, by controlling the linear valve 228, the timing at which the braking force is reduced is controlled to suppress the back-and-forth swinging of the vehicle (the longitudinal G of the vehicle) (described later in detail). Statement).

A pressurizing valve 229 capable of pressurizing the wheel cylinder 240 by bypassing the linear valve 228 is installed in order to prevent a decrease in braking force due to a decrease in brake oil pressure while a brake oil pressure described later is held. I do.

The accumulator 216 is connected to a portion of the passage 212 after passing through the check valve 222 via an electromagnetic closing valve 220. The electromagnetic closing / opening valve 220 is always in a state of interrupting the communication between the accumulator 216 and the liquid passage 212, but is opened at the same time as the start of the operation of the electromagnetic increasing / decreasing valve 232. The pressure is supplied to the pressure valve 232. The high-pressure brake fluid supplied from the accumulator 216 is prevented from flowing into the master cylinder 208 by the check valve 222.

Reference numeral 236 denotes a rotation speed sensor for detecting the rotation speed of the front wheel 238, and 202 denotes the brake pedal 2
This is a load cell that detects an operating force of 00.

Next, the operation of the present embodiment will be described.

Referring to FIG. 6, when the engine is started, clutches 26 and 28 are engaged, and motor generator 3 is driven to start engine 1 (the starter may be used together or alone, but will not be described here). ). At this time, by turning on the brake 31, the rotation of the motor generator 3 is transmitted at a reduced speed from the sun gear 33 side of the reduction mechanism R to the carrier 34 side. Thereby, even if the capacity of motor generator 3 and inverter 4 is reduced, the driving force necessary for cranking engine 1 can be secured. After the start of the engine 1, the motor generator 3 functions as a generator, and stores electric energy in the battery 5, for example, during braking of the vehicle.

When starting the engine, the motor generator 3
Is detected by the controller 7 and a switching signal is output to the inverter 4 so that the rotation of the motor generator 3 becomes a torque and a rotation speed necessary for starting the engine 1. For example, if the air conditioner is on when the engine is started, a larger torque is required than when the air conditioner is off. Therefore, the controller 7 outputs a switching signal so that the motor generator 3 can rotate with a large torque and a high rotational speed.

When a predetermined engine stop condition is satisfied with the eco-run mode signal turned on, the controller 7 outputs a signal to cut off the fuel supply to the engine 1 and automatically stops the engine. The eco-run mode signal is input to the controller 7 when the driver presses an eco-run switch 40 provided in the vehicle compartment.

In this embodiment, the stop conditions of the engine 1 are "vehicle speed is zero", "accelerator off", "brake on", and "the shift position is a non-drive position".
And "These conditions continue for a predetermined time Tstop
Has passed ". The predetermined time Tstop is counted by a timer.
The data is input to the engine ECU 80 and the brake ECU 82 and processed.

The predetermined time Tstop corresponds to the time until the automatic stop of the engine is started, and can be changed and set according to the situation. The predetermined time Tstop may be set to zero, and the engine may be automatically stopped as soon as the predetermined stop condition is satisfied. Alternatively, the predetermined time Tstop may be set to infinity to substantially prohibit the automatic stop of the engine. it can.

In the present embodiment, the above-mentioned condition is set as the engine automatic stop condition. However, the present invention is not limited to this. The same applies to an engine restart condition described later.

Since it is desired that the air conditioner and the power steering are operated even when the engine 1 is stopped, the controller 7 operates the inverter 7 so that the motor generator 3 rotates at a torque in consideration of the load of the power steering pump and the air conditioner compressor. 4 outputs a corresponding switching signal.

Next, the operation of the forward clutch C1 when the engine restart condition is satisfied and the engine 1 is restarted from an automatically stopped state will be described.

In the present embodiment, when a predetermined restart condition is satisfied, the engine restarts (automatic return of the engine).

