JP2013155827A - Transmission control device for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission control device for a continuously variable transmission that controls a transmission ratio capable of efficiently performing gear shift in a normal travel state and sudden acceleration.SOLUTION: A transmission control device for a continuously variable transmission sets a target transmission ratio based on an optimal operating line by performing transmission control of the continuously variable transmission connected to an output side of a power source in a power transmission path, wherein a target transmission ratio is set based on an optimal operating line which is displaced to a low-rotation side and a high torque side from the optimal operating line in a normal travel state in acceleration.

Description

  The present invention relates to a transmission control device for a continuously variable transmission that controls a transmission ratio of a continuously variable transmission mounted on a vehicle.

  In the continuously variable transmission, the speed of the internal combustion engine can be changed steplessly by continuously changing the gear ratio. Recently, it has become possible to electrically control the throttle opening, fuel supply amount, and the like. Therefore, by setting the rotational speed arbitrarily by the continuously variable transmission while electrically controlling the throttle opening, it is possible to satisfy the demand for driving force and at the same time perform the operation with the optimum fuel consumption. Therefore, the transmission ratio of the automatic transmission for vehicles including the continuously variable transmission basically includes the required driving amount represented by the accelerator opening degree and the driving of the internal combustion engine represented by the vehicle speed and the output shaft rotational speed. It is controlled based on the state.

  In the speed change control of the continuously variable transmission, the operating point of the internal combustion engine is set on the optimal fuel consumption line, and the speed ratio is set so that the rotation speed of the internal combustion engine becomes the rotation speed on the optimal fuel consumption line. As the optimum fuel consumption line, shift control using an operation line based on the fuel consumption rate according to the traveling state of the vehicle and the configuration of the vehicle is performed.

  For example, Patent Document 1 describes a transmission control device for a continuously variable transmission that sets a gear ratio using a power train optimum operation line that minimizes the fuel consumption rate of the entire power train including the engine and the transmission. ing.

  In Patent Document 2, the gear ratio is set by the optimum fuel consumption line when traveling in the acceleration-oriented mode, and the gear ratio is set by the operation line displaced to the lower torque side than the optimum fuel consumption line during normal traveling. Have been described.

  Patent Document 3 discloses a configuration in which shift control is performed using an engine operating point having a large margin with respect to the engine maximum torque when traveling with an emphasis on acceleration response.

JP 2010-13003 A JP 2010-47127 A JP 2007-269199 A

  The vehicle travel control device described in Patent Document 1 is configured to set the operating point of the internal combustion engine in consideration of the efficiency of the entire power train. The engine operating point is at a higher speed and lower torque at the same output than the engine operating point considered. In addition, when the acceleration is requested, the engine operating point is set outside the optimum operating line, so that there is a possibility that the fuel efficiency is not always optimal when viewed throughout the running state. Moreover, since the apparatus described in Patent Document 2 operates the internal combustion engine at an engine operating point that deviates from the engine operating point on the optimum fuel efficiency line during normal traveling, the fuel efficiency may deteriorate. Furthermore, the device described in Patent Document 3 increases so-called margin torque during acceleration and improves acceleration performance or acceleration response performance, but does not set a driving state in consideration of fuel consumption. There is a possibility that the fuel economy of will deteriorate.

  The present invention has been made paying attention to the above technical problem, and an object of the present invention is to provide a transmission control device for a continuously variable transmission that controls an efficient gear ratio during steady running and sudden acceleration. To do.

  In order to achieve the above object, the invention according to claim 1 is a shift control device for a continuously variable transmission that sets a target gear ratio based on an optimum operation line. The present invention is characterized in that the target gear ratio is set on the basis of an optimum operating line displaced toward the low rotation side and the high torque side.

  According to the first aspect of the present invention, the optimum operating line is set according to each of the normal running state and acceleration, and the engine operating point is set by selecting those optimum operating lines according to the degree of acceleration of the vehicle. As a result, the fuel efficiency is improved throughout the vehicle.

