JP2003120356A - Control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an engine that appropriately copes with a sudden change in characteristics of working fluid in a transmission due to fluid mixture. SOLUTION: If a fluid mixture ratio showing the ratio of nonstandard working fluid included in working fluid in the automatic transmission 3 is not lower than a threshold value (a) to cause a determination of a sudden change in working fluid characteristics, automatic stop/restart control of an engine 1 is prohibited. Under a sudden change in working fluid characteristics due to fluid mixture, an automatic stop of the engine 1 is disabled, and thus a restart of the engine 1 is also disabled. This avoids such a shock at engagement of a clutch C1 after an engine restart as results from a restart of the engine 1 under a sudden change in working fluid characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an engine mounted on a vehicle.

[0002]

2. Description of the Related Art Generally, in a vehicle such as an automobile, a power transmission mechanism such as an automatic transmission is provided in a power transmission path from an engine to wheels. Such an automatic transmission has, for example, five forward speeds and one reverse speed, and by operating frictional engagement devices such as various clutches and brakes by hydraulic pressure of hydraulic oil, any one of the above speed change steps can be performed. Is what is selected. The hydraulic oil is supplied to the friction engagement device by driving an oil pump by an engine, for example.

By the way, the hydraulic fluid of an automatic transmission shows a characteristic change that its viscosity increases as the period of use increases and deteriorates. Therefore, as the deterioration progresses, it is necessary for the operation of the friction engagement device. It takes a long time to apply the hydraulic pressure, which causes a disadvantage that the time required for gear shift becomes long. Therefore, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Application Laid-Open No. 0-205406, when the hydraulic oil is deteriorated, the hydraulic pressure of the hydraulic oil supplied to the friction engagement device is increased in advance, so that the hydraulic pressure required for the operation of the friction engagement device at the time of gear shifting. It has also been proposed to promptly be given.

[0004]

The change in the characteristics of the hydraulic oil due to the deterioration of the hydraulic oil does not occur suddenly. Therefore, when the hydraulic oil is judged to be deteriorated, the same operation is performed. This can be dealt with by adjusting the hydraulic pressure to increase the hydraulic pressure of the oil.

However, as a situation in which the characteristics of the hydraulic fluid change, there are situations in which the characteristics of the hydraulic fluid change abruptly in addition to the situations in which the characteristics of the hydraulic fluid change relatively slowly such as deterioration of the hydraulic fluid. For example, when replenishing hydraulic oil, a non-specified type of hydraulic oil may be replenished. In this case, non-specified hydraulic oil is mixed (mixed oil) with the specified hydraulic oil. The oil characteristics change suddenly.

When the characteristic of the hydraulic fluid changes suddenly in this way, there is a possibility that the hydraulic pressure adjustment of the hydraulic fluid as described above cannot be applied. For example, when the engine is started, the hydraulic pressure for operating the friction engagement device cannot be properly applied, or the friction coefficient of the friction engagement device changes with the change of the hydraulic fluid characteristics, so that the operation of the device is properly performed. I can not do it. As a result, a shock is generated when the frictional engagement device is operated and engaged.

The present invention has been made in view of the above circumstances, and an object thereof is to control an engine capable of appropriately coping with a sudden change in the characteristics of hydraulic fluid of a transmission due to mixed oil. To provide a device.

[0008]

[Means for Solving the Problems] Means for achieving the above-mentioned objects and their effects will be described below. In order to achieve the above object, the invention according to claim 1 is an engine control device that is applied to an engine that generates a driving force transmitted to a wheel of a vehicle, and that temporarily stops the engine according to a vehicle operating state. Represents the proportion of non-specified hydraulic oil mixed with the specified hydraulic oil in the hydraulic oil of the transmission, which is provided in the drive force transmission path from the engine to the wheels and has a friction engagement device that is hydraulically operated. The fuel cell system includes a determination unit that determines the oil blend ratio and a control unit that prohibits the engine from being temporarily stopped when the oil blend ratio is equal to or higher than a predetermined threshold value.

