JP2022050795A - Transmission control device of vehicle - Google Patents

Abstract

To provide a transmission control device of a vehicle, capable of suppressing excess and deficiency of driving force before/after a vehicle reaches an uphill road.SOLUTION: In a vehicle transmission control device of a vehicle equipped with an engine, and a continuously variable transmission capable of continuously changing a transmission ratio between the engine and a driving wheel, a controller controlling the engine and the continuously variable transmission is provided. The controller is configured to obtain a target transmission ratio of the continuously variable transmission for traveling on the uphill road before the vehicle at a target vehicle speed (step S3), and to continuously increase a transmission ratio of the continuously transmission toward the target transmission ratio and continuously decrease the output torque of the engine so as to make power outputted from the engine constant, before the vehicle reaches the uphill road (step S4).SELECTED DRAWING: Figure 3

Description

The present invention relates to a vehicle shift control device provided with a continuously variable transmission capable of continuously changing the gear ratio between the engine and the drive wheels, and the gear ratio of the continuously variable transmission particularly according to the road surface gradient angle ahead. It is related to the control device that changes.

Patent Document 1 describes a vehicle control device configured to change the engine output and the gear ratio of an automatic transmission so that the vehicle can travel at a constant vehicle speed without the driver's accelerator operation. The control device described in Patent Document 1 calculates a slope change position where the road surface gradient starts to change and an estimated value of the slope of the uphill road when there is an uphill road ahead. Then, when the estimated gradient value is equal to or higher than the predetermined value, the gear ratio and the engine output capable of traveling on the uphill road while maintaining the current vehicle speed are obtained, and the obtained gear ratio is obtained before the vehicle reaches the uphill road. It is configured to start a downshift towards or increase the engine output to the required engine output. That is, it is configured to start shift control and engine output control before reaching the uphill road so that the gear ratio and engine output for traveling on the uphill road at a constant vehicle speed are obtained when the uphill road is reached. ing.

Japanese Unexamined Patent Publication No. 2020-066315

According to the control device described in Patent Document 1, the time required for shifting is subtracted from the time required for the vehicle to reach the uphill road to start the shift, and the vehicle climbs the slope when the vehicle reaches the uphill road. It is possible to obtain the driving force required for traveling on the road at the target vehicle speed. On the other hand, if the shift is completed before reaching the uphill road, a driving force larger than the driving force required at the time when the shift is completed is output, and the driver may feel uncomfortable. Alternatively, in the case of a continuously variable transmission in which the automatic transmission can continuously change the gear ratio between the engine and the drive wheels, the shift is performed without interrupting (or limiting) the transmission of torque between the engine and the drive wheels. Therefore, the driving force gradually increases with the shift, and the driver may feel uncomfortable as well. That is, the control device described in Patent Document 1 may not be able to maintain the driving force required for the vehicle either before or after the vehicle reaches the uphill road.

The present invention has been made by paying attention to the above technical problems, and an object of the present invention is to provide a speed change control device for a vehicle capable of suppressing excess or deficiency of driving force before and after the vehicle reaches an uphill road. It is something to do.

To achieve the above object, the present invention relates to a vehicle shift control device comprising an engine and a continuously variable transmission capable of continuously changing the gear ratio between the engine and the drive wheels. A controller for controlling the continuously variable transmission and the continuously variable transmission is provided, and the controller obtains a target gear ratio of the continuously variable transmission for traveling on an uphill road in front of the vehicle at a target vehicle speed, and the vehicle obtains the target gear ratio of the continuously variable transmission. Before reaching the road, the gear ratio of the continuously variable transmission is continuously increased toward the target gear ratio, and the output torque of the engine is continuously increased so that the power output from the engine is constant. It is characterized in that it is configured to reduce the target.

According to the present invention, the target gear ratio of the continuously variable transmission for traveling on the uphill road in front of the vehicle at the target vehicle speed is obtained, and the gear ratio of the continuously variable transmission is targeted before the vehicle reaches the uphill road. Continuously increase towards the gear ratio. Therefore, when the vehicle reaches the uphill road, the maximum torque that can be output from the engine can be increased, and the amplification factor of the torque transmitted to the drive wheels can be increased. It is possible to suppress a decrease in vehicle speed due to insufficient driving force. Further, by reducing the output torque of the engine while changing the gear ratio in this way, even if the torque amplification factor increases as the gear ratio increases, the torque transmitted to the drive wheels becomes constant. As a result, it is possible to prevent the driver from feeling uncomfortable due to the excessive driving force before reaching the uphill road.

