JP2013193519A - Hybrid vehicle controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a rotary electric machine and a battery.SOLUTION: A hybrid vehicle controller (100) for controlling a hybrid vehicle with an internal combustion engine (200), a first rotary electric machine (MG1), a differential mechanism (300), a second rotary electric machine (MG2) connected to a drive shaft (800) linking an axle, and a torque converter (400) interposed between the drive shaft and a power output shaft of the differential mechanism and having a lockup clutch (430). The hybrid vehicle controller includes a control means that controls the lockup clutch so that a torque capacity of the lockup clutch is an average value of a direct transmission torque transmitted from the internal combustion engine to the power output shaft when an engine speed in stopping the internal combustion engine belongs to a resonant frequency band of the internal combustion engine and so that the torque capacity is larger than the average value when the engine speed during stop control is less than a lower limit value of the resonant frequency band.

Description

  The present invention relates to a technical field of a control device for a hybrid vehicle that controls a hybrid vehicle including a torque converter having a lock-up clutch between a power output shaft of a differential rotation mechanism and a drive shaft connected to the axle.

  This type of hybrid vehicle is disclosed in Patent Document 1. According to the vehicle disclosed in Patent Document 1, in the configuration in which the internal combustion engine and the first and second rotating electric machines are connected to the rotating elements of the differential mechanism, the ring gear of the differential mechanism and the second rotating electric machine include A torque converter having a lock-up mechanism is interposed between the connected drive shafts. When the low vehicle speed and the high driving force are requested, the lockup in the lockup mechanism is released, and the torque converter is slid to amplify the engine torque of the internal combustion engine and transmit it to the drive shaft.

  Patent Document 2 proposes a technique for suppressing vibration transmission to the drive shaft by performing vibration suppression control in accordance with engine torque fluctuations using a rotating electrical machine.

JP 2008-239063 A JP 2004-222439 A

  By the way, in the vehicle disclosed in Patent Document 1, the lockup mechanism is engaged when the internal combustion engine is stopped. For this reason, in order to prevent the torque pulsation of the internal combustion engine from being transmitted to the drive shaft and perceived by the driver as vehicle vibration, the first rotating electrical machine that gives the engine stop torque is disclosed in Patent Document 2 above. It is necessary to supply the disclosed damping torque.

  For this reason, in this type of hybrid vehicle, the physique of the first rotating electrical machine that supplies the stop torque must be correspondingly large, and accordingly, the second rotating electrical machine that is connected to the first rotating electrical machine and the drive shaft. The size of the battery that supplies power to the electric machine must be increased. That is, the conventional hybrid vehicle described in the above patent document has a technical problem that it is difficult to reduce the size of the rotating electrical machine and the battery.

  The present invention has been made in view of the technical problems described above, and an object of the present invention is to provide a control device for a hybrid vehicle that can reduce the size of a rotating electrical machine and a battery.

  In order to solve the above-described problems, a control apparatus for a hybrid vehicle according to the present invention includes an internal combustion engine, a first rotating electrical machine, a first rotating element coupled to the first rotating electrical machine, and the internal combustion engine. A differential mechanism having a plurality of rotational elements capable of differential rotation with each other, including a second rotational element and a third rotational element coupled to the power output shaft, and a second rotation coupled to a drive shaft connected to the axle An electric machine, and a torque converter having a lock-up clutch that is interposed between the drive shaft and the power output shaft and capable of controlling torque capacity, and the stop torque supplied from the first rotating electric machine A hybrid vehicle control apparatus for controlling a hybrid vehicle in which the internal combustion engine is stopped, the specifying means for specifying the engine speed of the internal combustion engine, and the specification at the time of stop control of the internal combustion engine. When the engine speed is within the resonance band of the internal combustion engine, the lockup clutch is adjusted so that the torque capacity of the lockup clutch becomes an average value of direct torque transmitted from the internal combustion engine to the power output shaft. Control means for controlling the lock-up clutch so that the torque capacity is larger than the average value when the engine speed during the stop control is less than a lower limit value of the resonance band. (Claim 1).

  In the hybrid vehicle according to the present invention, a torque converter having a lockup clutch is interposed between a power output shaft (for example, a ring gear shaft) of the differential mechanism and a drive shaft mechanically connected to the axle. . This lock-up clutch is an engaging device that mechanically couples a pump impeller of a torque converter and a turbine runner to transmit power without passing through fluid (hydraulic oil). By controlling the hydraulic pressure, the engagement torque of the clutch can be varied stepwise or continuously. Due to this action of the lock-up clutch, the torque converter has an engaged state in which the pump impeller and the turbine runner are mechanically coupled, a released state in which they are released from each other, and an intermediate state (so-called state) , Half-clutch state or sliding state).

  A book in which the first rotating electrical machine, the internal combustion engine, and the power output shaft are coupled to the first, second, and third rotating elements (typically, sun gear, planetary carrier, and ring gear, respectively) of the differential mechanism. In the configuration of the hybrid vehicle according to the invention, the first rotating electrical machine bears a reaction torque corresponding to a part of the engine torque of the internal combustion engine determined according to the gear ratio of each rotating element, so that the gear of each rotating element is obtained. A part of the engine torque determined according to the ratio can be output as a direct torque to the power output shaft. On the other hand, a second rotary electric machine is connected to the drive shaft connected to the power output shaft via a torque converter, and the excess or deficiency of the drive shaft torque with respect to the required torque of the drive shaft is the second rotary electric machine. Compensated by powering or regenerating. As a result, the operating point of the internal combustion engine can usually be maintained as much as possible at the optimum fuel consumption operating point at which fuel consumption is minimized.

