JP7430463B2 - Control device - Google Patents

Description

The present invention relates to a control device for a vehicle.

As a transmission installed in vehicles such as automobiles, it is equipped with a continuously variable transmission mechanism that changes power steplessly, and is capable of transmitting power by dividing it into two paths between an input shaft and an output shaft. There is a continuously variable transmission (CVT).

A power split type continuously variable transmission is provided with a continuously variable transmission mechanism, a parallel shaft gear mechanism, and a planetary gear mechanism. The continuously variable transmission mechanism has a configuration in which an endless belt is wound around a primary pulley and a secondary pulley. The secondary shaft of the continuously variable transmission mechanism is connected to the sun gear of the planetary gear mechanism. The parallel shaft gear mechanism includes a split drive gear to which the power of the input shaft is transmitted/cut off, and a split driven gear that forms a gear train with the split drive gear and rotates integrally with the carrier of the planetary gear mechanism. An output shaft is connected to the ring gear of the planetary gear mechanism. The rotation of the output shaft is transmitted to the differential gear, and from the differential gear to the left and right drive wheels.

A first mode (belt mode) and a second mode (split mode) are provided as power transmission modes during forward travel.

In the first mode, the first clutch that switches transmission/cutoff of power between the input shaft and the split drive gear is released, the split drive gear is placed in a free rotation state, and the carrier of the planetary gear mechanism is placed in a free rotation state. be made into Further, a second clutch that connects/disconnects the sun gear and ring gear of the planetary gear mechanism is engaged, and the sun gear and ring gear are connected. Therefore, the power output from the continuously variable transmission mechanism rotates the sun gear and the ring gear integrally, and the output shaft rotates integrally with the ring gear. Therefore, in the first mode, as the belt gear ratio (pulley ratio), which is the gear ratio of the continuously variable transmission mechanism, is larger, the unit, which is the gear ratio of the entire power split type continuously variable transmission, is proportional to that gear ratio. The gear ratio (input shaft rotation speed/output shaft rotation speed) increases.

In the second mode, the second clutch is released and the sun gear and ring gear of the planetary gear mechanism are disengaged. Further, the first clutch is engaged, and power is transmitted from the input shaft to the split drive gear. The power transmitted from the input shaft to the split drive gear is changed at a constant gear ratio (split point) from the split drive gear via the split driven gear, and then input to the carrier of the planetary gear mechanism. The sun gear rotates at a rotational speed according to the belt gear ratio. Therefore, in the second mode, the larger the belt speed ratio is, the smaller the unit speed ratio becomes, and it is possible to realize a unit speed ratio that is equal to or lower than the split point.

In shift control, for example, a target rotation speed is set according to the accelerator opening (the ratio of the operation amount to the maximum operation amount of the accelerator pedal) and the vehicle speed according to a shift diagram, and the rotation speed input to the continuously variable transmission is set. A gear ratio that matches the target rotational speed is set as a target gear ratio. Then, the belt speed ratio is changed so that the unit speed ratio matches the target speed ratio.

Switching between the first mode and the second mode is determined by comparing the target gear ratio and the gear ratio at the split point (split gear ratio). That is, in the first mode, if the target gear ratio is equal to or lower than the split gear ratio (high side), switching from the first mode to the second mode is determined. Further, in the second mode, if the target gear ratio is equal to or higher than the split gear ratio (low side), switching from the second mode to the first mode is determined.

Japanese Patent Application Publication No. 2016-142302

Since the second mode is a gear transmission method in which power is transmitted by a split drive gear and a split driven gear, the second mode has good power transmission efficiency and is effective in improving the running fuel efficiency of the vehicle. However, even if the accelerator pedal is pressed a little more, if the target gear ratio becomes equal to or higher than the split gear ratio, the second mode will be switched to the first mode, so the amount of time that can be driven in the second mode will be reduced. The problem is that it's short.

An object of the present invention is to provide a control device that can increase the time during which a vehicle can travel in the second mode.

In order to achieve the above object, the control device according to the present invention includes a belt-type idler between the input shaft into which power from the engine is input and the output shaft which outputs the engine driving force to be transmitted to the drive wheels. The first mode is equipped with a step change transmission mechanism, and the higher the belt speed ratio by the continuously variable transmission mechanism, the larger the overall unit speed ratio between the input shaft and the output shaft. is configured such that the unit gear ratio does not change even if the first mode and the second mode are switched when the belt gear ratio is at a constant switching value. A control device for a vehicle equipped with a transmission, comprising a parameter acquisition means for acquiring parameters corresponding to an acceleration request for accelerating the vehicle, and a transmission diagram defining a relationship between the parameters and a target rotation speed. A target rotational speed is set according to the parameter acquired by the parameter acquisition means, a gear ratio that makes the rotational speed of the input shaft match the target rotational speed is determined, and the gear ratio is set as the target gear ratio that is the target of the unit gear ratio. a target driving force calculation means that calculates the required driving force according to the parameters acquired by the parameter acquisition means; an engine driving force calculation means for calculating the engine driving force; a driving force increase amount calculation means for calculating the amount of increase in the engine driving force due to control for increasing the engine output; When the target gear ratio is less than or equal to the switching value, the first mode is switched to the second mode, and in the second mode, the increased amount calculated by the driving force increase amount calculating means is calculated by the required driving force calculating means. mode switching means for continuing the second mode even if the target gear ratio set by the target setting means is larger than the switching value if the engine driving force calculated by the engine driving force calculation means is greater than the value obtained by subtracting the engine driving force calculated by the engine driving force calculation means from the engine driving force calculation means; including.