As one example of the predetermined restart condition, any of the stop conditions “vehicle speed is zero”, “accelerator off”, “brake on”, and “shift position is non-drive position” is not satisfied. It can be adopted when it is established. In addition to this, as a case where the engine is automatically reset, there is a case where the charge amount SOC of the battery becomes insufficient.

In this embodiment, the shift position is set to the eco-run mode when the vehicle is in the non-drive position, and the eco-run mode is terminated when the shift position is detected. The present invention is not particularly limited to this, and may be a system that performs eco-run only at the driving position, or a system that performs eco-run at both the driving position and the non-driving position.

In FIG. 7, when the engine is restarted,
The oil pump 19 starts rotating, and the oil is supplied to the primary regulator valve 50 side. The line pressure adjusted by the primary regulator valve 50 is finally supplied to the forward clutch C1 via the manual valve 54.

In this embodiment, in order to engage the forward clutch C1 as soon as possible, a system for rapidly and temporarily supplying oil at the beginning of oil supply (rapid pressure increase control) is employed.

This is because by engaging the forward clutch C1 at an early stage, it is only necessary to pay attention to the "engine rotational speed" as the "index of driving force recovery" of the vehicle. In other words, when the engagement of the forward clutch C1 is slightly delayed, it is necessary to consider strictly the engagement state of the forward clutch C1 in addition to the state of increase in the engine driving force in order to see "recovery of driving force". However, if the forward clutch C1 is configured to be engaged early, the probability that the engaged state of the forward clutch C1 is involved in observing the recovery state of the "driving force" can be reduced accordingly.

First, the case where the rapid pressure increase control is performed will be described.

When the solenoid 60 controls the switching valve 58 to be opened in response to the rapid pressure increase control command from the cotton roller 7, the line pressure PL passing through the manual valve 54
Is supplied to the forward clutch C1 as it is after passing through the large orifice 56. In the stage where the rapid pressure increase control is being executed, the accumulator 70 does not function due to the setting of the spring constant of the spring 74.

Then, when the solenoid 60 receives the end command of the rapid pressure increasing control from the controller 7 and controls the switching valve 58 to shut off, the line pressure PL passing through the large orifice 56 is changed.
Is supplied to the forward clutch C1 through the small orifice 64 relatively slowly.

At this stage, since the hydraulic pressure supplied to the forward clutch C1 is high, the hydraulic pressure of the oil passage 66 connected to the accumulator 70 is reduced by the spring 74.
The piston 72 is moved upward in FIG. As a result, while the piston 72 is moving, the increase in the hydraulic pressure supplied to the forward clutch C1 becomes slow, and the forward clutch C1 can complete the engagement very smoothly.

In this embodiment, as described above, the linear valve 228 is closed by the brake system described with reference to FIG. 8 after the engine stop command.
The brake hydraulic pressure (wheel cylinder pressure) is set to the hold state, and the braking force Bt is secured.

That is, after the engine automatic stop command, the brake pressure is temporarily held (the braking force Bt is increased by confining the brake pressure) to keep the vehicle from moving (hill hold control).

Next, the relationship between the braking force Bt and the creep force (vehicle driving force) Kt when the engine is restarted will be described.

First, before describing this embodiment, the prior art will be briefly described with reference to FIG. 2A in order to compare the present invention with the prior art.

In FIG. 2A, at time t11, a predetermined condition is satisfied, the engine is automatically stopped, and at time t12, the creep force Kt is completely reduced to zero (the state disappeared).

At this stage, the hill hold control functions and the brake oil in the brake system is confined, so that the driver can obtain the same braking force without depressing the brake pedal 200 strongly.

However, when the brake pedal 200 is released at time t13, the engine is restarted (assuming that the restart condition is satisfied) (at time t1).
4) At the same time, the hill hold control is also released, so that there is no function of stopping the vehicle until the creep force reaches Kt at time t15. Therefore, in such a conventional system, for example, assuming that the vehicle is on a very steep hill, the brake is released, the time until the engine restarts and the creep force Kt is generated (time t13 to time t1).
4) The vehicle may move backward during T1.