  By the way, during the stop control of the internal combustion engine that is appropriately performed according to the traveling conditions of the hybrid vehicle, the engine speed passes through a resonance band unique to the internal combustion engine in the process of decreasing the engine speed of the internal combustion engine. This resonance band may be a resonance band of a resonance system including the internal combustion engine, the damper, and the first rotating electric machine. Here, when the stop control is performed when the lock-up clutch is in the engaged state, the torque pulsation of the internal combustion engine that is noticeably generated at the time of low rotation is amplified especially during the period in which the engine speed passes through the resonance band. Is done. As a result, torque pulsation of the internal combustion engine is transmitted to the drive shaft via the power output shaft and the lock-up clutch, which causes vehicle vibration.

  From a practical point of view, the lock-up clutch is released in a limited situation such as being released to obtain a torque amplification effect by the torque converter at low vehicle speed and high load. At times, the lock-up clutch is in an engaged state. In particular, in a configuration in which the internal combustion engine and the first and second rotating electrical machines are connected to the drive shaft via a differential mechanism as in this type of hybrid vehicle, it is better that the loss during power transmission is small. Specifically, it is desirable that the power output shaft and the drive shaft of the differential mechanism are mechanically coupled. For this reason, the vehicle vibration at the time of stop control mentioned above may become a subject which should be solved.

  On the other hand, at the time of the stop control, the internal combustion engine can be stopped quickly, safely and accurately, so that the stop torque supplied from the first rotating electrical machine is preferably used. That is, after stopping the fuel injection, instead of waiting for the engine to stop by the course, the stop torque of the first rotating electrical machine is applied to the engine output shaft of the internal combustion engine using the power transmission action of the differential mechanism, The first rotating electrical machine is actively used to stop the internal combustion engine according to the stop characteristics. At this time, in order to apply the torque of the first rotating electrical machine to the internal combustion engine, it is necessary to bear a reaction force corresponding to the torque of the first rotating electrical machine at the power output shaft of the differential mechanism. For the purpose of reduction, when the lockup clutch is released, especially when the engine speed belongs to the resonance band, the stop control by the first rotating electrical machine is accurately performed due to the power transmission loss of the torque converter. Becomes difficult. Furthermore, in the hybrid vehicle, an engine stop request can be appropriately generated according to the vehicle traveling condition, in addition to the engine stop request due to the ignition off operation or the like. Therefore, on the other hand, restart requests of the internal combustion engine that is in the engine stop state may frequently occur. Of course, it is not uncommon for a restart request to occur during stop control. If the lockup clutch is shifted to the released state during stop control for the purpose of reducing vehicle vibration, it is difficult to quickly restart in such a situation.

  Here, as a method of suppressing the vehicle vibration during this type of stop control, it is conceivable to superimpose a damping torque as a component for suppressing torque pulsation on the stop torque of the first rotating electrical machine. However, because the vibration damping torque cancels out the torque pulsation of the internal combustion engine, it has a waveform that pulsates in the same way as the torque pulsation. The stop torque to be supplied from one rotating electric machine varies greatly. Therefore, when adopting such a configuration, the size of the first rotating electrical machine tends to be relatively large. If the physique of the first rotating electrical machine is increased, the physique of the battery is inevitably increased accordingly. As a result, it is disadvantageous in terms of vehicle cost and vehicle size.

  In response to such a problem, the hybrid vehicle control device according to the present invention has a resonance band (practically, an internal combustion engine, a damper, and a first rotating electrical machine) in which the engine speed of the internal combustion engine during stop control is unique to the internal combustion engine. The lockup clutch is controlled to the above-mentioned intermediate state by the control means, and its torque capacity is directly transmitted from the internal combustion engine to the power output shaft. It is controlled to the average value of torque. That is, the engine speed of the internal combustion engine to be controlled during stop control is borne by the engagement torque corresponding to the torque capacity of the lockup clutch.

  In addition, when supplementing the direct torque, after the fuel injection of the internal combustion engine during the stop control is stopped, the internal combustion engine is only physically moved under the control of the stop torque, and spontaneously accompanying the combustion of fuel. The engine torque is zero. Therefore, the “direct torque transmitted from the internal combustion engine to the power output shaft” does not appear at first glance. However, the stop torque supplied from the first rotating electrical machine acts on the engine output shaft of the internal combustion engine at a ratio corresponding to the gear ratio of the rotating element. From the power output shaft side, the stop torque of the internal combustion engine There is no change in receiving a part of it as direct torque.

  That is, the direct torque transmitted from the internal combustion engine to the power output shaft, which is referred to when controlling the torque capacity, is preferably the rotation of the first rotating electrical machine itself out of the stop torque supplied from the first rotating electrical machine. The torque excluding the inertia torque consumed by the change is converted into engine torque (torque acting on the rotating shaft of the second rotating element) according to the gear ratio of the rotating element, and further, direct torque acting on the power output shaft The 1st component torque formed by converting into can be included.

  On the other hand, in the process in which the internal combustion engine that is invited to the engine stop state by the stop torque follows the strokes of intake → compression → expansion → exhaust, the engine torque is caused by the pumping motion of the piston particularly from the compression stroke to the expansion stroke. , That is, torque pulsation occurs. The pulsating torque derived from this torque pulsation is also transmitted as a direct torque to the power output shaft in accordance with the gear ratio of the rotating element due to the nature of the differential mechanism (for convenience, this torque is expressed as a second component torque). ). That is, the direct torque according to the present invention is defined by the total value of the first component torque and the second component torque, and the average value means the first component torque as a preferred form.

  Of the direct torque transmitted to the power output shaft, the second component torque resulting from the above-described torque pulsation of the internal combustion engine has a particularly large amplitude in the resonance band, but the average value of the direct torque is a fluctuation component due to pulsation. Corresponds to the steady-state component removed, so that it does not fluctuate greatly. Further, if the torque capacity of the lock-up clutch is an average value of the direct torque, it is necessary and sufficient as a reaction torque that antagonizes the stop torque, and the internal combustion engine is stopped quickly and accurately according to a desired profile. There are no practical problems.

