JP5712096B2 - Engine idling stop control device - Google Patents

Description

  The present invention relates to an engine idling stop control device for idling stopping an engine when a vehicle speed becomes a predetermined value or less during vehicle deceleration.

  While the vehicle is running, the driver releases his or her foot from the accelerator pedal and depresses the brake pedal.When the vehicle speed drops below the reference vehicle speed due to deceleration, the engine automatically stops and the driver stops the vehicle while the engine is stopped. If the engine is restarted by releasing the foot from the brake pedal and depressing the accelerator pedal in order to start the vehicle, if the lock-up clutch of the torque converter arranged between the engine and the transmission is in the engaged state, the vehicle Patent Document 1 below discloses that the engine is automatically stopped before the rotation of the engine becomes unstable by increasing the reference vehicle speed in accordance with the increase in deceleration.

  In a hybrid vehicle that includes an engine and a motor / generator as a driving source for travel, and a torque converter with a lock-up clutch is disposed between the engine and the motor / generator and the transmission, when switching the engine from stop to operation, Alternatively, it is known from Patent Document 2 below that a shock is prevented by temporarily disengaging or semi-engaging the lock-up clutch when switching from operation to stop.

Japanese Patent No. 4237132 Japanese Patent No. 3927325

  By the way, when an oil pump that supplies hydraulic pressure to a transmission is directly connected to an engine and driven, if the engine is stopped while the vehicle is decelerating as described in Patent Document 1, the engine is stopped. Since the connected oil pump cannot generate hydraulic pressure, there is a problem that hydraulic pressure cannot be supplied to the transmission even though the vehicle is still running. For example, when the transmission is a belt-type continuously variable transmission, if the supply of hydraulic pressure is interrupted by stopping the oil pump, not only the gear ratio cannot be controlled while the vehicle is running, but also the side pressure of the pulley There is a possibility that the metal belt slips due to the decrease in the resistance, and the durability is adversely affected.

  In order to prevent this, a second oil pump driven by an electric motor is provided in addition to the first oil pump driven by the engine, and a second oil pump driven by the electric motor is generated after idling of the engine is stopped. It is conceivable to continue the transmission control with the hydraulic pressure. However, as described above, there is a problem that not only a large-sized and large-capacity second oil pump is required, but also the time during which the second oil pump is activated increases and the power consumption of the electric motor increases.

  The present invention has been made in view of the above circumstances, and in a vehicle that performs idling stop control while the vehicle is decelerating, the transmission is controlled by operating the first oil pump driven by the engine as much as possible. The purpose is to make it possible.

In order to achieve the above object, according to the first aspect of the present invention, a traveling engine, a transmission that shifts the driving force of the engine and transmits it to driving wheels, the engine, and the transmission A torque converter disposed therebetween, a lock-up clutch provided in the torque converter, a first oil pump driven by the engine to supply hydraulic pressure to the transmission, and a second oil pump operated by an electric motor And an idling stop control device for allowing idling stop of the engine when the vehicle speed becomes equal to or lower than a predetermined vehicle speed and the gear ratio becomes equal to or higher than the predetermined gear ratio during deceleration traveling of the vehicle , The idling stop control means performs an idling while the engine is allowed to stop idling. With Jin speed disengages the lock-up clutch and equal to or less than a predetermined rotational speed, the engine speed is the lock-up clutch becomes equal to or less than the predetermined speed is disengaged simultaneously, actuating the second oil pump Then , an engine idling stop control device is proposed in which hydraulic pressure is supplied to the transmission .

According to the second aspect of the present invention, in addition to the configuration of the first aspect, the predetermined rotational speed is equal to or lower than the idling rotational speed, and the transmission is controlled by the hydraulic pressure supplied from the first oil pump. An engine idling stop control device is proposed, characterized in that it has a controllable speed or more .

According to the invention described in claim 3 , in addition to the configuration of claim 1 or claim 2 , the idling stop control means is configured such that the engine speed during the deceleration fuel cut of the engine is greater than the predetermined speed. An engine idling stop control device is proposed in which engagement of the deceleration fuel cut and the lock-up clutch is continued even when the maximum fuel cut lower limit rotational speed is reached.

  The belt type continuously variable transmission T of the embodiment corresponds to the transmission of the present invention, and the electronic control unit U of the embodiment corresponds to the idling stop control means of the present invention.

