Gear change control device of vehicle

Abstract

To provide a gear change control device of a vehicle which can suppress the generation of noise inside a cabin or outside the vehicle under a condition that an engine is operated.SOLUTION: A drive force control device of a vehicle having an engine as a drive source and an automatic transmission which can change a gear change ratio between the engine and drive wheels, capable of performing automatic control for traveling by automatically controlling a drive force without the need for a driver to perform a drive operation, sets a gear change ratio of the automatic transmission to a small gear change ratio when the inside of a cabin is required to be quiet at a start during the execution of the automatic control (Step S7), or switches an upshift threshold defined for changing the gear change ratio to the small gear change ratio, to a small value (Step S6).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a gear shift control device for a vehicle equipped with an automatic transmission capable of changing the gear ratio between an engine and drive wheels. [Background technology]

[0002] Patent Document 1 describes a control device that can improve quietness in a hybrid vehicle equipped with an engine and a motor as driving power sources. This control device is configured to switch between an EV mode in which the charging power of the power storage device is supplied to the motor and the series mode in which the motor is supplied with the generated power of the generator driven by the engine and the charging power of the power storage device, depending on the level of sound collected by a sound collection device provided inside the hybrid vehicle, when the charging rate of the power storage device that supplies power to the motor is within a target maintenance range. Specifically, when the level of the collected sound is equal to or higher than a threshold level that is a sound level loud enough that the operating sound of the engine cannot be heard by the occupants, the control device is configured to switch to the series mode, and when the sound level is lower than the threshold level, the control device is configured to switch to the EV mode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-157921 A Summary of the Invention [Problem to be solved by the invention]

[0004] The control device described in Patent Document 1 is configured to set a series mode in which the engine is operated when the sound level inside the vehicle cabin is high, so that the occupants are unlikely to find the engine operation noise unpleasant even if the engine is operated during that time. However, in vehicles that have the engine as the only driving force source or under conditions in which the engine operation is required, the engine will be operated even if the sound level inside the vehicle cabin is low, and there was room for the development of a control device that suppresses noise generated inside or outside the vehicle under such conditions.

[0005] The present invention has been made in consideration of the above-mentioned technical problems, and aims to provide a vehicle gear shift control device that can suppress noise generated inside or outside the vehicle when the engine is running. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a driving force control device for a vehicle which has an engine as a driving force source and an automatic transmission capable of changing the gear ratio between the engine and driving wheels, and which is capable of executing automatic control to automatically control the driving force to run without the driver operating the vehicle, and which includes a controller for controlling the automatic transmission, and which is characterized in that when starting while executing the automatic control, if certain conditions are met that require keeping the interior or exterior of the vehicle quiet, the controller sets the gear ratio of the automatic transmission to a smaller gear ratio than when the certain conditions are not met, or switches an upshift threshold value set for changing the gear ratio to a smaller gear ratio to a smaller value. Effect of the Invention

[0007] According to the present invention, when starting with driving force automatically controlled without the driver's driving operation, depending on whether a certain condition is met that requires keeping the interior and exterior of the vehicle quiet, the gear ratio of an automatic transmission capable of changing the gear ratio between the engine and the drive wheels is set to a small gear ratio or the upshift threshold value set for changing the gear ratio to a small gear ratio is switched to a small value when the certain condition is not met. Therefore, the engine speed can be reduced when the vehicle starts, and an increase in the engine speed during driving after starting can be suppressed. As a result, noise generated inside or outside the vehicle due to an increase in the engine speed can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram for explaining an example of a vehicle according to an embodiment of the present invention; [Diagram 2] 4 is a flowchart illustrating an example of control executed by an ECU. [Diagram 3] 5 is a flowchart for explaining an example of control for maintaining quietness outside the vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An example of a vehicle according to an embodiment of the present invention is shown typically in Fig. 1. The vehicle Ve shown in Fig. 1 is a hybrid vehicle equipped with an engine (Eng) 1 and a motor 2 as driving power sources.