When a non-specified hydraulic oil is replenished at the time of replenishing the hydraulic oil, the characteristic of the hydraulic oil changes rapidly when the mixing ratio is high. In this state, when the supply of hydraulic oil to the friction engagement device of the transmission is restarted when the engine is restarted after being temporarily stopped, the hydraulic pressure for operating the friction engagement device is applied accordingly. It will be. However, at this time, if the hydraulic oil characteristics suddenly change due to the mixed oil, the hydraulic pressure for operating the friction engagement device is not properly applied, or the friction coefficient of the friction engagement device changes. As a result, a shock may occur when the device is engaged because the device cannot be operated properly. However, according to the above configuration, when the oil mixture ratio becomes equal to or higher than the predetermined threshold value, the temporary stop of the engine is prohibited. Therefore, it is possible to avoid a shock when the friction engagement device is engaged when the engine is restarted. You can

According to a second aspect of the invention, in the first aspect of the invention, the control means prohibits the engine from being temporarily stopped in consideration of the temperature of the hydraulic oil. Since the characteristic of the hydraulic oil changes depending on the temperature of the hydraulic oil, the temporary stop prohibition of the engine can be accurately performed by taking into account the temperature of the hydraulic oil.

Incidentally, as a method of prohibiting the temporary suspension of the engine in consideration of the oil temperature of the hydraulic oil, it is conceivable to make the threshold value, which is a criterion for determining whether or not the temporary suspension is prohibited, variable according to the oil temperature. To be

According to the invention of claim 3, claim 1 or 2
In the invention described above, the control means changes the threshold value depending on whether the shift position of the transmission is in the neutral position or in the drive position.

Depending on whether the shift position of the transmission when the engine is restarted is the neutral position or the drive position, the above-described susceptibility to shock is different. According to the above configuration, it is possible to appropriately prohibit the temporary suspension of the engine according to the shift position of the transmission. Therefore, it is possible to prevent the situation where the engine temporary stop prohibition is unnecessarily performed or is not performed although it is necessary.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the control means changes the threshold value according to a characteristic of a prescribed hydraulic fluid contained in the hydraulic fluid. And

The susceptibility to the above-mentioned shock varies depending on the characteristics of the prescribed hydraulic oil contained in the hydraulic oil, for example, the degree of deterioration. According to the above configuration, it is possible to appropriately perform the engine suspension prohibition according to the characteristics of the specified hydraulic oil contained in the hydraulic oil. Therefore, it is possible to prevent the situation where the engine temporary stop prohibition is unnecessarily performed or is not performed although it is necessary.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an automobile engine that is automatically stopped and restarted will be described below with reference to FIGS.

As the engine 1 shown in FIG. 1 is driven,
When the crankshaft 2, which is the output shaft, rotates, the rotation is transmitted to the wheels of the automobile through the automatic transmission 3 and the like, so that the automobile runs.

The automatic transmission 3 has, for example, 5 forward gears and 1 reverse gear.
Any one of the above-described shift speeds is selected by operating the gear shift mechanism 4 having a gear shift stage having various shift speeds and equipped with friction engagement devices such as various clutches and brakes by hydraulic pressure of hydraulic fluid. is there. By setting the shift speed in the automatic transmission 3 as described above, the rotation speed transmitted from the engine 1 side to the wheel side is changed.

An oil pump 5 is connected to a crankshaft 2 of the engine 1 to discharge the hydraulic oil required to operate the automatic transmission 3. The hydraulic oil discharged from the oil pump 5 is supplied to the gear shift mechanism 4 via the hydraulic control device 6, and the hydraulic pressures acting on the various clutches and brakes of the mechanism 4 are controlled by the hydraulic control device 6 so that automatic gear shifting is performed. The desired gear is selected in the machine 3.