In the case of a vehicle equipped with an automatic transmission and employing a system for engaging the forward clutch C1 together with the restart of the engine, the time T1 is not limited to the time required for the engine to start. In addition, since the time for engaging the forward clutch is added, this problem may be more remarkable.

After the engine speed further rises (after time t14), since the creep force Kt has been recovered but the braking force Bt has already been completely zero at this time, If the hydraulic pressure supply to the forward clutch C1 is not performed optimally, the sudden engagement of the forward clutch C1 may cause a feeling of the vehicle jumping out.

On the other hand, if the hill hold function is not released even after the forward clutch C1 is engaged, the start may be slow. Therefore, it is important to properly cancel the hill hold function.

Therefore, in the present embodiment, the following control (form) is performed when the engine is restarted.

First, in the first embodiment, the braking force B
t is controlled so as to decrease in inverse proportion to the creep force Kt, that is, the recovery state of the driving force.

Here, control at the time of engine restart in the first embodiment will be described with reference to FIG.

FIG. 1 shows a vehicle speed V, an engine speed NE,
The on / off signal from the brake pedal 200, the creep force Kt, the brake oil pressure (brake force) Bt, and the degree of opening and closing of the linear valve 228 are shown along the time axis t.

In FIG. 1, at time t1, the running vehicle is braked, and the vehicle speed decreases. At this time, the brake oil pressure temporarily increases because the brake pedal 200 is depressed by the driver.

At time t2, the vehicle is completely stopped, and thereafter, it is determined whether an automatic engine stop condition is satisfied. Since the conditions for automatically stopping the engine are as described above, they are omitted here.

When the automatic engine stop condition is satisfied, the automatic engine stop control starts at time t3. In this case, since the engine is naturally stopped, the engine rotational speed NE becomes zero, and the forward clutch C
Since the hydraulic pressure to 1 is also released, no creep force Kt is generated.

In the first embodiment, as described above, the linear valve 228 is completely closed in order to secure the brake oil pressure even during the automatic stop of the engine. By doing so, the brake oil pressure can be confined in the wheel cylinder 240 even when the engine is stopped, so that the load on the brake pedal 200 can be reduced.

The control up to this point is basically the same as that of FIG. 2A.

At time t4, for example, when there is a brake-off signal which is one of the engine restart conditions, the engine immediately starts restarting.

In the first embodiment, when restarting the engine, the linear valve 228 is controlled as follows.

First, an enlarged view of III in FIG. 1 is shown in FIG. 3, and control of the linear valve 228 will be described.

When an engine restart command is issued at time t4, the engine starts to rotate, and the creep force Kt is gradually generated when the engine is started from time t5 with the engagement of the forward clutch C1.

As described above, for example, if the hill hold control by the linear valve 228 is released together with the engine restart (command) at time t4 (the brake pedal 2
00 is already released), and until time t5, neither driving force nor braking force acts on the vehicle at all, and the vehicle may retreat.

[0107] On the other hand, dislike this, for example, if the hill hold control is continued until the engine rotational speed NE reaches the idling rotational speed NEi and the braking force Bt is released here, the creep force is already completely generated. Brake force B (without depending on the driver's operation)
Since t is released, there is a possibility that a feeling of the vehicle jumping out may occur, and holding the braking force Bt up to this point causes a start-up sluggishness.

Therefore, in the first embodiment, the recovery state of the creep force (driving force) Kt of the vehicle at the time of restarting the engine is detected, and when the automatically stopped engine 1 is restarted, the brake of the vehicle is restarted. The force Bt is reduced in accordance with the recovery of the driving force of the vehicle.

As described above, by controlling (reducing) the braking force in accordance with the recovery of the driving force, the timing of the recovery of the driving force and the release of the brake operation can be optimized, and the feeling of the vehicle jumping out is suppressed. In addition, it is possible to prevent the vehicle from moving backward. In addition, good startability can be secured.

