Vehicle control device

Abstract

The present invention addresses the problem of providing a vehicle control device capable of effectively suppressing fluctuations in torque output to drive wheels and more reliably preventing deterioration in NV characteristics of a vehicle at the timing of switching from a vibration-damping state in which motor vibration-damping control is performed to a non-vibration-damping state in which motor vibration-damping control is stopped by relatively simple control. When switching from a damping control implementation state in which the lock-up clutch (134) is in the engaged state and motor damping control is implemented to a damping control non-implementation state in which the lock-up clutch (134) is in the slip state and the motor damping control is not implemented, a command to transition from the engaged state to the slip state is issued to the lock-up clutch (134). The motor damping control is continued until the transition to the slip state is completed, and the motor damping control is ended when it is determined that the transition to the slip state is completed.

Description

Technical Field

[0001] The present invention relates to a vehicle control device. Background Art

[0002] Conventionally, as disclosed in Patent Document 1, for example, the following technique has been known: in a hybrid vehicle capable of traveling by power of at least one of an internal combustion engine and a motor (electric motor) connected to the internal combustion engine, a damping torque in the form of a rectangular wave is generated from the motor such that it becomes a reverse phase with respect to the torque generated in the explosion stroke of the internal combustion engine, thereby suppressing the torque vibration of the internal combustion engine. Further, Patent Document 2 discloses the following technique: in a damping implementation region where the engine speed is lower than a specified damping implementation upper limit engine speed and the intake pipe negative pressure is on the high load side (the absolute value of the negative pressure is large) with respect to a specified damping implementation lower limit intake pipe negative pressure, the motor is used to damp the engine vibration.

[0003] However, in a vehicle having a lock-up clutch in the power transmission path from the internal combustion engine to the drive wheels, by bringing the lock-up clutch into an engaged state, the power of the internal combustion engine can be efficiently transmitted to the drive wheels for traveling. Therefore, by increasing the opportunity for the lock-up clutch to be in the engaged state, the fuel economy of the vehicle can be improved. However, on the other hand, if the lock-up clutch is brought into the engaged state when the torque vibration of such an internal combustion engine is large during the cylinder deactivation operation in a so-called cylinder deactivated engine, the torque vibration is transmitted to the drive wheels via the lock-up clutch, and the NV (Noise, Vibration) characteristics of the vehicle may deteriorate. Therefore, it is desired to improve the fuel economy while avoiding the deterioration of the NV characteristics of the vehicle.

[0004] Further, in a vehicle performing the above-described damping control of engine vibration based on the motor (motor damping control), at the timing of stopping the motor damping control and switching to the non-damping state from the damping state in which the motor damping control is implemented, since the damping torque of the motor stops and the torque output to the drive wheels changes abruptly, the NV characteristics of the vehicle may deteriorate. In particular, when switching from the damping state to the non-damping state for reasons such as a decrease in the SOC of the battery in vehicle control, the torque output to the drive wheels may change at an unintended timing of the vehicle driver. Therefore, at the timing of switching from the above-described damping state to the non-damping state, it is preferable to perform the switching using slip control that causes the lock-up clutch to slip.

[0005] However, even if an instruction to change the slip ratio of the lock-up clutch is issued at a stage where there is an instruction to switch from the shock-absorbing state to the non-shock-absorbing state, due to the responsiveness of the actual slip ratio of the lock-up clutch (the followability of the actual value with respect to the indicated value of the slip ratio), a slight time lag will occur before the actual slip ratio of the lock-up clutch decreases. Therefore, it is impossible to suppress the change in the torque output to the drive wheels during the above-mentioned switching, and it may not be possible to sufficiently avoid the deterioration of the NV characteristics of the vehicle.

[0006] Prior art documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-065408

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2007-296975 Summary of the invention

[0010] Problems to be solved by the invention

[0011] The present invention has been completed in view of the above problems, and an object thereof is to provide a vehicle control device that can effectively suppress the change in the torque output to the drive wheels at the timing of switching from the shock-absorbing state in which motor shock-absorbing control is implemented to the non-shock-absorbing state in which motor shock-absorbing control is stopped, can more reliably prevent the deterioration of the NV characteristics of the vehicle, improve the traffic safety of the vehicle, and suppress the reduction of traffic smoothness by relatively simple control.

[0012] Means for solving the problems

[0013] The present invention for solving the above problems is a vehicle control device that controls a vehicle (1), the vehicle including: an internal combustion engine (11); an electric motor (12); drive wheels (DW); and a lock-up clutch (134) provided in a power transmission path from the internal combustion engine (11) and the motor (12) to the drive wheels (DW). The vehicle control device is characterized in that the internal combustion engine (11) is configured to be able to switch between full-cylinder operation in which all cylinders operate and cylinder deactivation operation in which some cylinders are in a resting state. The lock-up clutch (134) can take an engaged state in which the output from at least one of the internal combustion engine (11) and the electric motor (12) is efficiently transmitted to the drive wheels (DW) and a slip state in which the output is transmitted to the drive wheels (DW) with an efficiency lower than that in the engaged state. When the internal combustion engine (11) performs cylinder deactivation operation, as vibration damping control for reducing the torque vibration of the internal combustion engine (11) transmitted to the drive wheels (DW), the vehicle control device (30) can execute motor vibration damping control for outputting vibration damping torque from the electric motor (12). The vibration damping torque includes a torque having a phase opposite to that of the engine torque output from the internal combustion engine (11). When switching from a vibration damping control execution state in which the lock-up clutch (134) is in the engaged state and the motor vibration damping control is executed to a vibration damping control non-execution state in which the lock-up clutch (134) is in the slip state and the motor vibration damping control is not executed, the vehicle control device (30) issues an instruction for the lock-up clutch (134) to transfer from the engaged state to the slip state, continues the motor vibration damping control until the transfer to the slip state is completed, and ends the motor vibration damping control when it is determined that the transfer to the slip state is completed.

