JP5447073B2 - Vehicle drive control device - Google Patents

Description

  The technology disclosed herein relates to a drive control apparatus for a hybrid vehicle that includes an electric motor and an engine, and that can be driven while switching between the driving thereof, and more particularly, to control when starting an engine that is stopped while the vehicle is running. Related.

  In recent years, a hybrid vehicle including an engine and an electric motor as a driving source of the vehicle is becoming widespread (see, for example, Patent Document 1). In such a hybrid vehicle, as described in Patent Document 1, a motor travel region where the engine is stopped and the vehicle is driven by driving the electric motor, and an engine drive where the electric motor is stopped and the engine is driven by driving the engine. When the vehicle is traveling, the driving region is switched based on the driving state of the vehicle determined by, for example, the vehicle speed and the accelerator opening, and the electric motor is driven and stopped, and the engine The driving and stopping of each are switched.

JP 2009-143264 A

  As described above, in the hybrid vehicle, since the travel region is switched, the engine stop and start are frequently repeated while the vehicle is traveling. For example, the hybrid vehicle described in Patent Document 1 includes an integrated starter generator (ISG) that integrates a starter and an alternator, and a CISG (Crank Integrated Starter Generator) that is directly connected to a crankshaft (hereinafter collectively referred to simply as “ When the engine is started while the vehicle is running, the engine is started by driving the starter.

  However, as described above, in the hybrid vehicle, the starter is frequently operated because the engine is frequently started while the vehicle is running. This can lead to inconveniences such as an increase in the size of the starter and a decrease in its life. In addition, restarting the engine using a starter has a disadvantage that the starting time becomes longer.

  The technology disclosed herein has been made in view of the above points, and the object of the technology is to start a running engine without using a starter in a hybrid vehicle and to stably start the engine. It is to be performed in a short time.

The technology disclosed herein, as a technique capable of performing without using the starter to start the engine in a short time, while utilizing the combustion start, reliably and, in order to realize a short time starting, during running Torque from the wheels of the vehicle is transmitted to the engine and used as assist torque when starting the engine.

  In addition, in the vehicle drive control device disclosed herein, the operation of the fluid transmission device is combined by combining the operation of the lockup clutch in the fluid transmission device with the lockup clutch disposed between the engine and the automatic transmission. By suppressing or avoiding the effect of slipping, an engine torque of a desired magnitude is applied to the engine even at a low vehicle speed, thereby realizing a reliable and short-time engine start.

  Specifically, a vehicle drive control device disclosed herein includes a multi-cylinder engine mounted on a vehicle, an automatic transmission that is connected to the engine and drives drive wheels, and without the automatic transmission. Between the electric motor that drives the drive wheel, a fluid transmission device with a lock-up clutch that performs torque transmission between the engine and the automatic transmission, and between the engine and the drive wheel And a controller for controlling the engine, the automatic transmission, the electric motor, the lock-up clutch, and the intermittent means so as to interrupt the torque.

The controller is configured to drive the driving wheels while switching between driving of the engine and the electric motor while the vehicle is traveling, and stops the engine while the vehicle is traveling. sometimes, the opening of the lock-up clutch and disconnecting means, respectively, said controller also during running of the vehicle, when the start condition of the engine is stopped is satisfied, and executes the combustion starting before SL engine When starting combustion of the engine, the lock-up clutch is operated, and then the engine is started in accordance with the timing at which torque is applied to the engine from the drive wheel side by fastening of the intermittent means. .

In addition, the vehicle drive control device further includes vehicle speed detection means for detecting the vehicle speed of the vehicle, and the controller operates the lockup clutch with a predetermined slip amount when starting combustion of the engine. The slip amount of the lock-up clutch is set to be larger as the detected vehicle speed is higher.

  Here, the “automatic transmission” may include both a multi-stage transmission including a gear transmission mechanism and a continuously variable transmission including a belt transmission mechanism, for example. The “fluid transmission device for transmitting torque via fluid” may include a torque converter, a fluid coupling, and the like. Further, the “driving wheel” may be either a front wheel or a rear wheel, and the driving wheel to which the engine applies driving force and the driving wheel to which the electric motor applies driving force may be the same. It may be good or different.