  On the other hand, a pulsation component having an amplitude exceeding the average value of the direct torque, that is, a pulsation component acting on the side of increasing the amplitude of the direct torque in the second component torque is absorbed by the torque converter, and Since it is buffered, it is not substantially transmitted to the drive shaft. That is, only the pulsation component below the average value of the direct torque, that is, the pulsation component acting on the side of reducing the amplitude of the direct torque among the second component torque is transmitted to the drive shaft side. Therefore, according to the hybrid vehicle control apparatus of the present invention, it is possible to suppress vehicle vibration caused by pulsating torque during stop control of the internal combustion engine.

  The “average value” according to the present invention is a concept encompassing the value of the direct torque subjected to a predetermined averaging process, and its practical aspect is ambiguous and is performed on the time axis. It is not necessarily limited to a simple average value. Further, since the control accuracy of the torque of the lockup clutch and the control accuracy of the torque of the first rotating electrical machine are different, it may be difficult to control the torque capacity to a strict average value. The average value according to the present invention is intended to encompass values that take this kind of realistic constraint into account, and is, for example, a value within a range defined by a certain tolerance for a strict average value. It may be.

  On the other hand, if the resonance speed is passed in the process of decreasing the engine speed, it is difficult for the torque pulsation of the internal combustion engine to manifest as vehicle vibration. In this case, it is better that the power loss between the power output shaft and the drive shaft is small. From this point, when the engine speed falls below the lower limit value of the resonance band, the control means sets the absolute value of the torque capacity of the lockup clutch in a binary, stepwise or continuous manner from the above average value. It becomes the composition which is greatly enlarged. In this way, in the process in which the absolute value of the stop torque to be supplied from the first rotating electrical machine decreases as the engine speed decreases, the relative rotational speed of the lockup clutch (the pump impeller and the turbine runner The differential rotation speed) is almost zero and no slipping occurs. Therefore, the engine speed immediately before the engine stop can be accurately estimated based on the rotation speeds of the first rotating electric machine and the second rotating electric machine, and the internal combustion engine can be stopped accurately (in short, without reverse rotation). To converge to zero rotation).

  In one aspect of the hybrid vehicle control device according to the present invention, the control means engages the lockup clutch when the engine speed during the stop control is less than a lower limit value of the resonance band ( Claim 2).

  According to this aspect, when the engine speed has decreased to a rotation region that is less than the lower limit value of the resonance band, the lockup clutch is engaged. When the lockup clutch is engaged, the power output shaft and the drive shaft are mechanically coupled, and the engine is stopped based on the rotational speed of the first rotating electrical machine and the rotational speed of the second rotating electrical machine. It is possible to accurately estimate the engine speed of the immediately preceding internal combustion engine. Therefore, it is possible to prevent the internal combustion engine from rotating reversely before and after the stop time due to the stop torque of the first rotating electrical machine.

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

1 is a schematic configuration diagram conceptually illustrating a configuration of a hybrid vehicle according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram conceptually showing a configuration of a hybrid drive device in the hybrid vehicle of FIG. 1. FIG. 3 is an operation collinear diagram when the engine is stopped in the hybrid drive device of FIG. 2. 3 is a flowchart of stop control executed in the hybrid vehicle of FIG. 1. It is explanatory drawing of the resonance band of the engine in the hybrid vehicle of FIG. 4 is a chart illustrating an hourly transition of the operating state of the hybrid drive device according to a comparative example to be used for comparison with the stop control of FIG. 3. FIG. 4 is a chart exemplifying a one-hour transition of the operating state of the hybrid drive device in the execution process of the stop control according to the effect of the stop control of FIG. 3.

<Embodiment of the Invention>
Embodiments of the present invention will be described below with reference to the drawings.

<Configuration of Embodiment>
First, with reference to FIG. 1, the structure of the hybrid vehicle 1 which concerns on one Embodiment of this invention is demonstrated. FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the hybrid vehicle 1.

  In FIG. 1, the hybrid vehicle 1 includes an ECU 100, a PCU (Power Control Unit) 11, a battery 12, an accelerator position sensor 13, a vehicle speed sensor 14, and a hybrid drive device 10 according to the present invention. It is.

  The ECU 100 is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM, and the like, and is configured to be able to control the operation of each part of the hybrid vehicle 1. It is an example of a “control device”. The ECU 100 is configured to be able to execute stop control described later according to a control program stored in the ROM.

  The ECU 100 is an integrated electronic control unit configured to function as an example of each of the “specifying unit” and the “control unit” according to the present invention, and all the operations related to these units are executed by the ECU 100. It is comprised so that. However, the physical, mechanical, and electrical configurations of each of the units according to the present invention are not limited to this. For example, each of these units includes a plurality of ECUs, various processing units, various controllers, a microcomputer device, and the like. It may be configured as various computer systems.

  The hybrid drive device 10 drives the hybrid vehicle 1 by supplying drive torque as drive force to the left axle DSL (corresponding to the left front wheel FL) and the right axle DSR (corresponding to the right front wheel FR), which are the axles of the hybrid vehicle 1. Drive unit. The detailed configuration of the hybrid drive device 10 will be described later. In the following description, the term “axle DS” will be used as appropriate to indicate the axle regardless of whether it is left or right.

  The PCU 11 converts the DC power extracted from the battery 12 into AC power and supplies it to a motor generator MG1 and a motor generator MG2, which will be described later, and also converts AC power generated by the motor generator MG1 and the motor generator MG2 into DC power. Including an inverter (not shown) configured to be supplied to the battery 12, and the power input / output between the battery 12 and each motor generator or the power input / output between the motor generators (ie, in this case, This is a control unit configured to be able to control power transfer between the motor generators without passing through the battery 12. The PCU 11 is electrically connected to the ECU 100, and its operation is controlled by the ECU 100.