[0014] According to the vehicle control device of the present invention, when switching from a vibration damping control execution state in which the lock-up clutch is in an engaged state to execute motor vibration damping control to a vibration damping control non-execution state in which the lock-up clutch is in a slip state and motor vibration damping control is not executed, a command to transfer from the engaged state to the slip state is issued to the lock-up clutch, and the motor vibration damping control is continued until the transfer to the slip state is completed. When the transfer to the slip state is completed, the motor vibration damping control is ended. Thus, when switching from the vibration damping control execution state to the vibration damping control non-execution state, the motor vibration damping control is ended after the transfer of the lock-up clutch to the slip state is completed. Thereby, it is possible to prevent a sudden change in the torque output to the drive wheels due to the stop of the vibration damping torque output from the motor during the motor vibration damping control, and it is possible to effectively prevent the deterioration of the NV characteristics of the vehicle. That is, in the conventional control, during the switching from the vibration damping control execution state to the vibration damping control non-execution state, due to the problem of the responsiveness of the actual slip ratio of the lock-up clutch (the followability of the actual value with respect to the indicated value of the slip ratio), it may not be possible to sufficiently avoid the deterioration of the NV characteristics of the vehicle. In the present invention, by setting the transfer time (the time required for state transfer) from the vibration damping control execution state to the vibration damping control non-execution state until the transfer of the lock-up clutch to the slip state is completed, the motor vibration damping control is ended after the transfer of the lock-up clutch to the slip state is completed during this transfer time. Therefore, there is no need to worry about a sudden change in the torque output to the drive wheels due to the stop of the vibration damping torque output from the motor. Thereby, it is possible to avoid a change in the torque output to the drive wheels at a timing not desired by the driver of the vehicle.

[0015] In addition, in the present invention, it may be that the vehicle control device (30) determines that the transfer of the lock-up clutch (134) to the slip state is completed when the rotational speed difference between the rotational speed (NE) of the input shaft and the rotational speed (NM) of the output shaft of the lock-up clutch (134) becomes equal to or greater than a specified value, or when the rotational speed ratio between the rotational speed (NE) of the input shaft and the rotational speed (NM) of the output shaft of the lock-up clutch (134) becomes equal to or less than a specified value.

[0016] According to this configuration, by determining that the transfer of the lock-up clutch to the slip state is completed when the rotational speed difference between the rotational speed of the input shaft and the rotational speed of the output shaft of the lock-up clutch becomes equal to or greater than a specified value, or when the rotational speed ratio between the rotational speed of the input shaft and the rotational speed of the output shaft of the lock-up clutch becomes equal to or less than a specified value, it is possible to more accurately determine that the transfer of the lock-up clutch to the slip control is completed. Therefore, it is possible to more effectively prevent a change in the torque output to the drive wheels at a timing not desired by the driver of the vehicle, and thus it is possible to more reliably avoid the deterioration of the NV characteristics of the vehicle.

[0017] Further, in the present invention, it may also be that the vehicle control device (30) determines that the transition of the lock-up clutch (134) to the slip state is completed based on the elapse of a predetermined time since the moment indicating the transition to the slip state.

[0018] According to this configuration, by determining that the transition of the lock-up clutch to the slip state is completed based on the elapse of a predetermined time since the moment indicating the transition to the slip state, it is possible to switch from the vibration damping control implementation state to the non-vibration damping control state regardless of the state of the lock-up clutch. Therefore, it is possible to prevent the vibration damping control implementation state from being unnecessarily continued due to abnormal engagement of the lock-up clutch or the like.

[0019] Further, in the present invention, it may also be that when the vehicle control device (30) switches from the vibration damping control implementation state to the non-vibration damping control state, the target engagement torque of the lock-up clutch (134) during the period from when the command to transition from the engaged state to the slip state is issued to the lock-up clutch (134) until the transition to the slip state is completed is set lower than the target engagement torque of the lock-up clutch (134) after the non-vibration damping control state is established.

[0020] According to this configuration, when switching from the vibration damping control implementation state to the non-vibration damping control state, by setting the target engagement torque of the lock-up clutch from when the command to transition from the engaged state to the slip state is issued to the lock-up clutch until the transition to the slip state is completed to be lower than the target engagement torque of the lock-up clutch after the non-vibration damping control state is established, it is possible to improve the responsiveness of the slip ratio during the transition to the slip state. Therefore, it is possible to more reliably complete the transition to the slip state earlier. That is, when switching from the vibration damping control implementation state to the non-vibration damping control state, it is necessary to complete the transition of the lock-up clutch to the slip state as quickly as possible. Therefore, it is preferable to set the target engagement torque of the lock-up clutch to be lower than the target engagement torque after the non-vibration damping control state is established, so that it is possible to quickly transition to the slip state in a shorter time.

[0021] In addition, the reference numerals in parentheses above are shown for reference to the reference numerals of the corresponding components in the embodiments described later.

[0022] Advantages of the Invention

[0023] According to the vehicle control device of the present invention, it is possible to effectively suppress fluctuations in the torque output to the drive wheels at the timing of switching from the vibration damping state in which motor vibration damping control is implemented to the non-vibration damping state in which motor vibration damping control is stopped through relatively simple control, and it is possible to more reliably prevent deterioration of the NV characteristics of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is a diagram showing an example of the vehicle of the present embodiment.

[0025] Figure 2 This is a diagram showing an example of the transmission included in the vehicle of the present embodiment.

[0026] Figure 3 This is a diagram showing an example of the brake-specific fuel consumption (BSFC) in the vehicle of the present embodiment.

[0027] Figure 4 This is a diagram showing an example of motor vibration damping control.

[0028] Figure 5 This is a diagram showing an example of slip vibration damping control.

[0029] Figure 6 This is a timing chart showing the time-dependent changes of various values in the control when switching from the vibration damping control implementation state to the vibration damping control non-implementation state.

[0030] Figure 7 This is a diagram showing a comparative example of the control of the present invention, and shows a timing chart in the case of switching from the vibration damping state to the non-vibration damping state due to vibration damping reasons such as deviating from the region where vibration damping control is required. Detailed Embodiment

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 This is a diagram showing an example of the vehicle of the present embodiment, Figure 2 This is a diagram showing an example of the transmission included in the vehicle of the present embodiment. As Figure 1 shown, the vehicle 1 in the present embodiment is a so-called Hybrid Electrical Vehicle, and includes an engine 11 as an example of an internal combustion engine, an electric generator 12 as an example of an electric motor, a transmission TM as an example of a power transmission device, drive wheels DW, a battery 20, a power conversion device 21, and a control device 30 that is responsible for the overall control of the vehicle 1. The control device 30 is an example of the vehicle control device of the present invention. In addition, in Figure 1 it, thick solid lines represent mechanical connections, double dashed lines represent electrical wirings, and solid arrows represent control signals.