Note that the creep force need not be directly detected (although, for example, a force sensor may be arranged in the power transmission system to directly detect the creep force). That is, it may be derived from the engine speed or the like.

The specific start trigger for "decreasing the braking force of the vehicle in accordance with the recovery of the driving force of the vehicle" is not particularly limited here.

In other words, as the start timing, the braking force may be reduced in inverse proportion immediately after the creep occurs, or may be inversely proportional from the time when the creep force (driving force) reaches a predetermined value. The braking force may be reduced at a rate corresponding to

More specifically, in this embodiment, when the engine rotation speed NE reaches a predetermined engine rotation speed NE1, the braking force is reduced so as to be inversely proportional to the creep force expected to be generated from that time. Let it.

The parameters (conditions) that can be used to detect the generation state of the creep force Kt are shown below. The start of the occurrence, the middle of the occurrence, and the completion of the occurrence can be determined by appropriately changing the threshold value of the conditional expression in each parameter. As the number of thresholds is increased, detection can be performed with higher accuracy. The braking force may be reduced accordingly.

(1) Engine rotational speed NE> predetermined engine rotational speed NE1 (2) Creep torque (creep force) Kt> predetermined creep torque Kt1 (3) Drive torque Ft> predetermined drive torque Ft1 (4) Oil pressure of forward clutch ( (Or line pressure) P> predetermined pressure P1 (5) Elapsed time Td after brake pedal off (engine restart command)> predetermined time Td1

Since the above conditions (1) to (4) are a method of direct detection or a method close to direct detection, the details are omitted here.

Condition (5) focuses on the fact that there is a substantially constant relationship between the elapsed time from the engine restart command and the recovery of the creep force. As shown in FIG. 4, the brake pedal is turned off. By confirming the elapsed time Td (Td1, Td2, Td3...) Since the start (when the restart instruction is issued), it means that the braking force Bt can be reduced accordingly.

For the control of the braking force, for example, the following conditions may be further considered.

(6) Accelerator pedal on (7) Vehicle speed Vc> predetermined vehicle speed Vc1 (8) Brake booster negative pressure Vs> predetermined brake booster negative pressure Vs1 (9) Total number of brake pedal depressions n> Total number of brake pedal depressions n1 (10) Brake pedal depression stroke ns> predetermined brake pedal depression stroke ns1 (11) Shift position (N → D) (12) Parking brake lever on

The condition (6) is that, when the accelerator is depressed while the brake is being depressurized, it is determined that the driver has a great intention to start, and as shown in FIG. The control for decreasing the creep force (driving force) in accordance with the recovery state is stopped, and the linear valve 228 is fully opened.

By doing so, the start of the vehicle can be eliminated and the vehicle can be started smoothly.

Further, when the vehicle speed is increased (stopped from zero) while the brake is being held (during the hill hold control) as in the condition (7), it is determined that the control need not be maintained. The end of the braking force holding is determined.

The conditions (8) to (8) are conditions for stopping the hill hold control in relation to fail-safe and the like. For example, when the internal pressure (negative pressure) of the brake booster 206 decreases or when the brake pedal is depressed n1 times in total, it is determined that the braking performance is not ensured, and the braking force holding is terminated (Hill Hall control). End), the engine is immediately restarted, and the brake negative pressure is secured.

The hatched portion of the creep force Kt is the force that would have been generated if the engine was not stopped.

As a specific method of decreasing the braking force Bt, the brake (braking) oil pressure is controlled by controlling the linear valve 228 described with reference to FIG.

The linear valve 228 is a valve capable of controlling the braking force other than the two types of ON / OFF, and is capable of finely and linearly controlling the braking force Bt.

In the first embodiment, specifically,
The creep force Kt is calculated and estimated from the engine rotation speed NE, and the pressure reduction gradient of the braking force Bt is determined so as to have an inversely proportional relationship with the creep force Kt, but is not limited to this (described later).

