Vehicle control device

Abstract

To provide a vehicle control device, which can suppress a vehicle equipped with a wet start clutch from vibrating.SOLUTION: An electronic control device (control device) 90 of a vehicle 10, which is equipped with an engine (front wheel driving device) 12 that drives front wheels 14, a start clutch (wet start clutch) WSC arranged on a power transmission path PT between the front wheels 14 and the engine 12, and a rear wheel driving electric motor (rear wheel driving device) MGr that electrically drives rear wheels 34, controls the start clutch WSC so that the clutch transmits power in a slip state, when the vehicle 10 runs at predetermined low speed (a), and when front wheel driving torque is included in a predetermined torque range, in a slip state of the starting clutch WSC, changes the front wheel driving torque Trf by a predetermined amount so that the torque increases or decreases to prevent the torque from being included in the predetermined torque range, and decreases or increases the rear wheel driving torque Trr in accordance with the predetermined amount.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle that includes a front-wheel drive unit that drives the front wheels, a wet start clutch arranged in a power transmission path between the front wheels and the front-wheel drive unit, and a rear-wheel drive unit that electrically drives the rear wheels. [Background technology]

[0002] There are known control devices for a vehicle that includes an internal combustion engine that drives the front wheels, a motor generator that is arranged in a power transmission path between the front wheels and the internal combustion engine, and a wet start clutch that is arranged in the power transmission path between the front wheels and the motor generator. For example, the device described in Patent Document 1 is one such control device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-170860 Summary of the Invention [Problem to be solved by the invention]

[0004] In the vehicle control device described in Patent Document 1, when the wet start clutch is in a slipping state, the amount of intake air to the internal combustion engine is increased under certain circumstances in order to prevent the wet start clutch from seizing, and the amount of electricity generated by the motor generator is increased to offset the increase in torque of the internal combustion engine.

[0005] In a vehicle equipped with a wet start clutch, if the torque transmitted to the drive wheels during low-speed driving is within a predetermined range when the wet start clutch is in a slipping state, large torque fluctuations may occur in the transmitted torque, which may cause vehicle vibration.

[0006] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a vehicle control device that can suppress vehicle vibrations in a vehicle equipped with a wet start clutch. [Means for solving the problem]

[0007] The gist of the present invention is that a control device for a vehicle equipped with a front-wheel drive unit that drives the front wheels, a wet start clutch arranged in a power transmission path between the front wheels and the front-wheel drive unit, and a rear-wheel drive unit that electrically drives the rear wheels (a) controls the wet start clutch to transmit power in a slip state when the vehicle is traveling at a predetermined low speed, and (b) when the torque transmitted to the front wheels in the slip state of the wet start clutch falls within a predetermined range in which fluctuations outside a predetermined allowable range occur, increases or decreases the torque transmitted to the front wheels by a predetermined amount so that it is not within the predetermined range, and decreases or increases the torque transmitted from the rear-wheel drive unit to the rear wheels according to the predetermined amount. [Effects of the Invention]

[0008] According to the vehicle control device of the present invention, (a) the wet start clutch is controlled to transmit power in a slip state when the vehicle is traveling at a predetermined low speed, and (b) if the torque transmitted to the front wheels in the slip state of the wet start clutch is within a predetermined range where fluctuations outside the predetermined allowable range occur, the torque transmitted to the front wheels is increased or decreased by a predetermined amount so as not to fall within the predetermined range, and the torque transmitted from the rear-wheel drive system to the rear wheels is increased or decreased according to the predetermined amount. In this way, if the torque transmitted to the front wheels in the slip state of the wet start clutch is within the predetermined range, i.e., if fluctuations in the torque transmitted to the front wheels fall outside the predetermined allowable range, the torque transmitted to the front wheels is increased or decreased so as not to fall within the predetermined range. Furthermore, the increase or decrease in the torque transmitted to the front wheels is compensated for by the torque transmitted from the rear-wheel drive system to the rear wheels. This prevents unintended changes in the drive torque of the entire vehicle, reduces torque fluctuations in the drive torque of the entire vehicle, and suppresses vehicle vibration. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a vehicle equipped with an electronic control device according to an embodiment; [Figure 2] 10 is an example showing the relationship between the front wheel drive torque and the torque fluctuation amount when the vehicle is traveling at a predetermined low speed and the starting clutch is in a slipping state. [Figure 3] 3 is an example of a flowchart illustrating a main part of the control operation of the electronic control device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0011] FIG. 1 is a schematic diagram of a vehicle 10 equipped with an electronic control device 90 according to an embodiment.