A motor generator 7 that functions as a generator or an electric motor is also connected to the crankshaft 2. The motor generator 7 charges the battery 8 as a generator when rotation is transmitted from the crankshaft 2 and forcibly rotates (cranks) the crankshaft 2 as an electric motor when the engine 1 is started.

On the other hand, in the automobile, the engine 1, the automatic transmission 3, the hydraulic control device 6, and the motor generator 7 are provided.
An electronic control unit 9 for controlling the above is installed. Detection signals from the various sensors described below are input to the electronic control unit 9.

A rotation speed sensor 10 for detecting the input rotation speed of the gear transmission mechanism 4. A shift position sensor 12 for detecting the operating position of the shift lever 11. An accelerator position for detecting the depression amount of the accelerator pedal 13 (accelerator depression amount). Sensor 14-Brake sensor 16 that detects whether or not the brake pedal 15 is depressed-Oil temperature sensor 17 that detects the temperature (oil temperature) of the hydraulic oil of the automatic transmission 3-Operating oil that does not meet the specifications is included The oil mixture sensor 18 that outputs a signal corresponding to the oil mixture ratio indicating the ratio calculates the vehicle speed from the input rotation speed of the gear transmission 4 and the current gear position (gear ratio) of the automatic transmission 3. . Then, according to the vehicle operating state such as the vehicle speed, the position information of the shift lever 11, and the accelerator pedal depression amount, the hydraulic pressure is selected so that the gear stage (gear ratio) of the automatic transmission 3 suitable for the operating state at that time is selected. The controller 6 is controlled to adjust the hydraulic pressure applied to the various clutches and brakes of the gear shift mechanism 4.

Here, the internal structure of the gear shift mechanism 4 will be described in detail with reference to FIGS. 2 and 3. As shown in FIG. 2, the gear transmission mechanism 4 includes a sub transmission 601 and a main transmission 602.

The carrier 611 of the overdrive planetary gear mechanism 610 constituting the auxiliary transmission 601 is connected to the input shaft 600 of the gear transmission mechanism 4. A clutch C0 and a one-way clutch F0 are provided between the carrier 611 and the sun gear 612 in the planetary gear mechanism 610. This one-way clutch F0
Indicates that the sun gear 612 has the input shaft 60 relative to the carrier 611.
The rotation direction of 0 is set to be positive, and it is set to engage when relatively rotating positively.

The rotation of the sun gear 612 causes the brake B to rotate.
Fixed by 0. In addition, the planetary gear mechanism 610
The ring gear 613, which constitutes the above, is connected to the intermediate input shaft 614 to the main transmission 602.

The rotational speed of the input shaft 600 is output at the same speed or increased by the auxiliary transmission 601 constructed as described above, and output from the intermediate input shaft 614. That is, when the clutch C0 or the one-way clutch F0 is engaged, the planetary gear mechanism 610 rotates integrally, so that the intermediate input shaft 614 rotates at the same speed as the input shaft 600. On the other hand, by engaging the brake B0, the sun gear 6
When 12 is fixed, the ring gear 613 rotates at an increased speed relative to the rotation speed of the input shaft 600.

On the other hand, the main transmission 602 comprises three sets of planetary gear mechanisms 620, 630, 640,
Using these, the main transmission 602 has one reverse gear and four forward gears.
Set the steps and. The engagement mode of the main transmission 602 will be described below.

The sun gear 62 of the first planetary gear mechanism 620.
2 and the sun gear 632 of the second planetary gear mechanism 630 are integrally connected to each other. In addition, the ring gear 623 of the first planetary gear mechanism 620 and the second planetary gear mechanism 6
The carrier 631 of 30 and the carrier 641 of the third planetary gear mechanism 640 are integrally connected. The carrier 641 of the third planetary gear mechanism 640 is connected to the output shaft 3a of the automatic transmission 3. Further, the ring gear 633 of the second planetary gear mechanism 630 is connected to the sun gear 642 of the third planetary gear mechanism 640.