According to this configuration, the vehicle is equipped with a continuously variable transmission that shifts the power of the engine and outputs the shifted power as engine driving force that is transmitted to the drive wheels.

In a continuously variable transmission, when the power transmission mode is switched between the first mode and the second mode, and the belt gear ratio is a constant switching value, the unit gear ratio changes even when the first mode and the second mode are switched. It is configured not to. In the first mode, the larger the belt speed ratio by the belt speed change mechanism, the larger the overall unit speed ratio between the input shaft and the output shaft. In the second mode, the larger the belt speed ratio, the smaller the unit speed ratio.

In the speed change control of the continuously variable transmission, a target speed ratio is set in accordance with an acceleration request based on a speed change diagram, and the belt speed ratio is changed so that the unit speed ratio matches the target speed ratio. In the first mode, when the target gear ratio is set to be less than or equal to the switching value, the first mode is switched to the second mode. In principle, in the second mode, when a target gear ratio larger than the switching value is set, the second mode is switched to the first mode, but the amount of increase in engine driving force due to control to increase engine output is accelerated. If the value is greater than the value obtained by subtracting the engine driving force at the unit gear ratio that matches the target gear ratio from the requested driving force according to the request, the second mode is switched even if a target gear ratio larger than the switching value is set. is maintained.

Thereby, even if the required driving force increases due to an increase in acceleration request or running load, the second mode can be continued for a longer period than before. Therefore, the time during which the vehicle can travel in the second mode can be increased, and the fuel efficiency of the vehicle can be improved. Furthermore, the feeling of busy shifting due to frequent switching between the first mode and the second mode can be reduced, and drivability can be improved.

The mode switching means is configured such that, in the second mode, the increase amount calculated by the driving force increase amount calculation means subtracts the engine driving force calculated by the engine driving force calculation means from the required driving force calculated by the required driving force calculation means. If the second mode is larger than the above value, it may be determined whether or not to continue the second mode, taking into consideration the advantages and disadvantages of continuing the second mode.

With this configuration, for example, if the gain from continuing the second mode exceeds the loss, the second mode can be continued to increase the time during which the vehicle can travel in the second mode. On the other hand, if the loss due to continuation of the second mode is greater than the gain, switching from the second mode to the first mode can suppress the loss greater than the gain.

According to the present invention, it is possible to increase the time during which the vehicle can travel in the second mode. As a result, the fuel efficiency of the vehicle can be improved. Furthermore, the feeling of busy shifting due to frequent switching between the first mode and the second mode can be reduced, and drivability can be improved.

FIG. 1 is a skeleton diagram showing the configuration of a drive system of a vehicle equipped with a control device according to an embodiment of the present invention. FIG. 3 is a diagram showing the states of a clutch and a brake when the vehicle is moving forward and when the vehicle is moving backward. FIG. 2 is a collinear diagram showing the relationship between the rotational speeds (rotational speeds) of a sun gear, a carrier, and a ring gear of a planetary gear mechanism. It is a figure which shows the relationship between the belt speed change ratio by a belt speed change mechanism, and the total speed change ratio of the whole transmission. FIG. 2 is a block diagram showing the configuration of a control system of a vehicle. FIG. 3 is a diagram showing an example of a shift diagram used for shift control. 3 is a flowchart showing the flow of mode switching determination processing.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<Vehicle drive system>
FIG. 1 is a skeleton diagram showing the configuration of a drive system of a vehicle 1. As shown in FIG.

The vehicle 1 is an automobile that uses an engine 2 as a driving source.

The power of the engine 2 is transmitted to a differential gear 5 via a torque converter 3 and a CVT (Continuously Variable Transmission) 4, and from the differential gear 5 left and right drive shafts 6L, 6R are transmitted. The signals are transmitted to the left and right drive wheels 7L and 7R, respectively.

The engine 2 includes an E/G output shaft 11. The E/G output shaft 11 is rotated by the power generated by the engine 2.