[0010] The engine 1 can be configured in the same way as a conventional engine. That is, the engine 1 is provided with a throttle valve for controlling the amount of intake air, a fuel injection device for injecting fuel, and an ignition plug for igniting an air-fuel mixture, and is configured to be able to control the throttle opening, the amount of fuel injection (including 0), and the ignition timing based on the output torque required of the engine 1. Also, the engine 1 is configured to be able to generate a braking force (engine braking force) according to the friction torque of the members that make up the engine 1 by stopping the injection of fuel into the engine 1 and allowing the engine 1 to rotate.

[0011] An automatic transmission (T / M) 3 for controlling the engine speed is connected to the engine 1. The automatic transmission 3 may be a stepped transmission mechanism that changes the gear ratio in a stepped manner, or a continuously variable transmission mechanism that changes the gear ratio continuously. The automatic transmission 3 may be configured to selectively cut off the transmission of torque between the engine 1 and an output shaft 4 of the automatic transmission 3. In the following description, an example in which the automatic transmission 3 is equipped with a stepped transmission mechanism will be described.

[0012] 1, the output shaft 4 of the automatic transmission 3 is provided so as to penetrate the motor 2, and the rotor of the motor 2 is connected to the output shaft 4 by a spline or the like so as to be able to rotate integrally with the motor 2. In other words, the output shaft 4 is configured so that the torque of the motor 2 can be applied to the output shaft 4.

[0013] The motor 2 can be configured in the same manner as a motor provided as a driving force source for a conventional hybrid vehicle or electric vehicle. That is, in addition to the function as a motor that outputs driving torque by electric power supplied from a power storage device (not shown), the motor 2 is configured to function as a generator that converts part of the power into electric power and charges the power storage device by generating torque (regenerative torque) in a direction that reduces the rotation speed of the output shaft 4 and rotating the motor 2. Specifically, the motor 2 can be configured by an AC motor such as an induction motor or a synchronous motor. The motor 2 may be provided on the input side of the automatic transmission 3, or may be connected to wheels other than the wheels (drive wheels) to which the torque is transmitted from the engine 1 so as to be capable of transmitting torque.

[0014] 1 is provided with a brake mechanism 6 for applying a braking torque to each wheel 5, as are various conventional vehicles. The brake mechanism 6 is composed of a brake disc 7 connected to the wheel 5 and a brake caliper 8 connected to the vehicle Ve.

[0015] The engine 1, automatic transmission 3, motor 2, and brake mechanism 6 are controlled by an electronic control unit (hereinafter, referred to as ECU) 9. Like ECUs provided in conventional vehicles, the ECU 9 is mainly composed of a microcomputer and is configured to output command signals for controlling the engine 1, automatic transmission 3, motor 2, and brake mechanism 6 based on input signals and pre-stored maps, arithmetic expressions, and the like. This ECU 9 corresponds to the "controller" in the embodiment of the present invention.

[0016] The signals input to the ECU 9 include, for example, a signal from an accelerator opening sensor that detects the amount of operation of the accelerator device, a signal from an engine speed sensor that detects the engine speed, a signal from an output speed sensor that detects the speed of the output shaft 4 of the automatic transmission 3, a signal from a vehicle speed sensor that detects the vehicle speed, a signal from a switch operated by the driver when executing the full-speed ACC control described later, a signal from an acceleration sensor that detects the acceleration acting on the vehicle Ve, a signal from a pressure sensor provided on the seat, a radar signal that detects the distance from the vehicle ahead, a signal of map information from a navigation system or the like, a received GPS signal, a signal from an on-board camera that photographs the inside of the vehicle, and a signal from an on-board camera that photographs the outside of the vehicle.

