JP6870463B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device, and more particularly to a vehicle control device provided with a lockup clutch.

Conventionally, in a vehicle, when the engine speed is equal to or higher than a predetermined speed when the vehicle decelerates due to the driver's accelerator off operation or the like, the control device supplies fuel to the engine in order to improve fuel efficiency. There is known a vehicle that implements so-called fuel cut control to stop the engine. In such a vehicle, if the engine speed drops below the fuel cut return speed for determining the restart of fuel supply after the fuel cut control is performed, the control device restarts the fuel supply to the engine. However, there is a possibility that an engine stall may occur when the engine is restarted. Therefore, it is necessary to restart the fuel supply in consideration of the operating condition of the vehicle so that the occurrence does not occur, that is, the engine stall resistance performance is not deteriorated.

As an example, in the vehicle of Patent Document 1, for example, the lower the engine temperature, the higher the fuel cut return rotation speed is set. In this case, the lower the engine temperature, the higher the engine speed and the restart of fuel supply. Further, in this conventional vehicle, the lockup clutch engagement minimum rotation speed (L / U engagement minimum rotation speed) used for determining the start of the engagement operation of the lockup clutch provided in the torque converter of the transmission. However, it is set higher than the fuel cut return rotation speed. In this case, the fuel supply to the engine after the fuel cut control is restarted with the lockup clutch released. As a result, in the conventional vehicle, the engine stall resistance is improved.

Japanese Unexamined Patent Publication No. 2012-237198

By the way, the above-mentioned fuel cut return rotation speed needs to be set higher than the rotation speed (idle rotation speed) in the idle operation state of the engine in order to avoid deterioration of the engine stall resistance performance when the fuel supply is restarted. Therefore, in this case, in the conventional vehicle, the minimum rotation speed at which the L / U can be fastened is inevitably set to a large value. As a result, the range in which the lockup clutch can be engaged in the range of the engine output range becomes narrow, and the fuel efficiency performance deteriorates.

In order to improve fuel efficiency, it is conceivable to lower the minimum number of revolutions that can be engaged with L / U, but for that purpose, lower the idle revolution speed, specifically, set a low target value for controlling it. There is a need. However, in such a case, if the idle speed of the engine is controlled to be low according to the target value, the engine stall resistance may be lowered, or the vehicle body may vibrate due to the resonance caused by the low idle speed. ..

Therefore, an object of the present invention is to provide a vehicle control device capable of achieving both improvement in fuel efficiency and improvement in engine stall resistance in a vehicle provided with a lockup clutch.

The vehicle control device according to the present invention is applied to a vehicle including an engine and a transmission having a torque converter having a lockup clutch, and sets a target value of the number of revolutions of the engine in an idle operation state. The vehicle control device is configured to control the intake amount of the engine so as to maintain the rotation speed of the engine at the target value in the idle operation state. The vehicle control device further sets the value of the minimum rotation speed at which the lockup clutch can be engaged is increased by a predetermined value based on the target value, and when the vehicle travels in the idle operation state, the vehicle speed is increased. As long as the speed is equal to or higher than the predetermined speed and is within the range of the minimum speed at which the lockup clutch can be engaged and the minimum speed at which the lockup clutch can be engaged for determining the engagement of the lockup clutch, the higher the vehicle speed, the more the target. The value is set small, and the ignition timing of the engine is advanced so as to maintain the rotation speed of the engine at a rotation speed for avoiding a predetermined engine stall.

In the vehicle control device according to the present invention, as long as the vehicle speed is in the range of a predetermined speed or more and less than the minimum speed at which the lockup clutch can be engaged, the higher the vehicle speed, the more the target of the number of revolutions in the idle operation state of the engine. The value is set small. By lowering the target value, the minimum rotation speed at which the lockup clutch can be engaged is lowered by a predetermined value, so that the fuel efficiency can be improved. Further, along with the decrease in the target value, the ignition timing of the engine is advanced so that the engine speed is maintained at a speed for avoiding a predetermined engine stall. As a result, the engine stall resistance can be improved.

Therefore, according to the vehicle control device according to the present invention, it is possible to achieve both improvement in fuel efficiency and improvement in engine stall resistance in a vehicle provided with a lockup clutch.

