JP2009255701A - Controller for power transmission mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise a temperature of a catalyst such that deterioration of mileage is suppressed to the utmost, for example, and to transmit a driving force necessary for traveling of a vehicle to driving wheels. <P>SOLUTION: An ECU (electronic control unit) 10 performs slip control to make a converter cover 26 and a facing 21b of a lockup piston 21a in a slipping state (a slip state). For example, when the catalyst temperature of the catalyst for purifying exhaust emission of an engine 1 is lower than the temperature that allows purification of the catalyst and when a temperature difference between the catalyst temperature and the temperature allowing the purification is larger than a prescribed temperature difference, the ECU 10 controls a torque converter 2 to increase a slip amount of a lockup clutch 21, and controls the torque converter 2 to release the lockup clutch 21, when the slip amount exceeds a prescribed slip amount. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technical field of a control device for a power transmission mechanism for controlling a power transmission mechanism (power train) including a torque converter that converts power such as torque for driving a vehicle, for example.

  As a power transmission mechanism of this type, a mechanism including a torque converter that mechanically connects an engine and a transmission via a fluid coupling such as oil is known. Further, a vehicle equipped with this type of power transmission mechanism is usually provided with a catalyst for purifying engine exhaust. The purification ability of the catalyst for purifying exhaust gas largely depends on the temperature of the catalyst, and the catalyst temperature is preferably equal to or higher than the activation temperature of the catalyst in order to improve the purification ability. For example, Patent Document 1 discloses a technique in which when the temperature of a catalyst is low, the rotational speed of the engine is increased by reducing the fastening force of the lockup clutch, and the temperature of the catalyst is increased by increasing the temperature of the exhaust gas. Yes.

  If the technique disclosed in Patent Document 1 is applied to a hybrid vehicle, the engine and the power transmission mechanism clutch are released and supplied from the motor on the assumption that the battery is sufficiently charged when the temperature of the catalyst is low. It is possible to drive the vehicle with only the driving force generated and raise the temperature of the catalyst by exhausting the engine in the idle state. In addition, for vehicles other than hybrid vehicles, that is, vehicles that travel using only the power generated by the engine as a driving force, it is possible to increase the engine load and increase the catalyst temperature when the vehicle is stopped.

  On the other hand, Patent Document 2 proposes a technique for improving fuel efficiency by prohibiting lock-up of a lock-up clutch, that is, engagement when raising the temperature of a catalyst.

JP-A-4-39460 JP 2004-36737 A

  However, according to the technique disclosed in Patent Document 1, it is possible to raise the temperature of the catalyst, but the fuel consumption is simply deteriorated, and it is difficult to efficiently generate power in the engine. There is a point. In addition, according to Patent Document 2, the temperature of the catalyst is increased only under a condition in which the load applied to the engine is low, such as when the vehicle is stopped or when the hybrid vehicle travels only with the power supplied from the motor. There is a problem that can not be. Therefore, when the load applied to the engine according to the operation by the driver is high (that is, a high load state), it is difficult to raise the temperature of the catalyst while suppressing deterioration of fuel consumption. is there.

  Further, simply increasing the engine speed by releasing the lock-up clutch causes a problem that the driving force transmitted from the power transmission mechanism to the drive wheels of the vehicle is insufficient.

  Therefore, the present invention has been made in view of the above problems and the like, for example, a power transmission mechanism that can increase the temperature of the catalyst so as not to deteriorate the fuel consumption as much as possible and transmit the driving force necessary for traveling of the vehicle to the driving wheels. It is an object of the present invention to provide a control device.

  In order to solve the above-described problems, a power transmission mechanism control device according to the present invention includes a torque converter having a lock-up clutch, and an engine connected to the input shaft of the torque converter and generating an engine power. A control device for a power transmission mechanism for controlling a transmission mechanism, wherein a catalyst temperature of a catalyst for purifying exhaust of the engine is lower than a purifiable temperature of the catalyst, and a temperature difference between the catalyst temperature and the purifiable temperature Is controlled to increase the slip amount of the lockup clutch when the temperature difference is larger than a predetermined temperature difference, and the lockup clutch is released when the slip amount exceeds the predetermined slip amount. First control means for controlling the torque converter, and the lockup clutch is released, and When the engine is in a high load state, the rate at which the driving force transmitted to the vehicle via the power transmission mechanism increases with respect to the throttle opening by adjusting the injection amount is suppressed. And a second control means for controlling the engine.

