Vehicle control device

Abstract

To provide a vehicle control device capable of suppressing a shock caused by vibration transmitted to a vehicle body and suppressing a deterioration in acceleration responsiveness of a vehicle.SOLUTION: In a plurality of vibration transmission paths between a second electric motor MG2 and a vehicle body 68, a vehicle 10 includes, as vibration members, a plurality of resonance members including: a reference resonance member (a power transmission device 36) having a reference resonance frequency Fs which is the lowest resonance frequency; and other resonance members (a suspension device 62, an engine 12, an engine mount 60, and an exhaust device 64) each set to a resonance frequency of an integral multiple of the reference resonance frequency Fs. In a case where target drive torque Tr_tgt is increased, if effective drive torque Tr_eff is equal to or less than a torque upper limit value Tr_up, an electronic control device 90 controls drive torque Tr such that it is increased at a fixed rate in a period of an inverse value of the reference resonance frequency Fs, and if not, controls the drive torque Tr such that it is increased at the fixed rate in a predetermined booting period Tboot.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle that has, as a drive unit, an engine, a power split mechanism that splits the engine's power between a first electric motor and a rotating member connected to a pair of drive wheels, and a second electric motor connected to the rotating member so that power can be transmitted. [Background technology]

[0002] There is known a control device for a vehicle that includes, as vibration members, a reference resonance member having a reference resonance frequency with the lowest resonance frequency and other resonance members different from the reference resonance member, each set to a resonance frequency that is an integer multiple of the reference resonance frequency, in multiple vibration transmission paths from an electric motor to the vehicle body. For example, the control device described in Patent Document 1 discloses such a device. When the target value of the drive torque is increased, the drive torque is increased at a constant rate for a period of time corresponding to the reciprocal of the reference resonance frequency. This suppresses shock (impact) caused by vibration transmitted to the vehicle body due to the increase in drive torque, and also suppresses a decrease in the vehicle's acceleration responsiveness.

[0003] There is also known a vehicle that includes, as a drive unit, an engine, a power split mechanism that splits the power of the engine between a first electric motor and a rotating member connected to a pair of drive wheels, and a second electric motor connected to the rotating member so as to be able to transmit power, as described in Patent Document 2, for example. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-99059 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-137823 Summary of the Invention [Problem to be solved by the invention]

[0005] When the vehicle control device described in Patent Document 1 is applied to the vehicle described in Patent Document 2, it may not be possible to increase the drive torque at a constant rate during the period of the reciprocal of the reference resonance frequency due to the vehicle configuration. In such cases, there is a risk that the shock caused by the vibration transmitted to the vehicle body will deviate from a predetermined allowable range.

[0006] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle control device that can suppress shocks caused by vibrations transmitted to the vehicle body and can suppress a decrease in the acceleration responsiveness of the vehicle. [Means for solving the problem]

[0007] The gist of the present invention is a control device for a vehicle that includes, as a drive device, an engine, a power split mechanism that splits the power of the engine between a first electric motor and a rotating member connected to a pair of drive wheels, and a second electric motor connected to the rotating member so that power can be transmitted to the rotating member, and that includes, as vibration members, a plurality of resonance members consisting of a reference resonance member having a reference resonance frequency that has the lowest resonance frequency in a plurality of vibration transmission paths between the second electric motor and the vehicle body, and other resonance members different from the reference resonance member, each of which is set to a resonance frequency that is an integer multiple of the reference resonance frequency, wherein, when a target value of drive torque is increased, (a) if an effective drive torque obtained by subtracting a predetermined backlash-removal torque from the target value is below a predetermined torque upper limit value, the control device controls the drive torque so that it increases at a constant rate over a period of the reciprocal of the reference resonance frequency, and (b) otherwise, controls the drive torque so that it increases at a constant rate over a period that exceeds the period of the reciprocal of the reference resonance frequency and is calculated using Fourier transform so that the amplitude at the reference resonance frequency is below a predetermined judgment value. [Effects of the Invention]