  Further, the “interruption means” is a means capable of switching the torque between the engine and the wheel, and may be, for example, a clutch element arranged on a torque transmission path between the engine and the wheel. Further, when the automatic transmission is a multi-stage automatic transmission including a gear transmission mechanism, a plurality of frictional engagement elements (including a clutch element and a brake element) included in the gear transmission mechanism are used. The intermittent means may be configured. That is, in general, the multi-stage gear transmission mechanism realizes each gear stage by driving at least two frictional engagement elements selected from a plurality of frictional engagement elements (drive state). That is, torque transmission is connected. On the other hand, when such an engagement is not performed, the rotation state (neutral state) occurs and torque transmission is not performed. In other words, this is equivalent to interrupting torque transmission.

  Therefore, an intermittent means for switching between connection and disconnection of torque transmission between the engine and the wheels may be configured by switching between opening and closing of each frictional engagement element included in the gear transmission mechanism.

  When the intermittent means is configured using the frictional engagement element in the automatic transmission, it is more preferable to adopt the following configuration from the viewpoint of torque intermittent response. In other words, as described above, in order to realize a predetermined shift stage in a multi-stage gear transmission mechanism, that is, to realize a connection state of torque transmission, it is necessary to fasten at least two frictional engagement elements. When any one of the frictional fastening elements that need to be fastened is not fastened and all the remaining fastening elements are fastened, the torque is cut off. On the other hand, from the shut-off state, it is possible to shift from the neutral state to the drive state and to switch to the torque transmission connection state by merely fastening one fastening element that has not been fastened. This means that, for example, the torque transmission can be switched from a shut-off state to a connected state with high responsiveness without increasing the size of the hydraulic pump. It is extremely effective in that the behavior after the engine starts can be made smooth by making it coincide with the speed required after starting the engine.

According to the arrangement, during running of the vehicle, when the start condition of the engine is stopped is satisfied, executes the combustion starting the engine. By not using the starter for starting the engine in this way, all the various inconveniences that may occur due to frequent use of the starter can be eliminated.

  In addition, although the above-described combustion start can be performed generally stably and in a short time, depending on the conditions, the start time of the engine may become long or the start may become unstable. Therefore, in the above configuration, when starting combustion of the engine, the assist torque from the drive wheel side is applied to the engine by fastening the intermittent means. The application of the assist torque greatly contributes to shortening the start time and stabilizing the start in engine combustion start. Further, when the assist torque is applied, the influence of slippage of the fluid transmission device can be suppressed or eliminated by operating the lock-up clutch. This means that an assist torque of a desired magnitude can be applied to the engine even when the vehicle is at a low vehicle speed.

Further, it is desirable that the assist torque to be applied to the engine is applied in synchronization with the start of the engine start. However, in the above configuration, the lock-up clutch having a relatively low response is first operated, and then Torque from the drive wheel side is applied to the engine by fastening the intermittent means. In other words, the assist torque is applied to the engine at an appropriate timing by matching the timing at which the assist torque is applied and the engine start timing by the fastening control of the intermittent means that is relatively easy to adjust the timing. Further, it is possible to further accelerate the shortening and ensuring of the engine start time.

Also, run the vehicle in a row, although the torque shock due to be transmitted torque from the driving wheel side to the engine by fastening intermittent means may occur, a torque shock by operating the lock-up clutch at a predetermined slip amount It can be mitigated or avoided.

Here, due to the relationship between the gear ratio of the automatic transmission and the vehicle speed, it is applied from the drive wheel side to the engine side in a state where the lock-up clutch is not engaged (in other words, including a slip of the fluid transmission mechanism). The size of assist torque that can be determined is determined. That is, the magnitude of the assist torque increases as the vehicle speed increases at the same gear ratio, and increases as the gear ratio increases at the same vehicle speed. For this reason, for example, depending on the combination of the vehicle speed and the gear ratio, the obtained assist torque may be less than the magnitude of torque necessary for assisting the engine. In that case, the desired assist torque can be ensured by increasing the assist torque by combining the operation of the lock-up clutch as described above and suppressing or eliminating slippage of the fluid transmission mechanism. On the other hand, when the obtained assist torque can sufficiently secure the torque required for assisting the engine, the torque shock can be mitigated by performing non-engagement or slip control of the lock-up clutch as described above. .

When the vehicle speed is high, a relatively large assist torque can be obtained even if the gear ratio is low (even at a high gear). Therefore, in the above configuration, the higher the vehicle speed detected by the vehicle speed detection means, the higher the lockup clutch. Give priority to alleviating torque shock by increasing the slip amount. In other words, since it is difficult to obtain a large assist torque at a low vehicle speed, priority is given to securing the assist torque by reducing the slip amount of the lockup clutch.