  According to the first aspect of the present invention, the idling stop control means permits idling stop of the engine when the vehicle speed becomes equal to or lower than a predetermined vehicle speed while the vehicle decelerates and the transmission gear ratio becomes equal to or higher than the predetermined gear ratio. Further, the idling stop control means disengages the lockup clutch when the engine speed is equal to or lower than the predetermined speed while the idling stop of the engine is permitted, so that the lockup clutch is engaged even after the idling stop is permitted. Thus, the engine can be rotated with the driving force transmitted in reverse from the driving wheel, and the control of the transmission can be continued by driving the first oil pump connected to the engine. The idling stop can be enabled and the fuel consumption can be saved. Moreover, since the lock-up clutch is disengaged when the vehicle starts following the engine restart, it is possible to avoid the vehicle jumping out.

Further, the idling stop control means drives the second oil pump operated by the electric motor to supply hydraulic pressure to the transmission at the same time as the engine speed becomes equal to or lower than the predetermined speed and the lockup clutch is disengaged. Even after the lockup clutch is disengaged and the first oil pump can no longer supply hydraulic pressure, the second oil pump can continue to supply hydraulic pressure to the transmission. When starting, the transmission can be controlled and the vehicle can be started quickly without waiting for the hydraulic pressure generated by the first oil pump driven by the engine to rise. The second oil pump is small and light because it only needs to generate the minimum required oil pressure while the engine is stopped. In addition, the second oil pump is used to extend the operating time of the first oil pump to the maximum. The operating time of the pump is shortened and power consumption is reduced.

According to the second aspect of the present invention, the predetermined rotational speed for releasing the engagement of the lockup clutch is equal to or lower than the idling rotational speed and equal to or higher than the rotational speed at which the transmission can be controlled by the hydraulic pressure supplied from the first oil pump. Therefore, even when the engine speed is equal to or lower than the idling speed, the engine is rotated by the driving force transmitted back from the drive wheels to the engine to maximize the operating time of the first oil pump, and Control can be possible .

According to the third aspect of the present invention, even if the engine speed during the deceleration fuel cut of the engine reaches the fuel cut lower limit speed, engagement of the deceleration fuel cut and the lockup clutch is continued without restarting the fuel supply. As a result, the vehicle can travel while saving fuel consumption.

Skeleton diagram of driving force transmission system of automobile. The block diagram of a control system. The time chart explaining idling stop control. The flowchart explaining idling stop control. Explanatory drawing of lockup clutch engagement cancellation | release speed.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the driving force of the engine E is transmitted through a torque converter 11, a forward / reverse switching mechanism 12, a belt-type continuously variable transmission T, a reduction gear 13, a differential gear D, and left and right foot shafts 14, 14. It is transmitted to the left and right drive wheels W, W.

  The torque converter 11 is disposed between the pump impeller 17 fixed to the front cover 16 connected to the crankshaft 15 of the engine E, the turbine runner 19 fixed to the output shaft 18, and the pump impeller 17 and the turbine runner 19. And a stator 21 fixed to the casing 20 and a lockup clutch 22 capable of directly connecting the front cover 16 and the turbine runner 19. When the lock-up clutch 22 is disengaged, the driving force of the crankshaft 15 is amplified by the working fluid circulating between the pump impeller 17, the turbine runner 19 and the stator 21, and is transmitted to the output shaft 18. When 22 is engaged, the driving force of the crankshaft 15 is directly transmitted to the output shaft 18.

  The forward / reverse switching mechanism 12 includes a planetary gear mechanism 23, a forward clutch 24, and a reverse brake 25. The planetary gear mechanism 23 includes a sun gear 26, a ring gear 27, a carrier 28, and a plurality of pinions 29 that are rotatably supported by the carrier 28 and simultaneously mesh with the sun gear 26 and the ring gear 27. The sun gear 26 fixed to the main shaft 31 of the belt type continuously variable transmission T and the output shaft 18 of the torque converter 11 can be coupled by the forward clutch 24, and the carrier 28 and the casing 30 can be coupled by the reverse brake 25. is there.

  Therefore, when the forward clutch 24 of the forward / reverse switching mechanism 12 is engaged, the rotation of the output shaft 18 of the torque converter 11 is directly transmitted to the main shaft 31 of the belt-type continuously variable transmission T to establish a forward shift stage. When the reverse brake 25 of the forward / reverse switching mechanism 12 is engaged and the carrier 28 is fixed to the casing 30, the rotation of the output shaft 18 of the torque converter 11 is decelerated and reversely rotated to become a belt type continuously variable transmission T. Is transmitted to the main shaft 31 to establish a reverse gear.