  According to the control device for a power transmission mechanism according to the present invention, the first control means is configured such that the catalyst temperature of the catalyst that purifies the exhaust of the engine is lower than the purifiable temperature of the catalyst, and the catalyst temperature and the purifiable temperature. The torque converter is controlled to increase the slip amount of the lockup clutch when the temperature difference is larger than a predetermined temperature difference. The purifiable temperature refers to the temperature at which the purification function of the catalyst begins to act, to a greater or lesser extent, and does not necessarily coincide with the activation temperature of the catalyst. The predetermined temperature difference is a temperature difference when the catalyst temperature is lower than the purifiable temperature to such an extent that the exhaust gas purifying action by the catalyst does not function, and the catalyst material or the environment where the power transmission mechanism is used. It can be set according to individual specific conditions such as temperature. Therefore, when the catalyst temperature is lower than the purifiable temperature of the catalyst and the temperature difference between the catalyst temperature and the purifiable temperature is larger than a predetermined temperature difference, the purifying action of the catalyst purifying the exhaust is completely functioning. It means no state.

  The lock-up clutch is an engagement means that can be switched between engagement and disengagement (that is, release) via a fluid coupling such as oil, and changes the oil pressure under the control of the first control means. Thus, the fastening state is changed, and the slip amount is changed. Therefore, the first control means controls the torque converter so as to increase the slip amount, more specifically, so that the engine speed increases as the slip amount increases.

  The first control means controls the torque converter so as to release the lockup clutch when the slip amount exceeds a predetermined slip amount. Thereby, the exhaust amount of exhaust can be increased, and the catalyst temperature can be increased by the thermal energy of the exhaust.

  More specifically, for example, when the lock-up clutch is disengaged and the engine is in a high load state, the second control means increases the amount of accelerator depression by the driver who drives the vehicle. When the driving force for driving the vehicle is set to a high level, the driving force transmitted to the vehicle via the power transmission mechanism increases with respect to the throttle opening by adjusting the injection amount. The engine is controlled so that the increasing rate is suppressed. Here, since the rotational speed of the engine has already increased under the control of the first control means, the driving force has increased compared to before the slip amount is increased. The second control means reduces the driving force compared to before increasing the slip amount when the driving force is increased, in other words, when the engine is in a high load state as the engine speed increases. For example, by setting the air-fuel ratio high (that is, in the A / F lean state) so that the rate of increase of the driving force with respect to the throttle opening is suppressed, the fuel consumption can be improved. Further, by making the A / F lean, the exhaust gas temperature rises and the catalyst temperature can be increased efficiently.

  Therefore, according to the control device for a power transmission mechanism according to the present invention, even when the engine is in a high load state, the driving force necessary for traveling of the vehicle is transmitted to the drive wheels, while the fuel consumption of the engine and the exhaust of the catalyst. Each of the purification actions can be improved.

  In one aspect of the power transmission mechanism control device according to the present invention, the second control means is configured to reduce the increase rate based on at least one of the engine speed and the throttle opening. May be controlled.

  According to this aspect, the load state applied to the engine can be specified by at least one of the engine speed and the throttle opening.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

  Embodiments of a control device for a power transmission mechanism according to the present invention will be described below with reference to the drawings.

<1: Configuration of power transmission mechanism and control device for power transmission mechanism>
First, a configuration of a power transmission mechanism (power train) 500 controlled by the power transmission mechanism control device according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic configuration diagram conceptually showing main components of the power transmission mechanism 500 together with the control device for the power transmission mechanism according to the present embodiment. In the present embodiment, a hybrid vehicle driven using an engine and a motor as a power source is taken as an example, but the control device for the power transmission mechanism according to the present invention is a vehicle other than the hybrid vehicle, more specifically, The present invention can also be applied to a vehicle driven using only the engine as a drive source.

  In FIG. 1, the power transmission mechanism 500 includes an engine 1, a motor generator MG, a torque converter 2, and an automatic transmission mechanism 3. The ECU 10 constitutes an example of the “control device for the power transmission mechanism” according to the present invention, and also serves as an example of each of the “first control means” and the “second control means” according to the present invention.