[0017] The ECU 9 is configured to be able to execute all-vehicle-speed ACC control. The all-vehicle-speed ACC control automatically controls the driving force and the braking force so that the vehicle speed is maintained at a target vehicle speed set by the driver without the driver operating the accelerator (driving operation) or the brake (braking operation) and the vehicle distance from the preceding vehicle is maintained at or above the target vehicle distance set by the driver and the vehicle follows the preceding vehicle. Specifically, when the preceding vehicle decelerates, the engine 1, the motor 2, or the brake mechanism 6 generates a braking force for the vehicle Ve to decelerate in order to maintain the target vehicle distance, and when the preceding vehicle stops, the engine 1, the motor 2, or the brake mechanism 6 generates a braking force for the vehicle Ve to stop the vehicle. Furthermore, when the vehicle distance from the preceding vehicle becomes long due to the preceding vehicle starting, the engine 1 or the motor 2 outputs a driving torque to start following the preceding vehicle, or accelerates to the target vehicle speed while maintaining the target vehicle distance. The all-vehicle-speed ACC control corresponds to the "automatic control" in the embodiment of the present invention.

[0018] The ECU 9 also includes a shift map for determining the gear position of the automatic transmission 3. This shift map is configured to set the gear position based on the vehicle speed and the required driving force, similar to the shift map provided in a vehicle equipped with a conventional stepped transmission. Specifically, the shift map is configured to change the gear position to a gear position one step larger (i.e., a gear position with a smaller gear ratio) when the vehicle speed increases across a predetermined upshift line or the required driving force decreases across the upshift line from a state in which the vehicle is traveling at a predetermined vehicle speed and a predetermined required driving force, and to change the gear position to a gear position one step smaller (i.e., a gear position with a larger gear ratio) when the vehicle speed decreases across a predetermined downshift line or the required driving force increases across the downshift line. The above-mentioned upshift line corresponds to the "upshift threshold" in the embodiment of the present invention.

[0019] The vehicle shift control device in the embodiment of the present invention is configured to appropriately change the gear position of the automatic transmission 3 in order to suppress the generation of noise when starting by outputting driving torque from the engine 1 while all-speed ACC control is being executed. A flowchart for explaining an example of this control is shown in Fig. 2, and the control example shown in Fig. 2 is executed when all-speed ACC control is being executed and the vehicle is stopped.

[0020] In the control example shown in Fig. 2, first, it is determined whether the vehicle is stopped on an uphill road with a gradient angle of a predetermined gradient or more (step S1). This step S1 can be determined, for example, based on map information from a navigation system or the like mounted on the vehicle Ve and the current position of the host vehicle Ve detected by a GPS or the like. Alternatively, it can be determined based on the gradient of the road ahead obtained by analyzing image data from an on-board camera mounted on the vehicle Ve, or a detection value from an acceleration sensor provided on the vehicle Ve.

[0021] When the vehicle is stopped on an uphill road, it has a relatively large driving force when starting. Therefore, if the answer to step S1 is affirmative, normal start control is set (step S2), and this routine is temporarily terminated. This normal start control controls the engine 1, motor 2, and automatic transmission 3 in the same manner as in conventional vehicles. That is, the gear stage of the automatic transmission 3 is set to the first forward gear stage, which has the largest gear ratio, and a torque corresponding to the required driving force is output from the engine 1 and motor 2.

[0022] On the other hand, if the vehicle is stopped on a road such as a flat road or a downhill road where the road gradient is less than the predetermined gradient and the result of step S1 is negative, it is determined whether or not there is a passenger (step S3). This step S3 can be determined by analyzing image data from an on-board camera facing the interior of the vehicle, or by a pressure sensor provided on the seat. The passenger may be seated either in the passenger seat or in the back seat.

[0023] If the answer to step S3 is negative because there is no passenger, the process proceeds to step S2, where normal start control is executed, and this routine ends for the time being. On the other hand, if the answer to step S3 is positive because there is a passenger, the process then determines whether the passenger is asleep (step S4). Like step S3, this step S4 analyzes image data from an on-board camera facing the interior of the vehicle, and can determine, for example, whether the passenger's head is drooping and whether the time the head has been drooping is a predetermined time or longer.