[0012] The vehicle 10 includes an engine 12 and a rear-wheel drive electric motor MGr, which are power sources for traveling. The vehicle 10 includes, in order from the engine 12 side, a crankshaft 20, a disconnecting clutch K0, a rotor shaft 22 of the front-wheel drive electric motor MGf, a starting clutch WSC, an input shaft 24, an automatic transmission 16, and an output shaft 26, all of which are well-known components, arranged in a power transmission path PT between the engine 12 and front wheels 14. The rear-wheel drive electric motor MGr is also well-known components that electrically drive rear wheels 34. The vehicle 10 also includes a hydraulic control circuit 40, an MGf control inverter 50, an MGr control inverter 52, a battery 60, and a DC / DC converter 62, all of which are well-known components. The vehicle 10 also includes an electronic control device 90.

[0013] The engine 12 is a well-known internal combustion engine. The front-wheel drive electric motor MGf and the rear-wheel drive electric motor MGr are, for example, motor generators having both an electric motor function and a generator function, and have a well-known configuration. The front-wheel drive electric motor MGf and the rear-wheel drive electric motor MGr are rotated and driven by power stored in a battery 60 via an MGf control inverter 50 and an MGr control inverter 52, respectively. The starting clutch WSC is a hydraulic friction engagement device that is in a fully engaged state or a slip state during driving, and is particularly in a slip state when starting. Hereinafter, unless otherwise specified, both the fully engaged state and the slip state are referred to as the engaged state.

[0014] The hydraulic control circuit 40 controls the front wheel drive torque Trf [N·m] by supplying the necessary hydraulic oil (which also serves as cooling oil) OIL to a hydraulic actuator 42 that controls the engagement and disengagement of the engagement / disengagement of the engagement / disengagement clutch K0, a hydraulic actuator 44 that controls the engagement and disengagement of the starting clutch WSC, and a hydraulic actuator 46 that performs gear shift control of the automatic transmission 16. The front wheel drive torque Trf is the torque transmitted to the front wheels 14.

[0015] The speed ratio γat in the automatic transmission 16 is the rotational speed ratio (=Nin / Nout) between the input shaft rotational speed Nin [rpm] and the output shaft rotational speed Nout [rpm]. The input shaft rotational speed Nin is the rotational speed of the input shaft 24, and the output shaft rotational speed Nout is the rotational speed of the output shaft 26.

[0016] The electronic control device 90 includes, for example, a so-called microcomputer, and executes various controls of the vehicle 10 by performing signal processing in accordance with pre-stored programs. The electronic control device 90 corresponds to the "control device" in the present invention. Various signals (e.g., accelerator opening θacc [%], vehicle speed V [km / h], engine rotation speed Ne [rpm] which is the rotation speed of the engine 12, MGf rotation speed Nmgf [rpm] which is the rotation speed of the front-wheel drive electric motor MGf, input shaft rotation speed Nin which is the rotation speed of the input shaft 24, output shaft rotation speed Nout which is the rotation speed of the output shaft 26, hydraulic pressure Pwsc [Pa] supplied to the hydraulic actuator 44) based on detection values ​​of various sensors (e.g., accelerator opening sensor 70, vehicle speed sensor 72, engine rotation speed sensor 74, MGf rotation speed sensor 76, input shaft rotation speed sensor 78, output shaft rotation speed sensor 80, hydraulic pressure sensor 82, etc.) are input to the electronic control device 90. The electronic control device 90 outputs various command signals (engine control signal Se, MGf control signal Smgf that controls the rotation of the front wheel drive motor MGf, MGr control signal Smgr that controls the rotation of the rear wheel drive motor MGr, disconnection control signal Sk0 that controls the connection and disconnection of the disconnection clutch K0, disconnection control signal Swsc that controls the connection and disconnection of the starting clutch WSC, shift control signal Sat that controls the shifting of the automatic transmission 16, etc.) to each device of the vehicle 10 (engine 12, MGf control inverter 50, MGr control inverter 52, hydraulic control circuit 40, etc.).