It is the flowchart which showed the shift control process performed by the shift control apparatus of the continuously variable transmission in one Embodiment of this invention. 7 is a flowchart showing a shift control process based on a shift control map in a normal running state. It is the flowchart which showed the shift control processing by the shift control map at the time of sudden acceleration. It is a shift control map at the time of sudden acceleration used in the shift control process at the time of sudden acceleration in this embodiment.

  Hereinafter, the present invention will be specifically described based on embodiments. First, in a vehicle to which the present invention can be applied, a fluid transmission device, a lockup clutch, a forward / reverse switching mechanism, a continuously variable transmission (CVT), and the like are provided in a power transmission path between a power source and wheels. . As the power source, for example, at least one of an internal combustion engine or an electric motor can be used, and an internal combustion engine having a mechanism capable of electrically controlling output, such as an internal combustion engine having an electronic throttle valve, is preferably used. As the electric motor, it is possible to use a motor generator having a power running function for converting electrical energy into kinetic energy and a regeneration function for converting kinetic energy into electrical energy. In the present invention, an internal combustion engine such as a gasoline engine, a diesel engine, or a natural gas engine is mainly used as a power source. In this embodiment, a case where an engine is used as a power source will be described.

  The fluid transmission device and the lockup clutch are provided in a power transmission path between the power source and the forward / reverse switching mechanism, and the fluid transmission device and the lockup clutch are arranged in parallel with each other. The fluid transmission device is a device that transmits power by the kinetic energy of the fluid, and the lockup clutch is a device that transmits power by frictional force. The forward / reverse switching mechanism is a device that selectively switches the rotation direction of the output member relative to the input member.

  The continuously variable transmission is a mechanism capable of continuously changing a gear ratio, and a belt-type or toroidal-type continuously variable transmission can be used. The belt-type continuously variable transmission is provided in a power transmission path between the forward / reverse switching mechanism and the wheels. More specifically, the continuously variable transmission is provided with a primary shaft and a secondary shaft that are arranged in parallel to each other. The primary shaft is provided with a primary pulley, and the secondary shaft is provided with a secondary pulley. The primary pulley has a fixed sheave fixed to the primary shaft and a movable sheave configured to be movable in the axial direction of the primary shaft. A V-shaped groove is formed between the fixed sheave and the movable sheave.

  In addition, a hydraulic servo mechanism is provided that moves the movable sheave in the axial direction of the primary shaft to bring the movable sheave and the fixed sheave closer to or away from each other. The hydraulic servo mechanism includes a hydraulic chamber and a piston that operates in the axial direction of the primary shaft in accordance with the oil amount or hydraulic pressure of the hydraulic chamber and is connected to a movable sheave.

  On the other hand, the secondary pulley has a fixed sheave fixed to the secondary shaft and a movable sheave configured to be movable in the axial direction of the secondary shaft. A V-shaped groove is formed between the fixed sheave and the movable sheave. And the belt is wound around each pulley in the state clamped by each groove | channel.

  In addition, a hydraulic servo mechanism is provided that moves the movable sheave in the axial direction of the secondary shaft to bring the movable sheave and the fixed sheave closer to or away from each other. This hydraulic servo mechanism includes a hydraulic chamber and a piston that operates in the axial direction of the secondary shaft in accordance with the hydraulic pressure or the amount of oil in the hydraulic chamber and is connected to a movable sheave.

  On the other hand, a hydraulic control device having a function of controlling each hydraulic servo mechanism, lockup clutch, and forward / reverse switching mechanism of the continuously variable transmission is provided. Furthermore, an electronic control unit (ECU) is provided as a controller for controlling the power source, the lockup clutch, the forward / reverse switching mechanism, the continuously variable transmission, and the hydraulic control device. This electronic control unit is composed of a processing unit (CPU), a storage unit (RAM and ROM), and a microcomputer mainly having an input / output interface. The transmission control device for a continuously variable transmission according to the present invention is included in the electronic control device.

