JP4131186B2 - Idle stop vehicle control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a device that realizes reduction of exhaust gas, fuel saving, and the like by executing automatic engine stop and automatic start when a predetermined condition is satisfied during operation of an AT (automatic) vehicle. The present invention relates to a control device for an idle stop vehicle that improves startability at the time.
[0002]
[Prior art]
Normally, a larger amount of air and fuel are supplied to the engine than when idling to ensure that the engine is started. For this reason, the engine rotation overshoots immediately after starting and a large engine torque is generated, and then gradually approaches the idle air amount and fuel amount.
[0003]
During normal start-up such as cold start, there is no problem because the transmission range is selected as the parking range or neutral range, but automatic stop or automatic for the purpose of exhaust gas reduction, fuel saving, etc. In the case of a so-called idle stop vehicle that repeats the start, it automatically starts in the travel range, so the engine rotation overshoot immediately after the start is transmitted to the axle and a shock is generated.
[0004]
As a solution to the above-described shock problem, a control system that reduces engine torque at the time of starting is known.
[0005]
Also, since the engine torque is not transmitted to the axle during the idle period of the torque converter at the beginning of the start, the engine is reliably started by normal start-up control, and then until a predetermined time elapses after the torque liner turbine liner starts rotating. Japanese Patent Application Laid-Open No. H10-228561 discloses a control system that reduces a shock at the time of starting by lowering the torque.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-164958
[Problems to be solved by the present invention]
However, although the control system described in Patent Document 1 is effective for reducing the shock at the time of starting, it is difficult to control, and when the action of ignition retard or the like is increased with the aim of a significant effect, There was a possibility of misfire, and the reliability was not enough.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide a control device that reliably performs automatic starting and reduces shock at the time of starting.
[0009]
[Means for Solving the Problems]
When the vehicle is stopped, the idle stop vehicle control device of the present invention automatically stops the engine when the engine stop permission condition is satisfied even if the transmission is in the travel range selection, and automatically starts the engine when the engine start condition is satisfied after the automatic stop. In a vehicle equipped with a restarting idle stop system, an engine speed detecting means for detecting the engine speed is provided, and at the time of automatic restart, the engine is first forcibly rotated so that the engine speed reaches the idle speed. The target engine speed is set and the engine is restarted. After the engine speed reaches the target engine speed, the target engine speed is maintained for a predetermined time, and after the predetermined time elapses until the idle speed is reached. The engine speed control means at the time of starting that gradually decreases is provided.
[0010]
[Action / Effect]
According to the present invention, when the engine of the idle stop vehicle is restarted, the maximum engine speed is maintained for a predetermined time after the engine speed reaches the preset target engine speed, and the idle speed is gradually increased after the predetermined time has elapsed. Since the engine speed is reduced to an engine speed, the rapid change of the front and rear G applied to the vehicle due to the overshoot of the engine speed when the engine is restarted can be reduced, and the G shock generated by the rapid change of the front and rear G can be reduced .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described below with reference to the drawings.
[0012]
FIG. 1 shows the system configuration of this embodiment. Reference numeral 1 denotes an engine, and 2 denotes an automatic transmission (including a continuously variable transmission) that transmits torque of the engine 1 via a torque converter 3. A motor 9 having a power generation function is disposed in the vicinity of the engine 1. A belt 19 is hung on a motor pulley 18 provided on a rotating shaft 21 of the motor 9 and a crank pulley 17 provided on one end of the crankshaft 20, and rotates in conjunction with each other when the rotating shaft 21 or the crankshaft 20 rotates. To do.
[0013]
The motor 9 is connected to the motor controller 13 via the inverter 16. The motor controller 13 controls the inverter 16 according to the signal from the control unit 7, drives the motor 9 by the power of the battery 14 when the engine 1 is started, and rotates the crankshaft of the engine 1. The motor 9 that rotates along with the rotation of the motor is caused to function as a generator, and electric power is regenerated and stored in the battery 14.
[0014]
The engine 1 is provided with an engine water temperature sensor 6, and the automatic transmission 2 is provided with an AT oil temperature sensor 4 and an AT oil pressure sensor 5, and detected values of these sensors are read into a control unit (ECM) 7.
[0015]
In addition to the above, the ECM 7 receives a detection signal from the brake stroke sensor 10 and the brake booster negative pressure sensor 11 and an electric capacity (battery SOC) detection signal of the battery 14 from the battery controller 8.
[0016]
The ECM 7 executes start / stop of the engine 1 and control of the motor controller 13 based on these detection values.
[0017]
Based on each detection signal, the ECM 7 executes control to reduce a shock caused by a change in the longitudinal G of the vehicle when restarting from the idle stop state. FIG. 2 is a flowchart of control executed by the ECM 7.
[0018]
In step S100, it is determined whether an idle stop is being performed. If it is during idle stop, the process proceeds to step S101, and it is determined whether or not there is an activation request. If it is not during idle stop, the process is terminated.
[0019]
If it is determined in step S101 that there is an activation request, the process proceeds to step S102, where the motor 9 is activated and the crankshaft 20 is rotated.
