JP4316480B2 - Automatic engine stop device for vehicle - Google Patents

Description

  The present invention relates to an automatic engine stop device for a vehicle that automatically stops the engine in accordance with vehicle driving conditions such as vehicle speed and brake pedal operation.

  In recent years, for the purpose of reducing fuel consumption and improving exhaust emission, an automatic engine stop device has been developed that automatically stops the engine when the vehicle is in a predetermined operating condition.

  For example, the engine automatic stop device automatically stops the engine on the condition that the brake pedal is depressed and the vehicle speed is equal to or lower than the reference vehicle speed. In a vehicle in which engine power is transmitted to wheels via an automatic transmission, a preparatory operation is performed on the automatic transmission side before the engine is actually automatically stopped.

For example, in the engine automatic stop device described in Patent Document 1, a delay time is provided from when the engine automatic stop condition is satisfied until the engine is automatically stopped, and the electric oil pump is started during the delay time. I try to let them. In this automatic engine stop device, the operating oil pressure in the automatic transmission is secured by a mechanical oil pump driven by the engine during normal driving, and the electric oil is started before the hydraulic pressure by the mechanical oil pump decreases during automatic engine stop. This makes it possible to compensate for a decrease in the operating oil pressure.
JP 2001-41067 A

  By the way, in the case of a vehicle in which engine power is transmitted to wheels via an automatic transmission, if the engine automatically stops with the input side and output side clutch engaged at a certain gear position in the automatic transmission, the output side (wheel Since the rotation on the input side (engine side) tends to stop before the rotation on the side) completely stops, a shock may occur due to the rotation difference at this time. This shock occurs not a little even when the engine and the automatic transmission are connected by a torque converter, and tends to cause discomfort and discomfort to the occupant.

As a countermeasure against this, a delay time is provided until the engine is automatically stopped after the automatic engine stop condition is satisfied as in the conventional automatic engine stop device. It has been considered to release the clutch engagement.
However, if the delay time is set longer in order to reduce the shock due to the automatic stop of the engine, the unnecessary combustion time in the engine becomes longer, and other problems such as deterioration in fuel efficiency and increase in emissions Will be invited. On the other hand, if the delay time is set short in consideration of the fuel efficiency, etc., the shock during the automatic engine stop cannot be sufficiently absorbed.

  Therefore, the present invention can improve the fuel efficiency and emission performance and comfort by reliably reducing the shock caused by the automatic engine stop without unnecessarily delaying the time from the establishment of the automatic engine stop condition to the actual engine stop. It is an object of the present invention to provide an automatic engine stop device for a vehicle that can achieve both comfortable riding comfort.

In order to achieve the above-mentioned object, the invention according to claim 1 is directed to the power of an engine (for example, an engine 1 in an embodiment described later) via an automatic transmission (for example, an automatic transmission 5 in an embodiment described later). An automatic engine stop device (for example, in an embodiment described later) is mounted on the vehicle transmitted to the wheel (for example, wheel 7 in the embodiment described later) and automatically stops the engine when the vehicle is in a predetermined driving condition. In the combustion operation unit 10 and the controller 11), a mechanical oil pump (for example, a mechanical oil pump 22 in an embodiment described later) that is driven using the driving force of the engine when the vehicle is running, and an automatic stop of the engine In the electric oil pump (for example, an electric motor 26 in an embodiment described later) Eg to the electric oil pump 23) will be described in the exemplary embodiment, during the automatic stop of the engine, a clutch for interrupting the power transmission of the automatic transmission of the input side and the output side by releasing the engagement pressure, the operation of the automatic transmission Oil temperature detecting means (for example, an oil temperature sensor 20 in an embodiment described later) for detecting the temperature of the oil, and when the engine is automatically stopped, from the start of releasing the engagement pressure of the clutch until the engine is actually automatically stopped. In addition, the delay time is longer than the time from the start to the completion of the clutch engagement pressure release, and the delay time is changed to become longer as the detected temperature of the oil temperature detecting means is lower. The electric oil pump is started simultaneously with the start of releasing the engagement pressure of the clutch when the delay time is started .

  Thus, the delay time until the engine automatic stop is actually performed is appropriately changed according to the difference in the clutch engagement pressure release time depending on the oil temperature. As a result, it is possible to reliably perform the automatic engine stop when the release of the clutch engagement pressure is completely completed without unnecessarily delaying the automatic engine stop.