It is a skeleton diagram which shows the structure of the vehicle which concerns on one Embodiment of this invention. It is a block diagram of the control device of the vehicle which concerns on one Embodiment of this invention. It is a conceptual diagram which shows the concept about the control which lowers the idle target rotation speed as the vehicle speed becomes higher. It is a flowchart for demonstrating the control of low rotation speed of an idle target rotation speed which a control device of a vehicle performs.

Hereinafter, embodiments of the present invention will be described. The present embodiment is a vehicle such as an automobile equipped with an automatic transmission, and the vehicle is provided with a vehicle control device to which the present invention is applied.

FIG. 1 is a skeleton diagram showing the configuration of the vehicle of the present embodiment.

The engine 10 is an internal combustion engine that uses gasoline as fuel, and an intake passage 11 and an exhaust passage 13 are connected to the main body of the engine 10. The engine 10 is provided with a spark plug (not shown) for igniting the air-fuel mixture. The intake passage 11 is provided with an electronically controlled throttle valve 12 for adjusting the intake air amount (intake amount) of the engine 10. Further, the intake passage 11 is provided with a fuel injection valve (not shown) on the downstream side of the throttle valve 12. As the fuel injection type, an in-cylinder injection type may be adopted instead of this port injection type.

The automatic transmission 20 shifts the torque converter 21 to which the power from the engine 10 is input and the power transmitted from the torque converter 21 at a predetermined gear ratio, and outputs the power after the shift. And have.

The torque converter 21 includes a pump impeller 21a that is connected to a crankshaft 14 that is an output shaft of the engine 10 to input power, a turbine runner 21b that is connected to an input shaft 23a of a transmission gear portion 22 and outputs power. It is composed of a stator 21c provided between them and provided with a one-way clutch. The torque converter 21 is provided with a lockup clutch 21d. The lockup clutch 21d can be controlled to any state between the engaged state and the disengaged state by supplying hydraulic oil. When the lockup clutch 21d is engaged, the power of the engine 10 is directly transmitted to the transmission gear portion 22 without going through the hydraulic oil filled in the torque converter 21.

The transmission gear unit 22 is configured as a stepped automatic transmission, and includes a gear mechanism that forms a gear ratio of each gear mechanism, and a clutch or brake that engages or disengages a rotating element included in the gear mechanism. (Neither is shown). The instruction of the shift operation to the transmission gear unit 22 is given by the driver's operation of the shift lever (not shown) being positioned in one of a plurality of ranges including N (neutral) and D (drive). .. Then, in the speed change gear unit 22, the speed change operation is performed by operating the friction engaging elements in the engaged state or the released state, respectively, according to the position of the shift lever. For example, when the shift lever is positioned in the "D" range, the transmission gear unit 22 selects the first forward gear from when the vehicle is stopped to when the vehicle starts, and friction is formed so that the gear ratio is formed. The engaging element is activated. Further, when the shift lever is positioned in the "N" range, the transmission gear portion 22 operates the friction engaging element so as to be in a power cutoff state in which the power of the engine is not transmitted to the drive wheels. The transmission gear unit 22 may be composed of a continuously variable automatic transmission.

Then, the output shaft 23b of the automatic transmission 20 (transmission gear portion 22) is connected to a final reduction gear 30 including a differential gear, and the final reduction gear 30 has left and right wheels (driving wheels W) via an axle. Each is connected. As a result, the power output from the output shaft 23b is transmitted to the left and right drive wheels W via the final speed reducer 30.

Next, the configuration of the control device provided in the vehicle of the present embodiment will be described with reference to FIG.

As shown in FIG. 2, the vehicle of the present embodiment is provided with an electronic control unit (ECU) 40 as a control device for controlling the vehicle in an integrated manner. The ECU 40 corresponds to a vehicle control device to which the present invention is applied. The ECU 40 includes a microprocessor (CPU), and the CPU includes a ROM that stores control programs, various map data, and the like, a RAM that temporarily stores data calculated by the CPU, and the like. I / O ports (all not shown) are connected. The CPU operates an actuator (not shown) or the like via the I / O port to operate the engine 10, the throttle valve 12, the lockup clutch 21d, the transmission gear portion 22, and the like provided in the vehicle of the present embodiment. Can be controlled. The CPU can also control the operation of the fuel injection device that controls the fuel supply by the fuel injection valve and the ignition device that controls the ignition of the spark plug (both not shown) through the I / O port. In addition, the CPU can acquire various information regarding the state of the vehicle from a plurality of sensors provided in the vehicle of the present embodiment via the I / O port.