  The belt type continuously variable transmission T includes a drive pulley 33 provided on the main shaft 31, a driven pulley 34 provided on the counter shaft 32, and a metal belt 35 wound around the drive pulley 33 and the driven pulley 34. Composed. The drive pulley 33 includes a fixed pulley half 36 and a movable pulley half 37, and the groove width can be controlled by controlling the hydraulic pressure supplied to the pulley oil chamber 38. The driven pulley 34 includes a fixed pulley half 39 and a movable pulley half 40, and the groove width can be controlled by controlling the hydraulic pressure supplied to the pulley oil chamber 41. Therefore, by changing the hydraulic pressure supplied to the pulley oil chambers 38 and 41 of the drive pulley 33 and the driven pulley 34, the gear ratio is controlled steplessly and between the drive pulley 33 and the driven pulley 34 and the metal belt 35. Slip can be prevented.

  The speed reducer 13 includes a first reduction gear 42 fixed to the counter shaft 32 of the belt-type continuously variable transmission T, a second reduction gear 43 fixed to the reduction shaft 44 and meshed with the first reduction gear 42. A final drive gear 45 fixed to the reduction shaft 44, and the final drive gear 45 meshes with a final driven gear 46 fixed to the case of the differential gear D.

  The crankshaft 15 of the engine E and a first oil pump (mechanical oil pump) 47 are connected via a drive sprocket 48, an endless chain 49 and a driven sprocket 50, and the oil discharged from the first oil pump 47 is a torque converter. 11, the forward / reverse switching mechanism 12, the belt type continuously variable transmission T, the speed reducer 13 and the like are supplied as hydraulic oil or lubricating oil. Further, a second oil pump (electric oil pump) 52 driven by the electric motor 51 is provided, and this second oil pump 52 is provided when the engine E stops and the first oil pump 47 becomes inoperable. Operate.

  As shown in FIG. 2, the electronic control unit U for controlling the idling stop of the engine E includes a vehicle speed detecting means Sa for detecting the vehicle speed, an accelerator pedal opening detecting means Sb for detecting the accelerator pedal opening, and a belt type. Gear ratio detecting means Sc for detecting the gear ratio of the continuously variable transmission T, brake operation detecting means Sd for detecting depression of the brake pedal, engine speed detecting means Se for detecting the engine speed, and fuel for the engine E A fuel injection amount control means 53 for controlling the injection amount, a hydraulic control means 54 for controlling the engagement of the lockup clutch 22, and an electric motor control means 55 for controlling the operation of the electric motor 51 of the second oil pump 52. Connected.

  Next, the operation related to the idling stop control executed by the electronic control unit U will be described based on the time chart of FIG. 3 and the flowchart of FIG.

  When the driver removes his or her foot from the accelerator pedal to decelerate the vehicle (see point a in FIG. 3) and the accelerator pedal opening detecting means Sb detects that the accelerator pedal opening has become zero, the electronic control unit U In response to the command, the fuel injection amount control means 53 executes a fuel cut to save fuel consumption (see point m in FIG. 3), and the hydraulic control means 54 locks the torque converter 11 in response to a command from the electronic control unit U. By controlling the hydraulic pressure supplied to the up clutch 22 to the LC pressure CMD, the lock up clutch 22 is controlled to a predetermined engagement force (see point b in FIG. 3). The reason for changing the engagement force of the lockup clutch 22 is that the lockup clutch 22 is already engaged during cruising of the vehicle, but the required engagement force of the lockup clutch 22 becomes smaller when the vehicle shifts to a deceleration state. Because.

  When the driver removes his / her foot from the accelerator pedal and subsequently depresses the brake pedal (see point c in FIG. 3), the vehicle speed detected by the vehicle speed detecting means Sa gradually decreases, and the transmission ECU controls the drive pulley 33 accordingly. By controlling the DR pressure supplied to the pulley oil chamber 38 of the movable pulley half 37 and the DN pressure supplied to the pulley oil chamber 41 of the movable pulley half 40 of the driven pulley 34, a belt type continuously variable While suppressing the slip between the pulleys 33 and 34 of the transmission T and the metal belt 35, the gear ratio is increased toward LOW. In the meantime, the electric motor 51 is not driven and the second oil pump 52 is stopped, but the first oil pump 47 driven by the crankshaft 15 of the operating engine E is operated by the belt-type continuously variable transmission T or the lock. The necessary hydraulic pressure is supplied to the up clutch 22.