[0032] The engine 11 is, for example, a so-called cylinder deactivation engine configured to be able to switch between full-cylinder operation and cylinder deactivation operation. The full-cylinder operation enables all cylinders to operate, and the cylinder deactivation operation enables operation in a state where some cylinders are deactivated. As an example, the engine 11 is a V-type 6-cylinder engine equipped with a variable valve timing mechanism (not shown), and is configured to be able to deactivate 3 cylinders in one cylinder bank through the variable valve timing mechanism. That is, in the engine 11, 6-cylinder operation using 6 cylinders in two cylinder banks is performed during full-cylinder operation, and 3-cylinder operation using only 3 cylinders in one cylinder bank is performed during cylinder deactivation operation. In addition, the engine 11 is configured such that, through the variable valve timing mechanism, for example, the valve opening period, opening and closing timing, lift amount, etc. of each intake valve can also be changed.

[0033] The engine 11 outputs mechanical energy (power) generated by burning the supplied fuel (e.g., gasoline) by driving the crankshaft 11a (see Figure 2 ). Specifically, the engine 11 is equipped with an injector (not shown). The injector is controlled by the control device 30, for example, using PWM (Pulse Width Modulation) control, to supply fuel to the engine 11. The power output from the engine 11 through fuel supply is transmitted to the drive wheels DW via a transmission TM that is mechanically connected to the engine 11, for the vehicle 1 to travel.

[0034] In addition, the engine 11 is also mechanically connected to the motor generator 12. The motor generator 12 is, for example, a three-phase AC motor and functions as an electric motor that outputs power when supplied with electricity. Specifically, the rotor (not shown) of the motor generator 12 is connected to the crankshaft 11a of the engine 11. Therefore, the power unit torque output from the power unit composed of the engine 11 and the motor generator 12 becomes the sum of the torque at the shaft end of the crankshaft 11a, i.e., the crankshaft end torque, which is the torque output from the engine 11 (hereinafter, also referred to as engine torque) and the torque output from the motor generator 12 (hereinafter, also referred to as motor torque).

[0035] By mechanically connecting the engine 11 and the motor generator 12, in the vehicle 1, it is possible to perform motor assist in which the output of the motor generator 12 is used to assist the driving of the drive wheels DW (i.e., the running of the vehicle 1) using the output of the engine 11.

[0036] In addition, by mechanically connecting the engine 11 and the motor generator 12, it is also possible to rotationally drive the motor generator 12 using the output of the engine 11, or rotationally drive the engine 11 using the output of the motor generator 12. For example, in the vehicle 1, the engine 11 can be started by the recoil start of the motor generator 12.

[0037] The electric generator 12 is electrically connected to the battery 20 via a power conversion device 21. The battery 20 is, for example, a battery having a plurality of power storage units connected in series and configured to be able to output a prescribed voltage (e.g., 50 [V] to 200 [V]). As the power storage unit of the battery 20, a lithium-ion battery, a nickel-metal hydride battery, etc. can be used.

[0038] The power conversion device 21 is a device that includes an inverter, a DC / DC converter (both not shown), etc. and is controlled by a control device 30 to perform power conversion. For example, the power conversion device 21 converts the DC power supplied from the battery 20 into three-phase AC power and supplies it to the electric generator 12, or converts the three-phase AC power supplied from the electric generator 12 into DC power and supplies it to the battery 20. The electric generator 12 is supplied with the power of the battery 20 via the power conversion device 21, and thus can perform the aforementioned motor assist.

[0039] In addition, the electric generator 12 also functions as a generator that generates electricity by being rotationally driven. The electric generator 12 can be rotationally driven not only by the output of the engine 11 as described above, but also by the power input from the drive wheel DW side accompanying braking of the vehicle 1 or the like. The electricity generated by the electric generator 12 is supplied to the battery 20 via the power conversion device 21 for charging the battery 20.

[0040] The transmission TM is, for example, a multi-stage transmission having a plurality of transmission stages (e.g., 7 stages), and is provided in the power transmission path from the engine 11 and the electric generator 12 to the drive wheel DW. Specifically, as Figure 2 shown, the transmission TM is configured to include a torque converter 13 and a gearbox 14.

[0041] The torque converter 13 includes an impeller 131, a turbine 132, a stator 133, and a lock-up clutch 134. The impeller 131 is mechanically connected to the engine 11 and the electric generator 12 (specifically, the crankshaft 11a) and rotates integrally with their rotational drive. The turbine 132 has a working oil inlet configured to be close to the working oil discharge port of the impeller 131, and is mechanically connected to the input shaft 141 of the gearbox 14 and rotates integrally with the input shaft 141. The stator 133 is disposed so as to be sandwiched between the turbine 132 and the impeller 131, and deflects the flow of the working oil returning from the turbine 132 to the impeller 131. In addition, the stator 133 is supported by a housing (not shown) of the torque converter 13 via a one-way clutch 135. The torque converter 13 can transmit power (rotational power) from the impeller 131 to the turbine 132 via the working oil by circulating the working oil in a circulation path formed between the impeller 131 and the turbine 132.

[0042] The lock-up clutch 134 is a clutch that can disconnect or engage the mechanical connection between the engine 11 (specifically, the crankshaft 11a) and the input shaft 141 of the gearbox 14. By bringing the lock-up clutch 134 into the engaged state, the output of the engine 11 can be directly transmitted to the input shaft 141 of the gearbox 14. That is, when the lock-up clutch 134 is in the engaged state, the crankshaft 11a of the engine 11 and the input shaft 141 of the gearbox 14 rotate integrally.

[0043] In addition, the lock-up clutch 134 can also attenuate the power (rotational power) from the crankshaft 11a by slip and transmit it to the input shaft 141. In other words, the lock-up clutch 134 can adopt an engaged state in which the output from at least one of the engine 11 and the motor generator 12 is transmitted to the drive wheels DW with high efficiency and a slip state in which the transmission efficiency to the drive wheels DW is lower than that in the engaged state.