[0008] According to the present invention, when the target value of the drive torque is increased, (a) if the effective drive torque, obtained by subtracting a predetermined backlash-reducing torque from the target value, is equal to or less than a predetermined torque upper limit, the drive torque is controlled to increase at a constant rate over a period of the reciprocal of the reference resonance frequency; (b) otherwise, the drive torque is controlled to increase at a constant rate over a period that exceeds the period of the reciprocal of the reference resonance frequency and is calculated using a Fourier transform such that the amplitude at the reference resonance frequency is equal to or less than a predetermined judgment value. In the case of (a), the period during which the drive torque is increased is set without calculation using a Fourier transform. In the case of (b), the period during which the drive torque is increased is set to a value calculated using a Fourier transform, thereby keeping the generated shock within a predetermined allowable range. As a result, in either case, shock caused by vibration transmitted to the vehicle body is kept within a predetermined allowable range, and a decrease in the vehicle's acceleration response is suppressed. [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 of the present invention; [Figure 2] FIG. 2 is a block diagram illustrating an example of a plurality of vibration transmission paths in a vehicle. [Figure 3] 4 is an example of a flowchart illustrating a control operation of an 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] 1 is a schematic diagram of a vehicle 10 equipped with an electronic control device 90 according to an embodiment of the present invention. The vehicle 10 is, for example, a hybrid vehicle equipped with an engine 12 and a second electric motor MG2 as a power source for traveling. The vehicle 10 includes, in a power transmission path between the engine 12 and a pair of drive wheels 14, a crankshaft 20, a damper 22, an input shaft 24, a power split mechanism 26, an output shaft 28, a differential 30, and a pair of axles 32, in that order from the engine 12 side, which are well-known components. The damper 22, the input shaft 24, and the power split mechanism 26 are housed in a case 18, which is a non-rotating member.

[0012] The engine 12 is a known internal combustion engine, and the engine torque Te [N·m], which is the output torque of the engine 12, is controlled by an electronic control device 90. In this specification, unless otherwise specified, the terms driving force, driving force, force (= power), and torque are synonymous. The first electric motor MG1 and the second electric motor MG2 are so-called motor generators, such as three-phase synchronous motor generators. The first electric motor torque Tmg1 [N·m], which is the output torque of the first electric motor MG1, and the second electric motor torque Tmg2 [N·m], which is the output torque of the second electric motor MG2, are each controlled by an inverter 50 controlled by the electronic control device 90. The power split mechanism 26 is, for example, a known single-pinion planetary gear device. The power split mechanism 26 is a known power split mechanism that mechanically splits the power output from the engine 12 between the first electric motor MG1 and an output shaft 28. The output shaft 28 is connected to a pair of drive wheels 14 via a differential 30 and a pair of axles 32. The second electric motor MG2 is coupled to an output shaft 28 so as to be able to transmit power. The output shaft 28 corresponds to the "rotating member" in this invention. The engine 12, the first electric motor MG1, the second electric motor MG2, and components provided in the power transmission path between the engine 12 and the pair of drive wheels 14 constitute a drive device 40.

[0013] The vehicle 10 includes an inverter 50 and a battery 52, which are of well-known configuration.

[0014] The vehicle 10 is equipped with an electronic control device 90. The electronic control device 90 includes, for example, a so-called microcomputer, and controls each part of the vehicle 10 by performing signal processing in accordance with a program previously stored in a ROM. The electronic control device 90 corresponds to the "control device" in the present invention. The electronic control device 90 receives various signals (such as an accelerator pedal position θacc [%] indicating the magnitude of the driver's acceleration operation, a vehicle speed V [km / h], a battery voltage Vbat [V], a battery current Ibat [A], and a battery temperature THbat [°C]) based on detection values ​​from various sensors (such as an accelerator pedal position sensor 70, a vehicle speed sensor 72, and a battery sensor 74) provided in the vehicle 10. The electronic control device 90 outputs various command signals (such as an engine control signal Se, a first electric motor control signal Smg1 and a second electric motor control signal Smg2 that respectively control the rotation of the first electric motor MG1 and the second electric motor MG2 via the inverter 50) to each device of the vehicle 10 (such as the engine 12 and the inverter 50).

[0015] In vehicle 10, it is possible to select between a BEV (Battery Electric Vehicle) driving mode in which power is output from only the second electric motor MG2 among the power sources for driving, thereby driving the vehicle as a BEV, and an engine driving mode in which power is output from at least the engine 12 among the power sources for driving, thereby driving the vehicle as an engine.