The torque converter 3 includes a front cover 21, a pump impeller 22, a turbine runner 23, and a lockup mechanism 24. The E/G output shaft 11 is connected to the front cover 21, and the front cover 21 rotates together with the E/G output shaft 11. The pump impeller 22 is arranged on the side opposite to the engine 2 side with respect to the front cover 21. The pump impeller 22 is provided to be rotatable integrally with the front cover 21. The turbine runner 23 is disposed between the front cover 21 and the pump impeller 22 and is rotatable about a common rotational axis with the front cover 21 .

The lockup mechanism 24 includes a lockup piston 25. Lockup piston 25 is provided between front cover 21 and turbine runner 23. The lock-up mechanism 24 is activated by the differential pressure between the oil pressure in the release oil chamber 26 between the lock-up piston 25 and the front cover 21 and the oil pressure in the engagement oil chamber 27 between the lock-up piston 25 and the pump impeller 22. Lockup is turned on (engaged)/off (released). That is, when the oil pressure in the release oil chamber 26 is higher than the oil pressure in the engagement oil chamber 27, the differential pressure causes the lockup piston 25 to separate from the front cover 21, and the lockup is turned off. When the oil pressure in the engagement oil chamber 27 is higher than the oil pressure in the release oil chamber 26, the lockup piston 25 is pressed against the front cover 21 due to the pressure difference, and the lockup piston 25 is turned on.

In the lock-up off state, when the E/G output shaft 11 is rotated, the pump impeller 22 is rotated. When the pump impeller 22 rotates, oil flows from the pump impeller 22 toward the turbine runner 23 . This oil flow is received by the turbine runner 23, and the turbine runner 23 rotates. At this time, an amplification effect of the torque converter 3 occurs, and a torque larger than the torque of the E/G output shaft 11 is generated in the turbine runner 23.

In the lockup-on state, when the E/G output shaft 11 is rotated, the E/G output shaft 11, the pump impeller 22, and the turbine runner 23 rotate together.

The CVT 4 is equipped with an input shaft 31 and an output shaft 32, and is configured to split the power input to the input shaft 31 into two paths and transmit it to the output shaft 32. ) is a transmission. In order to configure two power transmission paths, the CVT 4 includes a belt transmission mechanism 33, a front reduction gear mechanism 34, a planetary gear mechanism 35, and a split transmission mechanism 36.

The input shaft 31 is connected to the turbine runner 23 of the torque converter 3 and is provided so as to be rotatable integrally with the turbine runner 23 around the same rotational axis.

The output shaft 32 is provided parallel to the input shaft 31. An output gear 37 is supported on the output shaft 32 so as not to be relatively rotatable. The output gear 37 meshes with the differential gear 5 (the ring gear of the differential gear 5).

The belt transmission mechanism 33 has a configuration similar to that of a known belt-type continuously variable transmission (CVT). Specifically, the belt transmission mechanism 33 includes a primary shaft 41 , a secondary shaft 42 provided parallel to the primary shaft 41 , a primary pulley 43 supported by the primary shaft 41 so as not to be relatively rotatable, and a secondary shaft 42 . It includes a secondary pulley 44 that is supported so as not to rotate relative to each other, and a belt 45 that is wound around the primary pulley 43 and the secondary pulley 44.

The primary pulley 43 includes a fixed sheave 51 fixed to the primary shaft 41, and a movable sheave that is disposed opposite to the fixed sheave 51 with a belt 45 interposed therebetween, and is supported by the primary shaft 41 so as to be movable in its axial direction but not relatively rotatable. 52. A cylinder 53 fixed to the primary shaft 41 is provided on the opposite side of the movable sheave 52 from the fixed sheave 51, and an oil chamber 54 is formed between the movable sheave 52 and the cylinder 53.

The secondary pulley 44 includes a fixed sheave 55 fixed to the secondary shaft 42, and a movable sheave that is disposed opposite to the fixed sheave 55 with the belt 45 interposed therebetween, and is supported by the secondary shaft 42 so as to be movable in the axial direction and non-rotatably relative to the fixed sheave 55. 56. A cylinder 57 fixed to the secondary shaft 42 is provided on the opposite side of the movable sheave 56 from the fixed sheave 55, and an oil chamber 58 is formed between the movable sheave 56 and the cylinder 57. In the direction of the rotational axis, the positional relationship between the fixed sheave 55 and the movable sheave 56 is opposite to the positional relationship between the fixed sheave 51 and the movable sheave 52 of the primary pulley 43.

In the belt transmission mechanism 33, the oil pressures supplied to the oil chamber 54 of the primary pulley 43 and the oil chamber 58 of the secondary pulley 44 are controlled, and the groove widths of the primary pulley 43 and the secondary pulley 44 are changed. The belt speed ratio (pulley ratio) is continuously and steplessly changed.

The front reduction gear mechanism 34 is configured to reverse and decelerate the power input to the input shaft 31 and transmit it to the primary shaft 41. Specifically, the front reduction gear mechanism 34 includes an input shaft gear 61 that is supported by the input shaft 31 in a relatively non-rotatable manner, has a larger diameter and a larger number of teeth than the input shaft gear 61, and is spline-fitted to the primary shaft 41. The input shaft gear 62 includes a primary shaft gear 62 that is supported relatively unrotatably by and meshes with the input shaft gear 61.