  In normal idling stop control, when the speed ratio returns to the LOW side from the deceleration fuel cut state and the engine speed reaches the lock-up clutch disengagement speed, the lock-up clutch is disengaged and the lock-up clutch is engaged. When the engine speed further decreases to the fuel cut lower limit speed due to the release, the fuel supply is restarted to shift to idling operation to prevent the engine E from stalling, and then the vehicle stops and the vehicle speed becomes zero. The engine E is stopped when

  On the other hand, in the present embodiment, the vehicle speed detected by the vehicle speed detection means Sa in the deceleration fuel cut state becomes a predetermined value (for example, 10 km / h) or less (see point d in FIG. 3), and the gear ratio detection means. When the gear ratio detected at Sc becomes equal to or greater than a predetermined value close to LOW (see point e in FIG. 3), the electronic control unit U permits idling stop while the vehicle is traveling (point f in FIG. 3 and FIG. 4). (See step S1). However, even when the engine E is idling stop controlled, the lockup clutch 22 is still engaged, so the crankshaft 15 of the engine E continues to rotate with the driving force transmitted back from the driving wheels W, W, and the crank Since the first oil pump 47 connected to the shaft 15 is driven (see step S2 in FIG. 4), the belt-type continuously variable transmission T and lock-up can be performed without driving the second oil pump 52 by the electric motor 51. The required hydraulic pressure can be supplied to the clutch 22. Further, even if the engine speed during the deceleration fuel cut of the engine E reaches the fuel cut lower limit speed, the engagement of the deceleration fuel cut and the lock-up clutch 22 is continued without restarting the fuel supply. You can drive while saving.

  In FIG. 3, NTW is the rotational speed of the turbine runner 19 of the torque converter 11 (that is, the output shaft 18), and NE is the engine rotational speed. When the lockup clutch 22 is engaged, NTW corresponds to NE.

  When the engine speed NE detected by the engine speed detecting means Se is further reduced to be equal to or lower than the predetermined speed (see point g in FIG. 3), the hydraulic pressure control means 54 receives the LC pressure CMD in response to a command from the electronic control unit U. Is lowered to disengage the lockup clutch 22 (see point h in FIG. 3 and step S3 in FIG. 4). The predetermined rotational speed is equal to or lower than the idling rotational speed of the engine E, and the power plant including the engine E and the belt-type continuously variable transmission T resonates, and the rotational speed at which unpleasant vibration is generated in the vehicle body via the mount Is slightly higher.

  Since the crankshaft 15 is disconnected from the drive wheels W and W by disengaging the lockup clutch 22, the engine speed NE decreases more quickly than the vehicle speed (that is, the rotational speed NTW of the output shaft 18 of the torque converter 11). The first oil pump 47 that rotates in conjunction with the rotation of the crankshaft 15 stops rotating, and the belt-type continuously variable transmission T and the lockup clutch 22 are supplied with hydraulic pressure. It becomes impossible to supply. However, simultaneously with the disengagement of the lock-up clutch 22, the electric motor 51 is driven by a command from the electronic control unit U, and the second oil pump 52 is activated to generate hydraulic pressure. As a result, the DR pressure of the drive pulley 33 and the DN pressure of the driven pulley 34 are raised by the hydraulic pressure generated by the second oil pump 52 (see points i and j in FIG. 3), and the necessary minimum hydraulic pressure is supplied. Control of the belt type continuously variable transmission T can be continued.

  Eventually, the vehicle speed becomes zero and the vehicle completely stops. However, while the vehicle is stopped, the second oil pump 52 operates and the minimum hydraulic pressure required for the belt-type continuously variable transmission T and the forward clutch 24 is reached. (See step S5 in FIG. 4). Therefore, when the driver removes his / her foot from the brake pedal and depresses the accelerator pedal to restart the engine E, the belt does not wait for the hydraulic pressure generated by the first oil pump 47 driven by the crankshaft 15 to rise. The type continuously variable transmission T can be operated without delay, and the vehicle can be started quickly. When the engine E is restarted and the first oil pump 47 is operated, the operation of the second oil pump 52 by the electric motor 51 is immediately stopped.

  FIG. 5 illustrates the engine speed at which the lockup clutch 22 is disengaged in the idling stop control following the deceleration fuel cut control.

  From the side where the engine speed is high, N1 is the fuel cut lower limit speed, and if the idling stop permission condition is not satisfied during the deceleration fuel cut, the fuel cut lower limit speed N1 is used to prevent the engine E from stalling. It is necessary to stop the fuel cut and restart the fuel supply. N2 is the idling speed when the engine is not loaded, and is generally about 750 rpm.

  N4 is an unpleasant vibration generating rotational speed of 400 rpm, for example, and the power plant composed of the engine E and the belt type continuously variable transmission T resonates until the engine rotational speed becomes zero from the unpleasant vibration generating rotational speed N4. An unpleasant vibration is transmitted to the vehicle body via In the present embodiment, the lockup clutch 22 is disengaged at the lockup clutch disengagement rotation speed N3 slightly higher than the uncomfortable vibration generation speed N4, and the engine speed is quickly reduced to zero (FIG. 3). ), The unpleasant vibration generating rotation speed N4 can be quickly passed to minimize the unpleasant vibration.