Further, the hydraulic pressure by the electric oil pump is sufficiently raised when the engine is automatically stopped.

In the present invention, the delay time from when the engine stop condition is satisfied until the engine is automatically stopped is always appropriately changed according to the difference in the clutch engagement pressure release time depending on the oil temperature. It is possible to achieve both reduction of the shock at the time of automatic engine stop by reliable release and early automatic engine stop. Therefore, according to the present invention, it is possible to further improve the fuel consumption performance and the emission performance without impairing the comfortable riding comfort.

Further, the present invention is the activation of the electric oil pump, for performing the same timing as when the started delay time release of the clutch engagement pressure is started, the engine is sufficiently hydraulic by the electric oil pump until the automatic stop It is possible to secure the stable engagement of the other clutches in the automatic transmission and the stable operation of the auxiliary devices.

Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram showing a power transmission system of a vehicle according to this embodiment.
In this embodiment, an engine automatic stop device according to the present invention is applied to a hybrid vehicle having both an engine 1 and a motor 2 as drive sources. This hybrid vehicle employs a so-called parallel type in which a motor 2 that also serves as a generator is directly connected to an engine 1 to assist driving of the engine 1 and regenerate energy during braking.

  A drive shaft 3 from which the power of the engine 1 and the motor 2 is taken out is connected to a multistage automatic transmission 5 via a torque converter 4, and an output shaft 6 of the automatic transmission 5 is connected to left and right via a differential mechanism (not shown). Connected to the drive wheel 7. In FIG. 1, only one wheel 7 is schematically shown. The torque converter 4 includes a lockup clutch 8 for switching between torque transmission using hydraulic oil as a medium and mechanically connected torque transmission by friction engagement. The lockup clutch 8 is engaged and released by the control oil pressure supplied from the oil pressure control circuit 9 in the same manner as the speed change operation of the automatic transmission 5.

  The engine 1 is a reciprocating type multi-cylinder engine, and fuel injection and ignition in each cylinder are performed by a combustion operation unit 10 in which a spark plug and a fuel injection valve are integrated. The combustion operation unit 10 is controlled by an electronically controlled controller 11 (ECU) according to the driving situation of the vehicle. The combustion operation unit 10 optimally adjusts the combustion of the engine 1 under normal driving conditions under the control of the controller 11, but automatically stops the engine 1 when the vehicle state and the driving operation satisfy predetermined automatic stop conditions. Thereafter, the engine 1 is automatically restarted when the automatic restart condition is satisfied. In this embodiment, the combustion operation unit 10 and the controller 11 mainly constitute the engine automatic stop device according to the present invention.

  Further, a throttle (not shown) for adjusting the intake air amount of the engine 1 is constituted by an electronically controlled throttle, and the valve opening according to the depression amount of the accelerator pedal is controlled by the controller 11.

The following is connected to the input section of the controller 11 as main detection means.
(A) Brake switch 12 for detecting whether or not the brake pedal has been depressed.
(B) Accelerator pedal sensor 13 for detecting the depression amount of the accelerator pedal
(C) Crank angle sensor 14 for detecting the engine speed
(D) Input shaft rotation sensor 16 for detecting the rotational speed of the input shaft 15 of the automatic transmission 5
(E) Vehicle speed sensor 17 for detecting the vehicle speed
(F) Shift position sensor 18 for detecting the shift position of the automatic transmission 5
(G) A remaining capacity sensor (not shown) for detecting the remaining capacity of the battery 19
(H) Oil temperature sensor 20 (oil temperature detecting means) for detecting the temperature of the hydraulic oil in the automatic transmission 5

  The motor 2 is connected to the battery 19 via a PDU (power drive unit) 21, and rotates the drive shaft 3 by the electric power of the battery 19 under the control of the PDU 21 by the controller 11. The motor 2 functions as a generator during braking of the vehicle, and charges the battery 19 with regenerative energy by controlling the PDU 21 by the controller 11.

  This hybrid vehicle includes a mechanical oil pump 22 and an electric oil pump 23 as a hydraulic pressure supply source for the hydraulic control circuit 9. The mechanical oil pump 22 is linked to the rotating shaft of the engine 1 and is operated by the driving force of the engine 1 or the motor 2. The electric oil pump 23 is driven by an electric motor 26 connected to a 12V auxiliary battery 25 via a pump driver 24. The electric oil pump 23 is basically stopped when the mechanical oil pump 22 is normally operated by the power of the engine 1 or the motor 2, and the mechanical oil pump 22 is reduced by a decrease in the rotational speed of the drive shaft 3. When a sufficient discharge amount cannot be obtained, it is driven by control by the controller 11.