It is a schematic diagram for demonstrating an example of the vehicle in embodiment of this invention. It is a figure which shows the relationship between the engine speed and the engine torque. It is a flowchart for demonstrating the control example of the speed change control device of a vehicle in Embodiment of this invention. It is a time chart which shows the change of the indicated value to an engine when the required torque is equal to or less than the maximum torque of an engine which can be output at the current engine speed. It is a time chart showing the change of the indicated value to the engine when the required torque is larger than the maximum torque of the engine that can be output at the current engine speed.

The present invention will be described with reference to the embodiments shown in the figure. It should be noted that the embodiments described below are merely examples of cases where the present invention is embodied, and do not limit the present invention.

An example of a vehicle according to an embodiment of the present invention is shown in FIG. The vehicle Ve shown in FIG. 1 is a continuously variable transmission capable of continuously changing the gear ratio between the engine (ENG) 1, the drive wheels 2 to which torque is transmitted from the engine 1, and the engine 1 and the drive wheels 2. (T / M) 3 is provided.

The engine 1 can be configured in the same manner as a conventionally known engine, and a gasoline engine, a diesel engine, or the like can be adopted. Therefore, the engine 1 includes a throttle valve for controlling the amount of air supplied to the engine 1, a fuel injection device for injecting fuel to be supplied to the engine 1, a spark plug for igniting a mixture of air and fuel, and the like. Various devices (not shown) for controlling the torque generated by the engine 1 are provided.

As the continuously variable transmission 3, a conventionally known belt type continuously variable transmission or toroidal type continuously variable transmission can be adopted, and the speed is changed in a state where torque can be transmitted between the engine 1 and the drive wheels 2. It is configured so that the ratio can be changed continuously.

A forward / backward switching mechanism capable of reversing the direction of the output torque of the engine 1 between the engine 1 and the continuously variable transmission 3, a damper mechanism for reducing the pulsation of the output torque of the engine 1, or a damper mechanism. Various devices such as a torque converter that amplifies and transmits the torque of the engine 1 may be provided.

A differential gear 5 is connected to the output shaft 4 of the continuously variable transmission 3 via a reduction gear (not shown), and torque is transmitted from the differential gear 5 to the left and right drive wheels 2. There is.

An electronic control device (hereinafter referred to as an ECU) 6 for controlling the engine 1 and the continuously variable transmission 3 described above is provided. This ECU 6 corresponds to the "controller" in the embodiment of the present invention, and is mainly composed of a microcomputer like the ECU provided in a conventionally known vehicle, and signals are transmitted from various sensors. The output signal is obtained based on the input signal, the arithmetic expression stored in advance, the map, etc., and the output signal is output to each device such as the engine 1 and the stepless transmission 3. It is configured.

The signal input to the ECU 6 is, for example, an accelerator opening sensor that detects the amount of depression of the accelerator pedal, a brake sensor that detects the amount of depression of the brake pedal and its depression force, an engine speed, or an input shaft of the stepless transmission 3. An input rotation speed sensor for detecting the rotation speed of 7, a vehicle speed sensor for detecting the rotation speed (that is, vehicle speed) of the output shaft 4 of the stepless transmission 3, a road condition around the vehicle Ve (for example, a slope of the road surface). It is a sensor for detecting (angle).

Normally, the ECU 6 obtains a target engine torque based on a signal input from the accelerator opening sensor, a signal input from the vehicle speed sensor, and a signal input from the accelerator opening sensor, and the fuel efficiency of the engine 1 is good. The target rotation speed of the engine 1 to be obtained is obtained. Then, a signal is output to a device that can control the engine torque such as the fuel injection device and the intake air amount so that the output torque of the engine 1 becomes the target engine torque. Similarly, a signal is output to an actuator (not shown) that controls the gear ratio of the continuously variable transmission 3 so that the engine rotation speed becomes the target rotation speed. If it is required to generate power with an alternator (not shown) in order to secure the power to energize the accessories, the engine torque according to the required power generation amount is added to the target engine torque. Then, the target engine torque is corrected, or the target rotation speed of the engine 1 is corrected.

On the other hand, when the amount of depression of the accelerator pedal increases relatively significantly, the engine torque is first increased to the engine torque according to the accelerator opening, and then the engine speed is increased in order to satisfy the required driving force. , Gradually change to an engine speed with good fuel efficiency.

