JP5545018B2 - 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 can be driven by at least one driving force, and in particular, controls 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, at least a motor travel mode in which the engine is stopped and the vehicle travels by an electric motor and an engine travel mode in which the engine travels are set. During traveling of the vehicle, for example, the traveling mode is switched based on the vehicle operating state determined by the vehicle speed and the accelerator opening of the engine, and accordingly, the electric motor is activated and stopped, and the engine is operated and stopped. Are switched respectively.

JP 2009-143264 A

  In the hybrid vehicle, the stop and start of the engine are frequently repeated during the traveling of the vehicle with the switching of the traveling mode. Therefore, as described in Patent Document 1, an integrated starter generator (ISG) in which a starter and an alternator are integrated, and a CISG (Crank Integrated Starter Generator) directly connected to a crankshaft (hereinafter collectively referred to simply as a starter). The starter is frequently activated. This causes inconveniences such as an increase in the size of the starter and a decrease in its life. In addition, when the engine is restarted using the starter, there is an inconvenience that the starting time becomes long.

  On the other hand, as a technique for starting an engine in a short time without using a starter, for example, fuel is supplied to a cylinder in an expansion stroke when the engine is stopped, and the fuel in the expansion cylinder is ignited and burned. Combustion starting techniques are known in which the engine is started accordingly. In order to ensure the combustion start and reduce the time required for the start, it is conceivable to assist the start of combustion by transmitting torque from the wheels of the running vehicle to the engine.

  However, when assisting combustion start with the torque from the wheels, there is a concern of giving a shock to the occupant due to the pulling of the torque. As a countermeasure, it is conceivable to increase the torque on the electric motor side, but this electric motor may not have a sufficient margin to increase the torque so that the pulling shock can be reduced. For example, the vehicle speed is relatively high, and the generated torque of the electric motor is approaching the maximum torque that the electric motor can currently output.

  Therefore, the present invention adopts the combustion start method to switch from motor traveling to engine traveling, and even when there is not enough room for torque increase on the electric motor side, the torque shock at the time of switching is suppressed and quickly So that the switching can be completed.

  In order to solve the above-described problems, the present invention executes torque-up control of an electric motor and performs engine rotation when the assist torque is applied from the wheels to the engine when the travel mode is switched. Increased the number.

  That is, the vehicle drive control device disclosed herein includes a multi-cylinder engine, an automatic transmission coupled to the engine for driving the vehicle, transmission of power between the engine and the wheels of the vehicle, and A motor running mode for driving the vehicle by stopping the engine and operating the electric motor, comprising: intermittent means for cutting off; and an electric motor that drives the vehicle without going through the automatic transmission; The vehicle driving method is switched between an engine running mode in which the engine is operated to drive the vehicle.

  The intermittent means is in a transmission state in which the power is transmitted so that each shift stage of the automatic transmission is realized by engaging at least two friction engagement elements selected from a plurality of friction engagement elements of the automatic transmission. Then, any one of the at least two frictional engagement elements is engaged, and the remaining frictional engagement elements are not engaged, so that the transmission of the power is interrupted.

  This vehicle drive control device employs a combustion start system that starts the engine when the mode is switched from the motor travel mode to the engine travel mode. Further, the vehicle drive control device includes an engine speed increasing means for increasing the engine speed of the engine started by the combustion starting means, a maximum torque that the electric motor can currently output, and a current generated torque. And a surplus torque calculating means for calculating a surplus torque as a difference.

At the time of the mode switching, the engine is started by the combustion starting means, and the shift stage of the automatic transmission is set to a higher shift stage than the target shift stage according to the driving state of the vehicle. When the intermittent means is operated to apply the assist torque from the wheels to the engine, the engine speed is increased by the engine speed increasing means according to the margin torque amount, and the electric motor A torque increase for increasing the generated torque is executed.

  Further, when the margin torque amount is smaller than a predetermined value, the degree of increase in engine speed by the engine speed increasing means is made larger than when the margin torque amount is greater than or equal to the predetermined value.

Therefore, at the time of mode switching, the engine speed increasing means is operated according to the amount of surplus torque of the electric motor to increase the engine speed. Therefore, when assist torque is applied from the wheels to the engine by the operation of the intermittent means. Even when the amount of torque increase of the electric motor is small, it is possible to suppress the torque pulling shock and to reduce or eliminate the feeling of discomfort to the occupant. Moreover, the increase in engine speed by the engine speed increasing means is advantageous for quick mode switching. In addition, as the gear position increases, the engine speed corresponding to the vehicle speed and the gear ratio of the automatic transmission decreases. As described above, the gear position of the automatic transmission is higher than the target gear position. Since the intermittent torque is operated to apply the assist torque from the wheels to the engine, the engine speed after the combustion start can be quickly reached to the synchronous speed, and the mode can be switched quickly. Can do.