  The battery 12 has a configuration in which a plurality (for example, several hundreds) of unit battery cells such as lithium ion battery cells are connected in series, and a power supply source related to power for powering the motor generator MG1 and the motor generator MG2. As a battery unit.

  The accelerator opening sensor 13 is a sensor configured to be able to detect an accelerator opening Ta as an operation amount of an accelerator pedal (not shown) of the hybrid vehicle 1. The accelerator opening sensor 13 is electrically connected to the ECU 100, and the detected accelerator opening Ta is referred to by the ECU 100 at a constant or indefinite period.

  The vehicle speed sensor 14 is a sensor configured to be able to detect the vehicle speed V of the hybrid vehicle 1. The vehicle speed sensor 14 is electrically connected to the ECU 100, and the detected vehicle speed V is referred to by the ECU 100 at a constant or indefinite period.

  Next, a detailed configuration of the hybrid drive apparatus 10 will be described with reference to FIG. FIG. 2 is a schematic configuration diagram conceptually showing the configuration of the hybrid drive apparatus 10. In the figure, the same reference numerals are given to the same portions as those in FIG. 1, and the description thereof will be omitted as appropriate.

  In FIG. 2, the hybrid drive apparatus 10 includes an engine 200, a power split mechanism 300, a motor generator MG1 (hereinafter abbreviated as “MG1” as appropriate), a motor generator MG2 (hereinafter abbreviated as “MG2” as appropriate), a torque converter. 400, an MG2 reduction mechanism 500, an input shaft 600, a ring gear shaft 700, and a drive shaft 800.

  The engine 200 is a gasoline engine that functions as a main power source of the hybrid vehicle 1 and is an example of the “internal combustion engine” according to the present invention. The engine 200 is a known gasoline engine, and a detailed configuration thereof is omitted here, but the engine torque Te that is the output power of the engine 200 is input to the input shaft of the power split mechanism 300 via a crankshaft (not shown). 600 is transmitted. Further, the crankshaft and the input shaft 600 are connected via a torsion damper TDP which is an elastic vibration control device.

  A crank position sensor (not shown) that can detect the crank angle θcr, which is the rotational phase of the crankshaft, is attached around the crankshaft. The crank position sensor is electrically connected to the ECU 100, and the detected crank angle θcr is always acquired by the ECU 100. Further, the ECU 100 can calculate the engine speed NE of the engine 200 by time-processing the acquired crank angle θcr. That is, when calculating the engine speed NE, the ECU 100 functions as an example of the “specifying means” according to the present invention.

  The engine 200 is merely an example of a practical aspect that can be adopted by the internal combustion engine according to the present invention. The practical aspect of the internal combustion engine according to the present invention is not limited to the engine 200, and various known engines can be employed. It is.

  Motor generator MG1 is a motor generator having a power running function that converts electrical energy into kinetic energy and a regeneration function that converts kinetic energy into electrical energy, and is an example of the “first rotating electrical machine” according to the present invention. is there.

  The motor generator MG2 is a motor generator that is an example of the “second rotating electrical machine” according to the present invention, which is larger than the motor generator MG1, and the power rotating electrical machine described above. It has a power running function that converts kinetic energy and a regenerative function that converts kinetic energy into electrical energy. Motor generators MG1 and MG2 are configured as synchronous motor generators, and have a configuration including, for example, a rotor having a plurality of permanent magnets on the outer peripheral surface and a stator wound with a three-phase coil that forms a rotating magnetic field. Of course, you may have another structure.

  The power split mechanism 300 is a planetary gear mechanism that is an example of the “differential mechanism” according to the present invention.

  The power split mechanism 300 includes a sun gear S1 as an example of the “first rotating element” according to the present invention provided in the center, and a “third rotation” according to the present invention provided concentrically around the outer periphery of the sun gear S1. The ring gear R1, which is another example of the “element”, a plurality of pinion gears (not shown) which are arranged between the sun gear S1 and the ring gear R1 and revolve around the outer periphery of the sun gear S1, and each of the pinion gears And a carrier C1 as another example of the “second rotating element” according to the present invention, which supports the rotating shaft.

  Sun gear S1 is a reaction force element for bearing reaction torque against engine torque Te, and is fixed to an output rotation shaft to which the rotor of motor generator MG1 is fixed. Therefore, the rotational speed of sun gear S1 is equivalent to MG1 rotational speed Nmg1, which is the rotational speed of motor generator MG1.

  The ring gear R1 is an output element of the power split mechanism 300, and is connected to a ring gear shaft 700, which is a power output shaft of the power split mechanism 300, in a manner sharing its rotational axis.

  As described above, the carrier C1 is connected to the input shaft 600 connected to the crankshaft of the engine 200 so as to share the rotation shaft thereof, and the rotation speed thereof is equal to the engine speed NE of the engine 200. Is equivalent.

  In the power split mechanism 300, the engine torque Te supplied from the engine 200 to the input shaft 600 under the above-described configuration is applied to the sun gear S1 and the ring gear R1 by the carrier C1 (with a gear ratio between the gears). It is possible to divide the power of the engine 200 into two systems. At this time, in order to make the operation of the power split mechanism 300 easy to understand, when the gear ratio ρ as the number of teeth of the sun gear S1 with respect to the number of teeth of the ring gear R1 is defined, the engine torque Te is applied from the engine 200 to the carrier C1. In this case, the torque Tes acting on the sun gear S1 is represented by the following equation (1), and the direct torque Ter appearing on the ring gear shaft 700 is represented by the following equation (2).