[0044] The gearbox 14 has: an input shaft 141 to which the outputs of the engine 11 and the motor generator 12 are transmitted via at least one of the torque converter 13 and the lock-up clutch 134; a plurality of speed change mechanisms 142, 143 that can change the speed of the power transmitted to the input shaft 141; and an output member 144 that includes an output gear 144a for outputting the power changed by any one of these plurality of speed change mechanisms 142, 143 to the drive wheel DW side. In addition, the input shaft 141 is an example of a main shaft.

[0045] The plurality of speed change mechanisms provided in the gearbox 14 include a first speed change mechanism 142 and a second speed change mechanism 143. The first speed change mechanism 142 includes a first speed change clutch 142a, a first drive gear 142b that rotates integrally with the input shaft 141 when the first speed change clutch 142a is in the engaged state, and a first driven gear 142c that rotates integrally with the output member 144. The second speed change mechanism 143 includes a second speed change clutch 143a, a second drive gear 143b that rotates integrally with the input shaft 141 when the second speed change clutch 143a is in the engaged state, and a second driven gear 143c that rotates integrally with the output member 144.

[0046] In addition, in Figure 2 only the first speed change mechanism 142 and the second speed change mechanism 143 are illustrated as the speed change mechanisms provided in the gearbox 14, but the gearbox 14 may also have speed change mechanisms (not illustrated) other than the first speed change mechanism 142 and the second speed change mechanism 143, for example.

[0047] Whether the clutches included in the transmission TM, such as the lock-up clutch 134, the first speed change clutch 142a, and the second speed change clutch 143a (hereinafter also simply referred to as the clutches of the transmission TM), are in the engaged state (including the aforementioned slip state) or the released state is controlled by the control device 30.

[0048] Return Figure 1 , and the control device 30 is a device that controls the engine 11, the transmission TM, the power conversion device 21, etc. Moreover, the control device 30 can also control the electric generator 12 through the control of the power conversion device 21. In addition, the control device 30 can directly control the electric generator 12 or control the input and output of the battery 20. The control device 30 is realized, for example, by the following ECU (Electronic Control Unit: electronic control unit), which includes a processor that performs various operations, a storage device that stores various information, an input / output device that controls the input and output of data inside and outside the control device 30, etc. In addition, the control device 30 can be realized by one ECU or by the cooperation of multiple ECUs.

[0049] Various sensors are connected to the control device 30, and the control device 30 controls the engine 11, the transmission TM, the power conversion device 21 (i.e., the electric generator 12), etc. based on the information input from these various sensors. As the sensors connected to the control device 30, for example, an engine speed sensor 17 that detects the rotational speed of the engine 11 (crankshaft 11a) (hereinafter also referred to as the engine speed), a vehicle speed sensor 18 that detects the traveling speed of the vehicle 1 (hereinafter also referred to as the vehicle speed), and a main shaft speed sensor 19 that detects the rotational speed of the input shaft 141 (hereinafter also referred to as the main shaft speed) can be cited (refer to Figure 2 ).

[0050] Moreover, as other sensors connected to the control device 30, an AP sensor that detects the operation amount of the accelerator pedal of the vehicle 1 (hereinafter also referred to as the AP opening), a brake sensor that detects the operation amount of the brake pedal of the vehicle 1, a gear position sensor that detects the gear position of the transmission TM, a battery sensor that detects the output and temperature of the battery 20, an intake pressure sensor that detects the intake pressure (intake pipe pressure) of the engine 11 (all not shown) can be cited. In addition, an atmospheric pressure sensor (not shown) that detects the atmospheric pressure can also be connected to the control device 30.

[0051] For example, the control device 30 derives a target torque for the sum of the engine torque and the motor torque, i.e., the crankshaft-end torque (hereinafter also referred to as the crankshaft-end required torque), based on the driving state of the vehicle 1. As an example, the control device 30 derives the crankshaft-end required torque by referring to a map that determines the crankshaft-end required torque required for the driving of the vehicle 1 according to the vehicle speed detected by the vehicle speed sensor 18 and the AP opening detected by the AP sensor. In addition, this map is stored in advance in the storage device of the control device 30, for example. And the control device 30 controls the engine torque and the motor torque in such a way that the crankshaft-end torque becomes the crankshaft-end required torque.

[0052] In addition, the control device 30 switches the operating state of the engine 11 between full-cylinder operation and cylinder deactivation operation based on the crankshaft-end required torque. Specifically, the control device 30 causes the engine 11 to perform cylinder deactivation operation when the crankshaft-end required torque is relatively small, and causes the engine 11 to perform full-cylinder operation when the crankshaft-end required torque increases to a certain extent. That is, the control device 30 improves the fuel economy of the vehicle 1 by causing the engine 11 to perform cylinder deactivation operation when the crankshaft-end required torque is small, and ensures an appropriate crankshaft-end torque corresponding to the driving state of the vehicle 1 by causing the engine 11 to perform full-cylinder operation when the crankshaft-end required torque becomes large. In addition, a specific example of the switching of the operating state of the engine 11 by the control device 30 will be described later, so the description here is omitted.

[0053] [Brake Specific Fuel Consumption (BSFC)]

[0054] In addition, the control device 30 also controls the engine 11 considering the Brake Specific Fuel Consumption (hereinafter referred to as "BSFC"). BSFC is obtained by dividing the fuel consumed (fuel injection amount) in one cycle of the engine by the output of the engine (net horsepower), and the smaller its value, the better the fuel efficiency.

[0055] The control device 30 controls the engine torque based on the BSFC. Specifically, the control device 30 refers to a BSFC characteristic model representing the BSFC characteristics of the vehicle 1 stored in advance in the storage device of the control device 30 and controls the engine torque in such a way that the BSFC becomes the optimal value.

[0056] [BSFC Characteristics of the Vehicle 1 in the Present Embodiment]

[0057] Here, refer to Figure 3 to describe the BSFC characteristics of the vehicle 1. Figure 3This is a diagram showing an example of the brake-specific fuel consumption (BSFC) in the vehicle 1 of the present embodiment. In the graph of this diagram, the vertical axis represents the BSFC [g / kWh], and the horizontal axis represents the engine torque [Nm].