  N5 is a pump discharge pressure securing rotation speed of, for example, 300 rpm, and the first oil pump 47 driven by the crankshaft 15 can generate a minimum hydraulic pressure for operating the belt-type continuously variable transmission T and the torque converter 11. The number of revolutions. N3 is a lockup clutch disengagement speed slightly higher than the uncomfortable vibration generation speed N4. At this lockup clutch disengagement speed N3, the lockup clutch 22 is disengaged and the engine speed is zero. To fall.

  Since the lockup clutch engagement release speed N3 is lower than the idling speed N2, which is the minimum speed at which the engine E can rotate by itself, in the region from the idling speed N2 to the lockup clutch disengagement speed N3. Due to the engagement of the lock-up clutch 22, the engine E is driven from the outside by a driving force transmitted in reverse from the driving wheels W, W.

  As described above, according to the present embodiment, when idling stop of the engine E is permitted, the lockup clutch 22 of the torque converter 11 is engaged, and the lockup clutch slightly higher than the uncomfortable vibration generating rotational speed N4. Since the lockup clutch 22 is disengaged when the engagement speed N3 or less is reached, even after the fuel supply to the engine E is stopped by the idling stop control, the lockup clutch 22 is engaged so that the drive wheels W, W The engine E is rotated by the reversely transmitted driving force, the first oil pump 47 connected to the engine E is driven to continue the control of the belt-type continuously variable transmission T, the control of the gear ratio and the metal belt 35 Slip prevention can be enabled. As a result, the idling stop of the engine E can be performed while the vehicle is traveling at a reduced speed, thereby contributing to a reduction in fuel consumption.

  Further, since the lockup clutch disengagement release speed N3 for releasing the lockup clutch 22 is equal to or less than the idling speed N2 and more than the unpleasant vibration generating speed N4, the engine speed is equal to or less than the idling speed N2. Even in this case, the operation time of the first oil pump 47 is extended to the maximum by the driving force transmitted back from the drive wheels W, W to the engine E, and the operation of the second oil pump 52 driven by the electric motor 51 is performed. Power consumption can be reduced by minimizing time. Further, since the second oil pump 52 is operated immediately before the vehicle speed becomes zero, the hydraulic pressure required to continue the control of the belt type continuously variable transmission T is small, and is necessary when the vehicle is stopped. Therefore, the second oil pump 52 can be reduced in size and weight, and the power consumption can be reduced. Further, since the lock-up clutch 22 is disengaged when the vehicle starts following the restart of the engine E, the vehicle can be prevented from jumping out.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the transmission of the present invention is not limited to the belt type continuously variable transmission T of the embodiment, and may be another continuously variable transmission or a stepped automatic transmission.

11 Torque converter 22 Lock-up clutch 47 First oil pump 51 Electric motor 52 Second oil pump E Engine T Belt type continuously variable transmission (transmission)
U Electronic control unit (idling stop control means)
W drive wheel

Claims (3)

Between the engine (E) for traveling, the transmission (T) that changes the driving force of the engine (E) and transmits it to the drive wheels (W), and between the engine (E) and the transmission (T) A torque converter (11) arranged, a lockup clutch (22) provided in the torque converter (11), and a first driven by the engine (E) to supply hydraulic pressure to the transmission (T) The oil pump (47), the second oil pump (52) operated by the electric motor (51), and the engine when the vehicle speed falls below a predetermined vehicle speed and the gear ratio exceeds a predetermined gear ratio during vehicle deceleration. a idling stop control device for an engine and a idling stop control unit (U) to allow idling stop (E),
The idling stop control unit (U) is the engine rotational speed in a state in which idling stop is permitted to disengage the lock-up clutch (22) and equal to or less than a predetermined rotational speed of said engine (E), engine speed The hydraulic pressure is supplied to the transmission (T) by operating the second oil pump (52) at the same time that the lock-up clutch (22) is disengaged when the number becomes equal to or less than a predetermined number of revolutions. Engine idling stop control device. The predetermined speed is equal to or lower than an idling speed, and is equal to or higher than a speed at which the transmission (T) can be controlled by hydraulic pressure supplied from the first oil pump (47). The engine idling stop control device according to claim 1 . The idling stop control means (U) is configured to prevent the deceleration fuel cut and the lockup even when the engine speed during the deceleration fuel cut of the engine (E) reaches a fuel cut lower limit speed greater than the predetermined speed. The engine idling stop control device according to claim 1 or 2 , wherein the clutch (22) is continuously engaged.

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