[0016] 2 is a block diagram showing an example of a plurality of vibration transmission paths in the vehicle 10. A "vibration transmission path" is a path that transmits vibration between the second electric motor MG2 and the vehicle body 68, and a vibrating member is provided on the vibration transmission path. Note that, among the components that make up the vehicle 10, there may be cases where a vibrating member is provided on the vibration transmission path while also being a component of the drive unit 40.

[0017] For example, when the second electric motor torque Tmg2 is increased while the engine is running, vibrations caused by torque fluctuations accompanying the increase in the second electric motor torque Tmg2 are transmitted to the power transmission device 36. Note that the "power transmission device 36" is a general term for devices provided in a power transmission path, for example, from the second electric motor MG2 via the differential 30 to the pair of drive wheels 14. Vibrations in the power transmission device 36 are transmitted to the suspension device 62. The suspension device 62 is a device that reduces vibrations and shocks that occur when the vehicle 10 is running. Vibrations in the suspension device 62 are transmitted to a vehicle body 68. Furthermore, vibrations are also generated in, for example, the engine 12 due to a torque reaction force against torque fluctuations accompanying the increase in the second electric motor torque Tmg2. Vibrations in the engine 12 are transmitted to the vehicle body 68 via an engine mount 60 that supports the engine 12. Vibrations in the engine 12 are also transmitted to the vehicle body 68 via an exhaust device 64 that includes an exhaust pipe, a muffler, and the like. Vibrations transmitted to the vehicle body 68 via multiple vibration transmission paths in this way can cause shocks.

[0018] The power transmission device 36, the suspension device 62, the engine 12, the engine mount 60, and the exhaust device 64 each have a different resonance frequency. For example, in this embodiment, if the resonance frequency of the power transmission device 36 is a reference resonance frequency Fs [Hz], the resonance frequencies of the suspension device 62, the engine 12, the engine mount 60, and the exhaust device 64 are set to integer multiples of the reference resonance frequency Fs. Of the components, the power transmission device 36, which has the lowest resonance frequency, corresponds to the "reference resonance member" in this invention. Of the components, the suspension device 62, the engine 12, the engine mount 60, and the exhaust device 64, each of which has a resonance frequency set to an integer multiple of the reference resonance frequency Fs, correspond to the "other resonance members" in this invention. The "reference resonance member" and the "other resonance members" together constitute a vibrating member, and correspond to the "plurality of resonance members" in this invention.

[0019] Returning to FIG. 1, a case will now be described in which the drive torque Tr [N·m] is increased while the engine is running. The "drive torque Tr" is the torque transmitted to the pair of drive wheels 14 of the vehicle 10, i.e., the torque transmitted to the pair of axles 32. The target drive torque Tr_tgt is a target value for the drive torque Tr, and is the drive torque Tr that the driver has requested of the vehicle 10. The target drive torque Tr_tgt is calculated, for example, by applying the actual accelerator opening θacc and the actual vehicle speed V to a map in which the relationship between the accelerator opening θacc, the vehicle speed V, and the target drive torque Tr_tgt is determined in advance experimentally or by design and stored.

[0020] The electronic control device 90 calculates a torque upper limit value Tr_up. The "torque upper limit value Tr_up" is the upper limit value of the drive torque Tr that can be realized, i.e., transmitted, within a reference period Ts [s] (= 1 / Fs). The torque upper limit value Tr_up corresponds to the "predetermined torque upper limit value" in the present invention. There are three ways to increase the drive torque Tr: (a) increase the engine torque Te, (b) increase the second electric motor torque Tmg2, and (c) increase the power mechanically split to the output shaft 28 side of the power split mechanism 26. Option (c) is achieved by reducing the power mechanically split to the first electric motor MG1 side (i.e., the power generation torque Tpg [N·m] used for power generation by the first electric motor MG1, which can be controlled by the reaction torque output from the first electric motor MG1). The first electric motor torque Tmg1 and the second electric motor torque Tmg2 are each controlled by the amount of drive current flowing through the stator coil, and therefore can be increased or decreased within the reference period Ts. On the other hand, since engine torque Te is controlled by combustion phenomena, it is difficult to increase or decrease it within the reference period Ts. Therefore, the torque upper limit value Tr_up is calculated based on the above (b) and (c). Specifically, when the first electric motor MG1 is in a generating state during engine running, the generated torque Tpg is set to zero and distributed to the output shaft 28. Therefore, a converted torque value Tpg_conv [N·m] is calculated by converting the generated torque Tpg into a torque value at the pair of axles 32. Next, taking into account the dischargeable power Wout [W] of the battery 52 and the like, a converted torque value Tmg2_conv [N·m] is calculated by converting the maximum torque value Tmg2_max [N·m] that can be output as second electric motor torque Tmg2 into a torque value at the pair of axles 32. The torque upper limit value Tr_up is calculated as the sum of the converted torque value Tpg_conv and the converted torque value Tmg2_conv (=Tpg_conv+Tmg2_conv).