[0058] As Figure 3 shown, the BSFC of the vehicle 1 when the engine 11 performs cylinder deactivation operation, that is, the cylinder deactivation BSFC, gradually decreases as the engine torque increases before the engine torque reaches the cylinder deactivation bottom torque, and increases as the engine torque increases after reaching the cylinder deactivation bottom torque. That is, when the engine 11 performs cylinder deactivation operation, when the engine torque becomes the cylinder deactivation bottom torque, the value of the BSFC is the smallest and the fuel efficiency is the best. In other words, the cylinder deactivation bottom torque is the optimal operating point for the fuel efficiency of the engine 11 performing cylinder deactivation operation.

[0059] In addition, although only a part is illustrated in Figure 3 , the BSFC of the vehicle 1 when the engine 11 performs full-cylinder operation, that is, the full-cylinder BSFC, also has the same tendency as the cylinder deactivation BSFC. Specifically, the full-cylinder BSFC gradually decreases as the engine torque increases before the engine torque reaches the full-cylinder bottom torque (not shown, but the full-cylinder bottom torque > the cylinder deactivation bottom torque), and increases as the engine torque increases after reaching the full-cylinder bottom torque. That is, when the engine 11 performs full-cylinder operation, when the engine torque becomes the full-cylinder bottom torque, the value of the BSFC is the smallest and the fuel efficiency is the best.

[0060] [Cylinder Deactivation Bottom Assist Control]

[0061] During the cylinder deactivation operation of the engine 11, if the opportunity to operate the engine 11 is increased in such a way that the engine torque becomes the cylinder deactivation bottom torque (that is, at the optimal operating point for fuel efficiency), the fuel economy of the vehicle 1 is improved. On the other hand, if an appropriate crankshaft-end torque corresponding to the driving state of the vehicle 1 cannot be ensured by operating the engine 11 at the cylinder deactivation bottom torque, a sluggishness (so-called acceleration lag of the vehicle 1) may occur, and the driving performance may deteriorate.

[0062] Therefore, when the engine 11 is operating in a cylinder deactivation mode, when the engine torque reaches the cylinder deactivation bottom torque, the control device 30 performs cylinder deactivation bottom assist control. In the cylinder deactivation bottom assist control, the control device 30 increases the motor torque used for motor assist in response to an increase in the crankshaft end required torque while maintaining the engine torque at the cylinder deactivation bottom torque. In other words, in the cylinder deactivation bottom assist control, the control device 30 uses the motor torque to compensate for the torque shortage relative to the crankshaft end required torque by maintaining the engine torque at the cylinder deactivation bottom torque. Thereby, the engine 11 can be operated at the optimal fuel efficiency operating point, and an appropriate crankshaft end torque corresponding to the driving state of the vehicle 1 can be ensured. Therefore, while avoiding the occurrence of sluggishness and reducing the driving performance, the fuel economy of the vehicle 1 can be improved.

[0063] Moreover, when the crankshaft end required torque reaches a specified all-cylinder switching bottom torque during the execution of the cylinder deactivation bottom assist control, the control device 30 ends the cylinder deactivation bottom assist control and switches the operating state of the engine 11 to all-cylinder operation. Here, as Figure 3 shown, the all-cylinder switching bottom torque is the torque corresponding to the intersection point of the curve representing the cylinder deactivation BSFC and the curve representing the all-cylinder BSFC. Thereby, from the viewpoint of BSFC, the operating state of the engine 11 can be switched from cylinder deactivation operation to all-cylinder operation at an appropriate timing.

[0064] [Torque vibration of the engine]

[0065] Next, the torque vibration of the engine 11 will be described with reference to Figure 4 . Figure 4 FIG. is an example showing a motor vibration damping control described later. In the graph of this figure, the vertical axis represents torque [Nm], and the horizontal axis represents timing.

[0066] As Figure 4 shown by the thick solid line in, when the engine 11 is operating in a cylinder deactivation mode, compared with the all-cylinder operation, there is a tendency for the amplitude of the torque vibration generated in the combustion stroke (explosion stroke) of the engine 11 (hereinafter, also simply referred to as the torque vibration of the engine 11) to become larger. The reason why the torque vibration of the engine 11 becomes larger during cylinder deactivation operation is that, in order to ensure an appropriate crankshaft end torque, the torque output from each working cylinder is increased compared with the all-cylinder operation. In addition, during cylinder deactivation operation, the explosion interval of the engine 11 becomes longer than that during all-cylinder operation, so the frequency of the torque vibration of the engine 11 also tends to become lower.

[0067] In this way, during cylinder deactivation operation, sometimes a torque vibration with a large amplitude and a low frequency is generated in the engine 11. When such a torque vibration is transmitted to the drive wheel DW, it becomes the main cause of the vibration that gives discomfort to the driver, and the NV characteristics of the vehicle 1 may deteriorate.

[0068] Therefore, the control device 30 is configured to be able to execute vibration damping control for reducing the torque vibration of the engine 11 transmitted to the drive wheels DW when the engine 11 performs cylinder deactivation operation. Here, the vibration damping control includes motor vibration damping control for outputting a specified vibration damping torque from the motor generator 12 and slip vibration damping control for making the lock-up clutch 134 in a slip state. Hereinafter, an example of the motor vibration damping control and the slip vibration damping control will be described.

[0069] [Motor Vibration Damping Control]

[0070] In the motor vibration damping control, as Figure 4 indicated by the single-dot chain line in Figure 4 , the control device 30 causes the motor generator 12 to output a vibration damping torque including a torque having a phase opposite to the engine torque output from the engine 11. Specifically, as

[0071] indicated by the dotted line in

[0072] , the control device 30 causes the motor generator 12 to output a vibration damping torque such that the instantaneous combined torque obtained by combining the torques output from each cylinder of the engine 11 and the motor generator 12 at each time point is substantially equal to that during full-cylinder operation. Thus, if the vibration damping torque of the motor generator 12 is not insufficient with respect to the torque vibration of the engine 11, it is possible to achieve substantially the same NV characteristics as during full-cylinder operation even during cylinder deactivation operation. Figure 5 Next, the slip vibration damping control will be described with reference to Figure 5 is a diagram showing an example of the slip vibration damping control, and in the graph of this diagram, the temporal relationships between the engine speed, the main shaft speed, and the engine torque are shown.