  In this case, in the downshift from the high speed stage to the target gear stage, the synchronous rotational speed increases, so that torque is pulled in at the initial stage, and torque is increased thereafter. This can be dealt with by torque up and torque down of the electric motor.

Then, when the amount the surplus torque is smaller than a predetermined value, than when it is the predetermined value or more, since it is to a large degree of increase in engine speed by the engine rotational speed increase means, at the time of mode switching This is advantageous for torque shock suppression and quick mode switching.

  In addition, preferably, it further includes a fluid transmission device with a lock-up clutch that performs torque transmission via the fluid between the engine and the automatic transmission, and the control means is configured to switch the mode when the mode is switched. The lock-up clutch is operated with a predetermined slip amount according to the margin torque amount.

  That is, the slip control of the lockup clutch absorbs the rotational speed difference between the input shaft and the output shaft of the fluid transmission device, which is advantageous in mitigating the torque pulling shock, and further, the engine rotational speed increasing means As a result, even when the engine speed increases rapidly, the associated torque shock is alleviated.

  Alternatively, instead of the slip control of the lockup clutch, it is preferable that the intermittent means is operated with a predetermined slip amount according to the margin torque amount. Thereby, the same effect as the slip control of the lockup clutch can be obtained.

  In this case, in the slip control of the lock-up clutch or the intermittent means, the slip amount can be reduced as the margin torque amount is increased.

Further, in the mode switching, when the margin torque is larger than the predetermined value by a predetermined amount or more, the operating speed of the electric motor can be increased without operating the engine speed increasing means when operating the intermittent means. What is necessary is just to perform the torque up which raises generated torque. Thus, Ru can be relaxed pull shock torque during the engagement.

In here, "automatic transmission", for example multi-speed transmission comprising a gear transmission mechanism, and may include both of a continuously variable transmission composed of, for example, a belt transmission mechanism. Further, the “wheel” may be either the front wheel or the rear wheel, and the wheel to which the engine applies the driving force and the wheel to which the electric motor applies the driving force may be the same, May be different.

  Further, the “interrupting means” is means for switching between transmission and interruption of torque between the engine and the wheel, and may be, for example, a clutch element disposed 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, the torque transmission path 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 transmission and interruption of torque between the engine and the wheel 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 used for fastening and all the remaining fastening elements are not fastened, the transmission of 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 (switching to the torque transmission state) only by fastening one fastening element that has not been fastened. This means that, for example, it is possible to switch from the shut-off state to the torque transmission 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 gear stage required after the engine start.

  Further, as the “engine speed increasing means”, for example, a starter can be adopted, and the effect can be obtained by assisting the increase in the engine speed with the starter. Even in that case, there are not so many cases where the margin torque is not sufficient at the time of the mode switching, and this does not lead to frequent starter operation (to shorten the life of the starter).

  Alternatively, as the engine speed increasing means, engine output increasing means for increasing the engine output, specifically, increasing the throttle opening and the fuel injection amount can be employed. Instead of the starter assist or together with the starter assist, the engine output increasing means can be operated.

As described above, in the vehicle drive control device, in the mode switching from the motor travel mode to the engine travel mode, the engine is started by the combustion start means, and the shift stage of the automatic transmission is more than the target shift stage. The intermittent means is operated so as to achieve a high gear position so that assist torque is applied from the wheels to the engine . At that time, the engine speed is increased by the engine speed increasing means according to the amount of surplus torque of the electric motor. In addition to executing the torque increase of the electric motor, even if the amount of torque increase of the electric motor cannot be taken sufficiently, the torque pull-in shock is suppressed and the passenger feels uncomfortable. It can be eliminated, moreover, this to reach a rapid synchronous speed the engine speed after combustion starting The mode switching can be performed quickly, and when the amount of marginal torque of the electric motor is smaller than a predetermined value, the engine speed by the engine speed increasing means is larger than when it is greater than the predetermined value. This increases the degree of increase in the torque, which is advantageous for suppressing torque shock and switching modes quickly during mode switching.