The ring gear 633 of the second planetary gear mechanism 630 and the sun gear 64 of the third planetary gear mechanism 640.
A clutch C1 that engages at the forward stage is provided between the second shaft 2 and the intermediate input shaft 614. On the other hand, the sun gear 622 of the first planetary gear mechanism 620 and the second planetary gear mechanism 6
Between the sun gear 632 of 30 and the intermediate input shaft 614,
A clutch C2 that engages in the reverse gear is provided.

Further, the first and second planetary gear mechanisms 6 are also provided.
The sun gears 622 and 632 of 20,630 are the brakes B.
Fixed by 1. Furthermore, these sun gears 622,
A one-way clutch F1 and a brake B2 are connected to 632. The one-way clutch F1 is set to engage when the sun gears 622 and 632 rotate in the reverse direction.

Further, a brake B3 for fixing the carrier 621 of the first planetary gear mechanism 620 and a brake B4 for fixing the ring gear 643 of the third planetary gear mechanism 640.
And a one-way clutch F2. The one-way clutch F2 is set to engage when the ring gear 643 rotates in the reverse direction.

FIG. 3 shows an engagement mode of clutches and brakes for setting a shift speed in the sub transmission 601 and the main transmission 602 configured as described above. When the sub transmission 601 of the gear transmission 4 and the clutches and brakes of the main transmission 602 are engaged in the manner shown in FIG. 3, the power input to the gear transmission 4 via the input shaft 600 is , And is output from the output shaft 3a after the desired conversion.

Among the above clutches and brakes,
The clutches C0 to C2 and the brakes B1 to B4 are operated through hydraulic control by the electronic control unit 9. Further, when the vehicle is temporarily stopped or the like, the engagement state of the first speed (denoted as 1st in FIG. 3) is maintained as the shift speed for starting.

Next, the outline of the control for automatically stopping and restarting the engine 1 performed through the electronic control unit 9 will be described. As the automatic stop / restart control for the engine 1, the operation of the engine 1 is automatically stopped in order to improve the fuel consumption when the operation of the engine 1 is not required. Whether or not the engine 1 needs to be operated is determined, for example, according to whether or not the following conditions (a) to (e) are satisfied.

(A) The shift position of the automatic transmission 3 is the neutral position or the drive position (b) The vehicle speed is less than a predetermined value A (c) The accelerator depression amount is "0" (d) The brake pedal 15 is depressed ( e) When all the conditions (a) to (e) where the battery charge amount reaches the allowable level are satisfied,
It is determined that the operation of the engine 1 is not necessary.

On the other hand, when the engine 1 is automatically stopped, the accelerator depression amount becomes larger than "0" based on the depression of the accelerator pedal 13, and the conditions (a) to (e) are satisfied. If any one of them is not established, it is determined that the engine 1 needs to be operated independently.
Then, based on this determination, cranking by the motor generator 7 is started and the engine 1 is restarted.

After the engine 1 is restarted, hydraulic pressure is applied to engage the forward clutch C1 in the gear shift mechanism 4 at least before the vehicle is allowed to run on its own. That is, when the automatic stop of the engine 1 is started in a state where the shift position of the automatic transmission 3 is at the drive position, the hydraulic pressure acting on the clutch C1 increases immediately after the engine restarts, and the clutch C1 is operated. Hydraulic pressure is applied to engage them. Further, when the automatic stop of the engine 1 is started in a state where the shift position of the automatic transmission 3 is in the neutral position, the clutch C when the shift position is switched to the drive position after the engine is restarted.
The hydraulic pressure acting on No. 1 starts to increase, and the hydraulic pressure for engaging the clutch C1 is applied.