  The ECU 10 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and is an electronic device that controls the entire operation of the power transmission mechanism 500 and the hybrid vehicle equipped with the power transmission mechanism 500. Control unit. The ECU 100 is configured to be able to execute a control process of a power transmission mechanism 500 described later in accordance with a control program stored in a storage unit such as a ROM.

  The engine 1 and the motor generator MG correspond to the drive source of the hybrid vehicle and are connected in series with each other. The torque converter 2 and the automatic transmission mechanism 3 are connected to these drive sources. Specifically, engine 1 and motor generator MG are connected to the input shaft of torque converter 2. The output shaft of the torque converter 2 is connected to the input shaft of the automatic transmission mechanism 3. The output shaft 5 of the automatic transmission mechanism 3 is connected to drive wheels (not shown). Therefore, the power generated by the engine 1 and the motor generator MG is alternatively or jointly transmitted via the torque converter 2 and the automatic transmission mechanism 3 and transmitted to the drive wheels as the driving force of the hybrid vehicle.

  Further, when the accelerator pedal (not shown) is released during traveling and the vehicle decelerates, the driving force from the driving wheels is transmitted to the driving source via the automatic transmission mechanism 3 and the torque converter 2. At this time, a braking action by the friction torque of the engine 1 occurs, and power generation is performed by driving the motor generator MG. Since the motor generator MG is connected to the input shafts of the engine 1 and the torque converter 2, when the motor generator MG generates power, the motor generator MG is placed on the output shaft 1a of the engine 1 and the input shaft of the torque converter 2. More regenerative braking torque acts. Therefore, the ECU 10 can change the rotational speed of the engine 1 by controlling the motor generator MG.

  The engine 1 is a heat engine that generates power by burning fuel, and examples thereof include a gasoline engine and a diesel engine. The torque converter 2 is a kind of fluid type power transmission device having a function of transmitting power through oil. The torque converter 2 is configured to be able to fasten and release between the input shaft and the output shaft of the torque converter 2 by a lock-up clutch. In the state where the lock-up clutch is released, the driving force is transmitted between the driving source (engine 1 and motor generator MG) and the automatic transmission mechanism 3 via oil. In a state where the lockup clutch is engaged, the drive source and the automatic transmission mechanism 3 are directly connected, and the driving force from the drive source is directly transmitted to the automatic transmission mechanism 3. The hydraulic control device 4 is configured to be able to change the slip amount of the lockup clutch by adjusting the hydraulic pressure of the oil supplied to the torque converter 2 under the control of the ECU 10.

  An ECU (Electronic Control Unit) 10 includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like (not shown). Based on detection signals from various sensors, the engine 1, the motor generator MG, and the hydraulic pressure Each operation of the control device 4 is configured to be controllable.

  In FIG. 1, an arrow indicated by a one-dot chain line indicates a flow of a control signal supplied from the ECU 10. For example, ECU 10 detects the rotational speeds of engine 1 and motor generator MG based on detection signals from rotational speed sensors (not shown) provided in engine 1 and motor generator MG, respectively. The ECU 10 controls the operations of the motor generator MG and the hydraulic control device 4 based on these rotational speeds. In addition, the ECU 10 can control the operation of the engine 1 based on data acquired from a throttle opening sensor that detects the throttle opening.

  Next, the configuration of the torque converter 2 will be described with reference to FIG. FIG. 2 is a schematic diagram schematically showing the configuration of the torque converter. In FIG. 2, a solid line arrow and a broken line arrow without reference numerals indicate the flow of oil.

  The torque converter 2 includes a lockup clutch 21, a pump impeller 22, a turbine liner 23, and a stator 24 as main components. The lockup clutch 21 includes a lockup piston 21a having a facing 21b and a converter cover 26.

  Output shafts 1 a and Ma of engine 1 and motor generator MG are connected to input shaft 27 of torque converter 2. Therefore, the rotational speed of input shaft 27 of torque converter 2 matches the rotational speed of motor generator MG (motor rotational speed) and the rotational speed of engine 1 (engine rotational speed). The input shaft 27 of the torque converter 2 is connected to the pump impeller 22 via the converter cover 26. The output shaft 28 of the torque converter 2 is connected to the lockup piston 21 a and the turbine liner 23. The rotational speed of the output shaft 28 of the torque converter 2 matches the turbine rotational speed. The stator 24 has a one-way clutch 25 and has a torque amplification function.