Tes = −Te × ρ / (1 + ρ) (1)
Ter = Te × 1 / (1 + ρ) (2)
The MG2 speed reduction mechanism 500 is a planetary planetary gear that includes sun gear S2, ring gear R2, pinion gear (not shown), and carrier C2 rotating elements interposed between a drive shaft 800 connected to the axle DS and the motor generator MG2. It is a gear mechanism. In MG2 reduction mechanism 500, sun gear S2 is fixed to the output rotation shaft fixed to the rotor of motor generator MG2. The carrier C2 is fixed to the outer case of the hybrid drive device 10 so as not to rotate. Further, the ring gear R2 is connected to the drive shaft 800. In such a configuration, MG2 reduction mechanism 500 can reduce and transmit rotation speed Nmg2 of motor generator MG2 to drive shaft 800 according to a reduction ratio determined according to the gear ratio of each rotation element (gear).

  The configuration of MG2 reduction mechanism 500 is only one form that can be adopted by a mechanism that reduces the rotation of motor generator MG2, and this type of reduction mechanism can have various forms in practice. Further, this type of reduction mechanism is not necessarily provided in the hybrid drive device. That is, motor generator MG2 may be directly connected to drive shaft 800.

  The torque converter 400 is a known fluid torque converter that includes a pump impeller 410, a turbine runner 420, and a lock-up clutch 430 and is an example of a “torque converter” according to the present invention.

  In torque converter 400, pump impeller 410, which is a driving side impeller accommodated in a case, is connected to ring gear shaft 700 that is a power output shaft of power split mechanism 300. Further, the turbine runner 420 which is a driven side impeller is connected to the drive shaft 800 of the hybrid drive device 10. When the turbine runner 420 and the pump impeller 410 are opposed to each other in a space filled with ATF (Automatic Transmission Fluid) that is hydraulic oil, they are in a released state where they are not engaged by the lock-up piston 430. The ATF is used as a power transmission medium for power transmission.

  The lock-up clutch 430 is a hydraulic engagement device as an example of the “lock-up clutch” according to the present invention, which includes a lock-up piston 431 and a hydraulic drive device 432.

  The lock-up piston 431 is a metal disk-like engaging member that is moved substantially integrally with the turbine runner 420 and driven according to the driving state of the hydraulic drive device 440. The lock-up piston 431 is configured to be able to be pressed against a case that houses the pump impeller 410 depending on the driving state of the hydraulic drive device 400. When the lock-up piston 431 is pressed against the case with a pressure equal to or higher than a predetermined value, the turbine runner 420 is pressed. And the pump impeller 410 can be mechanically connected.

  The hydraulic drive device 432 is a device that includes a lockup control valve that drives the lockup piston 431, a hydraulic chamber that controls the hydraulic pressure of the ATF, and the like. And the pressing force acting between the lock-up piston 431 and the case can be continuously changed. This pressing force is proportional to the torque capacity Ctlu of the lockup clutch 430 in the range less than the predetermined range. The hydraulic drive device 432 is electrically connected to the ECU 100, and the torque capacity Ctlu of the lockup clutch 430 is appropriately controlled by the ECU 100.

  The lock-up clutch 430 includes a release state in which the turbine runner 420 and the pump impeller 410 are released from each other, an engagement state in which the turbine runner 420 and the pump impeller 410 are directly connected to each other, and an intermediate state between these achieved by continuous control of the torque capacity. The half-clutch state as a state can be taken.

<Operation of Embodiment>
<Outline of stop control>
In the hybrid vehicle 1 according to the present embodiment, the ECU 100 executes stop control. The stop control is control for stopping the engine 200 in operation. Here, the reason why the stop control according to this embodiment is required will be described with reference to FIG. FIG. 3 is a collinear diagram of the hybrid drive apparatus 10 when the engine is stopped. In the figure, the same reference numerals are given to the same portions as those in FIG. 2, and the description thereof will be omitted as appropriate.

  In FIG. 3A, the vertical axis represents the rotation speed, and the horizontal axis represents the motor generator MG1 (uniquely sun gear S1), engine 200 (uniquely carrier C1), and ring gear shaft 700 in order from the left. (Uniquely ring gear R1), drive shaft 800, carrier C2 (fixed element) and motor generator MG2 are shown.

  Here, as a traveling state of the hybrid vehicle 1, a state in which the drive shaft 800 is rotating at a rotational speed corresponding to the illustrated operation point A is considered. Since MG2 reduction mechanism 500 is a differential mechanism with two degrees of freedom of rotation and carrier C2 is a fixed element, in this case, the rotational speed of motor generator MG2 is uniquely determined. That is, motor generator MG2 rotates at a rotation speed corresponding to illustrated operation point B.

  On the other hand, except for some operating conditions, the above-described lock-up clutch 430 is in an engaged state, and the ring gear shaft 700 and the drive shaft 800 which are the power output shafts of the power split mechanism 300 are mechanically coupled. Yes. For this reason, the rotational speed of the ring gear shaft 700 becomes equal to the rotational speed of the drive shaft 800. That is, the operating point of the ring gear shaft 700 is the illustrated operating point C.

  Here, consider an operating condition in which the engine speed NE of the engine 200 is equal to the rotational speed of the ring gear shaft 700. That is, it is assumed that the operating point of the engine 200 before the stop control is the illustrated operating point D. Since power split mechanism 300 is a differential mechanism with two degrees of freedom of rotation, when these two operating points are determined, the rotational speed of sun gear S1 that is one remaining rotation element is inevitably determined, and motor generator MG1 It operates at the illustrated operating point E.

  In such a state, it is assumed that the stop condition of the engine 200 is satisfied. Such a situation can occur in various ways when the hybrid vehicle 1 travels. For example, the hybrid vehicle 1 can travel only with the MG2 torque Tmg2 supplied from the motor generator MG2 to the drive shaft 800, that is, EV. (Electric Vehicle) A request to stop the engine 200 is generated when traveling is possible.