1 is an overall block diagram of a vehicle powertrain and a control device. It is a flowchart of the control which a control apparatus performs. It is a characteristic view which shows the relationship between the torque diagram of an electric motor, and motor temperature. It is a characteristic view showing the relationship between the SOC coefficient TRsoc and SOC for obtaining the maximum torque Tmax of the electric motor. It is a characteristic view which shows a motor travel area and a gear shift pattern. It is a flowchart of driving mode switching control when the surplus torque of the electric motor is small. It is a time chart of the control. FIG. 6 is a characteristic diagram showing a relationship between a starter operating time ts and a target engine speed Net in the same control. FIG. 6 is a characteristic diagram showing a relationship between a decrease amount ΔNe of an engine speed Ne to a synchronous speed Net in the same control and a torque down amount ΔTd of the electric motor. It is a flowchart of driving mode switching control when the marginal torque of an electric motor is medium. It is a time chart of the control. FIG. 6 is a characteristic diagram showing a relationship between a torque increase amount ΔTa of the electric motor and a slip ratio Ns / Net of the lockup clutch in the same control. FIG. 6 is a characteristic diagram showing a relationship between a torque increase amount ΔTa and a throttle opening increase amount ΔTVOa in the same control. FIG. 6 is a characteristic diagram showing a relationship between a torque increase amount ΔTa and a fuel injection amount increase amount ΔQfa in the same control. FIG. 6 is a characteristic diagram showing a relationship between an engine speed decrease amount ΔNe and a torque down amount ΔTd in the same control. It is a flowchart of another traveling mode switching control when the marginal torque of an electric motor is medium. It is a time chart of the control. It is a flowchart of driving mode switching control when the surplus torque of the electric motor is large. It is a time chart of the control.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

  In FIG. 1, a power train PT receives 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 a shift, and an output from the gear transmission mechanism 12. Are disposed between the engine 11 and the gear transmission mechanism 12. The differential device 13 distributes the drive force to the left and right, the left and right drive wheels (for example, front wheels) 14 and 14 that receive the drive force from the differential device 13, In addition, a torque converter (fluid transmission device) 16 with a lock-up clutch 15 and an electric motor 17 that drives the drive wheels 14 through the differential device 13 without using the gear transmission mechanism 12 are provided. As described above, this vehicle is a hybrid vehicle including the engine 11 and the electric motor 17 as drive sources, and, as described later, according to the driving state set based on the vehicle speed and the accelerator opening of the engine, Driving while switching between a motor running mode in which the engine 11 is stopped and driven by the electric motor 17 and an engine running mode in which the electric motor 17 is stopped and driven by the engine 11 or driven by both the electric motor 17 and the engine 11 Is configured to do.

  Although detailed illustration is omitted, the engine 11 is a four-cycle spark ignition engine, and is a direct injection engine configured to be able to inject fuel directly into each cylinder. When the engine 11 is started, fuel is supplied into a predetermined cylinder, more precisely, a cylinder stopped in the expansion stroke, and ignition and combustion are performed to give the engine 11 torque in the forward rotation direction. Thus, the engine can be started 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 not specifically shown, the gear transmission mechanism 12 includes a planetary gear mechanism, a plurality of clutch elements and brake elements as frictional engagement elements that selectively restrict the rotation of the rotation elements included in the planetary gear mechanism. For example, it is comprised as a multi-speed automatic transmission with 6 forward speeds. 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.

  That is, the gear transmission mechanism 12 can achieve six forward speeds, and includes three sets of planetary gear mechanisms, two clutch elements C_L and C_H that respectively connect and disconnect the rotating elements, and the rotating elements. Three brake elements B_LR (low / reverse brake), B_26 (2-speed / 6-speed brake), and B_35 (3-speed / 5-speed brake) that connect / disconnect the motor and the fixed element (gear transmission housing) ing. Table 1 is a fastening table that achieves a plurality of shift speeds by selectively fastening a plurality of frictional engagement elements of the gear transmission mechanism 12. The first forward speed (D1) to the sixth forward speed (D6) are achieved by fastening two selected frictional engagement elements. “CL_1” in the table means that the element is selected and fastened as the first frictional engagement element, and “CL_2” means that the element is selected and fastened as the second frictional engagement element.

  As described above, the gear transmission mechanism 12 is configured such that the engine 11 and the driving wheel 14 are driven by engaging a selected gear stage by engaging at least two selected elements and disengaging all elements. It switches to the neutral state where the transmission of torque to and from is interrupted. Therefore, in this hybrid vehicle, the gear speed change mechanism 12 is caused to function as an interrupting means 121 for interrupting torque (power transmission) between the engine 11 and the drive wheel 14 by fastening and releasing the frictional engagement element.

  Further, in this hybrid vehicle, only one of the at least two frictional engagement elements necessary for realizing the predetermined shift speed is not engaged, so that the predetermined state is achieved while the neutral state is achieved. The standby state is set so that the shift to the gear stage 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 frictional engagement element to be non-engaged is set to a state immediately before engagement (so-called precharge state). This increases the responsiveness of switching from non-engagement to engagement, and as described above, coupled with the engagement of only one friction engagement element, the drive state from the standby state (in other words, the neutral state). The responsiveness to switch to 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.