  For this electronic control unit, the engine speed, vehicle speed, vehicle acceleration, accelerator pedal operation state, brake pedal operation state, throttle valve opening, shift position, primary shaft speed, secondary shaft speed The signal of the sensor (device) for detecting the number, presence / absence of failure of the solenoid valve of the hydraulic control device, the intake air amount of the engine, the uphill road, and the like is input. The vehicle speed is obtained based on the rotation speed of the secondary shaft, the rotation speed of the axle, or the rotation speed of the wheel. Various types of data are stored in the storage device of the electronic control unit. Based on the signal input to the electronic control unit and the stored data, the signal for controlling the power source from the electronic control unit, continuously variable A signal for controlling the transmission, a signal for controlling the forward / reverse switching mechanism, a signal for controlling the lockup clutch, a signal for controlling the hydraulic control device, and the like are output.

  The data stored in the storage device of the electronic control device includes a speed change control map that is a speed change ratio control map, a lockup clutch control map, and the like. The shift control map is a map for setting the gear ratio of the continuously variable transmission or the target rotational speed of the power source based on the vehicle speed, the accelerator opening, the deceleration, or the operating state of the brake. When an engine is used as the power source, control the speed ratio of the continuously variable transmission so that the engine speed approaches the optimal fuel consumption line or the engine speed becomes the rotation speed on the optimal fuel consumption line. it can. The rotational speed control of the power source is performed mainly by feedback control based on the deviation between the target rotational speed and the actual rotational speed, and feedforward control is executed or used together as necessary.

  As described above, the continuously variable transmission can function to control the rotational speed of the power source to the rotational speed at which the fuel consumption is optimized. In this so-called normal control, for example, the required driving force is obtained from an appropriate map based on the required driving amount represented by the accelerator opening and the vehicle speed, and the target output of the power source is calculated from the required driving force and the vehicle speed. Is calculated. The target rotational speed at which the target output can be output with the optimum fuel efficiency is obtained from the shift control map or the like as the rotational speed at the intersection of the so-called optimal fuel efficiency line and the target output line. The gear ratio of the continuously variable transmission is feedback-controlled by controlling the difference between the target rotational speed and the actual power source rotational speed. On the other hand, the target torque is calculated based on the target output and the vehicle speed at that time, and the output torque of the power source is controlled by an electronic throttle valve or the like so as to achieve the target torque.

  The speed change control is performed by changing the continuously variable transmission based on the running state determined by the vehicle speed and the required driving amount such as the accelerator opening, for example, the steady running state, the semi-steady running state close to the steady running or the running state at the time of sudden acceleration. Control. That is, the required travel state changes by increasing or decreasing the required drive amount such as the accelerator opening, and the shift control according to the changed travel state is performed. For example, when the required driving force increases due to a sudden depression of the accelerator pedal, in other words, the gear ratio set by the continuously variable transmission increases due to the shift control that requires rapid acceleration. Is controlled to increase the acceleration performance.

  Next, with reference to the drawings, the transmission control device for a continuously variable transmission in this embodiment will be described more specifically. The transmission control device of the continuously variable transmission changes the gear ratio according to the running state of the vehicle, and is configured to execute different shift control contents according to the required degree of acceleration. Yes. For example, the control content can be divided into shift control in steady running and quasi-steady running states and shift control in response to a rapid acceleration request. The steady running is a state where the vehicle is required to maintain the vehicle speed, and the quasi-steady traveling requires an acceleration compared to the steady running, but the drive is insufficient to keep the vehicle speed during the steady running. The driving state in which the acceleration request is made to compensate for the torque is a state close to the normal driving state, and the normal driving state and the quasi-stationary driving state will be described as a normal driving state. On the other hand, sudden acceleration is a traveling state that responds to a sudden increase in the required drive amount compared to a normal traveling state, and is described as a traveling state in which the driving torque is increased more rapidly than the driving torque in steady traveling. To do.