  When an engine stop request is generated, ECU 100 stops the fuel supply to engine 200 and supplies a stop torque from motor generator MG1 to control the rotational speed of engine 200. FIG. 3A illustrates the result of such stop control (see the thick broken line in the figure) and the state where the operating points of the motor generator MG1 and the engine 200 become the illustrated operating points F and G, respectively. The operating point G is an operating point corresponding to zero rotation speed, that is, the engine 200 is stopped.

  Here, torque pulsation occurs in the engine 200 in the process of the stop control. This torque pulsation is transmitted to the ring gear shaft 700 and the drive shaft 800, and as a result, is transmitted to the left and right wheels via the axle DS connected to the drive shaft 800, resulting in vehicle vibration.

  In order to prevent such vehicle vibration, in such a situation, vibration suppression torque is usually supplied from the motor generator MG1 in addition to the basic stop torque necessary for the original stop control (see the dotted oval frame in the figure). ). By supplying the stop torque obtained by adding the damping torque and the basic stop torque, torque pulsation when the engine 200 is stopped is suppressed without being transmitted to the drive shaft 800.

  However, since this damping torque is a torque having a pulsation waveform similar to the torque pulsation of engine 200, the amplitude of the stop torque supplied from motor generator MG1 is the case where only the basic stop torque is supplied as the stop torque. Compared to a large swing. As a result, in a configuration that requires such vibration damping torque, both motor generator MG1 and battery 12 are required to have a relatively large physique.

  On the other hand, the stop control according to the present embodiment is control for suppressing vehicle vibration without causing an increase in this kind of physique. An operation alignment chart related to the stop control of the present embodiment is shown in FIG.

  The essential point of the stop control according to the present embodiment is that the lock-up clutch 430 is in an intermediate state and mainly in a rotation region corresponding to a resonance band of a resonance system including the engine 200, the torsion damper TDP, and the motor generator MG1, and a rotation region below that. The torque capacity Ctlu is precisely controlled. When the lock-up clutch 430 is in the intermediate state, the lock-up piston 431 slides against a torque input having an amplitude greater than the torque capacity Ctlu at that time, and is not transmitted to the drive shaft 800. More specifically, the torque component exceeding the torque capacity Ctlu is attenuated by receiving the fluid buffer effect by the torque converter 400, and thus is not transmitted to the drive shaft 800 to the extent that it is actually manifested as vehicle vibration. .

  Therefore, according to the stop control according to the present embodiment, it is not necessary to supply the damping torque from the motor generator MG1, and only the basic stop torque needs to be supplied as the stop torque. As a result, it is not necessary to increase the size of the motor generator MG1 and the battery 12 described above, which is advantageous in terms of vehicle cost and vehicle size.

  If the lock-up clutch 430 is in the released state, the influence of the torque pulsation of the engine 200 is not transmitted to the drive shaft 800, but in the rotation region corresponding to the resonance band and the rotation region below it, Since it is desired to accurately control the engine speed NE of the engine 200, it is difficult to stop the engine speed according to a desired stop characteristic in a released state with transmission loss. For example, it is difficult to stop the engine 200 accurately at zero rotation. Further, if the lock-up clutch 430 is released when the restart request for the engine 200 is generated, the time required for the restart becomes longer, and it becomes difficult to accurately respond to the driver's request. . The stop control according to the present embodiment attenuates the influence of torque pulsation by the torque converter 400 while applying an appropriate torque reaction force to the ring gear shaft 700 and enabling the motor generator MG1 to control the rotation state of the engine 200. Is possible.

  Next, the general flow of stop control will be described with reference to FIG. FIG. 4 is a flowchart of the stop control. The stop control is a subroutine of the operation control of the hybrid vehicle 1 executed by the ECU 100, and is executed when a request for stopping the engine 200 is generated under various traveling conditions of the hybrid vehicle 1 (including the stop request described above). Control. Therefore, the state of the hybrid vehicle 1 at the time when the stop control is started is not uniquely defined.

  In FIG. 4, ECU 100 first sets a stop torque to be supplied from motor generator MG1 (step S110). As described above, this stop torque is a basic stop torque, and is set by referring to a basic stop torque map stored in the ROM in advance. The basic stop torque is set in consideration of an assumed engine friction, a target rotation rate, gear play (play), torsional rigidity of the torsion damper TDP, and the like.

  When the stop torque is set, ECU 100 determines whether or not engine speed NE is less than resonance band upper limit NEresul that defines the upper limit of the resonance band of engine 200 (step S120). When the engine speed NE is still higher than the resonance band (step S120: NO), the ECU 100 gradually decreases the torque capacity of the lockup clutch 430 (step S140).

  In this embodiment, the resonance band of the engine 200 is a resonance band of a resonance system including the engine 200, the torsion damper TDP, and the motor generator MG1, and is experimentally, empirically, or theoretically beforehand. The upper and lower limit values are obtained and stored as fixed values in the ROM.

  Here, the resonance band will be visually described with reference to FIG. FIG. 5 is a characteristic diagram of the resonance band of the engine 200.

  In FIG. 5, the resonance band is a hatched area B and is a rotation area sandwiched between the resonance band lower limit value NEresll and the resonance band upper limit value NEresul (NEresul> NEresll). A rotation region below the resonance band lower limit value NEresll is hereinafter appropriately expressed as a region A, and a rotation region higher than the resonance band upper limit value NEresul is hereinafter expressed as a region C as appropriate. In the stop control, the drive state of the lockup clutch 430 is made variable according to the rotation region to which the engine speed NE belongs.