  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 shown in FIG. 1 includes an output of the engine 11, connection / disconnection of the lockup clutch 15 (including slip control), operation of the electric motor 17 (including power running and regeneration) through control of the inverter, gears. It is a device that controls the gear position and the like of the transmission mechanism 12. 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 31 that provides information related to the traveling speed of the vehicle to the controller 2, an accelerator opening sensor 32 that provides information related to the accelerator opening corresponding to the amount of depression of the accelerator pedal to the controller 2, and a controller. 2, a crank angle sensor 33 that provides signals used for detecting the engine speed and crank angle, a cam angle sensor 34 that provides signals used for cylinder identification in the controller 2, and a state of charge of the battery (remaining charge amount SOC) : State of Charge) and battery state sensor 35 that provides information related to various battery states to the controller 2 including information related to the battery temperature, and various states of the electric motor 17 including information related to the temperature of the electric motor 17 A motor status sensor 36 that provides such information, It includes a turbine speed sensor 37 that provides information about the turbine speed of the 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 determines whether the motor travel mode and the engine travel mode (the travel mode using only the engine or the engine and the motor) according to the driving state set based on the vehicle speed and the accelerator opening. The operation mode of the electric motor 17 is switched between the operation and stop of the electric motor 17 and the operation and stop (start and stop) of the engine 11 are switched. 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 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. The establishment of the start condition of the engine 11 while the vehicle is traveling means mode switching from the motor travel mode to the engine travel mode. In this case, so-called combustion start is performed in which the engine 11 is started with the energy generated by combustion of the engine 11. Do.

  Then, the control device CR is a means for determining whether or not to perform the mode switching based on the required torque To of the vehicle and the maximum torque Tmax that the electric motor 17 can currently output. Means for executing combustion start of the engine 11, means for calculating the surplus torque ΔT of the electric motor 17, means for performing optimum motor torque control according to the magnitude of the surplus torque ΔT, and increasing the engine speed at high speed as necessary Means etc. are provided. This will be specifically described below.

<Mode switching control>
FIG. 2 is a flowchart of the mode switching control executed by the control device CR. In step S1, the vehicle speed V, the throttle opening TVO of the engine 11, the motor torque (currently generated torque of the electric motor 17) T1, the temperature of the electric motor 17, and the remaining charge SOC of the battery are read. In step S2, the required driving force of the vehicle is obtained based on the vehicle speed V and the throttle opening TVO, and the required torque To for the electric motor 17 is calculated from the required driving force. In step S3, the maximum torque Tmax that the electric motor 17 can currently output is calculated based on the temperature of the electric motor 17 and the SOC.

  FIG. 3 shows the relationship between the torque diagram of the electric motor 17 and the motor temperature. In the torque diagram, in a hyperbola of equal horsepower, the upper limit of torque is determined by the maximum current value, and the corresponding vehicle speed (motor rotation speed) V is limited by voltage or the like. The higher the motor temperature, the smaller the maximum torque Tmax ′ that can be output (the maximum torque when the SOC is equal to or greater than the predetermined value a). The maximum torque Tmax that can be actually output can be obtained by multiplying the maximum torque Tmax ′ by a coefficient TRsoc corresponding to the SOC. As shown in FIG. 4, the coefficient TRsoc decreases as the SOC decreases.

  Returning to FIG. 2 again, the description will be continued. In step S4, it is determined whether or not to switch from the motor travel mode to the engine travel mode based on the required torque To and the maximum torque Tmax. When the required torque To is equal to or less than the maximum torque Tmax, the motor travel mode is continued, and the automatic transmission 12 controls the first friction engagement element CL_1 to the precharge state and the lockup clutch L / U_CL to the engagement state ( Step S5).

  On the other hand, when the required torque To is greater than the maximum torque Tmax in step S4, it is determined that switching from the motor travel mode to the engine travel mode is necessary, and mode switching control is entered. For example, there is a case where it is determined that it is necessary to switch to the engine travel mode as a result of an increase in the required torque To accompanying the acceleration request of the vehicle, or the motor temperature rises even when the vehicle is maintained in a steady travel state Alternatively, there is a case where it is determined that switching to the engine travel mode is required as a result of the decrease in the maximum torque Tmax as the SOC decreases.

First, in step S6, a surplus torque ΔT (= Tmax−T1) of the electric motor 17 is calculated based on the current generated torque T1 of the electric motor 17 and the maximum torque Tmax that can be output. Surplus torque [Delta] T in the subsequent step S7 whether or not a predetermined value [Delta] T ₁ or more is determined. If it is determined that the margin torque ΔT is smaller than the predetermined value ΔT ₁ (for example, the case of A shown in FIG. 5), the process proceeds to step S8 and mode switching control with a small margin torque is executed. When excess torque [Delta] T is determined to be the predetermined value [Delta] T ₁ or more in step S7, the margin torque [Delta] T proceeds to step S9, whether or not a predetermined value [Delta] T ₂ or more is determined. In this case, ΔT ₁ <ΔT ₂ . When it is determined that the margin torque ΔT is smaller than the predetermined value ΔT ₂ (for example, the case B shown in FIG. 5), the process proceeds to step S10 to execute the mode switching control during the margin torque. If it is determined that the margin torque ΔT is equal to or greater than the predetermined value ΔT ₂ (for example, the case of C shown in FIG. 5), the process proceeds to step S11 to perform mode switching control with a large margin torque.