However, as shown in FIG. 2, when the engine rotation speed Ne is a predetermined rotation speed Ne1 or less, the maximum torque Temax that can be output from the engine 1 increases as the engine rotation speed Ne increases. Therefore, for example, even if the engine torque is increased in order to obtain the driving force for traveling on an uphill road while maintaining the vehicle speed on a flat road, the required engine torque cannot be output at the engine speed Ne_cur at that time. there is a possibility.

In such a case, when the shift control of the continuously variable transmission 3 is started in order to increase the maximum torque Temax of the engine 1 after starting to travel on the uphill road, the torque of the engine 1 is performed after the shift control is performed. This will increase the time required to output the required driving force, which may cause the driver to feel uncomfortable.

On the other hand, if shift control is performed while driving on a flat road so that the vehicle can travel uphill while maintaining the vehicle speed on a flat road, the torque amplification factor increases and the driving force increases, resulting in driving. There is a possibility that a person may feel uncomfortable.

Therefore, the speed change control device for the vehicle Ve in the embodiment of the present invention is configured to be able to maintain a constant vehicle speed and travel on an uphill road by suppressing excess or deficiency of the driving force on a flat road and an uphill road. ing. A flowchart for explaining an example of the control is shown in FIG. In the example shown in FIG. 3, first, the gradient information ahead of the vehicle Ve in the traveling direction is obtained (step S1). In this step S1, information is obtained for obtaining information such as the time required to reach the uphill road and the driving force required for traveling on the uphill road while maintaining the current vehicle speed.

Further, since the shift control device of the vehicle Ve in the embodiment of the present invention shifts gears before starting to travel on the uphill road, the region of the gradient information obtained in step S1 is the shift speed of the continuously variable transmission 3. During the time required to change the ratio to a predetermined ratio, at least information on the forward distance that can be traveled when traveling at the current vehicle speed is obtained. Further, as the information obtained in step S1, for example, the distance to a position where the road surface slope becomes larger than a predetermined angle and the slope angle θ of the road surface slope are obtained. Information about the angle θ of the road surface can be obtained by a sensor for detecting the road condition (for example, the slope angle of the road surface) around the vehicle Ve, and the sensor can be obtained in advance, for example, in a navigation system or the like. In addition to the information stored in the ECU 6, the sensor may be a sensor that directly detects information outside the vehicle Ve such as a radar or a laser.

Next, the engine torque (hereinafter referred to as the required torque) Te_ne required to drive on the uphill road detected in step S1 while maintaining the current vehicle speed is the maximum torque of the engine 1 that can be output at the current engine speed. It is determined whether or not it is larger than Temax_cur (step S2). Specifically, first, the driving force (that is, the current driving force) F required to maintain the current vehicle speed and drive on a flat road is combined with the vehicle weight M and the angle θ of the road surface gradient obtained in step S1. The required driving force is obtained by adding the traveling resistance (Mgsinθ) according to the gravity obtained from, and the required torque Te_ne is obtained based on the obtained required driving force and the current gear ratio γ_cur of the continuously variable transmission 3. .. Subsequently, as shown in FIG. 2, the maximum torque Temax_cur of the engine 1 that can be output at the current engine speed Ne_cur is obtained from a map or the like stored in advance in the ECU 6, and the obtained maximum torque Temax_cur of the engine 1 is obtained. Compare the required torque Te_ne. In other words, it is determined whether or not the following equation (1) is satisfied.
Temax_cur × γ_cur × γre × γdiff / r ＞ F × Mgsinθ… (1)

In the above equation, γre indicates the gear ratio of the reduction gear, γdiff indicates the gear ratio of the differential gear 5, and r indicates the tire radius.

If the required torque Te_ne is positively determined in step S2 because it is larger than the maximum torque Temax_cur of the engine 1 that can be output at the current engine speed, the gear ratio required to output the required torque Te_ne. (Hereinafter referred to as the required gear ratio γ_ne) is obtained (step S3). The required gear ratio γ_ne in step S3 corresponds to the “target gear ratio” in the embodiment of the present invention, and the engine speed Ne_ne capable of outputting the required torque Te_ne is obtained based on the map shown in FIG. It can be calculated based on the engine speed Ne_ne and the vehicle speed. Specifically, a gear ratio that satisfies the following equation (2) is obtained.
Temax_ne × γ_ne × γre × γdiff / r ＞ F × Mgsinθ… (2)