The vehicle drive control device further includes a traveling state detection unit that detects a traveling state of the vehicle, and the controller is configured to detect the traveling state of the automatic transmission according to the detected traveling state when starting combustion of the engine. which controls the transmission ratio, have row control of the lock-up clutch, the controller, while fastening the lock-up clutch, when the desired assist torque for starting the engine can not be obtained, the The transmission ratio of the automatic transmission may be changed to be larger than the transmission ratio set according to the traveling state .

  Here, as one of the “running state of the vehicle”, the vehicle speed can be exemplified. For example, when the engine is started for combustion and then the vehicle is driven by the engine (for example, the engine is driven), the speed change ratio of the automatic transmission is determined based on the vehicle speed and the accelerator opening. May be set in advance to the required gear ratio. At this time, as described above, when the automatic transmission is a multi-stage automatic transmission composed of a gear transmission mechanism, at least two frictions necessary for realizing the speed ratio (speed stage) required after the engine is started. Other frictional engagement elements except for one of the engagement elements may be in the engaged state.

When the low vehicle speed as described above, a large assist torque is difficulty pile obtained. Therefore, for example, when the very low vehicle speed, when even enters into the lock-up clutch so as not to obtain desired assist torque is further increased the speed ratio of the automatic transmission (gear position, lower Change to gear). Thus, an increase in the assist torque is achieved.

  When starting combustion of the engine, the controller supplies fuel to the cylinders in the compression stroke, performs ignition and combustion, and once operates the engine in the reverse rotation direction, and then compresses with the reverse rotation operation. The engine may be started by applying a torque in the normal rotation direction to the engine by performing ignition and combustion on the expansion stroke cylinder.

In other words, the combustion start of the engine can be restarted as it is by forwardly supplying the fuel to the expansion stroke cylinder, igniting and burning, but in addition to this , the startability of the engine is improved. In the above, reverse combustion start is also possible , in which the engine is operated once in reverse, thereby compressing the expansion stroke cylinder when stopped, and then igniting and burning, whereby the engine is rotated forward and restarted. In this case, it is desirable to match the timing at which torque is applied to the engine from the drive wheel side by fastening the intermittent means, and the ignition and combustion start timing for the expansion stroke cylinder.

As described above, according to the vehicle drive control device described above, when starting a stopped engine while the vehicle is running, it is caused by frequent use of the starter by performing so-called combustion start. All of the various inconveniences can be eliminated, and at the time of combustion start, assist torque from the drive wheel side is applied to the engine by fastening the intermittent means, thereby further shortening the engine start time and starting Is stabilized. In addition, by combining the operation of the lock-up clutch, the influence of slippage of the fluid transmission device can be suppressed or eliminated, and a desired amount of assist torque can be applied to the engine even at a low vehicle speed. Startability is ensured over a wide operating range. Further, the timing of the application of the assist torque, rather than adapt the operation of the lower lock-up clutch relatively responsive, after the lock-up clutch is operated in advance, start timing of the starting of the engine by the engagement control of the disconnecting means Accordingly, assist torque can be applied to the engine at an appropriate timing, and the engine start time can be further shortened and ensured.

1 is an overall block diagram of a vehicle powertrain and a control device. It is a flowchart which concerns on control of the power train about the engine starting in driving | running | working which a control apparatus performs. (A) traveling mode, (b) vehicle speed, (c) turbine rotational speed, (d) engine rotational speed, (e) intermittent means state, (f) lockup clutch state, (g) It is a time chart which shows an example of combustion of an engine and (h) change of motor drive torque. FIG. 4 is a diagram corresponding to FIG. 3 according to another embodiment.

  Hereinafter, an embodiment of a vehicle control device will be described with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature. FIG. 1 is an overall block diagram of a vehicle powertrain and control device. The power train PT is driven to the left and right by receiving a multi-cylinder (for example, four-cylinder) engine 11 that generates driving force, a gear transmission mechanism 12 that is connected to the engine 11 and performs shifting, and an output from the gear transmission mechanism 12. A lockup that is disposed between the differential device 13 that distributes the force, the left and right drive wheels (for example, front wheels) 14 and 14 that receive the drive force from the differential device 13, and the engine 11 and the gear transmission mechanism 12. A torque converter (fluid transmission device) 16 with a clutch 15 and an electric motor 17 that drives the drive wheel 14 through a differential device 13 without the gear transmission mechanism 12 being provided. As described above, this vehicle is a hybrid vehicle including the engine 11 and the electric motor 17 as drive sources. As will be described later, the electric motor depends on the driving state set based on the vehicle speed and the accelerator opening. While switching between a motor travel mode in which the engine 11 is driven by the motor 17 and the engine 11 is stopped by driving the engine 11, and a combined travel mode in which both the electric motor 17 and the engine 11 are driven. It is configured to run.