[Case with low torque]
FIG. 6 shows a mode switching control flow with a small margin torque. Hereinafter, the mode switching control when the margin torque is small will be described with reference to this flow, the map of FIG. 5, the time chart of FIG.

  In step A1, based on the current vehicle speed V and the required driving force F, the target shift stage after mode switching is read from the electronically stored motor travel region / shift pattern characteristic map shown in FIG. The engine speed Net is determined. The map is set so that the higher gear speed is selected as the vehicle speed V is higher and the required driving force F is lower, with the vehicle speed V and the required driving force F as parameters. In the present embodiment, the shift stage of the automatic transmission 12 is once controlled to a high shift stage that is one stage higher than the target shift stage and then shifted down to the target shift stage. For this reason, the target engine speed Net is the synchronous speed at the high gear position. Specifically, the engine synchronous speed (vehicle speed equivalent speed) when the clutch slip amount is determined by the vehicle speed V and the gear ratio of the high gear stage is set as the target engine speed Net.

  In the subsequent step A2, the combustion start of the engine 11 described above is executed, and the second friction engagement element CL_2 is brought into an engagement state. CL_2 in this case is a friction engagement element for realizing the high gear, and in the case of A with a small margin torque shown in FIG. 5, it is a friction engagement element (C_H shown in Table 1) that realizes the fourth speed. is there. Further, simultaneously with the start of combustion, the starter is operated for a predetermined time ts to assist in increasing the engine speed (starter assist). The starter assist time ts can be constant, but as shown in FIG. 8, the time ts may be lengthened as the target engine speed Net increases. Further, at step A3, the engine output is increased. That is, the throttle opening TVO is increased by ΔTVOa from the opening TVO1 when the margin torque is large, and the fuel injection amount Qf is increased by ΔQfa from the injection amount Qf1 when the margin torque is large.

  Therefore, as shown in FIG. 7, as the engine combustion starts, the traveling mode shifts from the motor traveling mode to the switching mode, and at the same time, starter assist and engine output increase control are performed, thereby increasing the engine speed Ne. This is advantageous for quick switching to the engine running mode.

  In step A4, the engine speed Ne is read, and in the subsequent step A5, it is determined whether or not the engine speed Ne has increased to [target speed Net + ΔN2] or more (see the engine speed time chart in FIG. 7). ΔN2 is a threshold value for ensuring that the engine speed Ne exceeds the target speed Net, and may be a negative value because it is set in consideration of a control delay (detection delay). When it is determined that the engine speed has increased, the process proceeds to step A6, where the engine output increase control is shifted to normal engine combustion control. That is, the throttle opening TVO is the opening TVO1 when the margin torque is large, and the fuel injection amount Qf is the injection amount Qf1 when the margin torque is large.

  Then, in the subsequent step A7, the first friction engagement element CL_1 is engaged, and in the subsequent step A8, the current generated torque T1 of the electric motor 17 is decreased by ΔTd. Since the first frictional engagement element CL_1 is precharged, it is quickly engaged as shown in FIG. As a result, a fourth speed (D4) shift stage is realized. Further, the torque-down shock (ΔTd) of the electric motor 17 mitigates the torque push-up shock associated with the fastening of CL_1. As CL_1 is engaged, the engine speed Ne drops to the target speed (synchronous speed corresponding to the vehicle speed) Net. Note that the vehicle speed V gradually increases.

  The torque reduction amount ΔTd is determined according to the degree of decrease in the engine speed Ne accompanying the engagement of CL_1. That is, as shown in FIG. 9, the torque reduction amount ΔTd is increased as the engine speed decrease amount ΔNe (= Ne−Net) is increased.

  In subsequent step A9, if it is determined that the engine speed Ne has decreased to a speed in the vicinity of the target speed Net (Net ± ΔNe1), the process proceeds to step A10 to perform shift control to the target gear stage. In this case, the target shift speed is the third speed. Therefore, as shown in FIG. 7, for the second frictional engagement element CL_2, the engagement of the frictional engagement element C_H that realizes the fourth speed is cut off, and the frictional engagement element B_35 that realizes the third speed (see Table 1) is engaged. .

  In the shift control to the target shift stage, the synchronous rotational speed is increased, so that the torque of the electric motor 17 is increased as shown in FIG. The torque of the electric motor 17 is reduced to alleviate the thrusting shock (step A11). In this case, since the torque reduction control of the electric motor 17 is performed in the previous step A8, the torque increase is possible. The engine speed Ne increases as a result of the shift control to the third speed.