FIG. 2 (B) shows the control of the first embodiment in which the time axis is the same as that of FIG. 2 (A) described earlier in "Prior Art".

As is clear from FIG. 2B, the braking force Bt and the creeping force Kt are reduced in an inversely proportional relationship to each other, or the braking force Bt and the creep force Kt are executed based on values obtained in advance by experimental data. .

Returning to FIG. 1, after time t6 when the engine rotational speed NE becomes the idling rotational speed NEi and the creep force Kt becomes stable, the brake oil pressure becomes completely zero (canceled), and a stable creep force as usual. Kt occurs. At time t7, the accelerator is turned on and the vehicle speed is increasing.

The calculation of the rate at which the braking force is reduced in accordance with the recovery state of the vehicle's creep force (driving force) Kt may be performed by, for example, the engine ECU 80, the brake ECU 82, or the like.

Next, FIG. 9 shows the control when the engine is restarted in the second embodiment.

FIG. 9 shows the vehicle speed V, the engine speed NE, the on / off signal from the brake pedal 200, the creep force (driving force) Kt, and the braking force (brake oil pressure: wheel cylinder pressure) Bt as in FIG. , Linear valve 22
8 shows the relationship between the opening / closing degree 8 and the front and rear G of the vehicle along the time axis t.

In FIG. 9, the time t14 at which the eco-run ends.
1 are the same as in FIG. 1, and the description is omitted here.

After the engine is started (time t14), the engine speed temporarily becomes higher than the idle speed (maximum speed) NEmax until the engine speed NE reaches the idle speed NEi.

In the second embodiment, when the engine is restarted, it is determined that the engine speed NE has reached this maximum speed NEmax before the engine speed NE has settled to the idle speed NEi, and the automatically stopped engine is restarted. At this time, the time when it is determined that the engine rotation speed NE has reached the maximum rotation speed NEmax before the engine rotation speed NE has settled at the idle rotation speed NEi is taken as the start timing of the braking force decrease, and the braking force Bt of the vehicle is reduced from this. Control.

This specifies the start timing (trigger for releasing the braking force Bt) when decreasing the braking force Bt.

More specifically, as shown in FIG. 9, in the second embodiment, the engine speed NE is changed to the maximum engine speed NEm.
The reduction (decompression) of the braking force Bt is started from a time t16 after the time t15 when the vehicle reaches ax.

When the engine speed NE is equal to the maximum speed NE
The determination as to whether or not the maximum has been reached is made, for example, when the engine speed NE is detected in real time or at extremely small intervals, and the value resulting from the detection is decreased or the decreasing tendency is continuously detected. I just need.

By doing so, even if the timing of starting the engine varies between when the engine is warm and when the engine is cold, that is, when the timing of generating the driving force (creep force) varies. Also, the timing for releasing the braking force can always be kept the same, and the reproducibility of the timing of the generation of the driving force and the start of the reduction of the braking force can be maintained at a high level.

Further, since the braking force Bt is maintained until the unstable state at the start of the engine start has elapsed, the vehicle can be largely prevented from swinging back and forth, and the feeling of the vehicle jumping out can be reduced. Suppression / retreat of the vehicle can also be prevented.

In the case where the main object is to prevent the vehicle from moving backward, it may be set not when the engine rotational speed NE reaches the maximum rotational speed NEmax, or immediately after the engine rotational speed NEmax, but after a lapse of a slight timer.

The engine speed NE is equal to the maximum speed NE.
After it is determined that the maximum value has been reached, the braking force Bt is reduced from time t16.
The degree of holding of t is detected, and after the engine is started, a gradient for decreasing the braking force Bt is determined according to the degree of holding of the braking force Bt.

In general, when the brake oil pressure is held, the held brake oil pressure value differs in most cases. In addition, the brake oil pressure varies depending on the operation of depressing the brake pedal when the engine is automatically stopped, or depending on the elapsed time or the like.