  The release-side oil chamber 31 and the fastening-side oil chamber 32 are connected to the hydraulic control device 4 via a passage 33, and the oil goes back and forth in the passage 33. Based on the control signal from the ECU 10, the hydraulic control device 4 supplies the oil hydraulic pressure to the release-side oil chamber 31 between the converter cover 26 and the lockup piston 21 a and the fastening-side oil chamber 32 on the pump impeller 22 side. And adjust the oil pressure. Note that the passage 33 actually passes through the output shaft 28 of the torque converter 2, but in FIG. 2, for convenience of explanation, the passage 33 is illustrated independently of the output shaft 28.

  When the hydraulic control device 4 supplies the hydraulic pressure to the fastening side oil chamber 32, the hydraulic pressure is drained from the release side oil chamber 31. Therefore, the oil flows in the direction from the fastening side oil chamber 32 toward the release side oil chamber 31 as indicated by the broken line arrow. In this case, since the hydraulic pressure in the fastening side oil chamber 32 is larger than the hydraulic pressure in the release side oil chamber 31, the force in the direction indicated by the arrow AW1, that is, the force in the direction in which the lockup piston 21a is pressed against the converter cover 26. Works. That is, a force that increases the fastening force of the lockup clutch 21 is applied. This fastening force is proportional to the hydraulic pressure supplied to the fastening side oil chamber 32.

  When the hydraulic control device 4 supplies the hydraulic pressure to the release side oil chamber 31, the hydraulic pressure is drained from the fastening side oil chamber 32. Therefore, the oil flows in a direction from the release side oil chamber 31 toward the fastening side oil chamber 32 as indicated by a solid line arrow. In this case, the hydraulic pressure in the release-side oil chamber 31 is greater than the hydraulic pressure in the engagement-side oil chamber 32. Therefore, the force in the direction indicated by the arrow AW2, that is, the force in the direction in which the lockup piston 21a is pulled away from the converter cover 26. Works. That is, the force which weakens the fastening force of the lockup clutch 21 acts.

  Therefore, the ECU 10 can control the hydraulic pressure control device 4 to adjust the hydraulic pressure supplied to the release-side oil chamber 31 or the engagement-side oil chamber 32 and adjust the engagement force of the lockup clutch 21. More specifically, the ECU 10 controls the hydraulic pressure control device 4 to adjust the hydraulic pressure supplied to the release-side oil chamber 31 or the engagement-side oil chamber 32, whereby the oil pressure of the release-side oil chamber 31 and the engagement-side oil are adjusted. The magnitude relationship between the hydraulic pressure of the chamber 32 can be changed. Thereby, in addition to being able to realize the engaged state in which the lockup clutch 21 is engaged and the converter (non-engaged) state in which the lockup clutch 21 is released, the slip of the lockup clutch 21 can be realized. It is possible to adjust the amount.

  In the intermediate region between the engaged state and the converter state of the lockup clutch 21, the ECU 10 supplies a control signal to the hydraulic control device 4 to adjust the hydraulic pressure of the release side oil chamber 31 or the hydraulic pressure of the engagement side oil chamber 32. By doing so, slip control is performed in which the facing 21b of the lockup piston 21a and the converter cover 26 are slid (slip state). For example, the ECU 10 locks up when the catalyst temperature of the catalyst that purifies the exhaust of the engine 1 is lower than the purifiable temperature of the catalyst and the temperature difference between the catalyst temperature and the purifiable temperature is larger than a predetermined temperature difference. The torque converter 2 is controlled to increase the slip amount of the clutch 21, and the torque converter 2 is controlled to release the lockup clutch 21 when the slip amount exceeds a predetermined slip amount.

  Next, a detailed configuration of the engine 1 will be described with reference to FIG. FIG. 3 is a schematic diagram schematically showing the configuration of the engine 1. In the figure, the same reference numerals are given to the same portions as those in FIGS. 1 and 2, and the detailed description thereof is omitted.

  In FIG. 3, an engine 1 is a gasoline engine configured to function as a power source of a vehicle, and includes an intake pipe 206, a cylinder 201, an exhaust pipe 210, a compressor 41 and a turbine 42 that constitute a turbocharger, Fluctuating valve mechanism 110, throttle valve 214, surge tank 111, intake valve 203 and pressure sensor 225, air flow meter (hereinafter referred to as AFM) 303, three-way catalyst 223 which is an example of the “catalyst” of the present invention, and temperature A sensor 224 is provided, and is configured to be able to generate power under the control of the ECU 10.