[Case 1 with extra torque]
FIG. 10 shows a mode switching control flow when the marginal torque in step S10 of FIG. 2 is medium. In case 1, slip control of the lockup clutch 15 is performed in mode switching control. The mode switching control will be described with reference to the flow of FIG. 10, the map of FIG. 5, the time chart of FIG.

In step B1, as in step A1 of the control flow with a small margin torque, the target gear speed after mode switching is read from the map shown in FIG. 5 based on the current vehicle speed V and accelerator opening, and the target engine speed Net is determined. The target engine rotational speed Net is a synchronous rotational speed at a high shift stage that is one stage higher than the target shift stage. In the subsequent step B2, since the surplus torque ΔT of the electric motor 17 is medium (ΔT ₁ ≦ ΔT <ΔT ₂ ), the torque of the electric motor 17 is increased so that the surplus torque ΔT can be fully used for the mode switching control. Control is performed (torque-up amount ΔTa = ΔT).

  In the subsequent step B3, the combustion of the engine 11 is started. At the start of combustion start, the throttle opening TVO is set to the opening TVO1 when the margin torque is large. Therefore, as shown in FIG. 11, the traveling mode shifts from the motor traveling mode to the switching mode as the engine combustion starts.

In a subsequent step B4, it is determined whether or not a margin torque ΔT at the time of the torque increase is less than ΔT ₁ ′. However, ΔT ₂ > ΔT ₁ ′> ΔT ₁ . When the surplus torque ΔT is less than ΔT ₁ ′, the process proceeds to step B5 and starter assist is performed. The starter assist time ts can be constant, but the time ts may be lengthened as the difference between the surplus torque ΔT and ΔT ₁ (ΔT−ΔT ₁ ) is small.

  And it progresses to step B6, and while fastening the 1st friction engagement element CL_1 of a pre-charge state, it makes the 2nd friction engagement element CL_2 a fastening state. They are frictional engagement elements for realizing the high gear. In the case of B in the margin torque shown in FIG. 5, the first friction engagement element CL_1 is C_H shown in Table 1 and the second friction engagement element CL_2 is C_H in order to realize the fourth speed on the first stage of the third speed. Become.

If the margin torque ΔT is equal to or greater than ΔT ₁ ′ in step B4, the process proceeds to step B6 without starter assist. When the margin torque ΔT is large, the starter is not used as much as possible.

  In step B7, slip control of the lockup clutch (L / U_CL) 15 is started. That is, the hydraulic pressure acting in the fastening direction of the lock-up clutch 15 is reduced to put the clutch in a slip state. In this case, as shown in FIG. 12, as the torque increase amount ΔTa increases, the ratio (slip rate) of the slip amount Ns to the target engine speed Net decreases, and in short, the slip amount decreases. ,Control. At this time, in the torque converter 16, since the engine-side input shaft has a smaller rotational speed than the automatic transmission 12-side output shaft, the slip amount becomes negative as shown in FIG.

  In the subsequent step B8, the engine output is increased. That is, the throttle opening TVO is increased by ΔTVOa from the opening TVO1 when the margin torque is large, and the fuel injection amount Qf is increased by ΔQfa from the injection amount Qf1 when the margin torque is large. In this case, as shown in FIG. 13, the throttle opening increase amount ΔTVOa is controlled to decrease as the torque increase amount ΔTa increases. Further, as shown in FIG. 14, the control is performed so that the increase amount ΔQfa of the fuel injection amount decreases as the torque increase amount ΔTa increases.

  Therefore, as shown in FIG. 11, the engine speed increases rapidly due to an increase in engine output (when the margin torque ΔT is small, due to an increase in engine output and starter assist). At the time of this mode switching, the frictional engagement elements CL_1 and CL_2 are brought into an engaged state (step B6), so that assist torque is applied to the engine 11 from the wheel (drive wheel) side. Therefore, it is advantageous for quick increase of the engine speed Ne, that is, quick transition to the engine running mode and stabilization of engine start.

  Thus, the application of the assist torque from the wheel to the engine 11 leads to the pulling of the torque on the wheel side, but the torque pulling shock of the electric motor 17 is alleviated by the torque up control of the electric motor 17. Further, the slip control of the lock-up clutch 15 absorbs the rotational speed difference between the input shaft and the output shaft of the torque converter 16, which is advantageous for alleviating the torque pulling shock, and further providing starter assist and engine output. Although the engine speed rapidly increases due to the increase, the torque shock associated therewith is also alleviated.