As sensors connected to the ECU 40, the vehicle has a crank angle sensor 41 that detects the rotation angle of the crankshaft 14 that is the output shaft of the engine 10, and an input shaft rotation that detects the rotation speed of the input shaft 23a of the transmission gear portion 22. A number sensor 42, a transmission output shaft rotation speed sensor 43 for detecting the rotation speed of the output shaft 23b of the transmission gear portion 22 (automatic transmission 20), and the like are provided. The crank angle sensor 41 also functions as an engine speed sensor that detects the engine speed, and the transmission output shaft speed sensor 43 also functions as a vehicle speed sensor that detects the vehicle speed. Further, the vehicle has an accelerator opening sensor 44 that detects the amount of depression of the accelerator pedal (accelerator opening) operated by the driver, a throttle opening sensor 45 that detects the opening of the throttle valve 12, and intake air from the engine 10. An intake air amount (air flow) sensor 46, etc. for detecting the amount are provided. Further, the vehicle has a brake switch 47 that switches the ON / OFF state according to the state of the brake pedal operated by the driver, and a shift position sensor that detects the shift position (selected range) in which the shift lever is held. 48, etc. are also provided.

In the vehicle of the present embodiment, the engine speed (idle speed) is controlled during idle operation of the engine 10 by adjusting the intake amount of the engine 10 by adjusting the opening degree of the throttle valve 12 by the ECU 40. Specifically, the ECU 40 sets the idle target rotation speed as the rotation speed at which the engine 10 can operate idle without causing a stall, and sets the actual rotation speed (idle rotation speed) of the engine 10 as the idle target rotation speed. The intake amount during idle operation is adjusted by feedback control so as to maintain the number. That is, the idle target rotation speed is used as a target value for controlling the idle rotation speed of the engine 10.

Further, the vehicle of the present embodiment has a function of executing the fuel cut control described above. The fuel cut control is executed by the ECU 40 when the engine speed is equal to or higher than the predetermined speed during deceleration running of the vehicle due to the driver's accelerator off operation or the like.

In the above description, the adjustment of the intake air amount during idle operation of the engine 10 is performed by adjusting the opening degree of the throttle valve 12. However, the present invention is not limited to this, and the intake passage 11 is provided with a bypass passage that bypasses the bypass passage, and an idle control valve is provided in the bypass passage. By adjusting the opening degree of the idle control valve, the engine 10 is idle-operated. The amount of intake air at the time may be adjusted. In such a case, during idle operation, the throttle valve 12 is closed so that air is supplied to the engine 10 through the bypass passage.

By the way, if the idle speed of the engine 10 is maintained high in order to improve the engine stall resistance performance, as described above, the fuel cut return rotation for determining the restart of the fuel supply after the fuel cut control is executed. The number should be set higher than its idle speed. Then, in such a case, it is necessary to set the lock-up clutch engagementable minimum rotation speed (L / U engagement possible minimum rotation speed) higher than the fuel cut return rotation speed, and as a result, the range of the engine output region The range in which our lockup clutch can be engaged becomes narrower, and fuel efficiency deteriorates. Here, regarding the engine stall resistance, when the vehicle is traveling, the higher the vehicle speed during the traveling, the greater the rotational driving force transmitted from the transmission side to the engine due to the inertial force of the power transmission system. , The engine stall resistance is improved. That is, if the vehicle speed during traveling is high, it is considered unlikely that the engine stall resistance will be lowered even if the idle speed of the engine is lowered. In a vehicle equipped with an automatic transmission having a torque converter, so-called creep running is known in which the vehicle runs by the power of the idle speed output from the engine in the idle running state, but even in this creep running state. If the vehicle speed is high, it is considered that the idle speed of the engine can be lowered.

Therefore, in the vehicle of the present embodiment, control is performed to reduce the idle target rotation speed as the vehicle speed during traveling is higher. Hereinafter, this control will be described with reference to FIG. 3, which shows the concept of the control.