  In FIG. 3, for convenience of explanation, only one cylinder of the engine 1 is shown, but the engine 1 is, for example, an in-line four-cylinder engine including four cylinders. A plurality of intake valves 203 and a plurality of exhaust valves 204 provided corresponding to each of the plurality of cylinders are configured such that a lift amount and a working angle (that is, a lift period) can be changed by a common variable valve mechanism 110. Has been.

  The intake pipe 206 and the surge tank 111 constitute an intake passage portion that takes air into the engine 1 from the outside. During operation of the engine 1, air taken in from the outside through the air cleaner 304 is taken into the engine 1 through the surge tank 111 and the intake pipe 206 at a flow rate corresponding to the opening degree of the throttle valve 214.

  The intake pipe 206 is controlled to communicate with the inside of the cylinder 201 by opening and closing the intake valve 203 during operation of the engine 1. That is, in the intake pipe 206, air sucked from the outside (that is, sucked air) and fuel injected from the injector 211 that is a fuel injection device are mixed (that is, an air-fuel mixture is formed), and the intake valve 203 is mixed. To be supplied to the cylinder 201.

  The accelerator position sensor 216 detects the amount of depression of the accelerator pedal 226 by the driver, that is, the accelerator opening. Whether or not the vehicle on which the engine 1 is mounted is requested to accelerate is determined based on the accelerator opening. The throttle valve motor 217 opens and closes the throttle valve 214 based on the depression amount of the accelerator 226.

  The surge tank 111 is shared by each cylinder as a part of an intake passage portion for supplying air, and distributes the air sent to each cylinder and suppresses fluctuations in pressure of the distributed air, that is, pulsation. The throttle position sensor 215 detects the throttle opening of the throttle valve 214.

  The cylinder 201 is configured so that the air-fuel mixture sent from the intake pipe 206 can be combusted by the spark plug 202 inside. Due to this combustion, the piston 205 reciprocates up and down in the cylinder 201. This reciprocating motion is converted into a rotational motion of the crankshaft 219. A vehicle on which the engine 1 is mounted is configured to be able to be driven by a driving force based on the rotational motion output from the engine 1. The crank position sensor 218 detects the rotation angle (ie, crank angle) of the crankshaft 219. The exhaust pipe 210 constitutes an exhaust passage portion that exhausts exhaust gas generated inside the cylinder 201 via the exhaust valve 204. The ECU 10 acquires data relating to the temperature of the three-way catalyst 223 measured by the temperature sensor 224 during the operation of the engine 1, that is, the catalyst temperature.

  The three-way catalyst 223 is disposed in the middle of the exhaust pipe 210 and can purify exhaust gas containing CO (carbon monoxide), HC (hydrocarbon), and NOx (nitrogen oxide) discharged from the engine 200. It is configured. The temperature sensor 224 measures the catalyst temperature of the three-way catalyst 223 during operation of the engine 1 and sends data relating to the measured catalyst temperature to the ECU 100.

  As will be described in detail later, according to the control method of the power transmission mechanism that can be executed by the ECU 100, the catalyst temperature of the three-way catalyst 223 is brought close to the purifiable temperature or is purified when the engine 1 is operating. Since the temperature can be raised above the possible temperature, it is possible to improve the purification capability of the three-way catalyst 223 that purifies the exhaust discharged from the engine 1.

  The variable valve mechanism 110 is, for example, a variable valve mechanism (VVT), and is configured to be able to change the valve characteristics of the intake valve 203 and the exhaust valve 204 under the control of the ECU 10. In addition, the variable valve mechanism 110 corresponds to each of a plurality of cylinders constituting the engine 1 by a drive unit 11 common to each cylinder such as a cam-by-wire (CambyWire) driven by an actuator or an electromagnetically driven valve. The lift amounts and operating angles of the plurality of intake valves 203 and the plurality of exhaust valves 204 provided in the above manner can be changed.

<2: Control method of power transmission mechanism>
Next, a method for controlling the power transmission mechanism 500 executed by the ECU 10 will be described with reference to FIGS. 4 to 7. FIG. 4 is a flowchart sequentially showing main processing routines of the control method of the power transmission mechanism according to the present embodiment. FIG. 5 is a schematic graph showing changes in the driving force output to the driving wheels of the vehicle via the power transmission mechanism with respect to the throttle opening. FIG. 6 is a graph schematically showing the amount of increase in load in the engine with respect to the throttle opening. FIG. 7 is a graph schematically showing the exhaust gas temperature in the engine 1 with respect to the air-fuel ratio.