  Returning to FIG. 4, step S140 is executed when the engine speed NE belongs to the region C. When the engine speed NE is in the region C on the higher rotation side than the resonance band, the torque pulsation of the engine 200 is not amplified by resonance, but the torque pulsation is easily manifested as vehicle vibration as the rotation decreases. Therefore, it is more convenient to allow some slippage with a certain torque capacity than to directly connect the drive shaft 800 and the ring gear shaft 700. Further, as will be described later, considering that the torque capacity is controlled to the average direct torque later, it is better to gradually decrease the torque capacity at this stage.

  However, in the stop control, the control when the engine speed NE is higher than the resonance band has a relatively high degree of freedom, and it is not always necessary to gradually decrease the torque capacity as in this embodiment. . Further, as described in various situations where the stop request is generated, there is a possibility that the stop request may be generated when the lock-up clutch 430 is in the released state. In such a case, the released state may be maintained. At least from the viewpoint of alleviating the influence of vehicle vibration due to torque pulsation, control in the rotation region below the resonance band upper limit value NEresul is more important, and in the region of higher rotation than the resonance band upper limit value NEresul, various forms are possible. Is acceptable. However, as described above, if the lock-up clutch 430 is in the released state, the controllability of the engine speed NE by the motor generator MG1 is deteriorated. Control equivalent to the capacity control (step S160) may be executed.

  When the engine speed NE is less than the resonance band upper limit value NEresul (step S120: YES), that is, when the engine speed NE enters the resonance band, the ECU 100 further determines that the engine speed NE is less than the resonance band lower limit value NEresll. It is determined whether or not (step S130).

  When the engine speed NE is equal to or greater than the resonance band lower limit value NEresll (step S130: NO), that is, when the engine speed NE belongs to the resonance band (rotation region B described above), the ECU 100 executes torque capacity control of the lockup clutch 430 ( Step S160). On the other hand, if the engine speed NE is less than the resonance band lower limit value NEresll in step S130 (step S130: NO), that is, if it belongs to the rotation region A described above, the ECU 100 puts the lockup clutch 430 in the engaged state. Control (step S150). Step S150 is an embodiment of the invention according to claim 2 in which the torque capacity is controlled to be equal to or greater than the average direct torque. When step S140, S150, or S160 is executed, the stop control ends. Since the stop control is a kind of subroutine as described above, the stop control is resumed from step S110 at a predetermined cycle while the stop control is not completed in the higher-level control even if the stop control is finished. Is done.

  Here, the details of the torque capacity control according to step S160 will be described. In the torque capacity control, the torque capacity Ctlu is maintained at an average direct torque Terave that is an average value of the direct torque Ter (this is an embodiment of the invention according to claim 1).

  The average direct torque Terave is an average value of the direct torque Ter, but no spontaneous engine torque is generated in the engine 200 in which the fuel supply is stopped. Accordingly, the direct torque Ter in this case is the first component torque Ter1 in which the torque acting on the engine 200 appears on the ring gear shaft 700 in accordance with the MG1 torque Tmg1 applied from the motor generator MG1 to the sun gear S1 (sun gear shaft). And the second component torque Ter2 resulting from the torque pulsation of the engine 200. Since the second component torque Ter2 is a pulsating torque, it can be treated as zero torque if averaged. Eventually, the average direct torque Terave can be treated equally with the first component torque Ter1.

  The average direct torque Terave (that is, in the present embodiment, the first component torque Ter1) is expressed by the following (1) and (2) by substituting Tes with MG1 torque Tmg1 that is the output torque of the motor generator MG1 ( 3) It is expressed as an equation.

Terave = | 1 / ρ × (Img1 × dωmg1 / dt−Tmg1) | (3)
In the above equation (3), Img1 is the moment of inertia of motor generator MG1, and dωmg1 / dt is the time differential value of time average value ωmg1 of MG1 rotation speed Nmg1. That is, the average direct torque Terave is a value obtained by excluding the inertia loss accompanying the rotation change of MG1 from the output torque Tmg1 (stop torque) of the motor generator MG1, and does not include a fluctuation component due to torque pulsation.

  Here, the effect of such torque capacity control will be described with reference to FIGS. Here, FIG. 6 relates to a comparative example to be used for comparison with the present embodiment, and exemplifies a temporal transition of the operating state of the hybrid drive device 10 when the vehicle vibration is suppressed by the above-described vibration damping torque. It is a chart. FIG. 7 is a chart illustrating an hourly transition of the operating state of the hybrid drive apparatus 10 in the stop control execution process according to the present embodiment. In each drawing, the same reference numerals are given to the same portions as those in the above-described drawings, and the description thereof is omitted as appropriate.

  6, in order from the top, MG1 torque Tmg1, torque capacity Ctlu of lock-up clutch 430, engine torque Te, engine speed NE, direct torque Ter, drive shaft direct torque Td appearing on drive shaft 800, torque converter differential rotational speed Each time transition of Ntc and vehicle vibration level is illustrated (that is, the horizontal axis is time). The torque converter differential rotation speed Ntc is a difference value between the rotation speeds of the pump impeller 410 and the turbine runner 420.

  Here, in the comparative example, that is, the configuration in which the vehicle vibration is caused by the above-described vibration damping torque, the lock-up clutch 430 is maintained in the engaged state even after the stop request generation time of the engine 200 (see Δ in the drawing). Therefore, the torque converter differential rotation speed Ntc is zero.

  After the stop request is generated, the engine speed NE of the engine 200 in which the fuel injection is stopped decreases due to inertia for a period of time. During this period, since the motor generator MG1 does not need to bear the reaction torque, the MG1 torque Tmg1 is zero. Since both the MG1 torque Tmg1 and the engine torque Te are zero, almost no direct torque acts on the ring gear shaft 700 and the drive shaft 800 during this period.

  On the other hand, when the engine speed NE passes through the resonance band as the engine speed NE decreases, stop torque including vibration damping torque having a pulsation waveform is supplied from the motor generator MG1 (see the broken line in the figure). . As a result, the direct torque Ter acting on the ring gear shaft 700 and the drive shaft direct torque Td acting on the drive shaft 800 are alleviated equally, and vehicle vibration caused by torque pulsation is suppressed.