  In addition, the hydraulic control circuit 9 is linked to a shift lever (not shown), a manual valve (not shown) for selecting and switching the basic oil path of forward, neutral and reverse, and the hydraulic oil pressure and details. A plurality of other valves (not shown) for controlling the switching of the oil passages are provided, and these valves are controlled by the controller 11 in accordance with the driving state of the vehicle, whereby the clutches in the automatic transmission 5 are controlled. Adjust the operating pressure. As a result, the automatic transmission 5 changes the gear position and cuts off the power. Further, the hydraulic control circuit 9 appropriately supplies the control hydraulic pressure to the lock-up clutch 8 of the torque converter 4 by the valve control by the controller 11 according to the driving state of the vehicle as described above.

  The automatic transmission 5 is a well-known multi-stage transmission whose gears are hydraulically operated, and includes a planetary gear mechanism (not shown) and a plurality of clutches (FIG. 1) for changing a power transmission path in the transmission. , Only one clutch is provided with reference numeral 30). In this specification, the “clutch” includes a brake in which one of the relatively rotating members is fixed to the casing. Each clutch in the automatic transmission 5 is engaged and disengaged by supplying and discharging hydraulic oil, and the hydraulic oil supply and discharge is controlled via a hydraulic control circuit 9. The change of the gear position of the automatic transmission 5 (including change to reverse) is performed by appropriately switching the combination of the clutch to be engaged and the clutch to be released.

The engine automatic stop control in this hybrid vehicle is executed by the controller 11 when all of the following conditions (1) to (3) are satisfied (see FIG. 3).
(1) Brake switch 12 is ON
(2) Depression amount detected by the accelerator pedal sensor 13 is 0 (not shown in FIG. 3)
(3) The vehicle speed once exceeds the control permission vehicle speed, and the current vehicle speed is below the reference vehicle speed V1.

  After all the engine automatic stop conditions (1) to (3) are satisfied, release of the engagement pressure of the clutch 30 that is responsible for the power transmission of the current gear stage in the automatic transmission 5 is started. Thereafter, the engine 1 is automatically stopped after a predetermined delay time DT has elapsed. The delay time DT is managed by a delay timer configured in the controller 11, and this delay time DT is changed according to the temperature of the hydraulic oil in the automatic transmission 5. That is, a table defining the relationship between the delay time DT and the oil temperature is stored in the storage unit in the controller 11, and the controller 11 sequentially reads the current temperature of the hydraulic oil by the oil temperature sensor 20, and the table The delay time DT suitable for the detected temperature is changed. The relationship between the delay time DT and the oil temperature in the table is defined so that the delay time DT becomes approximately proportionally longer as the oil temperature decreases, and the delay time DT corresponding to the oil temperature is The time from the start to the completion of releasing the clutch engagement pressure is longer.

On the other hand, the engine restart control after the engine automatic stop control is performed is executed by the controller 11 when the following conditions (4) and (5) are simultaneously satisfied.
(4) Brake switch 12 is OFF
(5) The amount of depression by the accelerator pedal sensor 13 is greater than or equal to a predetermined value. Note that the engine automatic stop condition and the engine restart condition described here are merely examples, and other conditions can be added.

  FIG. 2 is a flowchart showing the engine automatic stop control of this embodiment. Hereinafter, specific control will be described with reference to this flowchart.

In S101, it is determined whether all the engine automatic stop conditions (1) to (3) are satisfied. When it is determined that all the conditions (1) to (3) are satisfied, the process proceeds to S102, and it is determined that they are not satisfied. Sometimes the process proceeds to S106.
In S106, a delay time DT corresponding to the current oil temperature in the automatic transmission 5 is obtained by referring to the table, a timer value Ten corresponding to the time is set in the delay timer, and then the engine 1 is automatically stopped. Exit the process without performing
On the other hand, when the routine proceeds to S102, the activation of the electric oil pump 23 is started and the release of the engagement pressure of the clutch 30 in the automatic transmission 5 is started. Thereafter, in S103, the count of the timer value Ten of the delay time DT is decreased, and in S104, it is determined whether or not the delay time DT has passed (Ten ≦ 0). At this time, if it is determined that the delay time DT has not elapsed, the process is directly terminated. If it is determined that the delay time DT has elapsed, the engine 1 is automatically stopped at that time.