The planetary gear mechanism 35 includes a sun gear 71, a carrier 72, and a ring gear 73. The sun gear 71 is supported by the secondary shaft 42 by spline fitting so that it cannot rotate relative to the secondary shaft 42 . The carrier 72 is externally fitted onto the output shaft 32 so as to be relatively rotatable. The carrier 72 rotatably supports a plurality of pinion gears 74. The plurality of pinion gears 74 are arranged on the circumference and mesh with the sun gear 71. The ring gear 73 has an annular shape that collectively surrounds the plurality of pinion gears 74, and meshes with each pinion gear 74 from the outside in the rotational radial direction of the secondary shaft 42. Further, the output shaft 32 is connected to the ring gear 73, and the ring gear 73 is provided so as to be rotatable integrally around the same rotational axis as the output shaft 32.

The split transmission mechanism 36 is a parallel shaft gear mechanism including a split drive gear 81 and a split driven gear 82 that meshes with the split drive gear 81.

The split drive gear 81 is externally fitted onto the input shaft 31 so as to be relatively rotatable.

The split driven gear 82 is provided so as to be rotatable integrally with the carrier 72 of the planetary gear mechanism 35 about the same rotation axis. The split driven gear 82 is formed to have a smaller diameter than the split drive gear 81 and has fewer teeth than the split drive gear 81.

Further, a parking gear 83 is supported on the output shaft 32 so as to be relatively unrotatable. A parking pole (not shown) is provided around the parking gear 83. When the parking pole engages with the tooth groove of the parking gear 83, the rotation of the parking gear 83 is restricted (parking lock), and when the parking pole disengages from the tooth groove of the parking gear 83, the rotation of the parking gear 83 is restricted. Allowed (parking unlocked).

Further, the CVT 4 includes clutches C1 and C2 and a brake B1.

The clutch C1 is switched by hydraulic pressure between an engaged state in which the input shaft 31 and the split drive gear 81 are directly coupled (coupled so as to be rotatable together), and a released state in which the direct coupling is released.

Clutch C2 is switched by hydraulic pressure between an engaged state in which the sun gear 71 and ring gear 73 of the planetary gear mechanism 35 are directly coupled (coupled so as to be rotatable together), and a released state in which the direct coupling is released.

The brake B1 is switched by hydraulic pressure between an engaged state in which the carrier 72 of the planetary gear mechanism 35 is braked and a released state in which the carrier 72 is allowed to rotate.

FIG. 2 is a diagram showing the states of the clutches C1, C2 and the brake B1 when the vehicle 1 moves forward and backward. FIG. 3 is a collinear chart showing the relationship among the rotational speeds (rotational speeds) of the sun gear 71, carrier 72, and ring gear 73 of the planetary gear mechanism 35. FIG. 4 is a diagram showing the relationship between the belt speed change ratio of the belt speed change mechanism 33 and the total speed change ratio of the CVT 4 as a whole.

In FIG. 2, "○" indicates that the clutches C1, C2 and the brake B1 are in an engaged state. "X" indicates that clutches C1, C2 and brake B1 are in a released state.

A shift lever (select lever) is provided in the cabin of the vehicle 1 at a position that can be operated by the driver. The movable range of the shift lever includes, for example, a P (parking) position, an R (reverse) position, an N (neutral) position, and a D (drive) position arranged in a line in this order.

When the shift lever is in the P position, all of the clutches C1, C2 and brake B1 are released, and the parking gear 83 is fixed, so that the P range (parking range), which is one of the shift ranges of the CVT 4, is set. configured. In addition, when the shift lever is in the N position, all clutches C1, C2 and brake B1 are released and the parking lock gear is not fixed. ) is configured. When both the clutch C1 and the brake B1 are released, the power of the engine 2 is transmitted to the secondary shaft 42 and the secondary shaft 42 rotates, but the sun gear 71 and pinion gear 74 of the planetary gear mechanism 35 idle, and the engine The power of No. 2 is not transmitted to the drive wheels 7L and 7R.

When the shift lever is located at the D position, a D range (forward range), which is one of the shift ranges of the CVT 4, is configured. The power transmission modes in the D range include a belt mode (an example of a first mode) and a split mode (an example of a second mode). The belt mode and the split mode are switched by switching between a state where the clutch C1 is engaged and a state where the clutch C2 is engaged (switching the clutches C1 and C2).

In belt mode, as shown in FIG. 2, clutch C1 and brake B1 are released and clutch C2 is engaged. As a result, the split drive gear 81 is separated from the input shaft 31, the carrier 72 of the planetary gear mechanism 35 becomes free (free rotation state), and the sun gear 71 and ring gear 73 of the planetary gear mechanism 35 are directly connected.