  On the other hand, when the stop control according to this embodiment illustrated in FIG. 7 is executed, the torque capacity Ctlu of the lockup clutch 430 is directed toward Ctlu1 corresponding to the average direct torque Torave from the time when the engine stop request is generated. It is gradually reduced. Motor generator MG1 applies a stop torque from the time when the engine stop request is generated, and actively controls engine speed NE of engine 200. As a result, the engine speed NE is smoothly reduced as compared with the comparative example.

  Here, in the stop control according to the present embodiment, the component of the damping torque is not included in the MG1 torque Tmg1. Therefore, when the engine speed NE decreases and enters the resonance band indicated by hatching in the figure, the direct torque Ter acting on the ring gear shaft 700 pulsates due to the torque pulsation of the engine 200.

  However, in the stop control according to the present embodiment, the torque capacity Ctlu of the lock-up clutch 430 is maintained at Ctlu1 corresponding to the average direct torque Torave in this resonance band. That is, when the torque input exceeds the torque capacity Ctlu1, the lock-up piston 431 slips, and excess torque is absorbed by the torque converter 400 and relaxed. As a result, the torque converter differential rotation speed Ntc slightly varies in the resonance band, but a part of the pulsating torque generated in the ring gear shaft 700 is not transmitted to the drive shaft 800, and the pulsation of the drive shaft direct reaching torque Td is eliminated. Is suppressed. As a result, vehicle vibration is suppressed as in the comparative example.

  On the other hand, when the engine speed NE passes through the resonance band and enters the region A on the lower rotation side, the lockup clutch 430 is again engaged. When the lock-up clutch 430 is engaged, the ring gear shaft 700 and the drive shaft 800 are directly connected, which may be disadvantageous from the viewpoint of vehicle vibration suppression. However, in such an extremely low rotation region, the torque of the engine 200 The effect of pulsation is hardly manifested. Therefore, the vehicle vibration is not greatly deteriorated.

  Here, when the lock-up clutch 430 is in the engaged state in the region A on the lower rotation side than the resonance band, the torque capacity Ctlu is maintained at the average direct torque Torave that decreases as the engine speed NE decreases. In comparison, slipping of the lockup clutch 430 can be avoided. Therefore, the engine speed NE of the engine 200 can be accurately estimated from the MG1 rotational speed Nmg1 and the MG2 rotational speed Nmg2 based on the physical characteristics of the power transmission mechanism 300.

  Therefore, when the stop torque is supplied from motor generator MG1, engine speed NE can be accurately controlled so that engine 200 does not enter a reverse rotation state. Here, the lock-up clutch 430 is returned to the engaged state after passing through the resonance band. However, if the torque capacity Ctlu is maintained at a value equal to or greater than the average direct torque Torave equivalent value Ctlu1, substantially the same effect can be obtained. I can do it.

  As described above, according to the stop control according to the present embodiment, the torque capacity Ctlu of the lockup clutch 430 in the torque converter 400 is accurately controlled without increasing the physics of the MG1 and the battery 12 (damping torque). The vehicle vibration caused by the torque pulsation of the engine 200 can be suppressed.

  Further, since the lockup clutch 430 does not take the released state during the stop control, when the restart request of the engine 200 is made, the engine 200 is operated more quickly than when the lockup clutch 430 is released. It can be restarted.

  Further, since the lock-up clutch 430 maintains the torque capacity in the rotation region corresponding to the resonance band (region B) and the region A less than the resonance band lower limit value NEresll, the reaction force torque of the MG1 torque is generated by the ring gear shaft 700. The engine speed NE can be controlled by the motor generator MG1. Therefore, the engine speed NE can be reduced with a desired reduction characteristic during the stop control, and in particular, the engine 200 can be stopped very well without causing reverse rotation.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and control of a hybrid vehicle involving such a change. The apparatus is also included in the technical scope of the present invention.

  The present invention is applicable to stop control of an internal combustion engine in a hybrid vehicle including a torque converter having a lockup clutch between a power output shaft and a drive shaft of the internal combustion engine.

  DESCRIPTION OF SYMBOLS 1 ... Hybrid vehicle, 10 ... Hybrid drive device, 100 ... ECU, 200 ... Engine, 300 ... Power split mechanism, 400 ... Torque converter, 500 ... MG1 reduction mechanism, 600 ... Input shaft, 700 ... Ring gear shaft, 800 ... Drive axis.

Claims (2)

An internal combustion engine;
A first rotating electrical machine;
A plurality of rotations capable of differential rotation with each other, including a first rotating element connected to the first rotating electrical machine, a second rotating element connected to the internal combustion engine, and a third rotating element connected to a power output shaft. A differential mechanism with elements;
A second rotating electrical machine connected to a drive shaft connected to the axle;
A torque converter having a lock-up clutch that is interposed between the drive shaft and the power output shaft and capable of controlling torque capacity;
A hybrid vehicle control device that controls a hybrid vehicle in which the internal combustion engine is stopped by a stop torque supplied from the first rotating electrical machine,
Specifying means for specifying the engine speed of the internal combustion engine;
When the specified engine speed at the time of stop control of the internal combustion engine belongs to the resonance band of the internal combustion engine, the torque capacity of the lockup clutch is a direct torque transmitted from the internal combustion engine to the power output shaft. The lockup clutch is controlled to be an average value, and when the engine speed during the stop control is less than a lower limit value of the resonance band, the torque capacity is set to be larger than the average value. And a control means for controlling the lock-up clutch. 2. The control device for a hybrid vehicle according to claim 1, wherein the control unit engages the lockup clutch when the engine speed during the stop control is less than a lower limit value of the resonance band. .

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