Thus, in the present embodiment, control as shown in FIGS.

First, description will be made with reference to FIG.

FIG. 10 shows the case where the engine rotational speed NE at the time of starting the engine and the held brake oil pressure are high (thick line).
And the lower case (thin line). When the brake oil pressure is low, two more (solid line and broken line) pressure reduction methods are shown.

When the brake oil pressure is high, at time t16
, The pressure is reduced by a pressure reduction gradient α during a time T20 from time t17. When the brake oil pressure is low, the one indicated by the solid line decompresses during the time T20 from time t16 to the time t17 at the same pressure reduction gradient β as when the brake oil pressure is high, and the one indicated by the broken line The pressure is reduced at the same pressure reduction gradient α as when the brake oil pressure is high, and the pressure reduction is executed during a period T21 from time t18 to time t17 (control so that the pressure reduction end is the same time).

When the brake oil pressure is reduced for a fixed time, a constant pressure reduction time and a pressure reduction start timing can always be realized. Further, by making the gradient of the pressure reduction the same (when the held brake oil pressures are different), the end of the pressure reduction can be kept constant, and a stable starting performance can be secured.

Note that when decreasing the braking force Bt,
As described in the first embodiment, it is naturally effective to decrease the braking force Bt in an inversely proportional relationship with the driving force or to execute the braking force Bt based on a map. However, in the second embodiment (according to the recovery of the driving force)
Since the start timing is determined and reduced, it is preferable to reduce at a fixed rate from that point in the sense that a step immediately after the start is not generated.

The processing after the start timing is determined in accordance with the recovery of the driving force after the start of the reduction of the braking force is as follows. The braking force Bt is maintained at a predetermined value Bt1 while the engine is stopped. After the start timing is determined, the braking force Bt held at the predetermined value Bt1
May be reduced at a constant gradient.

A specific example is shown in FIG.

FIG. 11 shows the engine rotational speed NE and the brake oil pressure Bt in FIG. 9 when the engine is started, as in FIG.

As described above, when the brake pressure is maintained, the brake oil pressure Bt is different (for example, the broken line A, the broken line B, and the solid line C).

At this time, regardless of whether the held hydraulic pressure is low or high, the brake hydraulic pressure is changed to a predetermined hydraulic pressure value Bt.
It is pressurized to 1.

Then, the brake force Bt is reduced at a constant gradient γ from the predetermined brake oil pressure Bt1 from the above-described brake force decrease start timing t16.

In this way, even if the degree of holding the brake is different, the brake force Bt is set to a predetermined (constant pressure) value Bt1 and the brake force Bt is released from the value Bt1 with the same gradient γ. The vehicle can start stably and smoothly.

By the way, the first and second embodiments described above are executed only when it is determined that the engine starts normally.

"When it is determined that the start of the engine is performed normally" means, specifically, the predetermined rotational speed NEn1 at which the engine rotational speed NE can be determined to be almost certainly started.
It is when you reach.

That is, if the engine speed NE has not reached the predetermined engine speed NEn1, it is determined that the engine restart processing has failed and as a result there is no recovery of the driving force.

In such a case, it is determined that the recovery of the driving force has failed, and the state where the braking force Bt is secured is maintained.

In this way, even in the event that the engine starts in an unsuccessful manner, the braking force will not be released, and the vehicle will surely be stopped until the engine starts normally. Let it be.

The predetermined engine speed NEn
1 is naturally long before the engine rotation speed NE reaches the maximum rotation speed NEmax.

The control is performed by the above-described linear valve 228.

[0165]

According to the present invention, when the automatically stopped engine is restarted, the braking force of the vehicle is reduced in accordance with the state of recovery of the driving force of the vehicle, so that the driving force can be recovered and the braking operation can be performed. , The timing for canceling the vehicle can be made appropriate, and a good start-up performance can be ensured while suppressing the feeling of vehicle jumping out and preventing the vehicle from moving backward.