  Although detailed illustration is omitted, the engine 11 is a four-cycle spark-ignition engine and a direct-injection engine that can directly inject fuel into each cylinder. As will be described later, the engine 11 is started by injecting fuel into a predetermined cylinder, more precisely, a cylinder corresponding to the expansion stroke in a stopped state, and performing ignition and combustion. 11 is configured to start by applying a torque in the forward rotation direction, and can be started basically without using a starter. The engine 11 includes an alternator connected to the crankshaft. The alternator is an ISG 18 in which a starter and an alternator are integrated.

  Although detailed illustration is omitted, the gear transmission mechanism 12 includes, for example, a plurality of clutch elements as a planetary gear mechanism and a frictional engagement element that selectively restricts the rotation of each rotation element included in the planetary gear mechanism. And a brake element, for example, a forward four-speed multistage automatic transmission. The gear transmission mechanism 12 is configured to realize each gear stage by engaging at least two elements selected from a plurality of clutch elements and brake elements. In other words, the gear transmission mechanism 12 is configured so that the torque between the engine 11 and the drive wheels 14 is reduced by fastening at least two elements to achieve a drive state in which a predetermined shift speed is achieved and not fastening all of the elements. Since the transmission is switched to the neutral state in which the transmission is cut off, particularly in this hybrid vehicle, as will be described later, the gear transmission mechanism 12 is operated by switching the release and engagement of the clutch elements and brake elements. 11 and the driving wheel 14 are made to function as the intermittent means 121 for intermittently torque.

  Further, in this hybrid vehicle, the gear transmission mechanism 12 is configured such that only one of at least two elements necessary for realizing the predetermined shift speed is unfastened and the other elements are fastened. While in the neutral state, the standby state is set so that the switching to the predetermined gear position can be performed quickly. This standby state is a state that is executed when the engine 11 is stopped, including in the motor travel mode. That is, since the standby state is the neutral state, the drag phenomenon in which the engine 11 is dragged and rotated while the vehicle is traveling is avoided by setting the standby state in the motor travel mode.

  Further, in the standby state, the above-described non-fastened elements are brought into a state immediately before fastening (so-called precharge state). This enhances the responsiveness of switching from non-fastening to fastening, and as described above, coupled with fastening only one fastening element, from the standby state (in other words, the neutral state) to the drive state. The switching response is greatly improved. Since the engine 11 is stopped in the standby state, the hybrid vehicle is provided with an electric hydraulic pump, which is not illustrated in order to realize the precharge state. As described above, when the engine 11 is stopped, the lockup clutch 15 is also in a precharged state.

  The electric motor 17 is, for example, a three-phase AC synchronous motor, and is driven by a drive current supplied via a battery and an inverter (not shown). Here, in the motor running mode, the vehicle is running with the driving force of the electric motor 17, the vehicle is running while regenerating the electric motor 17, and the electric motor 17 runs without inertia at all. Including at least three states.

  The vehicle control device CR includes an output of the engine 11, connection / disconnection of the lock-up clutch 15 (including slip control), operation of the electric motor 17 (including power running and regeneration) through the control of the inverter, It is a device that controls gears and the like. The control device CR is configured to include a controller 2 and various sensors 31 to 37 that detect various states including the traveling state of the vehicle and provide the controller 2. Among these, the controller 2 is a normal microcomputer, for example, and although not shown, the controller 2 includes at least a CPU, a ROM, a RAM, an I / O interface circuit, and a data bus.

  The various sensors include at least a vehicle speed sensor (traveling state detecting means) 31 that provides information related to the traveling speed of the vehicle to the controller 2, and an accelerator that provides the controller 2 with information related to the accelerator opening corresponding to the depression amount of the accelerator pedal. An opening sensor 32, a crank angle sensor 33 that provides signals used for detecting the engine speed and crank angle in the controller 2, a cam angle sensor 34 that provides signals used for cylinder identification in the controller 2, and a battery charge A battery state sensor 35 that provides information related to various states of the battery to the controller 2, including information related to the state (SOC: State of Charge) and battery temperature, and information related to the temperature of the electric motor 17. A motor state sensor 36 for providing information on various states, and It includes a turbine speed sensor 37 that provides information about the turbine speed of the torque converter 16 to the controller 2. The controller 2 takes in sensor signals from these sensors 31 to 37 and performs arithmetic processing, and outputs control signals to the engine 11, the lockup clutch 15, the gear transmission mechanism 12, and the electric motor 17.