[0017] The vehicle 10 can select between a two-wheel drive mode in which the drive torque Tr of the drive wheels of the vehicle 10 is entirely provided by the front-wheel drive torque Trf, and a four-wheel drive mode in which the drive torque Tr is provided by both the front-wheel drive torque Trf and the rear-wheel drive torque Trr [N·m]. The rear-wheel drive torque Trr is the torque transmitted to the rear wheels 34.

[0018] In the two-wheel drive mode, the vehicle is selectively switched between a BEV (Battery Electric Vehicle) driving mode that realizes BEV (Battery Electric Vehicle) driving using only the front-wheel drive electric motor MGf as a power source, an HEV (Hybrid Electric Vehicle) driving mode that realizes HEV (Hybrid Electric Vehicle) driving using the engine 12 and the front-wheel drive electric motor MGf as a power source, and an engine driving mode that realizes engine driving using only the engine 12 as a power source. During BEV driving, the disconnecting clutch K0 is released and the starting clutch WSC is engaged. During HEV driving and engine driving, the disconnecting clutch K0 is fully engaged and the starting clutch WSC is engaged. In the four-wheel drive mode, the front wheels 14 are driven in the BEV driving mode, HEV driving mode, or engine driving mode, and the rear wheels 34 are driven using the rear-wheel drive electric motor MGr as a power source.

[0019] Next, the control function of the electronic control device 90 will be described when the starting clutch WSC transmits power in a slip state while the vehicle 10 is traveling at a predetermined low speed in the engine traveling mode in the two-wheel drive mode. In this case, the engine 12 corresponds to the "front-wheel drive device" in the present invention, and the rear-wheel drive electric motor MGr corresponds to the "rear-wheel drive device" in the present invention. First, the engine 12, the on-off clutch K0, the front-wheel drive electric motor MGf, the starting clutch WSC, and the automatic transmission 16 are each controlled so that the required driving torque Trdem [N·m] is transmitted from the engine 12 to the front wheels 14. The required driving torque Trdem is a required amount relative to the driving torque Tr [N·m]. The predetermined low-speed traveling will be described later. The starting clutch WSC corresponds to the "wet start clutch" in the present invention.

[0020] The electronic control unit 90 determines whether the starting clutch WSC is in a slip state. The starting clutch WSC enables power transmission between the engine 12 and the front wheels 14 according to a transmission torque capacity Tc [N·m] based on the slip state. When the starting clutch WSC is in a slip state, the transmission torque capacity Tc is lower than the torque input from the engine 12 to the starting clutch WSC, and therefore the torque transmitted from the starting clutch WSC to the front wheels 14 is equal to the transmission torque capacity Tc. The transmission torque capacity Tc can be calculated, for example, using a torque capacity map, which is a stored relationship between the hydraulic pressure Pwsc and the transmission torque capacity Tc that is determined in advance experimentally or by design. When the starting clutch WSC is in a slip state, the front wheel drive torque Trf is the transmission torque capacity Tc multiplied by the gear ratio γat (= Tc × γat). The front wheel drive torque Trf corresponds to the "torque transmitted to the front wheels" in this invention.