[Brief description of the drawings]

FIG. 1 shows a creep force according to a first embodiment of the present invention;
Time chart showing control of brake force, linear valve, etc. along the time axis

FIG. 2A is a time chart showing a conventional control of a braking force and a creep force along a time axis. FIG. 2B is a diagram showing a control of a braking force and a creep force according to an embodiment of the present invention along a time axis. Time chart

FIG. 3 is an enlarged view of a part III in FIG.

FIG. 4 is a graph showing an example of a method for reducing the braking force according to the embodiment.

FIG. 5 is a graph showing an example of the method for reducing the braking force according to the present embodiment, similarly to the above.

FIG. 6 is a system configuration diagram of a vehicle engine drive device to which the present invention is applied.

FIG. 7 is a hydraulic circuit diagram showing a main part of a hydraulic control device for performing rapid pressure increase control.

FIG. 8 is a skeleton diagram showing a configuration of a brake;

FIG. 9 shows the creep force according to the second embodiment of the present invention;
Time chart showing control of brake force, linear valve, etc. along the time axis

FIG. 10 is a time chart illustrating a method of reducing brake hydraulic pressure according to a second embodiment of the present invention.

FIG. 11 is a time chart showing control of brake hydraulic pressure in a second embodiment of the present invention.

FIG. 12 is a time chart showing a vehicle speed, an engine rotation speed, an on / off signal of a brake pedal, and a back-and-forth swing of a vehicle along a time axis in a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Automatic transmission 3 ... Motor generator 4 ... Inverter 5 ... Battery 19 ... Oil pump 40 ... Eco-run switch 80 ... Engine ECU 82 ... Brake ECU 200 ... Brake pedal 208 ... Master cylinder 228 ... Linear valve Bt ... Brake force Kt: creep force R: reduction mechanism NE: engine speed

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) CA02 CB05 DA01 DA06 DB05 DB11 DB12 DB15 DB23 DB25 EA05 EB03 EB04 FA04 FB01 FB02 FB03

Claims (5)

[Claims] An engine restart control device for a vehicle that automatically stops an engine when a predetermined stop condition is satisfied and restarts the automatically stopped engine when a predetermined restart condition is satisfied. Means for holding the braking force of the vehicle during the automatic stop of the engine; and means for detecting a recovery state of the driving force of the vehicle when the engine is restarted. A control device for restarting an engine of a vehicle, wherein when starting the vehicle, a braking force of the vehicle is reduced in accordance with a recovery state of a driving force of the vehicle. 2. A control system for restarting an engine of a vehicle which automatically stops an engine when a predetermined stop condition is satisfied and restarts the automatically stopped engine when a predetermined restart condition is satisfied. Means for holding the braking force of the vehicle during the automatic stop of the engine, and means for determining that the engine speed has reached the maximum speed before the engine speed has settled to the idle speed when the engine is restarted. When the automatically stopped engine is restarted, the braking force of the vehicle is reduced from a point in time when it is determined that the engine rotation speed has reached the maximum rotation speed before settling to the idle rotation speed. Control device for restarting the engine of the vehicle. 3. The apparatus according to claim 1, further comprising means for detecting the degree of holding of the braking force, and determining a gradient for decreasing the braking force according to the degree of holding of the braking force. A control device for restarting the engine of a vehicle. 4. The method according to claim 1, wherein the braking force is maintained at a predetermined value while the engine is stopped, and the braking force maintained at the predetermined value is reduced at a constant gradient. Control device when restarting the engine of a running vehicle. 5. The method according to claim 1, further comprising setting a predetermined engine rotation speed at which the engine can be determined to be able to be started reliably, and determining whether the engine rotation speed has reached the predetermined engine rotation speed. A control device for restarting an engine of a vehicle, comprising: means for detecting, wherein the control for reducing the braking force is executed only when the engine rotation speed reaches the predetermined engine rotation speed.