  FIG. 1 is a process flowchart for explaining an example of control executed by the transmission control device for a continuously variable transmission according to this embodiment. This control processing routine is repeatedly executed every predetermined short time. As illustrated in FIG. 1, when the vehicle is in a normal traveling state, the transmission control device for the continuously variable transmission refers to a normal transmission control map stored in the storage device and performs a transmission control process. Is executed (step S1). The normal shift control map is a map in which the horizontal axis is the engine speed Ne and the vertical axis is the engine torque Te, and the optimum fuel consumption line 10 corresponding to the engine fuel efficiency rate line 11 and the equal output line at the target output. This is a map in which the engine operating point is set by the intersection with. Next, it is determined whether or not the requested driving amount such as the accelerator opening is suddenly accelerated (step S2). In the rapid acceleration determination, for example, it is determined whether or not there is a sudden increase in the requested acceleration amount by comparing and determining a change amount of the requested drive amount and a predetermined threshold value. Further, for example, a case where the gear ratio needs to be 1 or more may be determined as a rapid acceleration. As a result of the rapid acceleration determination, when it is determined that the rapid acceleration is not in effect (No in step S2), control based on a normal shift control map is executed (step S1). That is, when it is not during rapid acceleration, in other words, when the normal running state continues, shift control is performed based on the normal shift control map.

  On the other hand, if it is determined as a result of the sudden acceleration determination that the requested drive amount has suddenly increased (Yes in step S2), refer to the shift control map for sudden acceleration stored in the storage device. Then, a shift control process corresponding to the degree of acceleration at the time of sudden acceleration is executed (step 3). The shift control map for sudden acceleration is a map in which the engine operating point is set by the intersection of the optimum fuel consumption line 1 for sudden acceleration and the equal output line 2 at the target output. In addition, in order to obtain a processing flow that returns from step S3 to step S2 every predetermined short time, the shift control process of step S3 is executed only during sudden acceleration. That is, the shift control is performed based on the shift control map for sudden acceleration only during sudden acceleration.

  Next, with reference to FIG. 2, the shift control process (step S <b> 1) in the normal running state in the process flow illustrated in FIG. 1 will be described more specifically. FIG. 2 is a process flow of the shift control in the normal traveling state, and shows a flowchart for executing the shift control process based on the normal shift control map. The shift control process (step S1) in the normal running state obtains the required driving force from an appropriate map based on the requested driving amount and the vehicle speed, and calculates the target output of the engine from the obtained requested driving force and the vehicle speed. (Step S11).

  After the target output is calculated, the target engine speed at which the calculated target output can be output with the optimum fuel consumption is determined according to the target output with reference to the normal shift control map stored in the storage device. It is determined from the intersection of the iso-output line and the so-called optimum fuel consumption line (step S12). In the normal shift control map, the intersection between the target output iso-output line and the optimum fuel consumption line 10 is a so-called engine operating point including the engine speed Ne and the engine torque Te. That is, the engine speed as the target engine speed is obtained from the intersection of the target output line and the optimum fuel consumption line 10. The difference between the target engine speed and the actual engine speed is controlled so that the speed ratio of the continuously variable transmission is feedback-controlled. In this normal shift control process, the optimum fuel consumption line 10 derived from the efficiency of the engine alone is used. Note that the shift control in the normal traveling state may be performed by using the optimum fuel consumption line on the high rotation side and the low torque side as compared with the optimum fuel consumption line 1 at the time of rapid acceleration described later. For example, the optimal fuel consumption line for the entire power train including the engine and the continuously variable transmission may be used as long as the engine operating point is higher than the optimal fuel consumption line for sudden acceleration. .

  Then, the target engine torque is calculated based on the target output calculated in step S11 and the vehicle speed at that time (step S13). The calculation of the target engine torque in step S13 may be calculated based on the target engine speed determined in step S12 and the target output calculated in step S11. Although not shown, the continuously variable transmission control device sets a target speed ratio from the target engine speed and the vehicle speed, and controls the operation of the continuously variable transmission to achieve the target speed ratio. Further, the engine output torque is controlled by controlling the operation of the electronic throttle valve or the like so as to achieve the target engine torque.