[0021] The electronic control device 90 determines whether the front wheel drive torque Trf is within a predetermined torque range. The "predetermined torque range" refers to a torque range determined in advance by experiment or design in which the torque fluctuation amount ΔTrf [N·m], which is the fluctuation amount of the front wheel drive torque Trf (= the maximum amplitude, i.e., displacement amount, of the front wheel drive torque Trf), falls outside a predetermined allowable range when the starting clutch WSC is in a slip state during predetermined low-speed driving. The "predetermined low-speed driving" refers to driving within a vehicle speed range determined in advance by experiment or design in which the front wheel drive torque Trf can fall within the predetermined torque range when the starting clutch WSC is in a slip state. The "predetermined allowable range" refers to a range within which the discomfort felt by passengers of the vehicle 10, including the driver, due to vehicle vibration is acceptable. The "predetermined torque range" corresponds to the "predetermined range" in this invention.

[0022] FIG. 2 shows an example of the relationship between the front wheel drive torque Trf and the torque fluctuation amount ΔTrf when the vehicle 10 is traveling at a predetermined low speed and the starting clutch WSC is in a slipping state.

[0023] As shown in FIG. 2, when the front wheel drive torque Trf falls within a predetermined torque range (=Trf_jdg2≧Trf≧Trf_jdg1), the torque fluctuation ΔTrf is equal to or greater than the reference value ΔTrf_jdg. The reference value ΔTrf_jdg is a lower limit of the torque fluctuation ΔTrf, determined experimentally or by design, at which vehicle vibration falls outside a predetermined allowable range. Thus, the torque fluctuation ΔTrf varies depending on the input shaft rotation speed Nin, which corresponds to the vehicle speed V during predetermined low-speed driving, and the front wheel drive torque Trf. This is thought to be because, when the starting clutch WSC is put into a slip state during predetermined low-speed driving, the slip state is not smoothly established in accordance with the front wheel drive torque Trf, resulting in fluctuations in the front wheel drive torque Trf. Furthermore, the torque fluctuation ΔTrf depends not only on the input shaft rotation speed Nin and the front wheel drive torque Trf, but also on the condition of the clutch friction surface of the starting clutch WSC (for example, the oil film condition of the cooling oil on the clutch friction surface and the temperature of the clutch friction surface). For example, the oil film condition (e.g., the viscosity of the cooling oil) and the temperature of the clutch friction surface are correlated with the temperature of the cooling oil. In Fig. 2, for example, over the entire practical temperature range of the cooling oil, the determination value ΔTrf_jdg is the lower limit value of the torque fluctuation amount ΔTrf at which vehicle vibration falls outside a predetermined allowable range. Preferably, the determination value ΔTrf_jdg is predetermined based on, for example, the input shaft rotation speed Nin, the front wheel drive torque Trf, and the actual temperature of the cooling oil, and thereby the determination values ​​Trf_jdg1 and Trf_jdg2 are each predetermined.

[0024] Returning to FIG. 1 . When it is determined that the starting clutch WSC is in a slip state and the front wheel drive torque Trf is within a predetermined torque range, the electronic control device 90 changes the front wheel drive torque Trf by a predetermined amount so that the front wheel drive torque Trf does not fall within the predetermined torque range. For example, assuming that the front wheel drive torque Trf is a torque value Trfx (see FIG. 2 ), when the front wheel drive torque Trf is increased, the “predetermined amount” is a value that exceeds the difference between the determination value Trf_jdg2 and the torque value Trfx (=Trf_jdg2-Trfx). For example, assuming that the front wheel drive torque Trf is a torque value Trfx, when the front wheel drive torque Trf is decreased, the “predetermined amount” is a value that exceeds the difference between the torque value Trfx and the determination value Trf_jdg1 (=Trfx-Trf_jdg1). The change in the front wheel drive torque Trf is achieved, for example, by changing the hydraulic pressure Pwsc to change the transmission torque capacity Tc. When the electronic control device 90 increases or decreases the front wheel drive torque Trf so that it does not fall within a predetermined torque range, it decreases or increases the MGr torque Tmgr [N·m] so that the increase or decrease in the front wheel drive torque Trf is compensated for by the rear wheel drive torque Trr [N·m]. The rear wheel drive torque Trr corresponds to the "torque transmitted to the rear wheels" in this invention. The MGr torque Tmgr is the output torque of the rear wheel drive motor MGr. Note that a decrease in the rear wheel drive torque Trr also includes a case where the rear wheel drive motor MGr is regenerated to increase the negative torque on the rear wheels 34. The drive torque Tr (= Trf + Trr), which is the sum of the front wheel drive torque Trf and the rear wheel drive torque Trr, does not change before or after the front wheel drive torque Trf is changed so that it does not fall within the predetermined torque range.