  In FIG. 4, the ECU 10 acquires data on the catalyst temperature acquired by the temperature sensor 224 during the operation of the engine 1 (step S100). Next, the ECU 10 determines whether or not the catalyst temperature T of the three-way catalyst 223 that purifies the exhaust of the engine 1 is lower than the purifiable temperature T0 of the three-way catalyst 223 (step S110). When the catalyst temperature T is equal to or higher than the purifiable temperature T0, the process returns to step S100 again, and the ECU 10 executes the same process.

  When it is determined that the catalyst temperature T is lower than the purifiable temperature T0, the ECU 10 determines whether or not the temperature difference between the purifiable temperature T0 and the catalyst temperature T is greater than a predetermined temperature difference ΔT (step S120). The purifiable temperature T0 is a temperature at which the purifying function for purifying the exhaust gas by the three-way catalyst 223 to a greater or lesser extent and does not necessarily coincide with the activation temperature of the three-way catalyst 223. The predetermined temperature difference ΔT is a temperature difference when the catalyst temperature T is lower than the purifiable temperature T0 to such an extent that the exhaust purification action by the three-way catalyst 223 does not function, and the three-way catalyst material or power transmission It can be set according to individual specific conditions such as the temperature of the environment in which the mechanism 500 is used. Therefore, when the catalyst temperature T is lower than the purifiable temperature T0 and the temperature difference between the catalyst temperature T and the purifiable temperature T0 is larger than the predetermined temperature difference ΔT, the three-way catalyst 223 has a purifying action for purifying exhaust. When not functioning. When the temperature difference between the purifiable temperature T0 and the catalyst temperature T is equal to or less than the predetermined temperature difference ΔT, the process returns to step S100 again, and the ECU 10 performs the same process.

  When it is determined that the temperature difference between the purifiable temperature T0 and the catalyst temperature T is larger than the predetermined temperature difference ΔT, the ECU 10 controls the torque converter 2 so that the slip amount of the lockup clutch 21 increases (step S130). . More specifically, the ECU 10 controls the torque converter 2 so that the rotational speed of the engine 1 increases as the slip amount of the lockup clutch 21 increases.

  Next, the ECU 10 determines whether or not the slip amount S of the lockup clutch 21 exceeds a predetermined slip amount S0 (step S140). When it is determined that the slip amount S is equal to or less than the predetermined slip amount S0, the ECU 10 returns to step S100 again and sequentially executes the processing.

  When it is determined that the slip amount S of the lockup clutch 21 exceeds the predetermined slip amount S0, the ECU 10 controls the torque converter 2 to release the lockup clutch 21 (step S150). As a result, the amount of exhaust discharged from the engine 1 can be increased, and the catalyst temperature T can be increased by the thermal energy of the exhaust. Therefore, it is possible to enhance the purification action that the three-way catalyst 223 purifies the exhaust gas.

  Here, the rotational speed Ne of the engine 1 is higher than before the lock-up clutch 21 is released. Therefore, the operating state of the engine 1 is in a high load state in which a relatively high load is applied to the engine 1. More specifically, for example, as the amount of depression of the accelerator pedal 226 by the driver driving the hybrid vehicle increases, the driving force for driving the hybrid vehicle is set to a relatively high level. . That is, since the rotational speed Ne of the engine 1 has already increased under the control of the ECU 10, the driving force has increased compared to before increasing the slip amount.

  Next, the ECU 10 reads data relating to the throttle opening and the engine speed Ne via various sensors (step S160).

  Next, the ECU 10 determines whether or not the engine 1 is in a high load state (step S170). When the engine 1 is not in a high load state, the process returns to step S100 again, and the above-described processes are executed in order.

  When it is determined that the engine 1 is in a high load state, the ECU 10 reduces the increase rate at which the driving force transmitted to the hybrid vehicle via the power transmission mechanism 500 increases with respect to the throttle opening S. The engine 1 is controlled. More specifically, the ECU 10 specifies the load increase rate applied to the engine 1 based on at least one of the throttle opening S and the engine speed Ne (step S180) and corrects the load increase rate applied to the engine 1. (Step S190).