[0020]
The determination of the start request is made when the automatic transmission 2 is in the travel range, the vehicle speed is zero, the brake is ON, the vehicle door and the hood are closed, the accelerator is ON, the brake is OFF, the battery SOC is lowered during the idle stop, When any of brake booster negative pressure shortage, engine water temperature drop, automatic transmission oil temperature drop, automatic transmission oil pressure drop is detected, it is determined that there is an activation request.
[0021]
If there is no activation request in step S101, the process ends.
[0022]
After starting the motor 9 at step S102, the process proceeds to step S103, the engine speed to determine whether or not has reached a predetermined rotational speed N _0. The predetermined rotation speed N ₀ is set in advance to a value suitable for idle rotation in the vehicle.
[0023]
The flow advances to step S104, it sets the target engine speed Nt to the N _P. Target rotational speed N _P is obtained by predetermined as the maximum value engine speed that is estimated to reach when restarting from an idle stop in the vehicle.
[0024]
In step 105, the engine 1 is started, and the process proceeds to step S106 to determine whether or not a predetermined time has elapsed. After the predetermined time has elapsed, the target engine speed Nt is gradually changed to N ₀ in step S107. If the rotational speed is reduced to the idle rotational speed N ₀ immediately after reaching the maximum rotational speed N _P , the vehicle return G shock generated by the rapid change in the longitudinal G applied to the vehicle becomes large.
[0025]
Wait for the target engine speed Nt at step S106 in this embodiment until a predetermined time elapses while the maximum rotational speed N _P, as it reduces the subsequent number slowly rotated until idle speed N _0, longitudinal G according to the vehicle Can be prevented and a vehicle return G shock can be prevented.
[0026]
Reduced to either slow the engine speed Nt to the idle speed N ₀ in step S107, determines whether or not a stop request in step S108. The determination of the stop request is made with the battery SOC, the brake booster negative pressure, the engine water temperature while the engine is running with the automatic transmission 2 in the traveling range, the vehicle speed is zero, the brake is ON, the door and the hood are closed. When both the automatic transmission oil temperature and the automatic transmission hydraulic pressure exceed a preset threshold value, a stop request is made.
[0027]
If there is a stop request in step S108, the engine 1 is stopped in step S109 and the process is terminated. If there is no stop request, the operation of the engine 1 is continued.
[0028]
FIG. 3 is a time chart showing changes in the engine speed immediately after the restart, the target engine speed, and the vehicle longitudinal G when the engine is restarted by the above control. A solid line A in the figure indicates a change by the control of the present embodiment, and a dotted line C indicates a change by the control of the conventional example (a chain line B indicates a control of the second embodiment described later).
[0029]
The engine speed reaches N ₀ at t0 after the motor 9 is started. At this time, the target engine speed is switched from N ₀ to N _P.
[0030]
greet the maximum rotational speed Nm at t2, but has a higher rotational speed than the maximum value N _P set in advance by the overshoot. Thereafter engine speed decreases, and N _P is set as the target engine rotational speed at t3. In the present embodiment, this engine speed is maintained, but in the conventional example, the engine speed is decreased to the idle speed N ₀ as it is.
[0031]
The vehicle front-rear G has a maximum value in the vicinity of t2, but this embodiment and the conventional example have substantially the same size. Thereafter, as the engine speed decreases from the maximum value, the vehicle front-rear G also decreases, and reaches the minimum value at t4. Here, when comparing the swing width from the maximum value to the minimum value, it can be seen that the swing width of the present embodiment is smaller than that of the conventional example. That is, it can be seen that the vehicle return G shock caused by the change in the vehicle longitudinal G can be reduced as compared with the conventional example.
[0032]
As described above, in the present embodiment, when the engine is restarted from the idle stop, the state where the engine speed reaches the maximum value is maintained for a predetermined time, so that the change amount of the front and rear G applied to the vehicle can be reduced. It is possible to reduce the vehicle return G shock caused by the change in G.
[0033]
Since the maximum value that the engine speed reaches when the engine is restarted is set to one preset value, the control can be simplified.
[0034]
A second embodiment will be described. This embodiment is basically the same as the first embodiment in both system configuration and control. However, the setting of the target engine speed Nt in step S104 is different. In the present embodiment, the engine speed at step S103 is reached in N _0, a subroutine for setting the target engine speed shown in FIG. 4 at step S104.
[0035]
In step S201, the target engine speed Nt is set as a variable Nr, and the process proceeds to step S202. The variable Nr is the actual engine speed detected by the crank angle sensor 15.
[0036]
In step S202, the maximum value Nrmax of the variable Nr after the current engine start is read as the provisional maximum rotational speed Nm, and the process proceeds to step S203.
[0037]
In step S203, the target engine speed Nr is compared with the provisional maximum speed Nm. If the target engine speed Nr is greater than the provisional maximum speed Nm, the process proceeds to step S204. If not, the process returns to step S201, and the above control is repeated.