[0021] After calculating the torque upper limit value Tr_up, the electronic control device 90 determines whether the effective drive torque Tr_eff (=Tr_tgt-Tgata), which is the difference between the target drive torque Tr_tgt and the backlash-removing torque Tgata [N·m], is equal to or less than the torque upper limit value Tr_up. The "backlash-removing torque Tgata" is a converted torque value obtained by converting the torque required to remove backlash (=backlash) of gears and the like in the power transmission path from the second electric motor MG2 and the power split device 26 to the pair of drive wheels 14 when the drive torque Tr is increased into a torque value at the pair of axles 32.

[0022] When the electronic control device 90 determines that the effective drive torque Tr_eff is equal to or less than the torque upper limit value Tr_up, it sets the transition period Tchg [s] to the reference period Ts.

[0023] On the other hand, when the electronic control unit 90 determines that the effective drive torque Tr_eff exceeds the torque upper limit value Tr_up, it calculates a predetermined start-up period Tboot [s]. The start-up period Tboot is a period during which the drive torque Tr can be increased to the target drive torque Tr_tgt when the increase in engine torque Te is added to the torque upper limit value Tr_up, and is a period during which the shock generated even if the drive torque Tr is increased at a constant rate during this start-up period Tboot falls within a predetermined allowable range. "Within a predetermined allowable range" means that the discomfort felt by the driver is within an allowable range. The start-up period Tboot corresponds to "a period exceeding the period of the reciprocal of the reference resonance frequency and calculated using Fourier transform such that the amplitude at the reference resonance frequency is equal to or less than a predetermined judgment value" in this invention.

[0024] Specifically, the start-up period Tboot is calculated as follows. First, a period Tx [s] during which the engine torque Te can be increased to increase the drive torque Tr by, for example, the torque difference ΔT (= Tr_eff - Tr_up) between the effective drive torque Tr_eff and the upper torque limit Tr_up is calculated based on a torque increase map. The torque increase map is a map in which the relationship between the torque difference ΔT and the period Tx is determined experimentally or by design. Next, it is determined whether the shock generated by the drive torque Tr is within a predetermined allowable range when the drive torque Tr is increased at a constant rate during the period Tx. For example, the amplitude of each frequency component of the increase waveform of the drive torque Tr in this assumed case is calculated using a Fourier transform (preferably a fast Fourier transform). If the amplitude Afs [N·m] of the reference resonance frequency Fs is equal to or less than a predetermined threshold value Afs_jdg, it is determined that the shock generated is within the predetermined allowable range. The predetermined threshold value Afs_jdg is the upper limit of the amplitude Afs, determined experimentally or by design, such that the shock generated is within the predetermined allowable range. Assuming that the drive torque Tr is increased at a constant rate over the period Tx, if the amplitude Afs is equal to or less than a predetermined reference value Afs_jdg, the start-up period Tboot is set to the assumed period Tx. Assuming that the drive torque Tr is increased at a constant rate over the period Tx, if the amplitude Afs exceeds the predetermined reference value Afs_jdg, the period Tx is lengthened by a predetermined time ΔTx [s] and the determination using the Fourier transform is repeated until the amplitude Afs falls below the predetermined reference value Afs_jdg. If, as a result of this repeated determination, the amplitude Afs falls below the predetermined reference value Afs_jdg, the start-up period Tboot is set to the period Tx calculated in this manner. The transition period Tchg is then set to the start-up period Tboot calculated in this manner. The predetermined time ΔTx is a predetermined time determined in advance so that the delay time in the start of control to increase the drive torque Tr through repeated determination is within an acceptable range of discomfort felt by the driver.