  Thus, when the engine automatic stop control is performed, the delay time DT corresponding to the current oil temperature in the automatic transmission 5 is satisfied after the engine automatic stop conditions (1) to (3) are satisfied. The engine 1 is automatically stopped after the elapse of time. Therefore, in the automatic transmission 5, the engine is automatically stopped when the clutch 30 reliably completes the release of the engagement pressure, and the rotational difference between the engine side and the wheel side when the engine is stopped is the clutch portion. It is absorbed and the occurrence of shock is prevented. Further, the delay time DT until the actual automatic stop of the engine 1 is set to be substantially the same as the clutch release completion time corresponding to the oil temperature of the hydraulic oil, so that no shock is always generated. The engine 1 can be automatically stopped in the shortest time. Therefore, in this automatic engine stop device, it is possible to further improve the fuel efficiency and exhaust emission without giving the passenger an uncomfortable feeling or an uncomfortable feeling due to the occurrence of a shock.

  By the way, the automatic transmission 5 is switched to a one-way clutch that allows only power transmission from the engine side to the wheel side, for example, at a low gear. In such a shift stage, even if a rotation difference occurs between the input side and the output side of the automatic transmission 5 due to the automatic stop of the engine 1, the rotation difference of the one-way clutch can be absorbed. . Therefore, in the case of such a shift stage that switches to the one-way clutch, it is possible to eliminate the control of the delay time DT according to the oil temperature of the hydraulic oil.

  Further, in the engine automatic stop device of the above embodiment, since the automatic oil pump 23 is started simultaneously with the release of the clutch engagement pressure after the automatic engine stop conditions (1) to (3) are satisfied, the delay is delayed. When the engine 1 actually stops automatically after the time DT has elapsed, a sufficient driving pressure by the electric oil pump 23 can be raised. As shown in FIG. 3, the drive pressure of the mechanical oil pump 22 gradually decreases while the automatic engine stop conditions (1) to (3) are satisfied and the delay time DT is advanced. There arises a situation in which the hydraulic pressure by the mechanical oil pump 22 cannot be maintained above a specified value. However, in this embodiment, since the driving pressure by the electric oil pump 23 can be ensured before the engine 1 automatically stops, the engagement pressure of other clutches in the automatic transmission 5 is reliably maintained. be able to. In addition, the operation of auxiliary devices that continue to operate after engine operation can be stabilized.

  In addition, this invention is not limited to the said embodiment, A various design change is possible in the range which does not deviate from the summary. For example, in the above-described embodiment, the engine automatic stop device according to the present invention is applied to a hybrid vehicle including an engine and a motor. However, the engine automatic stop device may be applied to a vehicle including only an engine as a power source.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram centering on the power transmission system of the hybrid vehicle carrying the engine automatic stop apparatus concerning this invention. The flowchart which shows the control at the time of the engine automatic stop of one Embodiment of this invention. The timing chart which shows the relationship between the vehicle speed at the time of the engine automatic stop of the embodiment, an engine speed, a brake signal, clutch fastening pressure, and each drive pressure of a mechanical oil pump and an electric oil pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 5 ... Automatic transmission 7 ... Wheel 10 ... Combustion operation unit (engine automatic stop device) 11 ... Controller (engine automatic stop device) 20 ... Oil temperature sensor (oil temperature detection means) 23 ... Electric oil pump 30 ... Clutch DT ... Delay time

Claims (1)

It is mounted on a vehicle in which engine power is transmitted to wheels via an automatic transmission,
In an engine automatic stop device that automatically stops the engine when the vehicle is in a predetermined driving condition,
A mechanical oil pump driven using the driving force of the engine when the vehicle is running;
An electric oil pump driven using the driving force of the electric motor when the engine is automatically stopped;
A clutch that shuts off the power transmission between the input side and the output side in the automatic transmission by releasing the fastening pressure when the engine is automatically stopped;
Oil temperature detecting means for detecting the temperature of hydraulic oil in the automatic transmission,
When the engine is automatically stopped, a delay time longer than the time from the start of the release of the clutch engagement pressure until the completion of the clutch is given until the engine is actually automatically stopped from the start of the release of the clutch engagement pressure . The delay time is changed so as to become longer as the detection temperature of the oil temperature detection means is lower,
An automatic engine stop device for a vehicle , wherein the electric oil pump is activated simultaneously with the start of releasing the engagement pressure of the clutch when the delay time is started .

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