[0038]
In step S204, the provisional maximum engine speed Nm is set as the target engine speed, and the process proceeds to step S105.
[0039]
As a result, the provisional maximum rotational speed Nm is updated every time the engine is started using the actual engine rotational speed Nr, so that it is possible to accurately recognize the maximum reached rotational speed that changes every time the engine is restarted.
[0040]
A case where the control of the present embodiment is executed is indicated by a one-dot chain line B in the time chart of FIG.
[0041]
The process is the same as in the first embodiment up to t2, but after the maximum speed is reached at t2, the first embodiment (solid line A) maintains the engine speed slightly lower than the maximum speed. In this embodiment (solid line B), the engine speed is maintained substantially the same as the maximum speed Nm.
[0042]
As a result, as is apparent from the vehicle front-rear G graph, the swing width of the vehicle front-rear G is smaller in the present embodiment than in the first embodiment. That is, it can be seen that this embodiment can further reduce the vehicle return G-shock at the time of starting than the first embodiment.
[0043]
As described above, in the present embodiment, since the setting of the maximum reached rotational speed set as the target engine rotational speed at each engine restart is updated using the actual rotational speed of the crankshaft 20, the target engine rotational speed and the actual maximum rotational speed are updated. The deviation from the rotational speed can be eliminated, thereby suppressing the fluctuation of the vehicle longitudinal G and reducing the vehicle return G shock when the engine is restarted.
[0044]
A third embodiment will be described.
[0045]
Similar to the second embodiment, the present embodiment is basically the same in system configuration and control as the first embodiment, except for the method of setting the target engine speed Nt in step S104.
[0046]
In the present embodiment, the target rotation speed Nt is set to Nb or Nit in FIG. Nit is the maximum rotation speed estimated from the negative pressure in the collector tank when the engine is restarted. The relationship between the negative pressure and the maximum reached rotational speed is previously set as a map through experiments or the like, and the search is performed based on the negative pressure in the collector tank when the engine is restarted.
[0047]
The closer the internal pressure of the collector is to the atmospheric pressure, the greater the actual amount of air taken into the engine at the time of restart, and the higher the maximum reached rotational speed. Therefore, by setting the target rotational speed Nit based on the negative pressure in the collector, it is possible to make the value close to the actual maximum rotational speed, and to reduce the G shock accordingly.
[0048]
Nb is the maximum rotation speed estimated from the idle stop time. Like Nit, it is mapped in advance and searched from the idle stop time when the engine is restarted.
[0049]
The longer the idle stop time, the closer the negative pressure in the collector approaches atmospheric pressure. Therefore, as described above, the longer the idle stop time, the higher the maximum reached rotational speed. By setting the target engine rotational speed Nb accordingly, the G shock can be appropriately reduced as described above.
[0050]
As described above, in the present embodiment, since the target engine speed Nt is set according to the restart condition of the engine 1, the deviation between the target engine speed Nt and the maximum reached speed that is different at each restart can be eliminated. it can. This makes it possible to reduce the vehicle return G shock when the engine 1 is restarted.
[0051]
The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a system configuration of a first embodiment.
FIG. 2 is a flowchart of control according to the first embodiment.
FIG. 3 is a time chart when the first embodiment is implemented.
FIG. 4 is a subroutine for target engine speed setting executed in the second embodiment.
[Explanation of symbols]
1 Engine 2 Automatic transmission (including continuously variable transmission)
3 Torque converter 4 AT oil temperature sensor 5 AT oil pressure sensor 6 Engine water temperature sensor 7 Control unit (ECM)
8 Battery controller 9 Motor 10 Brake stroke sensor 11 Brake booster negative pressure sensor 13 Motor controller 14 Battery 15 Crank angle sensor 16 Inverter 17 Crank pulley 18 Motor pulley 19 Belt 20 Crankshaft 21 Motor rotation shaft

Claims (5)

When the vehicle is stopped, the engine is automatically stopped when the engine stop permission condition is satisfied even if the transmission is in the travel range selection.
In vehicles equipped with an idle stop system that automatically restarts the engine when the engine start condition is satisfied after automatic stop,
An engine speed detecting means for detecting the engine speed is provided;
At the time of automatic restart, set the target engine speed higher than the idle speed,
After the engine speed reaches the target engine speed, a target engine speed control means is provided for maintaining the target engine speed for a predetermined time and gradually decreasing the engine speed to an idle speed after a predetermined time has elapsed. An idle stop vehicle control device. The idle stop vehicle control device according to claim 1, wherein a fixed value corresponding to a maximum rotation speed that is predicted to increase upon restart is used as the target engine speed. 2. The idle stop vehicle control device according to claim 1, wherein a maximum value of an actual engine speed detected by the engine speed detection means at the time of automatic restart is used as the target engine speed. The idle stop vehicle control device according to claim 1, wherein the target engine speed is determined based on a negative pressure in a collector tank of the engine at the time of automatic restart. The idle stop vehicle control device according to claim 1, wherein the target engine speed is determined based on a stop time from automatic stop to automatic restart.

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