A hydraulic circuit for adjusting the hydraulic pressure acting on the clutch C1 will be described with reference to FIG. The original pressure generated by the oil pump 5 is adjusted to the line pressure PL by driving and driving the primary regulator valve 21 by the line pressure control solenoid 21a. In addition, the oil passage 22 between the oil pump 5 and the primary regulator valve 21 is connected to the accumulator 2 via the accumulator control solenoid 23a.
3 is connected.

The line pressure PL is the manual valve 24.
Will act on the clutch C1 located downstream of the.
The manual valve 24 is mechanically connected to the shift lever 11 and causes the line pressure PL to act on the clutch C1 side when the lever 11 is set to the drive position or the like.

A large orifice 25, a switching valve 26, a check ball 27, and a small orifice 28 are provided between the manual valve 24 and the clutch C1. The large orifice 25 and the switching valve 26 are connected in series, and the check ball 27 and the small orifice 28 are connected so as to bypass the switching valve 26. An accumulator 31 is connected to an oil passage 29 between the switching valve 26 and the clutch C1 via an orifice 30.

The switching valve 26 is opened / closed through drive control by the solenoid 26a, and is for performing first apply control for early increasing the hydraulic pressure acting on the clutch C1 when the engine is restarted. As a method of increasing the hydraulic pressure acting on the clutch C1 at an early stage, it is possible to use, for example, boost control that increases the line pressure PL in addition to the fast apply control.

The first apply control will be described below with reference to the time chart of FIG. 5A to 5D show changes in hydraulic pressure acting on the clutch C1, changes in engine rotation speed, first apply timing, and changes in turbine rotation speed in the automatic transmission 3.

In the process of increasing the engine speed such as when the engine is restarted, when the fast apply control is not performed, the switching valve 26 is closed and the hydraulic pressure is applied to the clutch C1 through the small orifice 28. Like Therefore, when the first apply control is not performed, the oil pressure acting on the clutch C1 increases as the engine speed increases, as shown by the chain double-dashed line in FIG. 5A, and the clutch C1 is engaged. It takes a relatively long time.

On the other hand, in the process of increasing the engine speed, when the first apply control is performed, the switching valve 26 is kept open for, for example, the time TFAST, and the hydraulic pressure is applied to the clutch C1 during that time. It is no longer done through the small orifice 28. Therefore, when performing the first apply control, the hydraulic pressure acting on the clutch C1 increases as shown by the solid line in FIG.
The time required for 1 to engage can be reduced.
It should be noted that the turbine rotational speed of the automatic transmission 3 is increased as shown in FIG.
It changes as shown in (d).

By the way, when the clutch C1 is engaged as described above, the hydraulic pressure acting on the clutch C1 is adjusted so that the shock associated with the engagement can be suppressed as much as possible. However, since the characteristic of the hydraulic oil changes due to deterioration and the like, if the hydraulic pressure adjustment is always performed in a constant manner, the shock at the time of engagement cannot be suppressed as the characteristic change progresses. Therefore, in the case where the change of the hydraulic fluid characteristics such as deterioration is relatively gradual, the hydraulic pressure adjustment (for example, the adjustment of the line pressure PL) may be made variable according to the deterioration degree of the hydraulic oil in an appropriate mode. Conceivable.

However, when replenishing the operating oil with a fluid other than the prescribed type, the non-specified operating oil is mixed with the prescribed operating oil (mixed oil). The characteristics of the hydraulic oil used for engagement of C1 will change suddenly. When the hydraulic oil characteristics suddenly change in this way, it is not possible to deal with them by the above-mentioned hydraulic pressure adjustment, and there is a risk that the engagement of the clutch C1 may be hindered. For example, when the clutch C1 is engaged after the engine restart is started, the hydraulic pressure for the engagement cannot be properly applied, or the friction coefficient of the clutch C1 is changed so that the engagement operation cannot be appropriately performed. Then, an engagement shock may occur.