[0025] When the transition period Tchg is set, the electronic control device 90 controls the engine 12, the first electric motor MG1, and the second electric motor MG2 so that the drive torque Tr increases from the current value to the target drive torque Tr_tgt at a constant rate during the transition period Tchg.

[0026] FIG. 3 is an example of a flowchart illustrating the control operation of the electronic control unit 90.

[0027] First, in step (hereinafter, step will be omitted) S10, the torque upper limit value Tr_up is calculated, and in S20, it is determined whether the effective drive torque Tr_eff (=Tr_tgt-Tgata) is equal to or less than the torque upper limit value Tr_up. If the determination in S20 is YES, in S30, the transition period Tchg is set to the reference period Ts (=1 / Fs). If the determination in S20 is NO, in S40, the start-up period Tboot is calculated, and in S50, the transition period Tchg is set to the start-up period Tboot. After both S30 and S50 are executed, in S60, the drive torque Tr is controlled to increase to the target drive torque Tr_tgt at a fixed rate during the transition period Tchg. After S60 is executed, the process ends.

[0028] According to this embodiment, when the target drive torque Tr_tgt is increased, (a) if the effective drive torque Tr_eff is equal to or less than the torque upper limit value Tr_up, the drive torque Tr is controlled to increase at a constant rate over a period equal to the reciprocal of the reference resonance frequency Fs; (b) otherwise, the drive torque Tr is controlled to increase at a constant rate over a predetermined start-up period Tboot. In the case of (a), the period during which the drive torque Tr is increased is set without being calculated using a Fourier transform. In the case of (b), the period during which the drive torque Tr is increased is set to a value calculated using a Fourier transform, thereby keeping the shock that occurs within a predetermined allowable range. As a result, in either case, the shock that occurs due to vibration transmitted to the vehicle body 68 is kept within a predetermined allowable range, and a decrease in the acceleration responsiveness of the vehicle 10 is suppressed.

[0029] The above-described embodiments of the present invention are merely illustrative, 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. [Explanation of symbols]

[0030] 10: vehicle, 12: engine (multiple resonating members, other resonating members), 14: pair of drive wheels, 26: power split mechanism, 28: output shaft (rotating member), 36: power transmission device (multiple resonating members, reference resonating member), 40: drive unit, 60: engine mount (multiple resonating members, other resonating members), 62: suspension system (multiple resonating members, other resonating members), 64: exhaust system (multiple resonating members, other resonating members), 68: vehicle body, 90: electronic control unit (control unit), Fs: reference resonant frequency, MG1: first electric motor, MG2: second electric motor, Tboot: start-up period (period exceeding the period of the reciprocal value of the reference resonant frequency and calculated using Fourier transform so that the amplitude at the reference resonant frequency is equal to or less than a predetermined judgment value), Tr: drive torque, Tr_eff: effective drive torque, Tr_tgt: target drive torque (target value of drive torque), Tr_up: torque upper limit value (predetermined torque upper limit value)

Claims

[Claim 1] A control device for a vehicle including, as a drive device, an engine, a power split mechanism that splits power of the engine between a first electric motor and a rotating member connected to a pair of drive wheels, and a second electric motor connected to the rotating member so as to be able to transmit power, and including, as vibration members, a plurality of resonance members that are made up of a reference resonance member having a reference resonance frequency that is the lowest resonance frequency in a plurality of vibration transmission paths between the second electric motor and a vehicle body, and other resonance members different from the reference resonance member, each of which has a resonance frequency that is an integer multiple of the reference resonance frequency, When increasing the target value of the drive torque, if the effective drive torque obtained by subtracting a predetermined backlash-reducing torque from the target value is equal to or less than a predetermined torque upper limit value, the drive torque is controlled so as to increase at a constant rate during a period of the reciprocal value of the reference resonance frequency; otherwise, the drive torque is controlled so as to increase at a constant rate during a period that exceeds the period of the reciprocal value of the reference resonance frequency and is calculated using Fourier transform such that the amplitude at the reference resonance frequency is equal to or less than a predetermined judgment value. A vehicle control device characterized by:

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