As shown in FIG. 3, in the vehicle of the present embodiment, after the start of traveling, while the vehicle speed does not reach a predetermined speed, an idle target as a target value of the idle speed is used in order to improve the engine stall resistance performance. Try to set the rotation speed high. Specifically, while the vehicle speed is "V0 km / h (speed when the vehicle is stopped)" or more and less than "V1 km / h (predetermined speed)", the idle target rotation speed should be set to "N1 rpm". To. This setting to increase is also to avoid the occurrence of vibration of the vehicle body due to the resonance caused by the idle speed controlled based on the setting. Then, based on the set idle target rotation speed, the value is set larger by a predetermined value in the order of the fuel cut return rotation speed and the minimum rotation speed at which L / U can be fastened. Specifically, based on the set idle target rotation speed "N1 rpm", the fuel cut return rotation speed is "N2 rpm", the minimum rotation speed at which L / U can be fastened is "N3 rpm", and so on. Try to set it as large as possible.

On the other hand, while the vehicle speed is in the range (low rotation control range) that is equal to or higher than the predetermined speed and less than the minimum speed at which the lockup clutch can be engaged (the minimum speed at which the L / U can be engaged), the higher the vehicle speed, the more idle. Try to set the target rotation speed small. Specifically, while the vehicle speed is in the low rotation speed control range, that is, in the range of "V1 km / h" or more and less than "V2 km / h (minimum speed at which L / U can be concluded)", the idle target rotation speed is set to "N1 rpm". The higher the vehicle speed, the smaller the value, such as "N1'rpm". This means that after the vehicle speed becomes "V1km / h", even if the idle speed of the engine is lowered by setting the idle target speed to a small value, the engine stall resistance performance can be lowered at that speed. This is because there is little sex. The minimum speed at which L / U can be engaged is a threshold value used for determining the start of engagement of the lockup clutch 21d together with the above-mentioned minimum rotation speed at which L / U can be engaged. Further, based on the idle target rotation speed set to be small, the value is set to be larger by a predetermined value in the order of the fuel cut return rotation speed and the minimum rotation speed at which L / U can be fastened. As a result, the fuel cut return rotation speed is changed from "N2 rpm" to "N2'rpm" and L / U is concluded based on the idle target rotation speed set as small as "N1 rpm" to "N1'rpm" as the vehicle speed increases. The minimum possible rotation speed is set to be smaller as the vehicle speed increases, such as from "N3 rpm" to "N3'rpm". After the vehicle speed becomes "V2 km / h", the idle target rotation speed is maintained at "N1'rpm". As described above, in the vehicle of the present embodiment, after the vehicle speed reaches a predetermined speed (“V1 km / h” in FIG. 3), the L / U can be concluded by lowering the idle target rotation speed as the vehicle speed increases. The minimum number of revolutions is lowered to improve fuel efficiency.

By the way, when the idle target rotation speed is lowered in this way, the intake amount of the engine 10 is lowered as the idle speed of the engine 10 is controlled according to the low target value, so that the engine stall resistance performance is lowered. Alternatively, the vehicle body may vibrate due to resonance caused by its low controlled idle speed. Therefore, in order to deal with this, in the vehicle of the present embodiment, the ignition timing of the engine is advanced to set the idle speed of the engine 10 to a predetermined rotation speed for avoiding deterioration of engine stall resistance and the like. It is kept at (engine stall avoidance speed). This engine stall avoidance speed is set to, for example, the same value as the high idle target rotation speed when the vehicle is stopped. Specifically, for example, as shown in FIG. 3, the engine stall avoidance rotation speed is set to "N1 rpm", which is a high (large) idle target rotation speed when the vehicle speed is "V0 km / h". In order to improve fuel efficiency, it is desirable to set the engine stall avoidance speed to be equal to or higher than the minimum L / U speed that can be fastened. Specifically, for example, as shown in FIG. 3, the engine stall avoidance rotation speed is set so that the vehicle speed is equal to or higher than the minimum L / U rotation speed "N3'rpm" at "V2km / h". Is desirable.

In the vehicle of the present embodiment, by performing such control by the ECU 40 which is a control device of the vehicle, it is possible to achieve both improvement of fuel efficiency performance and improvement of engine stall resistance performance.