In the present embodiment, in view of such circumstances, when the oil mixture ratio of the hydraulic oil of the automatic transmission 3 is equal to or higher than a predetermined threshold value, it is judged that the hydraulic oil characteristic is suddenly changed, and the engine 1 is automatically stopped. Prohibit restart control. As a result, the engine 1 is not restarted, so that a shock is generated when the clutch C1 is engaged after the restart of the engine 1 with the restart of the engine 1 in a state where the oil mixture ratio is high. Can be avoided.

Next, the procedure for prohibiting the automatic stop of the engine 1 will be described with reference to the flowchart of FIG. 6 showing the automatic stop / restart routine. This automatic stop / restart routine is executed through the electronic control unit 9 by, for example, a time interruption at every predetermined time.

In the automatic stop / restart routine, a threshold value a for determining whether or not the oil mixture ratio is a value at which automatic stop of the engine 1 should be prohibited is calculated (S101). Then, if the oil mixture rate is less than the threshold value a (S102: NO).
The automatic stop / restart control of the engine 1 is permitted (S10
4) If the oil mixture rate is equal to or greater than the threshold value a (S102: YE
S) Automatic stop / restart control of the engine 1 is prohibited (S)
103).

The calculation of the threshold value a in step S101 is performed based on the oil temperature, the degree of deterioration of the specified hydraulic oil contained in the hydraulic oil, and the shift position of the automatic transmission 3. Here, the prescribed degree of deterioration of the hydraulic oil can be obtained based on, for example, the period of use of the hydraulic oil or the time required for shifting the automatic transmission 3. The degree of deterioration can be obtained in this way because the longer the operating period of the hydraulic oil, the more the deterioration progresses, and the higher the deterioration, the higher the viscosity of the hydraulic oil and the longer the time required for shifting.

FIG. 7 is a graph showing the transition tendency of the threshold value a calculated as described above. In the figure, the solid line L1
Under the condition that the shift position of the automatic transmission 3 is in the drive position and the degree of deterioration is constant,
It shows the transition of the threshold value a when the oil temperature changes. The solid line L1 representing the transition of the threshold value a shifts downward in the figure as the degree of deterioration increases. Therefore,
The threshold value a has a smaller value (a value on the side where the oil mixing rate is lower) as the oil temperature increases and the degree of deterioration increases.
In this case, it is set to an optimum value for judging whether or not the hydraulic fluid characteristic is suddenly changed under the condition that the shift position of the automatic transmission 3 is in the drive position.

Further, in FIG. 7, the broken line L2 shows the transition of the threshold value a with respect to the change of the oil temperature under the condition that the shift position of the automatic transmission 3 is in the neutral position and the degree of deterioration is constant. It is a thing. The broken line L2 representing the transition of the threshold value a shifts downward in the figure as the degree of deterioration increases. Therefore, the threshold value a
Also, the higher the oil temperature and the greater the degree of deterioration, the smaller the value becomes (the lower value as the oil mixing ratio). In this case, however, under the condition that the shift position of the automatic transmission 3 is in the neutral position. It is set to the optimum value for determining whether or not the hydraulic fluid characteristics have changed suddenly.

As can be seen from FIG. 7, under the condition that the oil temperature and the degree of deterioration are the same, the threshold a at the neutral position (broken line L2) and the threshold a at the drive position (solid line L1) are the neutral position. The threshold value a in (1) is set to a larger value (a value on the higher side as the oil mixing rate). This is because a shock is not generated when the clutch C1 is engaged after the engine is restarted when the neutral position is set, as compared with when the drive position is set, even when the oil mixing ratio is large.

It is also conceivable that the oil temperature is not taken into consideration when calculating the threshold a, but the threshold a in this case is the threshold a when the oil temperature is taken into account as shown by the solid line L3 and the broken line L4. It is set to a value larger than (solid line L1 and broken line L2) (value on the lower side as the oil mixing rate). In addition,
A solid line L3 indicates the threshold value a when the shift position of the automatic transmission 3 is in the drive position, and a broken line L4
Indicates the threshold value a when the shift position of the automatic transmission 3 is in the neutral position. These solid lines L
3 and the broken line L4 also move downward in the figure as the degree of deterioration increases.