  Specifically, the controller 2 operates the electric motor 17 in order to switch between the motor travel mode, the engine travel mode, and the combined travel mode described above according to the driving state set based on the vehicle speed and the accelerator opening. And switching between stop and operation and stop (start and stop) of the engine 11. At the same time, the controller 2 switches the state of the gear transmission mechanism 12 to a drive state (including shift control according to a shift map), a neutral state, and a standby state so as to correspond to the switching of the travel mode. The operation control of the lockup clutch 15 is also executed as necessary.

  In particular, in such a hybrid vehicle, the engine 11 is repeatedly started and stopped while the vehicle is running. The controller 2 executes predetermined stop control based on stopping the fuel supply and stopping the engine 11 when the stop condition of the engine 11 being driven is satisfied, while the engine 11 is stopped. When the start condition is satisfied, the start control of the engine 11 is executed. Here, the start control of the engine 11 while the vehicle is running does not use the ISG 18 but performs the so-called combustion start in which the engine 11 is automatically started with the energy of the combustion of the engine 11 as described above. When starting the combustion during the running, the controller 2 applies the assist torque to the engine 11 from the drive wheel 14 side so that the engine 11 can be started in a short time and more reliably. Yes.

  FIG. 2 is a control flowchart of the power train PT executed by the control device CR. Hereinafter, the control of the power train PT by the control device CR with reference to this flowchart and the time chart shown in FIG. In particular, the start control of the engine 11 will be described.

  First, in step S21, it is determined whether or not the vehicle is traveling. This may be determined based on the detection value of the vehicle speed sensor, for example. When not running (NO), the flow returns. On the other hand, when the vehicle is running (YES), the process proceeds to step S22.

  In step S22, it is determined whether a condition for starting the stopped engine 11 is satisfied. For example, as shown in FIG. 3A, when the vehicle is in the motor travel mode, the accelerator is depressed to switch to the engine travel mode or the combined travel mode in which the electric motor 17 and the engine 11 are used together. The case of changing is included. In the motor travel mode here, in addition to the so-called power running state in which the vehicle is driven by the driving force of the electric motor 17, the regenerative state of the electric motor 17 and the state where the electric motor 17 is not performing any work. Can be included. Further, the starting condition of the stopped engine 11 is not limited to the switching of the travel mode described above. For example, a battery in which the SOC of the battery has decreased below a predetermined value even during steady travel (constant speed travel) of the vehicle. The temperature of the electric motor 17 is higher than the predetermined temperature, and the temperature of the electric motor 17 is higher than the predetermined temperature.

  When the starting condition of the stopped engine 11 is not satisfied (NO), the process proceeds to step S23, and the gear transmission mechanism 12 is set to the standby state described above. Specifically, when the engine 11 is started according to a shift map that is preset and stored in the controller 2 based on the vehicle speed and the accelerator opening, a shift speed required after the start (in the following, This shift speed is sometimes referred to as a post-start required shift speed). Therefore, the gear transmission mechanism 12 is engaged with the remaining engagement elements except for one of the at least two friction engagement elements necessary for achieving the required shift speed after starting, while the one engagement. The element is brought into a precharged state (see the “interrupt means fastening” diagram in FIG. 3 (e)). Further, the lock-up clutch 15 is also brought into a precharged state (see the “L / U clutch engagement” diagram in FIG. 3F). At this time, the gear transmission mechanism 12 (intermittent means 121) cuts off the torque transmission between the engine 11 and the drive wheels 14, but, as will be described later, is waiting for the engine 11 to start. become.

  On the other hand, when the start condition of the engine 11 is satisfied in step S22 (YES), the process proceeds to step S24, and the controller 2 reads various signals necessary for the start control of the engine 11. The signal read here includes at least the vehicle speed, the turbine rotational speed, and the crank position, for example.

  In the subsequent step S25, the lockup clutch 15 that has been in the precharged state is engaged (see FIG. 3F). Here, “engagement of the lock-up clutch 15” means that the controller 2 outputs an engagement signal of the lock-up clutch 15. Generally, there is a time lag until the lock-up clutch 15 is actually engaged. As a result, the lock-up clutch 15 may actually be engaged later than this. Note that, from the viewpoint of alleviating torque shock, the lockup clutch 15 may be in a predetermined slip state.