Hereinafter, the control for lowering the idle target rotation speed, which is performed by the ECU 40, will be described with reference to the flowchart of FIG. The ECU 40 of the present embodiment repeats the processing of this flowchart at predetermined time intervals, for example, while the automatic transmission is set to a traveling range such as a D (drive) range by a shift operation of the driver. It is configured to run. Further, the ECU 40 of the present embodiment is configured to separately execute a control program for controlling the idle speed of the engine and controlling the return from the fuel cut while the processing of this flowchart is repeatedly executed. ing. Since these controls are well known, the description thereof will be omitted.

When the processing of the flowchart is started, in step S1, the ECU 40 acquires the information detected by the transmission output shaft rotation speed sensor (vehicle speed sensor) 43 as the vehicle speed information.

Next, in step S2, the ECU 40 sets the idle target rotation speed based on the acquired vehicle speed information. The idle target rotation speed is set, for example, by using a value (rotation speed) obtained by searching map data stored in advance in a ROM or the like at the vehicle speed.

Next, in step S3, the ECU 40 sets the fuel cut return rotation speed by a predetermined value based on the set idle target rotation speed. This fuel cut return rotation speed is set by using, for example, a return value (rotation speed) obtained by giving the set idle target rotation speed as an argument to a function stored in advance in a ROM or the like. To do.

Next, in step S4, the ECU 40 sets the minimum L / U fastening speed by a predetermined value based on the set fuel cut return speed. The minimum rotation speed at which L / U can be fastened is set by using, for example, a return value (rotation speed) obtained by giving the set fuel cut return rotation speed as an argument to a function stored in advance in a ROM or the like. To do it.

Next, in step S5, the ECU 40 acquires the information detected by the crank angle sensor (engine rotation speed sensor) 41 as the engine rotation speed information.

Next, in step S6, the ECU 40 determines whether or not the engine speed is lower than the predetermined engine stall avoidance speed based on the acquired information. When the ECU 40 determines that the engine speed is lower than the engine speed avoiding engine speed (less than the engine speed), the process proceeds to the process of step S7 (Yes side). On the other hand, when the ECU 40 determines that the engine speed is equal to or higher than the engine speed avoiding engine speed, the ECU 40 shifts to the process of step S8 (No side).

Next, in step S7, the ECU 40 controls an ignition device (not shown) to advance the ignition timing of the engine so as to maintain the idle speed of the engine 10 at the engine stall avoidance speed.

Next, in step S8, the ECU 40 determines whether or not the engine speed is equal to or higher than the minimum L / U speed that can be fastened set above, based on the engine speed information acquired above. When the ECU 40 determines that the engine speed is equal to or higher than the minimum L / U speed that can be fastened, the ECU 40 shifts to the process of step S9 (Yes side). On the other hand, when the ECU 40 determines that the engine speed is lower than the minimum L / U speed that can be fastened (less than the speed), the process proceeds to the process of step S11 (No side).

Next, in step S9, the ECU 40 determines whether or not the vehicle speed is equal to or higher than the minimum L / U concluding speed set above, based on the vehicle speed information acquired above. When the ECU 40 determines that the vehicle speed is equal to or higher than the minimum speed at which the L / U can be fastened, the ECU 40 shifts to the process of step S10 (Yes side). On the other hand, when the ECU 40 determines that the vehicle speed is lower than the minimum speed at which the L / U can be fastened (less than that speed), the process proceeds to the process of step S11 (No side).

Next, in step S10, when the lockup clutch 21d is in the released state, the ECU 40 controls and engages the lockup clutch 21d, while the lockup clutch 21d is already in the engaged state. The processing here is omitted. Then, the ECU 40 ends this routine.

In step S11, when the lockup clutch 21d is in the engaged state, the ECU 40 controls to release the lockup clutch 21d so that the lockup clutch 21d is not engaged. On the other hand, when the lockup clutch 21d is in the released state, the process here. Is omitted. Then, the ECU 40 ends this routine.