  In subsequent step B9, the engine speed Ne is read, and in step B10, it is determined whether or not the engine speed Ne has increased to the target engine speed Net + ΔN2 or more. ΔN2 is a threshold value for ensuring that the engine speed Ne exceeds the target speed Net as in the case of the control when the margin torque is small, and is set in consideration of the control delay (detection delay). It may be a value. When the increase in the engine speed is determined, the process proceeds to step B10, and the engine output increase control is shifted to normal engine combustion control. That is, the throttle opening TVO is the opening TVO1 when the margin torque is large, and the fuel injection amount Qf is the injection amount Qf1 when the margin torque is large.

  In subsequent step B12, the lockup clutch 15 is brought into an engaged state. As a result, as shown in FIG. 11, the slip amount of the lock-up clutch 14 that has once turned positive decreases to zero. Further, the engine speed Ne falls to the target engine speed Net. Then, in order to alleviate the torque shock caused by the engagement of the lockup clutch 15, the current generated torque T1 of the electric motor 17 is decreased by ΔTd in the subsequent step B13. The torque reduction amount ΔTd is determined according to the degree of decrease in the engine speed Ne accompanying the engagement of the lockup clutch 15. That is, as shown in FIG. 15, the torque reduction amount ΔTd is increased as the engine speed decrease amount ΔNe (= Ne−Net) is increased.

  In subsequent step B14, if it is determined that the engine speed Ne has decreased to a speed (Net ± ΔNe1) near the target speed Net, the process proceeds to step B15 to perform shift control to the target gear stage. In this case, the target shift speed is the third speed. Therefore, as shown in FIG. 11, with respect to the second friction engagement element CL_2, the engagement of the friction engagement element C_H that realizes the fourth speed is cut off, and the friction engagement element B_35 that realizes the third speed is engaged.

  In the shift control to the target shift stage, the synchronous rotational speed is increased, so that the torque of the electric motor 17 is increased as shown in FIG. The torque of the electric motor 17 is reduced to alleviate the thrusting shock (step B16). The engine speed Ne increases as a result of the shift control to the third speed.

[Case 2 with extra torque]
In the previous case 1, the slip control of the lock-up clutch 15 is performed in the mode switching control during the surplus torque, but in this case 2, the slip control of the first frictional engagement element CL_1 is performed. A flow of the mode switching control is shown in FIG. 16, and a time chart is shown in FIG.

  Steps C1 to C5 in FIG. 16 are the same as steps B1 to B5 in FIG. In step C6 subsequent to step C5 in which starter assist is executed, the second friction engagement element CL_2 (C_H for 4th speed) is brought into an engaged state. The lock-up clutch 15 maintains the engaged state (step S5 in FIG. 2).

  In the subsequent step C7, the hydraulic pressure acting on the first frictional engagement element CL_1 is increased and slip control of the CL_1 is started. In this case, as in the slip control of the lockup clutch 15, the ratio (slip rate) of the slip amount Ns to the target engine speed Net is decreased as the torque increase amount ΔTa increases (see FIG. 12). Subsequent steps C8 to C11 are the same as steps B8 to B11 in FIG.

  Therefore, as shown in FIG. 17, the first frictional engagement element CL_1 is in the slip state and the second frictional engagement element CL_2 is in the engagement state, so that the assist torque is applied to the engine 11 from the wheel (drive wheel) side. Is granted. Therefore, it is advantageous for quick increase of the engine speed Ne, that is, quick transition to the engine running mode and stabilization of engine start. In this case, the application of the assist torque from the wheel to the engine 11 leads to the pulling of the torque on the wheel side, but the torque pulling shock of the torque is alleviated by the motor torque increase control in step C3. Further, the slip control of the first frictional engagement element CL_1 absorbs the rotational speed difference between the input shaft and the output shaft of the automatic transmission 12, which is advantageous for alleviating the torque pulling shock, and further, the starter assist As the engine output increases, the engine speed rapidly increases, but the torque shock associated therewith is alleviated.

  Then, in step C12 after the engine speed Ne rises to the target engine speed Net + ΔN2 or more (see step C10), the first friction engagement element CL_1 is brought into an engaged state. As a result, as shown in FIG. 17, the slip amount once shifted from the negative value of CL_1 to the positive value decreases and becomes zero. Further, the engine speed Ne falls to the target engine speed Net. Then, in order to alleviate the torque shock due to the fastening of CL_1, the current generated torque T1 of the electric motor 17 is decreased by ΔTd in the subsequent step C13. Steps C13 to C16 are the same as steps C13 to C16 in FIG.

[Case with extra torque]
FIG. 18 shows a mode switching control flow when the margin torque in step S11 of FIG. 2 is large. In step D1, as in step A1 of the control flow with a small surplus torque, the target shift speed after mode switching is read from the map shown in FIG. 5 based on the current vehicle speed V and accelerator opening TVO, and the target engine speed The number Net is determined. The target engine rotational speed Net is a synchronous rotational speed at a high shift stage that is one stage higher than the target shift stage. In the subsequent step D2, torque up control of the electric motor 17 is performed (torque up amount ΔTa = room torque ΔT).