  In step S26, fuel injection is performed on the expansion stroke cylinder when the engine 11 is stopped (refer to the “engine combustion” diagram in FIG. 3G). This is to ensure that the fuel is sufficiently vaporized at the ignition point described later. Here, in order to perform fuel injection early in consideration of the fuel vaporization time, the start condition of the engine 11 is satisfied here. Immediately after that, fuel injection is executed.

  In step S27, the controller 2 outputs the fastening signal of the intermittent means 121 (refer FIG.3 (e)). That is, the gear transmission mechanism 12 that is in the standby state at the requested shift stage after start-up outputs a signal for fastening the friction engagement element in the precharge state. Also here, since a time lag generally occurs before the frictional engagement element is actually engaged, as will be described later, the frictional engagement element may actually be engaged later (for example, (See the change in “turbine speed” in FIG. 3C). However, since the frictional engagement element of the gear transmission mechanism 12 has higher responsiveness than the lockup clutch 15 and is engaged from the precharged state, the time lag is considerably small.

  In the subsequent step S28, the torque of the electric motor 17 is increased (see FIG. 3 (h)). As will be described later, this increase in motor torque can cause a torque shock due to torque being deprived from the drive wheel 14 side to the engine 11 side (torque pulling) when the engine 11 is started. This is to compensate for this by increasing the torque of the electric motor 17. By doing so, torque shock at the start of the engine 11 is alleviated or eliminated, and the driver's uncomfortable feeling is reduced. As will be described later, the increment of the motor torque is preferably set according to the rate of increase in the rotational speed of the engine 11 after the assist torque is applied. As an example, it is set in accordance with a map that is set in advance and stored in the controller 2 based on the assist torque that is expected in accordance with the vehicle speed, the required post-starting shift speed (speed ratio), and the slip amount of the lockup clutch 15. May be. Alternatively, it may be set according to the rate of increase in the rotational speed of the engine 11 detected by the crank angle sensor 33.

  Then, in step S29, the intermittent means 121 is actually engaged after a predetermined time lag, and in accordance with the timing at which torque (assist torque) is applied from the drive wheel 14 side to the engine 11 side, Ignition is started for the expansion stroke cylinder when the engine 11 is stopped (see FIG. 3I). As a result, the combustion start is performed with the assist torque applied to the engine 11, and the engine 11 is started stably and in a short time (increase in the "engine speed" in FIG. 3 (d)). reference). Here, in the graph of “engine speed” in FIG. 3, the inflection point in the rising curve corresponds to the timing at which the stop-time expansion stroke cylinder exceeds the bottom dead center after ignition, and the inflection point. Hereinafter, a state where the engine 11 has been started and blown up is shown.

  In step S210 after the start of the engine 11 is completed, the motor torque increase performed in step S28 is terminated. This end timing corresponds to the timing of the inflection point in the above-mentioned rising curve of “engine speed”. That is, after the engine 11 is started, the torque is not pulled in, so the motor torque increase control is terminated.

  In subsequent step S211, control is performed so that the lock-up clutch 15 has a preset target slip amount (see FIG. 3F). As shown in FIG. 3D, the slip control is a control for alleviating or avoiding a shock caused by the engine speed increasing immediately after the engine 11 is started. The target slip amount in the slip control is set in advance according to the blow-up behavior and stored in the controller 2 because the blow-up behavior of the engine speed is predicted in advance based on the accelerator depressing operation and the vehicle speed. You can decide according to the map.

  Then, after the start of the engine 11 is completed, for example, at a constant speed, the electric motor 17 is controlled so that its motor driving torque gradually decreases as shown by a solid line in FIG. Finally, the electric motor 17 is stopped (see also the figures of “vehicle speed” in FIG. 3B, “turbine speed” in FIG. 3C, and “engine speed” in FIG. 3D). On the other hand, for example, when accelerating, the electric motor 17 is controlled so that its motor driving torque gradually increases as shown by a one-dot chain line in FIG. (That is, combined running mode). By smoothing the torque change of the electric motor 17 in this way, the occurrence of a torque step before and after the engine 11 is started is avoided or suppressed.

  Here, the steps from S25 to S211 in the flow of FIG. 2 are executed by sequence control, but the order of the steps in the flow shown here is for convenience of explanation. Of course, it is possible to change the order appropriately, or to change the execution of each step in parallel in time.