The power from the engine 2 input to the input shaft 31 is reversed and decelerated by the front reduction gear mechanism 34, and is transmitted to the primary shaft 41 of the belt transmission mechanism 33, causing the primary shaft 41 and the primary pulley 43 to rotate. The rotation of the primary pulley 43 is transmitted to the secondary pulley 44 via the belt 45, causing the secondary pulley 44 and the secondary shaft 42 to rotate. Since the sun gear 71 and ring gear 73 of the planetary gear mechanism 35 are directly connected, the sun gear 71, the ring gear 73, and the output shaft 32 rotate together with the secondary shaft 42. Therefore, in the belt mode, as shown in FIG. 3 and FIG. match the value multiplied by the number).

In the split mode, as shown in FIG. 2, clutch C1 is engaged and clutch C2 and brake B1 are released. As a result, the input shaft 31 and the split drive gear 81 are coupled, and the rotation of the input shaft 31 can be transmitted to the carrier 72 of the planetary gear mechanism 35 via the split drive gear 81 and the split driven gear 82. 35 sun gear 71 and ring gear 73 are separated.

The power from the engine 2 input to the input shaft 31 is increased in speed and transmitted from the split drive gear 81 to the carrier 72 of the planetary gear mechanism 35 via the split driven gear 82. The power transmitted to carrier 72 is divided and transmitted from carrier 72 to sun gear 71 and ring gear 73. The power of sun gear 71 is transmitted to primary shaft gear 62 via secondary shaft 42 , secondary pulley 44 , belt 45 , primary pulley 43 and primary shaft 41 , and from primary shaft gear 62 to input shaft gear 61 . Therefore, in the belt mode, the input shaft gear 61 becomes the driving gear and the primary shaft gear 62 becomes the driven gear, whereas in the split mode, the primary shaft gear 62 becomes the driving gear and the input shaft gear 61 becomes the driven gear. .

Since the gear ratio between the split drive gear 81 and the split driven gear 82 is constant and unchangeable (fixed), in the split mode, if the power input to the input shaft 31 is constant, the rotation of the carrier 72 of the planetary gear mechanism 35 is constant. is held at a constant speed. Therefore, when the belt gear ratio is increased, the rotation speed of the sun gear 71 of the planetary gear mechanism 35 decreases, so as shown by the broken line in FIG. goes up. As a result, in the split mode, as shown in FIG. 4, the larger the belt gear ratio of the belt transmission mechanism 33, the smaller the total gear ratio of the CVT 4 becomes. The ratio of the amount of change in the total gear ratio to the amount of change) is lower than that in the belt mode.

The engine driving force that rotates the output shaft 32 is transmitted to the differential gear 5 via the output gear 37, and from the differential gear 5 to the drive wheels 7L, 7R via the left and right drive shafts 6L, 6R. This causes the drive wheels 7L, 7R to rotate in the forward direction.

When the shift lever is in the R position, an R range (reverse range), which is one of the shift ranges of the CVT 4, is configured. In the R range, as shown in FIG. 2, clutches C1 and C2 are released and brake B1 is engaged. As a result, the split drive gear 81 is disconnected from the input shaft 31, the sun gear 71 and ring gear 73 of the planetary gear mechanism 35 are disconnected, and the carrier 72 of the planetary gear mechanism 35 is braked.

The power from the engine 2 that is input to the input shaft 31 is reversed and decelerated by the front reduction gear mechanism 34, and is transmitted to the primary shaft 41 of the belt transmission mechanism 33, and from the primary shaft 41 to the primary pulley 43, belt 45, and secondary It is transmitted to the secondary shaft 42 via the pulley 44, and rotates the sun gear 71 of the planetary gear mechanism 35 together with the secondary shaft 42. Since the carrier 72 of the planetary gear mechanism 35 is braked, when the sun gear 71 rotates, the ring gear 73 of the planetary gear mechanism 35 rotates in the opposite direction to the sun gear 71. The rotational direction of the ring gear 73 is opposite to the rotational direction of the ring gear 73 during forward movement (belt mode and split mode). Then, the output shaft 32 rotates together with the ring gear 73. The rotation of the output shaft 32 is transmitted to the differential gear 5 via the output gear 37, and from the differential gear 5 to the drive wheels 7L, 7R via the left and right drive shafts 6L, 6R. This causes the drive wheels 7L, 7R to rotate in the backward direction.

When the vehicle 1 is moving forward, the rotation speed of the sun gear 71 and the ring gear 73 match due to the direct connection between the sun gear 71 and the ring gear 73 of the planetary gear mechanism 35, whereas when the vehicle 1 is moving backward, the rotation speed of the sun gear 71 and the ring gear 73 are the same. Due to the configuration, the rotational speed of ring gear 73 is always lower than the rotational speed of sun gear 71. Therefore, in the R range, the gear ratio is larger than the maximum pulley ratio, and if the maximum pulley ratio is configured in the D and R ranges, the gear ratio will be larger when the vehicle 1 is traveling backwards than when moving forward. Therefore, the power output from the output shaft 32 increases.