As described above, in the vehicle of the present embodiment, for example, when the automatic transmission is set to a traveling range such as a D (drive) range by a shift operation of the driver, the ECU 40 which is a control device of the vehicle idles the automatic transmission. Control of lowering the target rotation speed (processing of steps S1 to S11) is performed. In this control, the idle target rotation speed is set based on the vehicle speed information acquired through the sensor, and based on the set idle target rotation speed, the fuel cut return rotation speed and the minimum possible L / U conclusion are possible. The values are set larger by a predetermined value in the order of the number of rotations (steps S1 to S4). Here, the idle target rotation speed is in a range (low rotation) in which the vehicle speed is equal to or higher than a predetermined speed (V1 km / h in FIG. 3) and less than the minimum speed at which L / U can be concluded (V2 km / h in FIG. 3). While in the control range), the value is set so that the vehicle speed becomes smaller as the vehicle speed increases (from N1 rpm to N1' rpm in FIG. 3). Further, based on the idle target rotation speed set in this way, the fuel cut return rotation speed and the minimum rotation speed at which L / U can be fastened are set (from N2 rpm in FIG. 3 to N2'rpm and from N3 rpm, respectively. It is set to decrease as the vehicle speed increases (such as N3'rpm). In this case, after the vehicle speed reaches a predetermined speed, the idle target rotation speed is lowered as the vehicle speed is increased, so that the minimum rotation speed at which the L / U can be concluded is lowered. Therefore, in the vehicle of the present embodiment, as compared with the case where such control is not performed, the range in which the lockup clutch can be engaged in the range of the engine output region becomes wider due to the reduced amount. The fuel efficiency of the vehicle can be improved.

Further, in the above control, based on the information of the engine speed acquired through the sensor, it is determined whether or not the engine speed is lower than the engine stall avoidance speed, and when it is determined to be lower than that. Is to advance the ignition timing of the engine so that the idle speed of the engine 10 is maintained at the engine stall avoidance speed (steps S5 to S7). Therefore, as described above, when the idle target rotation speed is set so as to decrease as the vehicle speed increases while the vehicle speed is within the low rotation speed control range, the target value is reached by controlling the intake air amount. At the same time, the idle speed of the engine is about to be reduced. However, when the engine is to be lowered, the ignition timing of the engine is advanced so that the idle speed of the engine is controlled so as not to fall below the engine stall avoidance speed. In the vehicle of the present embodiment, the engine stall avoidance rotation speed is set to the same value as, for example, a high idle target rotation speed when the vehicle is stopped (N1 rpm when the vehicle speed is V0 km / h in FIG. 3). Therefore, in the vehicle of the present embodiment, the deterioration of the engine stall resistance performance is suppressed, and the occurrence of resonance is suppressed according to the idle rotation speed, so that the generation of vibration in the vehicle body is suppressed.

Therefore, in the vehicle of the present embodiment, in the vehicle provided with the lockup clutch, both the improvement of the fuel efficiency performance and the improvement of the engine stall resistance performance can be achieved at the same time.

10 Engine 11 Intake passage 12 Throttle valve 14 Crankshaft 21 Torque converter 21d Lockup clutch 40 Electronic control unit (ECU)
41 Crank angle sensor (engine speed sensor)
43 Transmission output shaft rotation speed sensor (vehicle speed sensor)
45 Throttle opening sensor 46 Intake amount (air flow) sensor 47 Brake switch 48 Shift position sensor

Claims (1)

Applicable to vehicles with an engine and a transmission with a torque converter with a lockup clutch,
A target value of the rotation speed of the engine in the idle operation state is set , and in the idle operation state, the intake amount of the engine is controlled so as to maintain the rotation speed of the engine at the target value, and the engine is supplied to the engine. A vehicle control device configured to perform a fuel cut that shuts off the fuel supply of the engine.
This controller also
Based on the target value, the value of the minimum speed at which the lockup clutch can be engaged is set larger than the target value by a predetermined value, and the value of the fuel cut return rotation speed is set to the target value and the minimum possible speed at which the lockup clutch can be engaged. Set between the number of revolutions and
When the vehicle is running at the idle operating state, the vehicle speed is more than a predetermined speed, or One, while the previous SL in the locked-up range of clutch engagement possible below the minimum speed for determining the engagement of the lock-up clutch The higher the vehicle speed , the smaller the target value, the fuel cut return rotation speed, and the minimum rotation speed at which the lockup clutch can be engaged are set, and the rotation speed of the engine is set to a rotation speed for avoiding a predetermined engine stall. A vehicle control device characterized in that it is configured to advance the ignition timing of the engine so as to maintain.

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