[0073] As Figure 5 shown, the control device 30 executes slip vibration damping control when the engine 11 performs cylinder deactivation operation, whereby the lock-up clutch 134 can be made in a slip state (shown as "LC slip"), and the power transmitted from the crankshaft 11a to the input shaft 141 via the lock-up clutch 134 is attenuated.

[0074] Specifically, when executing the slip vibration damping control, the control device 30 appropriately controls the hydraulic pressure supplied to the lock-up clutch 134 while referring to the engine speed detected by the engine speed sensor 17 and the main shaft speed detected by the main shaft speed sensor 19, thereby controlling the power transmission efficiency via the lock-up clutch 134 (hereinafter, also simply referred to as the power transmission efficiency). By executing the slip vibration damping control, for example, as Figure 5 shown, even if the engine speed changes, the control device 30 can keep the main shaft speed constant.

[0075] However, if the power transmission efficiency decreases due to the execution of the slip vibration damping control, in order to make the vehicle 1 travel in the same manner as when the slip vibration damping control is not executed, more power needs to be output from the engine 11 and the motor generator 12. Therefore, the slip vibration damping control may cause a decrease in the fuel economy of the vehicle 1.

[0076] Therefore, in order to suppress the decrease in fuel economy caused by the slip vibration damping control, when the vibration damping control is executed, the control device 30 preferentially executes the motor vibration damping control over the slip vibration damping control. When the deterioration of the NV characteristics cannot be avoided only by the motor vibration damping control, the slip vibration damping control is executed. In addition, when the control device 30 executes the slip vibration damping control, it also executes it together with the motor vibration damping control, thereby minimizing the amount of decrease in the power transmission efficiency required to avoid the deterioration of the NV characteristics as much as possible.

[0077] Specifically, the control device 30 stores a map table that pre-determines each of a non-vibration damping region where neither the motor vibration damping control nor the slip vibration damping control is executed, a first vibration damping region where both the motor vibration damping control and the slip vibration damping control are executed, and a second vibration damping region where the motor vibration damping control is executed and the slip vibration damping control is not executed, based on the crankshaft end required torque and the engine speed. The control device 30 refers to this map table and determines whether to execute only the motor vibration damping control (that is, whether the crankshaft end required torque and the engine speed are included in the second vibration damping region), and whether to execute the slip vibration damping control in addition to the motor vibration damping control (that is, whether the crankshaft end required torque and the engine speed are included in the first vibration damping region), based on the crankshaft end required torque and the engine speed during the cylinder deactivation operation. Moreover, based on this determination result, the control device 30 executes the motor vibration damping control, or executes the motor vibration damping control and the slip vibration damping control as needed.

[0078] In addition, in the vibration damping control as described above, preferably, when switching from the vibration damping state in which vibration damping is implemented only by the motor vibration damping control to the non-vibration damping state, the switching is performed while also using the slip vibration damping control that causes the lock-up clutch 134 to slip, thereby preventing a sudden change in the torque output to the drive wheels DW due to the stop of the vibration damping torque of the motor generator 12. However, due to the responsiveness of the lock-up clutch 134 (the followability of the actual value with respect to the indicated value of the slip ratio), there is a certain time lag between the indicated value (target slip ratio) of the slip ratio of the lock-up clutch 134 and the actual slip ratio. Therefore, even if the command value of the slip ratio is changed in such a way that the lock-up clutch 134 is transferred from the engaged state to the slip state at the stage where there is a switching command, the follow-up of the actual slip ratio of the lock-up clutch 134 cannot be sufficiently timely, and the torque variation output to the drive wheels DW during the above switching may deteriorate the NV characteristics of the vehicle 1 at the time of switching. In particular, when the switching from the vibration damping state to the non-vibration damping state is required not for vibration damping reasons such as deviating from the region where vibration damping control is required, but for reasons of vehicle 1 control such as a decrease in the SOC of the battery 20, for example, a change in the torque output to the drive wheels DW may occur at an unintended timing for the driver or passengers of the vehicle 1.

[0079] In order to address this situation, in the control device 30 of the present embodiment, when the implementation of the vibration damping control is transferred to non-implementation due to control restrictions (such as a decrease in SOC) of the vehicle 1 in the region where vibration damping control is required, the NV of the vehicle 1 at the time of switching the vibration damping control is improved by appropriately performing the slip control of the lock-up clutch 134 during the transfer.

[0080] Specifically, when switching from the vibration damping control implementation state in which the lock-up clutch 134 is in the engaged state and the vibration damping control is implemented to the vibration damping control non-implementation state in which the lock-up clutch 134 is in the slip state and the vibration damping control is not implemented, a command to transfer from the engaged state to the slip state is issued to the lock-up clutch 134, and the motor vibration damping control is continued until the transfer to the slip state is completed, and the motor vibration damping control is ended when the transfer to the slip state is completed. Hereinafter, the control when switching from this vibration damping control implementation state to the vibration damping control non-implementation state will be described in detail.

[0081] Figure 6It is a timing chart showing the time-dependent changes of various values in the control when switching from the vibration damping control implementation state to the vibration damping control non-implementation state. In the timing chart of this figure, the changes in the vibration damping control state (implementation / transition / non-implementation), engine torque and motor vibration damping torque, transmission (TM) input torque, vibration damping control permission signal (permission / non-permission), slip ratio ETR of the lock-up clutch 134 (target ETR, actual ETR), and output torque (drive wheel torque) output to the drive wheel DW are shown with respect to the elapsed time t. In addition, the slip ratio ETR (%) of the lock-up clutch 134 mentioned here is calculated by the following formula.