Then, the gear ratio of the continuously variable transmission 3 is increased toward the required gear ratio γ_ne, and the engine torque Te is reduced so that the output power (power) of the engine 1 becomes constant (step S4). Since this step S4 is not a shift control caused by an accelerator operation by the driver or the like, the gear ratio of the continuously variable transmission 3 is set so that the driver does not feel uncomfortable. Specifically, the gear ratio of the continuously variable transmission 3 is swept so that the rate of change in the engine speed due to the shift is a predetermined rate of change by experiments and simulations so that the driver does not feel uncomfortable. Bring it up. When the gear ratio of the continuously variable transmission 3 is swept up in this way, the engine speed increases and the amplification factor of the engine torque increases accordingly. That is, if the engine torque is maintained, the driving force increases. Therefore, the engine torque Te is swept down according to the amount of increase in the engine speed so that the driving force does not change. In this case, an inertia torque is generated so as to reduce the driving force as the engine speed increases. Therefore, the amount of decrease in engine torque Te in step S4 is determined in consideration of the inertial shuttle.

In addition, step S4 may be executed so that the gear ratio of the continuously variable transmission 3 becomes the required gear ratio γ_ne when the vehicle Ve arrives at the uphill road, or the response delay of the engine torque or the current position may be executed. In consideration of the error of the GPS signal for determining the above, the continuously variable transmission 3 may be executed so that the gear ratio of the continuously variable transmission 3 becomes the required gear ratio γ_ne before the vehicle Ve arrives at the uphill road.

Following step S4, or if the required torque Te_ne is negatively determined in step S2 because it is equal to or less than the maximum torque Temax_cur of the engine 1 that can be output at the current engine speed, the vehicle Ve is on an uphill road. It is determined whether or not the vehicle has arrived at (step S5). This step S5 can be determined based on the information of the navigation system, the signal of the acceleration sensor provided on the vehicle Ve, and the like. Note that step S5 is a step for determining the timing for increasing the engine torque. Therefore, in step S5, whether or not the vehicle has arrived at a position a predetermined distance before the uphill road in consideration of the response delay of the engine torque. You may judge whether or not.

If it is negatively determined in step S5 because the vehicle Ve has not arrived at the uphill road, step S5 is executed again. That is, the required gear ratio γ_ne obtained in step S3 is maintained and the engine torque Te reduced in step S4 is maintained until a positive determination is made in step S5.

On the contrary, if the vehicle Ve arrives at the uphill road and is positively determined in step S5, the engine torque is increased (step S6) and this routine is temporarily terminated. This step S6 increases the engine torque to a torque that can maintain the current vehicle speed. That is, even when the driver keeps the accelerator operation amount constant, the engine torque is automatically increased. Specifically, the engine torque is increased to satisfy the following equation (3).
Te × γ_ne × γre × γdiff / r ＝ F × Mgsinθ… (3)

If the driver changes the accelerator operation amount relatively significantly after arriving at the uphill road, the engine torque and the gear ratio of the continuously variable transmission 3 are determined based on the control during the uphill road. , May be configured to switch to another control. That is, it suffices if the engine torque and the gear ratio of the continuously variable transmission 3 can be controlled as described above when the vehicle is traveling with a constant accelerator operation amount.

FIG. 4 shows a case where the required torque Te_ne is equal to or less than the maximum torque Temax_cur of the engine 1 that can be output at the current engine speed, that is, a case where it is negatively determined in step S2 in the control example shown in FIG. It is a time chart which shows the change of the indicated value to engine 1. In the example shown in FIG. 4, the accelerator opening degree is kept constant.

If it is negatively determined in step S2 as described above, the vehicle travels without changing the gear ratio. That is, step S3 and step S4 are not executed. Therefore, as shown in FIG. 4, when the vehicle is constantly traveling on a flat road (between the time t0 and the time t1), the output power, engine speed, and engine torque of the engine 1 are kept constant. Then, when the vehicle Ve arrives at a position before a predetermined distance from the uphill road (at the time of t1), it is positively determined in step S5 in FIG. 3, so that the engine torque is increased so as to maintain the vehicle speed. On the other hand, the gear ratio of the continuously variable transmission 3 is maintained. Therefore, as the engine torque increases at t1, the output power of the engine 1 also increases.

As described above, the engine torque that started to increase at the time of t1 has increased to the engine torque that can maintain the vehicle speed at the time of t2, and as a result, the engine torque and the output power of the engine 1 are kept constant from the time of t2. ing. The change in engine torque shown in FIG. 4 is shown by A in FIG.