  In the following step D3, the combustion of the engine 11 is started. The throttle opening is TVO1. Moreover, let the 2nd friction engagement element CL_2 be a fastening state. In the case of C with a large margin torque shown in FIG. 5, the second frictional engagement element CL_2 is C_H (see Table 1) in order to realize the fourth speed, which is the first speed of the third speed. At this time, the first friction engagement element CL_1 remains in the precharged state. Accordingly, as shown in FIG. 19, with the start of engine combustion, the travel mode shifts from the motor travel mode to the switching mode, and the engine speed Ne increases.

  In the following step D4, the engine speed Ne is read. In step D5, if it is determined that the engine speed Ne has increased to the speed near the target speed Net (Net ± ΔNe1), the process proceeds to step D6 and the first friction engagement element is reached. Set CL_1 to the fastening state. Thereby, assist torque is applied to the engine 11 from the wheel (drive wheel) side. The application of the assist torque leads to the pulling of the torque on the wheel side, but the pulling shock of the torque is alleviated by the motor torque increase control in step D2.

  In subsequent step D7, the torque-up control of the electric motor 17 is terminated. In the subsequent step D8, shift control to the target shift stage is performed. In this case, the target shift speed is the third speed. Accordingly, as shown in FIG. 19, for the second frictional engagement element CL_2, the engagement of the frictional engagement element C_H that realizes the fourth speed is cut off, and the frictional engagement element B_35 that realizes the third speed is engaged. In subsequent step D9, the torque of the electric motor 17 is reduced to zero and the mode switching control is terminated.

  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 17 to the left and right driving wheels 14 via the differential device 13 as described above, but independently to the left and right driving wheels 14. At least two electric motors 17 may be provided so that a driving 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). Is applied to the front wheels, and the driving force of the electric motor 17 is applied to the rear wheels, 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.

  Further, regarding combustion start of the engine 11, first, fuel is supplied to the cylinder 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 17
2 Controller CR Controller PT Powertrain

Claims (5)

A multi-cylinder engine, an automatic transmission coupled to the engine for driving a vehicle, an intermittent means for transmitting and interrupting power between the engine and the wheels of the vehicle, and the automatic transmission. An electric motor that drives the vehicle without intervention, a motor driving mode in which the engine is stopped and the electric motor is operated to drive the vehicle, and an engine driving mode in which the engine is operated to drive the vehicle A vehicle drive control device that switches the vehicle drive system between
The intermittent means is in a transmission state in which the power is transmitted so that each shift stage of the automatic transmission is realized by engaging at least two friction engagement elements selected from a plurality of friction engagement elements of the automatic transmission. The power transmission is cut off by fastening any one of the at least two friction fastening elements and fastening the remaining friction fastening elements; and
Combustion starting means for starting the engine at the time of mode switching to switch from the motor traveling mode to the engine traveling mode;
Engine speed increasing means for increasing the engine speed of the engine started by the combustion starting means;
A margin torque calculating means for calculating a margin torque that is a difference between the maximum torque that the electric motor can currently output and a current generated torque;
At the time of switching the mode, the engine is started by the combustion starting means, and the intermittent means is further set so that the speed stage of the automatic transmission is higher than the target speed stage according to the driving state of the vehicle. When operating and applying assist torque from the wheels to the engine, the engine speed is increased by the engine speed increasing means according to the margin torque amount, and the generated torque of the electric motor is increased. And a control means for executing torque up ,
The control means increases the degree of increase in engine speed by the engine speed increasing means when the margin torque amount is smaller than a predetermined value than when the margin torque amount is greater than or equal to the predetermined value. Drive control device. In claim 1 ,
A fluid transmission device with a lock-up clutch that performs torque transmission via the fluid between the engine and the automatic transmission;
The vehicle drive control device, wherein the control means operates the lock-up clutch with a predetermined slip amount in accordance with the margin torque amount when the mode is switched. In claim 1 ,
The vehicle drive control device characterized in that the control means operates the intermittent means with a predetermined slip amount in accordance with the margin torque amount when the mode is switched. In claim 2 or claim 3,
The vehicular drive control apparatus, wherein the slip amount is reduced as the margin torque amount is increased. In any one of Claims 1 thru | or 4 ,
The control means operates the intermittent means so that assist torque is applied from the wheels to the engine when the margin torque is larger than the predetermined value by a predetermined amount or more during the mode switching. In addition, the vehicle drive control apparatus is configured to execute torque increase for increasing the torque generated by the electric motor without operating the engine speed increasing means.

Images