[0082] ETR (%) =

[0083] (Rotation speed NM of the main shaft of the transmission TM / Crankshaft speed NE) × 100

[0084] Figure 6The timing chart is for the case where the switching from the vibration damping state to the non-vibration damping state is performed not due to reasons such as deviation from the region requiring vibration damping control of the engine 11 for equal vibration damping, but due to reasons such as a decrease in the SOC of the battery 20 in the control of the vehicle 1. And in this timing chart, before time t11, it is in the vibration damping control implementation state where the motor vibration damping control is performed in the engaged state of the lock-up clutch 134. Then, at time t11, for reasons such as the SOC of the battery 20 becoming below a preset threshold in the control of the vehicle 1, it is determined that a transfer from the vibration damping control implementation state to the vibration damping control non-implementation state is required. Thus, the vibration damping control state transfers from the "implementation" state to the "transition" state of implementation → non-implementation. Also, thereby, the target slip ratio (target ETR) of the lock-up clutch 134 is set to S1. This target slip ratio = S1 is a value for transferring the lock-up clutch 134 to the slip state and is a value lower than the target slip ratio = S0 in the previously engaged state of the lock-up clutch 134 (S0 > S1). Additionally, the target slip ratio S1 is set to be lower than the target slip ratio (target engagement torque) = S2 of the lock-up clutch 134 after the vibration damping control non-implementation state is established (S2 > S1). And in this "transition" state, the output of the vibration damping torque of the motor generator 12 also continues. After that, at time t12, the actual ETR starts to decrease. Thus, the lock-up clutch 134 transfers to the slip state. Then, at time t13, it is determined that the transfer of the lock-up clutch 134 to the slip state is completed. Thus, the vibration damping control state transfers from the "transition" state to the "non-implementation" state. The determination of the completion of the transfer to the slip state here is made based on the actual slip ratio (actual ETR) of the lock-up clutch 134 (the rotational speed difference between the rotational speed NE of the crankshaft 11a and the rotational speed NM of the main shaft 141) becoming equal to or greater than a specified value. By determining at time t13 that the transfer to the slip state is completed, the vibration damping control permission signal is switched from "permitted" to "not permitted", and the output of the motor vibration damping torque of the motor generator 12 stops. In addition, the target slip ratio of the lock-up clutch 134 is set to the target slip ratio (target engagement torque) = S2 of the lock-up clutch 134 after the vibration damping control non-implementation state is established. After that, in the case shown in this figure, the actual slip ratio gradually increases, and at time t14, the actual slip ratio becomes a value that roughly follows the target slip ratio S2.

[0085] By providing the transfer period to the vibration damping control non-implementation state as described above, after the lock-up clutch 134 becomes the slip state, the output of the vibration damping torque of the motor generator 12 stops. Therefore, as Figure 6 shown by the drive wheel torque, when transferring from the vibration damping control implementation state to the vibration damping control non-implementation state, the torque output to the drive wheel DW becomes a stable state, and deterioration of the NV characteristics of the vehicle 1 during the transfer can be prevented.

[0086] Note that in the above description, a case is shown where the transition to the slip state is determined when the actual slip ratio (actual ETR) of the lock-up clutch 134 (the rotational speed difference between the rotational speed NE of the crankshaft 11a and the rotational speed NM of the main shaft 141) becomes equal to or greater than a specified value. However, in addition to this, the determination of the completion of the transition to the slip state can also be made based on the condition that a specified time has elapsed since the time when the transition to the slip state is instructed. In this case, a timer that measures the specified time starting from the time t11 in the timing chart of Figure 6 can be provided, and it is possible to determine that the transition to the slip state is completed at the moment when the counting of this timer ends.

[0087] As described above, according to the control device 30 of the present embodiment, when switching from the vibration damping control execution state in which the lock-up clutch 134 is in the engaged state and the motor vibration damping control is executed to the vibration damping control non-execution state in which the lock-up clutch 134 is in the slip state and the motor vibration damping control is not executed, an instruction to transfer from the engaged state to the slip state is issued to the lock-up clutch 134. The motor vibration damping control is continued until the transition to the slip state is completed, and the motor vibration damping control is terminated when the transition to the slip state is completed. Thus, when switching from the vibration damping control execution state to the vibration damping control non-execution state, the motor vibration damping control is terminated after the lock-up clutch 134 has completed the transition to the slip state. Thereby, in the motor vibration damping control, it is possible to prevent a sudden change in the torque output to the drive wheels DW due to the stop of the motor vibration damping torque output from the motor generator 12, and it is possible to effectively prevent the deterioration of the NV characteristics of the vehicle 1. That is, in the conventional control, in the switching from the vibration damping control execution state to the vibration damping control non-execution state, due to the problem of the responsiveness of the actual slip ratio of the lock-up clutch 134 (the followability of the actual value with respect to the indicated value of the slip ratio), it may not be possible to sufficiently avoid the deterioration of the NV characteristics of the vehicle 1. In the control of the present embodiment, when switching from the vibration damping control execution state to the vibration damping control non-execution state, by setting the transition time (the time required for the state transition) until the lock-up clutch 134 has completed the transition to the slip state and terminating the motor vibration damping control after the lock-up clutch 134 has completed the transition to the slip state during this transition time, there is no possibility of a sudden change in the torque output to the drive wheels DW due to the stop of the motor vibration damping torque output from the motor generator 12. Thereby, it is possible to avoid a change in the torque output to the drive wheels DW at a timing that is not desired by the driver of the vehicle 1.

[0088] In addition, in the control device 30 of the present embodiment, it is determined that the transition of the lock-up clutch 134 to the slip state is completed when the actual slip ratio (ETR) of the lock-up clutch 134 becomes equal to or less than a specified value, or when the rotational speed difference between the rotational speed NE of the crankshaft 11a (the input shaft of the lock-up clutch 134) and the rotational speed (NM) of the main shaft 141 (the output shaft of the lock-up clutch 134) becomes equal to or greater than a specified value. Alternatively, as described above, it is also possible to determine that the transition of the lock-up clutch 134 to the slip state is completed when a specified time has elapsed since the instruction to transition to the slip state was issued.

[0089] With these configurations, it is possible to more accurately determine the completion of the transition of the lock-up clutch 134 to slip control. Therefore, it is possible to more effectively prevent fluctuations in the torque output to the drive wheels DW at a timing not desired by the driver of the vehicle 1, and thus it is possible to more reliably avoid deterioration of the NV characteristics of the vehicle 1.

[0090] In addition, in the control device 30 of the present embodiment, when switching from the vibration damping control execution state to the vibration damping control non-execution state, the target engagement torque of the lock-up clutch 134 (target ETR = S1) during the period from when the instruction to transition from the engaged state to the slip state is issued to the lock-up clutch 134 until the transition to the slip state is completed is set lower than the target engagement torque of the lock-up clutch 134 (target ETR = S2) after the vibration damping control non-execution state is established.