[0024] If the answer to step S4 is YES because the passenger is asleep, it is determined whether the gradient angle of the road on which the vehicle is stopped is a downhill road with a predetermined angle or more (step S5). This step S5 can be performed by detecting the road gradient as in step S1, and making a determination based on the road gradient. The predetermined angle in step S5 can be set to an angle that allows the vehicle Ve to start under its own weight.

[0025] If the answer to step S4 is negative because the passenger is not asleep, or if the answer to step S5 is negative because the gradient angle of the road is not a downhill road of a predetermined angle or more, the first low noise start control is set (step S6) and this routine is temporarily terminated.

[0026] This first low noise start control is configured to set the target rotation speed of the engine 1 at the time of starting to a lower rotation speed than the target rotation speed of the engine 1 set by the normal start control so as to provide quieter operation than the normal start control. The gear position of the automatic transmission 3 at the time of starting is set to the same gear position as the normal start control, i.e., the first forward gear position.

[0027] The first low noise start control is configured to be continuously executed until the target vehicle speed set by the full speed ACC control is reached, and to upshift the gears before reaching the target vehicle speed earlier than the upshift by the normal start control. Specifically, the upshift line for upshifting from the first forward gear to the second forward gear is offset to a lower speed side than when the normal start control is set, and similarly, the upshift line for upshifting from the second forward gear to the third forward gear is offset to a lower speed side than when the normal start control is set.

[0028] Furthermore, in the first low noise start control, the output torque of the motor 2 is set to a higher torque than when the normal start control is being executed, within the limit of the output of the motor 2. In other words, the output torque required of the engine 1 is reduced.

[0029] On the other hand, if the gradient angle of the road is a downhill road of a predetermined angle or more, the vehicle Ve can start by its own weight without outputting a large torque from the engine 1 or the motor 2. That is, the vehicle Ve can start while reducing the output torque required of the engine 1 and reducing the operating noise of the engine 1. Therefore, if the answer to step S5 is YES, the second low noise start control is set (step S7), and this routine is temporarily terminated.

[0030] This second low noise start control is executed while the passenger is asleep and is configured to suppress shocks caused by gear shifts and changes in acceleration. That is, in addition to providing good quietness like the first low noise start control, it is configured to suppress shocks that occur when starting and traveling.

[0031] Specifically, the second low noise start control is configured to reduce the acceleration at the time of starting by setting the gear of the automatic transmission 3 to the second forward gear at the time of starting. Also, the second low noise start control is configured to reduce the acceleration at the time of starting the vehicle Ve by reducing the output torque of the engine 1 at that time. In other words, the required driving force at the time of starting is reduced. The gear of the automatic transmission 3 after starting may be set in the same manner as in the first low noise start control. In other words, the upshift line for upshifting from the second forward gear to the third forward gear is offset to the lower speed side than when the normal start control is set.

[0032] Moreover, the second low noise start control is configured to set the output torque of the motor 2 to a lower torque than when the normal start control is set. This is to suppress changes in the acceleration of the vehicle Ve, as described above.

[0033] As described above, when the full-speed ACC control is being performed and the engine 1 is outputting a drive torque to start the vehicle, if there is a passenger and it is required to keep the vehicle interior quiet, the gear ratio of the automatic transmission 3 is set to a smaller gear ratio than when it is not required to keep the vehicle interior quiet, or the upshift line determined to change the gear ratio to a smaller gear ratio is offset to the lower speed side. This makes it possible to reduce the engine speed when the vehicle Ve starts to move, and to suppress an increase in the engine speed during driving after the vehicle starts to move. As a result, it is possible to suppress noise in the vehicle interior that would be caused by an increase in engine speed.

[0034] In addition, when a passenger is asleep and the vehicle starts from a downhill road, the automatic transmission 3 is set to the second forward gear, thereby reducing the chance of shifting after starting, and the associated shift shock can be suppressed. As a result, discomfort felt by the sleeping passenger due to the shift shock can be suppressed. Furthermore, by setting the output torque of the motor 2 to a lower torque than when starting normally, changes in acceleration of the vehicle Ve can be suppressed. As a result, discomfort felt by the sleeping passenger due to the shock caused by the change in acceleration at the time of starting can be suppressed.