<Vehicle control system>
FIG. 5 is a block diagram showing the configuration of the control system of the vehicle 1. As shown in FIG.

The vehicle 1 is equipped with a plurality of ECUs (Electronic Control Units). Each ECU includes a microcomputer (microcontroller unit), and the microcomputer includes, for example, a CPU, a nonvolatile memory such as a flash memory, and a volatile memory such as a DRAM (Dynamic Random Access Memory). The plurality of ECUs are connected to enable bidirectional communication using a CAN (Controller Area Network) communication protocol. FIG. 5 shows one ECU 91 among the plurality of ECUs.

Various sensors necessary for control are connected to the ECU 91, and detection signals from the connected sensors are input. For example, an accelerator sensor outputs a detection signal according to the amount of operation of the accelerator pedal, a vehicle speed sensor outputs a detection signal according to the speed of the vehicle 1, and an engine rotation sensor outputs a detection signal according to the rotation speed of the engine 2. etc. are connected to the ECU 91. In addition to the detection signals input from various sensors, information necessary for control is input to the ECU 91 from other ECUs.

The engine 2 is equipped with an electronic throttle valve 92 for adjusting the amount of intake air into the combustion chamber of the engine 2, a spark plug 93 for generating electric discharge in the combustion chamber, an alternator 94 for generating electricity by the rotation of the engine 2, and the like. It is provided. Furthermore, the engine 2 is equipped with an EGR (Exhaust Gas Recirculation) system. The EGR system is a system that recirculates a portion of exhaust gas discharged from the engine 2 to the engine 2. The EGR system includes an EGR valve 95 for adjusting the flow rate of exhaust gas in an EGR passage through which exhaust gas flows. The ECU 91 controls the operations of an electronic throttle valve 92, a spark plug 93, an alternator 94, and an EGR valve 95.

The unit including the torque converter 3 and CVT 4 is equipped with a hydraulic circuit 96 for supplying hydraulic pressure to each part. The ECU 91 controls various valves included in the hydraulic circuit 96 to control the speed change of the CVT 4 and the like.

Further, the vehicle 1 is equipped with an air conditioner (A/C) 97 that air-conditions the interior of the vehicle (vehicle interior), and the ECU 91 controls the operation of the air conditioner 97.

Note that the electronic throttle valve 92, the alternator 94, the EGR valve 95, the hydraulic circuit 96, and the air conditioner 97 may be controlled by cooperation of a plurality of ECUs including the ECU 91; for example, the electronic throttle valve 92, the spark plug 93 , the alternator 94 and the EGR valve 95 may be controlled by the engine ECU, the hydraulic circuit 96 may be controlled by the ECU 91, and the air conditioner 97 may be controlled by the air conditioner ECU.

<Shift control>
FIG. 6 is a diagram showing an example of a shift diagram used for shift control of the CVT 4. As shown in FIG.

The unit gear ratio of the CVT 4 is controlled by changing the belt gear ratio and engaging/releasing the clutches C1, C2 and brake B1 by the ECU 91. In the shift control for changing the unit gear ratio, a target rotation speed is set according to the accelerator opening degree and the vehicle speed based on the shift diagram. The shift diagram is a map that defines the relationship between the accelerator opening (Ap), the vehicle speed, and the target rotational speed, and is stored in the nonvolatile memory of the ECU 91. The accelerator opening degree is the ratio of the operation amount to the maximum operation amount of the accelerator pedal, and is determined from the detection signal of the accelerator sensor. The vehicle speed is calculated from the detection signal of the vehicle speed sensor. Once the target rotational speed is set, a target gear ratio is determined, which is the target of the unit gear ratio to match the rotational speed input to the input shaft 31 with the target rotational speed, and the belt gear ratio is determined according to the target gear ratio. Goals are set.

Thereafter, command values for the primary pressure, which is the hydraulic pressure supplied to the movable sheave 52 of the primary pulley 43, and the secondary pressure, which is the hydraulic pressure supplied to the movable sheave 56 of the secondary pulley 44, are set based on the target of the belt speed ratio. , based on each command value, the primary pressure and the secondary pressure are controlled so that the deviation between the target belt speed ratio and the actual belt speed ratio approaches zero. The actual belt speed ratio is determined by dividing the primary rotation speed by the secondary rotation speed.

In the speed change control, the unit speed ratio may be changed across the split point shown in FIG. 5, and in that case, switching between belt mode and split mode (hereinafter simply referred to as "mode switching") is involved. The split point is a point where the unit gear ratio does not change even if the belt mode and the split mode are switched, and the switching value, which is the belt gear ratio at the split point, is the gear ratio of the split drive gear 81 and the split driven gear 82. is equal to the split gear ratio.