  As described above, when the start condition of the engine 11 that is stopped while the vehicle is traveling is satisfied, the fuel is supplied to the cylinder in the stop expansion stroke, and the engine 11 is started by performing ignition and combustion. By performing the combustion start and not using the ISG (starter) 18, various inconveniences caused by frequent use of the starter, such as an increase in the size of the starter and a decrease in the life of the starter, can be solved.

  When the combustion of the engine 11 is started, the gear transmission mechanism 12 is brought into a drive state, and the assist torque from the drive wheel 14 side is applied to the engine 11, thereby shortening the start time of the engine 11 and starting the engine 11. Stabilization can be achieved.

  In addition, when the assist torque is applied, the lock-up clutch 15 is operated to reduce or eliminate the effect of slipping of the torque converter 16 and to apply the desired amount of assist torque to the engine 11 even at a low vehicle speed. This makes it possible to expand the operating range in which the engine 11 can start combustion.

  Further, it is desirable that the assist torque to be applied to the engine 11 is applied in synchronization with the ignition of the engine 11 and the start of combustion. However, in the above configuration, the lock-up clutch 15 having relatively low responsiveness is first engaged. (Step S25), and then the gear transmission mechanism 12 is switched to the drive state (step S27). That is, the frictional engagement element included in the gear transmission mechanism 12 has a smaller diameter and higher response than the lockup clutch 15. For this reason, it is easier to set the fastening timing when the friction fastening element is fastened than when the lock-up clutch 15 is fastened. That is, when the lock-up clutch 15 having relatively low responsiveness is fastened first and the gear transmission mechanism 12 having good responsiveness is controlled later, as described above, assist torque is applied to the engine 11. This is advantageous in making the timing coincide with the ignition and combustion start timing of the engine 11. Applying the assist torque to the engine 11 at an appropriate timing can further promote the reduction and sureness of the start time of the engine 11.

  Here, as the operation control of the lock-up clutch 15 (step S25 in the flow of FIG. 2), control for changing the slip amount according to the traveling state of the vehicle, specifically, the vehicle speed may be performed. That is, for example, when the vehicle speed is low, the lock-up clutch 15 is disengaged, and depending on the required gear position after the gear transmission mechanism 12 is started (specifically, when the gear speed mechanism is relatively high), the necessary assist torque is I can't get it. For this reason, the operation (including the slip state) of the lockup clutch 15 described above is extremely effective in obtaining a desired assist torque. On the other hand, when the vehicle speed is high, the required assist torque can be obtained regardless of the post-start required shift speed of the gear transmission mechanism 12 even if the lockup clutch 15 is released. In such a case, operating the lock-up clutch 15 causes a shock and is not preferable.

  Therefore, as shown in “L / U clutch engagement” in FIG. 4 (f), the slip amount of the lockup clutch 15 is reduced (including the engagement of the lockup clutch) at a low vehicle speed according to the vehicle speed. Priority is given to securing a sufficient assist torque (see the solid line), and at high vehicle speeds, the slip amount of the lock-up clutch 15 is increased (including the release of the lock-up clutch 15) and priority is given to shock mitigation (see the dashed-dotted line) ) At the medium vehicle speed, the slip amount of the lock-up clutch 15 may be set to an intermediate level (see the broken line) in order to achieve both.

  This can be paraphrased as follows. That is, for example, although it is possible to increase the assist torque by changing the gear position of the gear transmission mechanism 12 (the required shift speed after start), the change of the required shift speed after the start is performed after the engine 11 is started. This is not preferable in terms of vehicle behavior because the gear is unmatched. Therefore, increasing the assist torque by appropriately setting the slip amount of the lockup clutch 15 without changing the required shift speed after starting can make the behavior of the vehicle after starting the engine 11 smooth. It is also effective in terms.

  Further, for example, even at the extremely low vehicle speed, even if the lockup clutch 15 is engaged, the necessary assist torque may not be obtained depending on the required shift speed after the gear transmission mechanism 12 is started. In such a case, the required shift speed after start of the gear transmission mechanism 12 may be shifted down from the actual shift speed to ensure the assist torque required when starting the engine 11. In that case, in order to make the vehicle behavior after starting the engine 11 smooth, it is not preferable to shift down significantly from the actual shift stage, and it is preferable to keep the shift down to about one stage.