  Next, with reference to FIGS. 3 and 4, the shift control process (step S3) at the time of rapid acceleration in the process flow illustrated in FIG. 1 will be described more specifically. First, the shift control map for sudden acceleration will be described with reference to FIG. FIG. 4 shows an example of a shift control map for sudden acceleration, and shows a shift control map including the optimum fuel consumption line 1 and the engine equal output line 2 used in the shift control process during sudden acceleration. For the purpose of explanation here, FIG. 4 shows the optimum fuel consumption line 10 in the normal running state and the equal fuel consumption rate line 11 of the engine alone, which is an actual shift control map for sudden acceleration. Of course, the optimum fuel consumption line 10 is not included. Further, the equal fuel consumption rate line in the entire power train including the engine and continuously variable transmission is not shown in FIG. The optimum fuel consumption line 1 during the rapid acceleration is set such that the engine operating point at the same output is lower than the optimum fuel consumption line 10 in the normal running state. In other words, the optimum fuel consumption line 1 used in the shift control process at the time of rapid acceleration is displaced to the low rotation side and the high torque side as compared with the optimum fuel consumption line 10 in the normal running state. The optimum fuel consumption line 1 has a plurality of optimum fuel consumption lines according to acceleration. For example, when the acceleration α2 is greater than the acceleration α1, the optimum fuel consumption line 1b at the acceleration α2 has a higher degree of acceleration, so the engine operating point at the same engine output is lower and higher than the optimum fuel consumption line 1a at the acceleration α1. It is set to be on the torque side. That is, the optimum fuel consumption line 1b having a relatively large acceleration is displaced to the lower rotation side and the higher torque side than the optimum fuel consumption line 1a having a relatively small acceleration.

  Further, as the optimum fuel consumption line 1 for sudden acceleration, an optimum fuel consumption line derived from the efficiency of the entire power train including the engine and the continuously variable transmission can be used. The optimum fuel consumption line for the entire power train is derived based on the transmission efficiency of the entire power train including the engine and the continuously variable transmission derived from the product of the efficiency of the engine alone and the transmission efficiency of the continuously variable transmission. . For example, each is an efficiency map with the engine torque on the vertical axis and the engine speed on the horizontal axis, and the thermal efficiency map of the engine alone and the transmission of a continuously variable transmission having a distribution that optimizes efficiency on the low rotation side and high torque side The product with the efficiency map reflects the thermal efficiency of the engine and the transmission efficiency of the continuously variable transmission, that is, a transmission efficiency map is derived in which the transmission efficiency of the entire power train is taken into consideration. Therefore, the optimum fuel consumption line in the entire power train is displaced to reflect the optimum distribution of the transmission efficiency of the continuously variable transmission on the low rotation side and the high torque side compared to the engine alone. In other words, the optimum fuel consumption line displaced from the optimum fuel consumption line of the engine alone to the low rotation side and the high torque side is the optimum fuel consumption line of the entire power train. In other words, the speed change control device for a continuously variable transmission according to the present invention has an optimum fuel consumption line for the entire power train during sudden acceleration, as well as an optimum fuel consumption line for normal driving conditions and an optimum fuel consumption line based on the efficiency of the engine alone. Also, the gear ratio is set based on the optimum fuel consumption line for sudden acceleration, which is the optimum fuel consumption line displaced to the high torque side on the low rotation side.

  FIG. 3 is a flowchart of the shift control process at the time of sudden acceleration, and is a flowchart for executing the shift control process based on the shift control map for sudden acceleration. In the speed change control process (step S3) at the time of sudden acceleration, a required driving force is obtained from an appropriate map based on the requested driving amount and the vehicle speed, and a target output of the engine is calculated from the obtained required driving force and the vehicle speed. (Step S21).