According to this embodiment described in detail above, the following effects can be obtained. (1) When it is determined that the oil mixture ratio is equal to or greater than the threshold value a and the hydraulic oil characteristic is suddenly changed, the engine 1 automatic stop / restart control is prohibited, so that the engine 1 is automatically stopped / restarted. It will not be done. Therefore, it is possible to prevent a shock from being generated when the clutch C1 is engaged after the engine restart is started as the engine 1 is restarted in a state where the hydraulic oil characteristics are suddenly changed. Further, it is possible to prevent the durability of the automatic transmission 3 from being lowered due to a shock when the clutch C1 is engaged.

(2) After starting the engine restart, when moving the vehicle backward, hydraulic pressure is applied to engage the clutch C2 instead of the clutch C1. Even in this case, when the hydraulic oil characteristics are suddenly changed due to the mixed oil, the operation for engaging the clutch C2 cannot be properly performed, and a shock may occur at the time of the engagement. However, when the oil mixture ratio is equal to or higher than the threshold value a, the automatic stop / restart control is prohibited and the engine 1 is not restarted. Therefore, it is possible to avoid the shock when the clutch C2 is engaged as described above. You can also do it. Further, it is possible to prevent the durability of the automatic transmission 3 from being lowered due to a shock when the clutch C2 is engaged.

(3) The hydraulic oil characteristics change not only depending on the oil mixture, but also depending on the oil temperature. Therefore, by adding the oil temperature to the calculation of the threshold value a used to determine whether or not the hydraulic oil characteristic is suddenly changed, the automatic stop / restart control performed when the oil mixture rate is equal to or higher than the threshold value a. Can be properly prohibited.

(4) Clutch C after engine restart is started
The susceptibility to a shock when 1 is engaged depends on whether the shift position of the automatic transmission 3 is in the neutral position at the start of restarting and is switched to the drive position later, or when the restart is started. It will be different in some cases. Therefore, by changing the threshold value a depending on whether the shift position of the automatic transmission 3 is in the neutral position or in the drive position, the automatic stop / restart control can be appropriately prohibited according to the shift position. . Therefore, the automatic stop and restart of the engine 1 is wastefully performed,
It is possible to suppress a situation in which it is necessary but not performed.

(5) Further, the susceptibility of the above-mentioned shock varies depending on the degree of deterioration of the specified hydraulic oil contained in the hydraulic oil. Therefore, by changing the threshold value a according to the degree of deterioration of the specified hydraulic oil, the automatic stop / restart control can be appropriately prohibited according to the degree of deterioration. Therefore, it is possible to prevent the situation in which the automatic stop and restart of the engine 1 are wastefully performed, or a situation in which the engine 1 is not performed when necessary is prevented.

The above embodiment can be modified as follows, for example. The threshold value a at the neutral position (broken line) and the threshold value a at the drive position (solid line) are larger under the condition that the oil temperature and the degree of deterioration of the hydraulic oil are the same. However, the magnitude relationship between these two threshold values a may be reversed.

The automatic stop / restart control based on the oil mixture rate is prohibited both when the shift position of the automatic transmission 3 is at the neutral position and when it is at the drive position. Is not limited to this. For example, when the shift position of the automatic transmission 3 is in the neutral position, the automatic stop / restart control may be prohibited regardless of the oil mixture rate.

The automatic stop / restart control of the engine 1 is prohibited when the oil mixing rate obtained from the detection signal of the oil mixing sensor 18 is the threshold value a or more, but the present invention is not limited to this. For example, when it is considered from the shift characteristics of the automatic transmission 3 that the oil mixture is substantially above a certain level, the automatic stop / restart control of the engine 1 may be prohibited because the oil mixture rate is equal to or greater than the threshold value a. In this case, the mixed oil sensor 18 can be omitted. As described above, it is possible to determine whether or not a certain amount of oil has been mixed from the shift characteristics of the automatic transmission 3 because the gear transmission mechanism 4 of the automatic transmission 3 is determined as the oil mixing rate increases. This is because the friction characteristic (μ characteristic) of the friction engagement device such as the provided brake or clutch is out of the proper state, and the shift characteristic of the automatic transmission 3 is out of the proper state.