[0035] Moreover, the engine sound becomes noise not only in the vehicle interior but also outside the vehicle. Therefore, the vehicle shift control device in the embodiment of the present invention is configured to output a driving torque from the engine 1 while the full-speed ACC control is being executed, and to appropriately change the gear position of the automatic transmission 3 in order to suppress noise when starting in a residential area or starting at night. A flow chart for explaining an example of the control is shown in FIG. 3, and the control example shown in FIG. 3 is executed when the full-speed ACC control is being executed and the vehicle is stopped. In the following explanation, the same steps as those in the control example shown in FIG. 2 are labeled with the same steps and their explanations are omitted.

[0036] 3, if the vehicle is stopped on a road such as a flat road or a downhill road with a road surface gradient less than a predetermined gradient and the result of the negative determination in step S1 is negative, it is determined whether the vehicle is stopped in a residential area (step S11). This step S11 can be determined based on map information from a navigation system or the like and the current position of the vehicle Ve detected by a GPS or the like.

[0037] If the vehicle is not parked in a residential area and the result of step S11 is negative, the process proceeds to step S2 and normal start control is set. On the other hand, if the vehicle is parked in a residential area and the result of step S11 is positive, the process determines whether the current time is within a predetermined time period (step S12). The predetermined time period in step S12 is a quiet time period with few people and vehicles, and is set, for example, between 9 p.m. and 6 a.m.

[0038] If the current time is not within the predetermined time period and therefore the answer is negative in step S12, the process proceeds to step S2 and normal start control is set. Conversely, if the current time is within the predetermined time period and therefore the answer is positive in step S12, the process proceeds to step S5. That is, depending on whether the gradient angle of the road is a downhill road with a predetermined angle or more, either the first low noise start control or the second low noise start control is set.

[0039] As described above, when the full-speed ACC control is being performed and the engine 1 is outputting a drive torque to start the vehicle, if it is a quiet time with few people and vehicles on the road and it is required to keep the outside of the vehicle quiet, the gear ratio of the automatic transmission 3 is set to a smaller gear ratio than when it is not required to keep the outside of the vehicle quiet, or the upshift line determined to change the gear ratio to a smaller gear ratio is offset to the lower speed side. This makes it possible to reduce the engine speed when the vehicle Ve starts to move, and to suppress an increase in the engine speed during driving after the vehicle starts to move. As a result, it is possible to suppress noise generated outside the vehicle due to an increase in the engine speed.

[0040] The vehicle in the embodiment of the present invention is not limited to a hybrid vehicle equipped with the engine 1 and the motor 2, but may be a so-called conventional vehicle equipped with only the engine 1 as a driving force source. Furthermore, whether or not it is required to keep the interior of the vehicle quiet is not limited to whether or not there is a passenger, and other factors may be the conditions, and similarly, whether or not it is required to keep the exterior of the vehicle quiet is not limited to when the vehicle is traveling in a residential area and during a specific time period, and may be the conditions of either one of them, or other factors. [Explanation of symbols]

[0041] 1 Engine 2 Motors 3. Automatic transmission 4 Output Shaft 5 wheels 6 Brake mechanism 9 Electronic Control Unit (ECU) Vehicle

Claims

[Claim 1] A transmission control device for a vehicle that is equipped with an engine as a driving force source and an automatic transmission that can change a gear ratio between the engine and driving wheels, and that can execute automatic control to automatically control the driving force to travel without a driver's driving operation, A controller for controlling the automatic transmission is provided. The controller: When starting while the automatic control is being executed, if a predetermined condition is met that requires maintaining a quiet interior or exterior of the vehicle, the gear ratio of the automatic transmission is set to a smaller gear ratio than when the predetermined condition is not met, or an upshift threshold value determined for changing the gear ratio to a smaller gear ratio is switched to a smaller value. A vehicle shift control device comprising:

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