Mode switching is achieved by switching engagement of clutches C1 and C2. That is, by controlling the oil pressure supplied to clutches C1 and C2, clutch C1 (on the engaged side) in the disengaged state is engaged, and clutch C2 (in the disengaged state) in the engaged state is released, thereby changing from the belt mode. Switch to split mode. Conversely, when the engaged clutch C1 (disengaged side) is released and the disengaged clutch C2 (engaged side) is engaged, the split mode is switched to the belt mode.

FIG. 7 is a flowchart showing the flow of mode switching determination processing in split mode.

In the split mode, the ECU 91 performs the mode switching determination process shown in FIG.

In the mode switching determination process, it is determined whether the target gear ratio is larger than the switching value (step S1). If the target gear ratio is less than or equal to the switching value (NO in step S1), it is determined to continue the split mode.

If the target gear ratio is larger than the switching value (YES in step S1), the required driving force is calculated according to the accelerator opening and vehicle speed. In order to calculate the required driving force, an engine torque characteristic line stored in the form of a map in the nonvolatile memory of the ECU 91 is referred to, and the engine torque corresponding to the accelerator opening degree and the engine rotation speed is determined. The accelerator opening degree is a value used to calculate the target gear ratio. The engine rotation speed is calculated from the detection signal of the engine rotation sensor. Furthermore, the torque ratio of the torque converter 3 is calculated from the engine rotation speed and the turbine rotation speed. The turbine rotation speed is the rotation speed of the turbine runner 23 of the torque converter 3, and is calculated from a detection signal of a turbine rotation sensor that outputs a pulse signal synchronized with the number of rotations of the turbine runner 23 (input shaft 31) as a detection signal. Then, the required driving force is calculated from the engine torque, the torque ratio of the torque converter 20, and the current unit gear ratio. Further, from the engine torque, the torque ratio of the torque converter 20, and the target gear ratio, the engine driving force transmitted from the engine 2 to the output shaft 32 in a state where the unit gear ratio matches the target gear ratio is calculated.

Further, the amount of increase in engine driving force due to assist control that increases the output of the engine 2 (hereinafter simply referred to as "driving force increase amount") is calculated. Control to increase the output of the engine 2 includes, for example, changing the electronic throttle characteristic that indicates the relationship between the accelerator opening and the throttle opening of the electronic throttle valve 92, advancing the ignition timing by electrical discharge of the spark plug 93, and changing the alternator. 94 (reducing the load due to power generation), stopping the operation of the EGR system by closing the EGR valve 95, stopping the operation of the air conditioner 97, etc.

Then, it is determined whether the amount of increase in driving force is greater than the value obtained by subtracting the engine driving force from the required driving force (step S2).

If the amount of increase in driving force is larger than the value obtained by subtracting the engine driving force from the required driving force (YES in step S2), the advantages and disadvantages of continuing the split mode are taken into consideration, and it is determined whether there is an advantage to continuing the split mode. A determination is made (step S3).

Since the split mode has better power transmission efficiency than the belt mode, an improvement in power transmission efficiency can be cited as a gain by continuing the split mode. However, depending on the duration of the split mode, fuel consumption may be greater if the split mode is continued than if the split mode is switched to the belt mode. Taking these advantages and disadvantages into consideration, specifically, based on the target rotation speed (target gear ratio), the time-integrated amount of fuel consumption when switching from split mode to belt mode is determined as the first time-integrated amount. Further, from the current unit gear ratio, the time-integrated amount of fuel consumption when the split mode is continued is determined as the second time-integrated amount. Furthermore, the time-integrated amount of fuel consumption that worsens by performing assist control to increase the output of the engine 2 is determined as a third time-integrated amount. Then, the magnitude of the value obtained by subtracting the second time integrated amount from the first time integrated amount is compared with the third time integrated amount, and the value obtained by subtracting the second time integrated amount from the first time integrated amount is the value obtained by subtracting the second time integrated amount from the first time integrated amount. If it is equal to or greater than the integrated amount, it is determined that the gain from continuing the split mode exceeds the loss, and there is an advantage to continuing the split mode. On the other hand, if the value obtained by subtracting the second time cumulative amount from the first time cumulative amount is less than the third time cumulative amount, the loss due to continuing the split mode is greater than the gain, and there is no benefit from continuing the split mode. It is judged that.

If there is a benefit to continuing the split mode (YES in step S3), it is determined to continue the split mode even if the target gear ratio is greater than the switching value.

On the other hand, if there is no benefit from continuing the split mode (NO in step S3), switching from the split mode to the belt mode is determined (step S4).

In the belt mode, if the target gear ratio is set to be less than or equal to the switching value, the belt mode is switched to the split mode, and if the target gear ratio is greater than the switching value, the belt mode is maintained.