It is not always necessary to use the specified characteristic of the hydraulic oil contained in the hydraulic oil (deterioration degree in the embodiment) for calculating the threshold value a.・ Operating oil is supplied to the automatic transmission 3 only by an electric oil pump or the like that does not use the engine 1 as a drive source,
It may be performed in combination with the oil pump 5 driven by the engine 1.

Although the present invention is applied to the automatic transmission 3, other transmissions such as a transmission in which the gear ratio is manually switched or a continuously variable transmission in which the gear ratio is adjusted steplessly The present invention may be applied to.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of an automobile to which a control device of this embodiment is applied.

FIG. 2 is a skeleton diagram showing an arrangement mode of clutches and the like in a gear transmission mechanism of the automatic transmission.

FIG. 3 is a diagram showing an engagement mode of a clutch or the like corresponding to each shift position.

FIG. 4 is a schematic diagram of a hydraulic circuit for adjusting the hydraulic pressure acting on the clutch C1.

FIG. 5 is a time chart showing changes in hydraulic pressure acting on the clutch C1, changes in engine rotation speed, first apply timing, and changes in turbine rotation speed in the automatic transmission.

FIG. 6 is a flowchart showing an execution procedure of automatic stop / restart control.

FIG. 7 is a graph showing how the threshold value for determining whether or not the hydraulic oil characteristic has changed suddenly changes according to the oil temperature and the shift position of the automatic transmission.

[Explanation of symbols]

1 ... Engine, 3 ... Automatic transmission, 4 ... Gear transmission mechanism, 5
... oil pump, 6 ... hydraulic control device, 7 ... motor generator, 9 ... electronic control device, 10 ... rotation speed sensor, 1
2 ... shift position sensor, 14 ... accelerator position sensor, 16 ... brake sensor, 17 ... oil temperature sensor,
18 ... Oil mixture sensor, C0-C2 ... Clutch, B0-B4
…brake.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16H 63:12 F16H 63:12 F term (reference) 3G092 AC03 CA02 EA10 EA14 FA30 HF02Z HF08Z HF12Z HF13Z HF21Z HF26Z 3G093 BA21 BA22 DA06 DB00 DB05 DB09 DB11 DB12 DB15 FA11 FB05 3J552 MA02 NA01 NB01 PA02 PA51 PB05 RB17 RC01 UA07 VA48W VA50W VA65W VA66W VA77W

Claims (4)

[Claims] 1. A controller for an engine, which is applied to an engine for generating a driving force transmitted to a wheel of a vehicle and temporarily stops the engine according to a driving state of the vehicle, wherein the driving force is transmitted from the engine to the wheel. For the hydraulic fluid of the transmission provided with the frictional engagement device that is provided on the path and that is operated by hydraulic pressure, a determination unit that determines an oil mixture ratio that represents the proportion of non-regular hydraulic fluid mixed with the prescribed hydraulic fluid, An engine control device comprising: a control unit that prohibits suspension of the engine when the oil mixture rate is equal to or higher than a predetermined threshold value. 2. The engine control device according to claim 1, wherein the control means prohibits the engine from being temporarily stopped in consideration of the temperature of hydraulic oil. 3. The engine control device according to claim 1, wherein the control means changes the threshold value depending on whether the shift position of the transmission is in the neutral position or in the drive position. 4. The control means changes the threshold value according to a characteristic of a prescribed hydraulic fluid contained in the hydraulic fluid.
4. The engine control device according to any one of 3 above.