  Further, the electronic control unit to which a signal is input from a sensor for detecting the acceleration of the vehicle determines the optimum fuel consumption line 1 corresponding to the acceleration as the optimum fuel consumption line for shift control at the time of sudden acceleration (step S22). In other words, in the process of step S22, the optimum fuel consumption line 1 is determined according to the amount of change in the drive request amount, that is, the degree to which acceleration is requested. In FIG. 4, a plurality of optimum fuel consumption lines 1a and 1b are shown. However, there is only one optimum fuel consumption line 1 used for determining the target engine speed, and the optimum fuel consumption line 1 determined according to the acceleration in step S22. The candidate of the fuel consumption line 1 is only illustrated by a plurality of 1a, 1b. It should be noted that in this shift control process during sudden acceleration, a plurality of optimum fuel consumption lines are included in one shift control map for sudden acceleration, and one of them is determined as the optimum fuel consumption line to be processed according to the acceleration. Alternatively, a plurality of shift control maps at the time of rapid acceleration having only one optimum fuel consumption line may be stored, and a shift control map including the optimum fuel consumption line corresponding to the acceleration may be searched and specified as a processing target.

  Further, referring to the shift control map for sudden acceleration having the optimal fuel consumption line 1 determined in step S22 among the shift control maps stored in the storage device, the calculated target output is output with the optimal fuel consumption. The target engine speed that can be determined is determined from the intersection of the optimum fuel consumption line 1 and the equal output line 2 corresponding to the target output (step S23). In other words, during sudden acceleration, shift control is performed based on the shift control map for sudden acceleration in the shift control map, and the shift control map during sudden acceleration has an optimal fuel consumption line 2 corresponding to the degree of acceleration. . The intersection is the engine operating point 3, and the target engine speed is determined. Note that the speed ratio of the continuously variable transmission is feedback-controlled by controlling the difference between the target engine speed and the actual engine speed. In the determination processing of the target engine speed in step S23, based on the shift control map at the time of sudden acceleration as illustrated in FIG. 4, the equal output line 2 corresponding to the target output and the optimum fuel consumption line 1 at the time of sudden acceleration The target engine speed is obtained from the intersection of. For example, in the case of the optimum fuel consumption line 1a, the intersection point is the engine operation point 3, which is lower than the engine operation point of the equal output line 2 and the optimum fuel consumption line 10 in the normal running state and on the high torque side. Located in.

  Then, the target engine torque is calculated based on the target output calculated in step S21 and the vehicle speed at that time (step S24). The calculation of the target engine torque in step S24 may be calculated based on the target engine speed determined in step S23 and the target output calculated in step S21. Although the control device for the continuously variable transmission is not shown, the target gear ratio is set from the target engine speed and the vehicle speed, and the operation of the continuously variable transmission is controlled to achieve the target gear ratio, Further, the engine output torque is controlled by controlling the operation of an electronic throttle valve or the like so as to achieve the target engine torque.

  As described above, according to the transmission control device for a continuously variable transmission according to the present invention, the engine operating point is set on the optimum fuel consumption line during steady running, quasi-steady running, and sudden acceleration running. Therefore, fuel consumption can be improved. Further, since the gear ratio can be set using the optimum fuel consumption line corresponding to the acceleration in the sudden acceleration state, the accuracy of the gear ratio is improved. Further, according to the above-described shift control process at the time of rapid acceleration, the engine operating point can be rotated at a lower speed than the process using the optimum fuel consumption line in the normal traveling state.

  DESCRIPTION OF SYMBOLS 1 ... Optimum fuel consumption line at the time of rapid acceleration, 2 ... Equipotential output line, 3 ... Engine operating point, 10 ... Optimum fuel consumption line of normal driving | running | working state, 11 ... Engine equal fuel consumption rate line.

Claims (1)

In a transmission control device for a continuously variable transmission that sets a target gear ratio based on an optimum operation line,
The continuously variable transmission is configured to set a target gear ratio based on an optimum operation line displaced to a low rotation side and a high torque side from an optimum operation line in a normal running state during acceleration. Shift control device.

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