<Effect>
As described above, in the shift control of the CVT4, the target gear ratio is set according to the accelerator opening (parameter according to the acceleration request) based on the shift diagram, and the unit gear ratio matches the target gear ratio. As such, the belt transmission ratio is changed.

In the belt mode, which is the first mode, when the target gear ratio is set to be less than or equal to the switching value, the belt mode is switched to the split mode, which is the second mode. In split mode, in principle, when a target gear ratio larger than the switching value is set, split mode is switched to belt mode, but the amount of increase in driving force due to assist control that increases the output of engine 2 is determined by the accelerator opening. If the value is greater than the value obtained by subtracting the engine driving force at the unit gear ratio that matches the target gear ratio from the corresponding requested driving force, and there is a benefit from continuing the split mode, a target gear ratio larger than the switching value is set. split mode is maintained even if

As a result, even if the required driving force increases due to an increase in acceleration request or running load, the split mode can be continued for a longer period of time than before. Therefore, the time during which the vehicle can run in split mode can be increased, and the fuel efficiency of the vehicle can be improved. Furthermore, it is possible to reduce the busy shift feeling caused by frequent switching between belt mode and split mode, and improve drivability.

Also, considering the advantages and disadvantages of continuing split mode, if there is an advantage to continuing split mode, split mode is maintained, and if there is no advantage to continuing split mode, split mode is switched to belt mode. By doing so, it is possible to suppress the loss that exceeds the gain due to the continuation of the split mode.

<Modified example>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other forms.

For example, as a loss (disadvantage) due to the continuation of split mode, there is also a loss such as insufficient power generation (insufficient battery voltage) due to suppression of power generation by the alternator 94, so if insufficient power generation occurs, split mode will not continue. In addition, the split mode may be switched to the belt mode.

In addition, although vehicle 1 is assumed to have adopted the FF system, it is also possible to adopt a 4WD (four-wheel-drive) system in which all front and rear wheels are drive wheels. good.

In the above-mentioned embodiment, a configuration was taken up in which power is transmitted by branching into the first power transmission path passing through the split transmission mechanism 36 and the second power transmission path passing through the belt transmission mechanism 33, but the split transmission mechanism 36 is not limited to a parallel shaft gear mechanism including the split drive gear 81 and the split driven gear 82, but may be a mechanism other than a gear mechanism such as a belt mechanism. When a belt mechanism is employed, the belt mechanism may have a fixed speed ratio or may have a variable speed ratio.

In addition, various design changes can be made to the above-described configuration within the scope of the claims.

1: Vehicle 2: Engine 7L, 7R: Front wheels (drive wheels)
31: Input shaft 32: Output shaft 33: Belt transmission mechanism (continuously variable transmission mechanism)
91: ECU (control device, target setting means, required driving force calculating means, engine driving force calculating means, mode switching means)

Claims (2)

A belt-type continuously variable transmission mechanism is provided between an input shaft into which power from the engine is input and an output shaft which outputs engine driving force to be transmitted to the drive wheels, and the belt speed ratio by the continuously variable transmission mechanism is A first mode in which the overall unit gear ratio between the input shaft and the output shaft increases as the belt gear ratio increases, and a second mode in which the unit gear ratio decreases as the belt gear ratio increases. For vehicles equipped with a continuously variable transmission configured such that the unit gear ratio does not change even if the first mode and the second mode are switched when the belt gear ratio is at a constant switching value. A control device,
parameter acquisition means for acquiring parameters according to an acceleration request for accelerating the vehicle;
A target rotation speed is set according to the parameter acquired by the parameter acquisition means based on a shift diagram defining a relationship between the parameter and the target rotation speed, and the rotation speed of the input shaft is set to the target rotation speed. target setting means for determining a gear ratio to match and setting the gear ratio to a target gear ratio that is a target of the unit gear ratio;
a required driving force calculation means for calculating a required driving force according to the parameter acquired by the parameter acquisition means;
engine driving force calculating means for calculating the engine driving force at the unit speed ratio that matches the target speed ratio set by the target setting means;
Driving force increase amount calculation means for calculating an increase amount of the engine driving force due to control to increase the output of the engine;
In the first mode, when the target gear ratio set by the target setting means is equal to or less than the switching value, the first mode is switched to the second mode, and in the second mode, the driving force increase amount is If the amount of increase calculated by the calculation means is larger than the value obtained by subtracting the engine driving force calculated by the engine driving force calculation means from the required driving force calculated by the required driving force calculation means, the target setting A control device comprising: mode switching means for continuing the second mode even if the target gear ratio set by the means is larger than the switching value. The mode switching means is configured such that, in the second mode, the increase amount calculated by the driving force increase amount calculation means is calculated by the engine driving force calculation means from the required driving force calculated by the required driving force calculation means. The control device according to claim 1, wherein the control device determines whether or not to continue the second mode by considering advantages and disadvantages of continuing the second mode when the engine driving force is greater than the value obtained by subtracting the engine driving force. .

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