  By the processing of steps S180 and S190, the ECU 10 causes the slip amount when the driving force for driving the hybrid vehicle is increased, in other words, when the engine 1 is in a high load state as the engine speed Ne increases. For example, the air-fuel ratio is set high (that is, in the A / F lean state) so that the increase rate of the driving force with respect to the throttle opening S is reduced without reducing the driving force compared with before increasing S. The fuel consumption of the engine 1 can be increased.

  Here, the reason why the fuel efficiency can be improved while securing the driving force for driving the hybrid vehicle will be described in detail with reference to FIGS.

  In FIG. 5, a characteristic line L1 indicates the relationship between the throttle opening and the driving force before the load increase rate of the engine 1 is corrected. A characteristic line L2 indicates the relationship between the throttle opening and the driving force when the engine 1 is in a high load state. A characteristic line L3 indicates the relationship between the throttle opening and the driving force after the characteristic line L2 is corrected.

  As shown in FIG. 5, since the rotational speed Ne of the engine 1 is increased in step S130, the driving force is increased in the characteristic line L2 after increasing the slip amount compared to the characteristic line L1. However, in the characteristic line L2, as the rotational speed Ne of the engine 1 is increased compared to the characteristic line L1, the fuel consumption is deteriorated.

  Therefore, the ECU 10 corrects the characteristic line L2 to the characteristic line L3, thereby reducing the increase rate of the drive amount with respect to the throttle opening while maintaining the drive force at a higher level than before increasing the slip amount. More specifically, as shown in FIG. 6, the increase amount of the load applied to the engine 1 is reduced in the range of the throttle openings A to B.

  By such processing, the ECU 10 does not reduce the driving force as compared with before increasing the slip amount S, even when the engine 1 is in a high load state (the range of throttle opening A to B), and the air-fuel ratio. Can be set high (that is, in the A / F lean state), and fuel consumption can be improved.

  More specifically, as shown in FIG. 7, by setting the air-fuel ratio in the engine 1 to the A / F lean side, the engine 1 transmits the driving force necessary for traveling of the hybrid vehicle to the drive wheels. It is possible to improve both the fuel consumption and the exhaust gas purification effect of the catalyst. That is, when the amount of increase in the load applied to the engine is decreased by bringing A / F close to the stoichiometric air-fuel ratio, the exhaust gas temperature rises and the catalyst temperature can be raised.

It is the schematic block diagram which showed notionally the main structure of the said power transmission mechanism with the control apparatus of the power transmission mechanism which concerns on embodiment of this invention. It is the schematic diagram which showed the structure of the torque converter typically. It is the schematic diagram which showed the structure of the engine typically. 5 is a flowchart showing the main processing routine of the power transmission mechanism control method executed by the power transmission mechanism control device according to the present embodiment in order. It is the graph which showed the change of the driving force output to the driving wheel of a vehicle via a power transmission mechanism with respect to the throttle opening. It is the graph which showed the increase amount of the load in an engine typically with respect to throttle opening. 3 is a graph schematically showing exhaust gas temperature in an engine with respect to an air-fuel ratio.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 10 ... ECU, 2 ... Torque converter, 21 ... Lock-up clutch, 223 ... Three-way catalyst

Claims (2)

A control device for a power transmission mechanism for controlling a power transmission mechanism having a torque converter having a lock-up clutch and an engine connected to an input shaft of the torque converter and generating the power of the vehicle,
The slip amount of the lockup clutch when the catalyst temperature of the catalyst that purifies the exhaust of the engine is lower than the purifiable temperature of the catalyst and the temperature difference between the catalyst temperature and the purifiable temperature is larger than a predetermined temperature difference Controlling the torque converter so as to increase the torque converter, and controlling the torque converter so as to release the lock-up clutch when the slip amount exceeds a predetermined slip amount;
When the lock-up clutch is released and the engine is in a high load state, the driving force transmitted to the vehicle via the power transmission mechanism is adjusted with respect to the throttle opening by adjusting the injection amount. A control device for a power transmission mechanism, comprising: second control means for controlling the engine so that an increasing rate of increase is suppressed. 2. The power transmission according to claim 1, wherein the second control unit controls the engine so that the increase rate becomes smaller based on at least one of the engine speed and the throttle opening. Control device for the mechanism.

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