FIG. 5 shows a case where the required torque Te_ne is larger than the maximum torque Temax_cur of the engine 1 that can be output at the current engine speed, that is, when it is positively determined in step S2 in the control example shown in FIG. It is a time chart which shows the change of the indicated value to engine 1. In the example shown in FIG. 5, the accelerator opening degree is kept constant.

If it is positively determined in step S2 as described above, the gear ratio is swept up. Therefore, from the time of t10, the engine speed gradually increases with the change of the gear ratio. If the result is positively determined in step S2, the engine torque is swept down as the gear ratio increases and the engine speed increases so as to maintain the output power of the engine 1. Therefore, the engine torque gradually decreases from the time of t10. The output power of the engine 1 is maintained constant.

Then, when the vehicle Ve arrives at a position before a predetermined distance from the uphill road (at t11), it is positively determined in step S5 in FIG. 3, so that the engine torque is increased so as to maintain the vehicle speed. On the other hand, the gear ratio of the continuously variable transmission 3 is maintained. Therefore, as the engine torque increases at t11, the output power of the engine 1 also increases.

As described above, the engine torque that started to increase at t11 has increased to the engine torque that can maintain the vehicle speed at t12, and as a result, the engine torque and the output power of the engine 1 are kept constant from t12. ing. The change in engine torque shown in FIG. 5 is shown in FIG. 2 by B.

As described above, in the state where the current gear ratio is maintained, that is, when the engine speed is maintained, if the vehicle cannot travel on the uphill road ahead while maintaining the vehicle speed, the gear shift allows the vehicle to travel on the uphill road while maintaining the vehicle speed. Up to the ratio, the gear ratio of the continuously variable transmission 3 is swept up before arriving at the uphill road. Therefore, when the vehicle Ve arrives at the uphill road, the maximum torque that can be output from the engine 1 can be increased, and the amplification factor of the torque transmitted to the drive wheels 2 can be increased. As a result, after the time when the vehicle Ve arrives at the uphill road, it is possible to obtain a driving force for traveling while maintaining the vehicle speed only by increasing the engine torque. That is, it is possible to suppress a decrease in vehicle speed due to insufficient driving force when traveling on an uphill road.

Further, even if the engine speed increases due to shifting before arriving at the uphill road, the engine torque is reduced so as to maintain the output power of the engine 1 in response to the increase in the engine speed. The driving force of the vehicle is maintained constant, and it is possible to prevent the driver from feeling uncomfortable due to the excessive driving force before the vehicle Ve arrives at the uphill road.

The vehicle shift control device according to the embodiment of the present invention is not limited to the one that controls the engine torque and the shift ratio according to the accelerator operation by the driver, and keeps the vehicle speed constant, such as the conventionally known cruise control. The vehicle may be targeted so as to automatically control the engine torque and the gear ratio.

Further, in the above-mentioned example, since the engine torque and the gear ratio are controlled according to the accelerator operation by the driver, it is assumed that the vehicle travels at a constant vehicle speed. That is, the vehicle speed traveling on a flat road is defined as the "target vehicle speed" in the embodiment of the present invention. On the other hand, in an autonomous driving vehicle that can travel without accelerator operation, brake operation, or steering operation by the driver, the vehicle speed when traveling on the previous traveling road is appropriately determined, and the vehicle is traveling on a flat road, for example. In some cases, the vehicle may travel on an uphill road at a vehicle speed higher than the vehicle speed, and in such a case, the planned vehicle speed when traveling on the uphill road may be set as the "target vehicle speed" in the embodiment of the present invention. Even in such an autonomous vehicle, by performing the same control as above, it is possible to suppress a shortage of driving force at the time of switching to an uphill road, and the driving force becomes excessively large immediately before the uphill road. It can be suppressed.

1 Engine 2 Drive wheels 3 Continuously variable transmission 6 Electronic control unit (ECU)
Ve vehicle

Claims (1)

In a vehicle shift control device including an engine and a continuously variable transmission capable of continuously changing the gear ratio between the engine and the drive wheels.
A controller for controlling the engine and the continuously variable transmission is provided.
The controller
The target gear ratio of the continuously variable transmission for traveling on the uphill road in front of the vehicle at the target vehicle speed is obtained.
Before the vehicle reaches the uphill road, the gear ratio of the continuously variable transmission is continuously increased toward the target gear ratio, and the power output from the engine becomes constant. A vehicle shift control device characterized in that it is configured to continuously reduce the output torque of the vehicle.

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