  Various configurations can be adopted as the configuration of the hybrid vehicle. For example, the electric motor 17 does not distribute the driving force from one electric motor to the left and right driving wheels 14 via the differential device 13 as described above, but independently drives each of the left and right driving wheels 14. At least two electric motors may be provided so that a force can be applied. In that case, an in-wheel motor may be employed.

  Further, the driving force of the electric motor 17 is not limited to being applied to the front wheels, but may be applied to the rear wheels. Similarly, the driving force of the engine 11 is not limited to being applied to the front wheels, and may be applied to the rear wheels. Here, the wheel for applying the driving force of the electric motor 17 and the wheel for applying the driving force of the engine 11 may be the same as shown in FIG. 1 or may be different (for example, the engine 11). Before, after the drive force of the electric motor 17 or vice versa. For example, when the driving force of the electric motor 17 is applied to the rear wheel, the electric motor 17 may be connected to the middle of the drive shaft, not limited to the configuration in which the electric motor 17 is connected to the driving shaft of the rear wheel.

  Further, the starter of the engine 11 is not limited to the ISG, but may be a CISG directly connected to the crankshaft.

  In the power train PT, a continuously variable transmission mechanism such as a belt type may be employed instead of the gear-type multi-speed transmission mechanism. The fluid transmission mechanism may adopt a fluid coupling instead of the torque converter.

  In addition, a hybrid vehicle may be configured by appropriately combining the features of the above-described configurations within a possible range.

  As for engine combustion start, first, fuel is supplied to the cylinders in the compression stroke at the time of stop, ignition and combustion are performed, the engine 11 is once operated in the reverse rotation direction, and then compressed along with the reverse rotation operation. The engine 11 may be started by applying a torque in the normal rotation direction to the engine 11 by performing ignition and combustion on the expansion stroke cylinder. Such reverse combustion start can further improve the startability of the engine 11. In this case, it is desirable to match the timing at which torque is applied to the engine 11 from the drive wheel 14 side by the control of the gear transmission mechanism 12 with the start timing of ignition and combustion for the expansion stroke cylinder.

11 Engine 12 Gear transmission mechanism (automatic transmission)
121 Intermittent means 15 Lock-up clutch 16 Torque converter (fluid transmission mechanism)
17 Electric motor 2 Controller 31 Vehicle speed sensor (traveling state detecting means)
CR control device PT Powertrain

Claims (3)

A multi-cylinder engine mounted on the vehicle,
An automatic transmission coupled to the engine for driving drive wheels;
An electric motor that drives the drive wheels without going through the automatic transmission;
A fluid transmission device with a lock-up clutch for transmitting torque via fluid between the engine and the automatic transmission;
Intermittent means for switching between opening and closing so that torque is intermittent between the engine and the drive wheel;
A controller for controlling the engine, the automatic transmission, the electric motor, the lock-up clutch, and the intermittent means;
The controller is configured to drive the driving wheel while switching the driving of the engine and the electric motor during traveling of the vehicle, and when the engine is stopped during traveling of the vehicle, Opening the lock-up clutch and the intermittent means,
The controller also during running of the vehicle, when the start condition of the engine is stopped is satisfied, and executes the combustion starting before SL engine, when combustion starting of the engine, the lock-up clutch And then start the engine in accordance with the timing at which torque is applied to the engine from the drive wheel side by fastening the intermittent means ,
Vehicle speed detecting means for detecting the vehicle speed of the vehicle,
The controller operates the lock-up clutch with a predetermined slip amount at the start of combustion of the engine, and sets the slip amount of the lock-up clutch to be larger as the detected vehicle speed is higher. . In the vehicle drive control device according to claim 1,
The vehicle further comprises a traveling state detecting means for detecting a traveling state of the vehicle,
Wherein the controller, when combustion starting of the engine, in response to said detected running state, which controls the speed ratio of the automatic transmission, have row control of the lock-up clutch,
The controller is configured to change a gear ratio of the automatic transmission according to the running state when a desired assist torque for starting the engine cannot be obtained with the lock-up clutch engaged. The vehicle drive control device is changed so as to be larger than the ratio . In the vehicle drive control device according to claim 1 or 2 ,
When starting combustion of the engine, the controller supplies fuel to the cylinders in the compression stroke, performs ignition and combustion, and once operates the engine in the reverse rotation direction, and then compresses with the reverse rotation operation. A vehicle drive control device for starting up the engine by applying a torque in a normal rotation direction to the engine by performing ignition and combustion on the expansion stroke cylinder.

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