[0091] With this configuration, when switching from the vibration damping control execution state to the vibration damping control non-execution state, by setting the target engagement torque of the lock-up clutch 134 during the period from when the instruction to transition from the engaged state to the slip state is issued to the lock-up clutch 134 until the transition to the slip state is completed to be lower than the target engagement torque of the lock-up clutch 134 after the vibration damping control non-execution state is established, it is possible to improve the responsiveness of the slip ratio during the transition to the slip state and to more reliably complete the transition to the slip state earlier. That is, when switching from the vibration damping control execution state to the vibration damping control non-execution state, it is necessary to complete the transition of the lock-up clutch 134 to the slip state as quickly as possible. However, by setting the target engagement torque of the lock-up clutch 134 to be lower than the target engagement torque after the vibration damping control non-execution state is established, it is possible to quickly transition to the slip state in a shorter time.

[0092] In addition, Figure 7It is a diagram showing a comparative example of the control of the present invention, and is a timing diagram showing the case of switching from the vibration damping state to the non-vibration damping state due to reasons such as deviation from the area requiring vibration damping control. In the timing diagram of this figure, the changes in the vibration damping control state (implemented / not implemented), engine torque, motor vibration damping torque, transmission (TM) input torque, vibration damping control permission signal (permitted / not permitted), main shaft speed (NM rotation), slip ratio ETR of the lock-up clutch 134 (target ETR, actual ETR), and output torque output to the drive wheels DW (drive wheel torque) with respect to the elapsed time t are shown respectively.

[0093] In Figure 7 the chart, at time t21, the lock-up clutch 134 becomes the engaged state, so that before time t22, it is in the vibration damping control implementation state where the lock-up clutch 134 is in the engaged state and motor vibration damping control is implemented. Here, in the case where the rotational speed such as MN rotation (main shaft speed) is in a relatively high rotational speed region, it is assumed that even if the slip amount of the lock-up clutch 134 is reduced to become the engaged state, the region where the influence on the NV of the vehicle 1 is small. In this state, at time t22, it is determined that it has entered the region (non-vibration damping region) where the NV characteristics of the vehicle 1 can be satisfied without motor vibration damping control and without slip of the lock-up clutch 134. Therefore, the vibration damping control implementation state is switched from "implemented" to "not implemented". In addition, thereby, the output of the motor vibration damping torque by the motor generator 12 is stopped. Furthermore, before and after the vibration damping control implementation state is switched from "implemented" to "not implemented", the vibration damping control permission signal is always in the "permitted" state, and the lock-up clutch 134 is always in the engaged state.

[0094] In Figure 7 the example of the graph, when the vibration damping control implementation state is switched from "implemented" to "not implemented", no Figure 6 transfer period as in the example is provided, and the output of the vibration damping torque by the motor generator 12 is immediately stopped. However, originally, in the case where the rotational speed such as the main shaft speed is in a relatively high rotational speed region, even if the slip amount of the lock-up clutch 134 is reduced to become the engaged state, it is a region where the influence on the NV of the vehicle 1 is small. Therefore, the drive wheel DW torque when transferring from the vibration damping control implementation state to the vibration damping control non-implementation state maintains a stable state, and does not cause deterioration of the NV characteristics of the vehicle 1 during the switching.

[0095] Above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and various changes can be made within the scope of the technical idea described in the claims, the specification, and the drawings.

[0096] For example, in the above-described embodiment, an example in which the engine 11 and the motor generator 12 are connected via the crankshaft 11a has been described, but it is not limited thereto. For example, the motor generator 12 may also be connected to a drive shaft that rotates integrally with the drive wheel DW.

Claims

1. A vehicle control device for controlling a vehicle comprising an internal combustion engine, an electric motor, drive wheels, and a lockup clutch provided in a power transmission path from the internal combustion engine and the electric motor to the drive wheels, wherein: The internal combustion engine is capable of switching between full-cylinder operation in which all cylinders are activated and cylinder-deactivation operation in which a part of the cylinders are deactivated. The lockup clutch can adopt: an engaged state in which the output from at least one of the internal combustion engine and the electric motor is transmitted to the drive wheels with high efficiency; and a slip state in which the output is transmitted to the drive wheels with a lower efficiency than in the engaged state. When the internal combustion engine is in cylinder deactivation operation, the vehicle control device can execute motor vibration reduction control for outputting a vibration reduction torque from the electric motor as vibration reduction control for reducing torque vibration of the internal combustion engine transmitted to the drive wheels, wherein the vibration reduction torque includes torque having a phase opposite to that of the engine torque output from the internal combustion engine. When the vehicle control device switches from a vibration reduction control execution state in which the motor vibration reduction control is executed by setting the lockup clutch to the engaged state to a vibration reduction control non-execution state in which the motor vibration reduction control is not executed by setting the lockup clutch to the slip state, A command is issued to the lockup clutch to shift from the engaged state to the slipping state, the motor vibration reduction control is continued until the shift to the slipping state is completed, and the motor vibration reduction control is terminated when it is determined that the shift to the slipping state is completed.

2. The vehicle control device according to claim 1, wherein: The vehicle control device determines that the lockup clutch has completed transition to the slip state when a rotational speed difference between a rotational speed of an input shaft and a rotational speed of an output shaft of the lockup clutch becomes equal to or greater than a predetermined value.

3. The vehicle control device according to claim 1, wherein: The vehicle control device determines that the lockup clutch has completed transition to the slip state when a rotation speed ratio between a rotation speed of an input shaft and a rotation speed of an output shaft of the lockup clutch becomes equal to or less than a predetermined value.

4. The vehicle control device according to claim 1, wherein: The vehicle control device determines that the lock-up clutch has completed transition to the slip state based on a lapse of a predetermined time from a time when transition to the slip state is instructed.

5. The vehicle control device according to claim 1, wherein: When switching from the vibration reduction control implementation state to the vibration reduction control non-implementation state, the vehicle control device sets the target engagement torque of the lockup clutch from the issuance of a command to the lockup clutch to transition from the engaged state to the slipping state to be lower than the target engagement torque of the lockup clutch after the vibration reduction control non-implementation state is established.

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