[0025] Fig. 3 is an example of a flowchart illustrating the main control operations of the electronic control unit 90. The flowchart in Fig. 3 is repeatedly executed when the vehicle 10 is traveling at a predetermined low speed.

[0026] First, in step (hereinafter, "step" will be omitted) S10, it is determined whether the starting clutch WSC is in a slip state. If the determination in S10 is YES, it is determined in S20 whether the front wheel drive torque Trf is within a predetermined torque range. If the determination in S20 is YES, the drive torque distribution between the front and rear wheels is changed in S30, and the process returns. Specifically, in S30, the front wheel drive torque Trf is increased or decreased so that the front wheel drive torque Trf does not fall within the predetermined torque range, and the rear wheel drive torque Trr is increased or decreased accordingly. In both cases where the determination in S10 is NO and where the determination in S20 is NO, the drive torque distribution between the front and rear wheels is not changed in S40, and the process returns.

[0027] According to this embodiment, (a) when the vehicle 10 is traveling at a predetermined low speed, the starting clutch WSC is controlled to transmit power in a slip state, and (b) when the front wheel drive torque Trf in the slip state of the starting clutch WSC falls within a predetermined torque range where fluctuations outside the predetermined allowable range occur, the front wheel drive torque Trf is increased or decreased by a predetermined amount so as not to fall within the predetermined torque range, and the rear wheel drive torque Trr is increased or decreased accordingly. In this way, when the front wheel drive torque Trf in the slip state of the starting clutch WSC falls within the predetermined torque range, i.e., when fluctuations in the front wheel drive torque Trf fall outside the predetermined allowable range, the front wheel drive torque Trf is increased or decreased so as not to fall within the predetermined torque range. Furthermore, the increase or decrease in the front wheel drive torque Trf is compensated for by the rear wheel drive torque Trr. This prevents unintended changes in the drive torque Tr of the entire vehicle 10, reduces torque fluctuations in the drive torque Tr of the entire vehicle 10, and suppresses vehicle vibration.

[0028] The above-described embodiments of the present invention are merely examples, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

[0029] In the above-described embodiment, the engine 12 corresponds to the "front-wheel drive device" in the engine driving mode of the two-wheel drive mode, but this is not limiting. For example, when the front-wheel drive electric motor MGf is powered in the HEV driving mode or the BEV driving mode of the two-wheel drive mode, the front-wheel drive electric motor MGf corresponds to the "front-wheel drive device" in the present invention. [Explanation of symbols]

[0030] 10: vehicle, 12: engine (front-wheel drive system), 14: front wheels, 34: rear wheels, 90: electronic control unit (control unit), MGr: rear-wheel drive motor (rear-wheel drive system), PT: power transmission path, Trf: front-wheel drive torque (torque transmitted to front wheels), Trr: rear-wheel drive torque (torque transmitted to rear wheels), WSC: starting clutch (wet start clutch)

Claims

[Claim 1] A control device for a vehicle including a front-wheel drive unit that drives front wheels, a wet start clutch that is disposed in a power transmission path between the front wheels and the front-wheel drive unit, and a rear-wheel drive unit that electrically drives rear wheels, comprising: When the vehicle is traveling at a predetermined low speed, the wet start clutch is controlled to transmit power in a slip state, If the torque transmitted to the front wheels in the slip state of the wet start clutch falls within a predetermined range in which fluctuations outside a predetermined allowable range occur, the torque transmitted to the front wheels is increased or decreased by a predetermined amount so that it does not fall within the predetermined range, and the torque transmitted from the rear wheel drive unit to the rear wheels is increased or decreased according to the predetermined amount.

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