Vehicular control device

Abstract

To provide a vehicular control device that suppresses noise generated by a transmission and fluctuation in vehicle speed, when down-shifting the transmission during coast traveling.SOLUTION: An ECU causes a motor to generate motor torque so as to suppress rotational fluctuation of a transmission and the motor in a down-shifting period (Step S6), under a condition of down-shifting the transmission during coast traveling when decelerating in traveling by inertia in a state that an accelerator pedal is returned (YES at Steps S1, S2). The ECU executes Step S6, under conditions that a vehicle speed is lower than a predetermined vehicle speed (YES at Step S4) and the transmission is down-shifted from a predetermined high-speed side gear shift stage to a predetermined low-speed side gear shift stage (YES at Step S3). The ECU executes Step S6, under a condition that the motor is not generating regenerative torque (YES at Step S5).SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Patent Document 1 describes a technology that aims to suppress vibrations and noise that occur when backlash between gears in a front-wheel drive gearbox and a rear-wheel drive gearbox is eliminated. When the vehicle's operating state changes, such as from slow deceleration to re-acceleration, the drive torque of the drive shaft on the side where the torque changes polarity is changed is changed until it is just before reaching zero, and then the drive torque is slowly changed to reverse the polarity of the torque. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-57169 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the invention described in Patent Document 1 does not consider the gear rattle noise that occurs in the process of downshifting a parallel shaft gear transmission while coasting. As a result, there is a problem in that noise generated by the transmission and fluctuations in vehicle speed cannot be suppressed when downshifting the transmission while coasting.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle control device that can suppress noise generated from the transmission and fluctuations in vehicle speed when the transmission is downshifted during coasting. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a vehicle control device that is mounted on a vehicle that includes an engine, an AMT that automates the shifting operation of a parallel shaft gear type manual transmission, a transmission to which power is transmitted from the engine, drive wheels to which power is transmitted from the transmission, and a motor that applies power between the transmission and the drive wheels, and that includes a control unit that controls the transmission and the motor, wherein the control unit generates motor torque in the motor so as to suppress rotational fluctuations in the transmission and the motor during the downshift, on the condition that the transmission is downshifted during coasting, in which the vehicle is decelerating by inertia with the accelerator pedal released. [Effects of the Invention]

[0007] Thus, according to the present invention, a vehicle control device can be provided that can suppress noise generated from the transmission and fluctuations in vehicle speed when the transmission is downshifted during coasting. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the structure of a transmission of a vehicle equipped with a vehicle control device according to one embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart showing the operation of the vehicle control device according to one embodiment of the present invention. [Figure 4] FIG. 4 is a timing chart showing the transition of the vehicle state due to the operation of the vehicle control device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A vehicle control device according to one embodiment of the present invention is mounted on a vehicle including an engine, an AMT that automates gear shifting of a parallel shaft gear type manual transmission, a transmission to which power is transmitted from the engine, drive wheels to which power is transmitted from the transmission, and a motor that applies power between the transmission and the drive wheels, and the vehicle control device includes a control unit that controls the transmission and the motor, wherein the control unit generates motor torque in the motor so as to suppress rotation fluctuations of the transmission and the motor during the downshift, on the condition that the transmission is downshifted during coasting, in which the vehicle is decelerating by inertia with the accelerator pedal released. As a result, the vehicle control device according to one embodiment of the present invention can suppress noise generated by the transmission and fluctuations in vehicle speed when the transmission is downshifted during coasting. [Example]

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle equipped with a control device according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0011] As shown in FIG. 1, a vehicle 1 according to one embodiment of the present invention includes an engine 2, a driving motor 3, a transmission 4, a differential device 5, drive wheels 6, and an ECU (Electronic Control Unit) 10 as a control unit.

[0012] The engine 2 is formed with a plurality of cylinders. In this embodiment, the engine 2 is configured to perform a series of four strokes for each cylinder, including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

[0013] An ISG (Integrated Starter Generator) 20 is connected to the engine 2. The ISG 20 is connected to a crankshaft 2A of the engine 2 via a belt 21 or the like. The ISG 20 functions as an electric motor that rotates when supplied with electric power to drive the engine 2, and also functions as a generator that converts the rotational force input from the crankshaft 2A into electric power.

[0014] A starter 2B is connected to the engine 2. The starter 2B is connected to a flywheel (not shown) of the engine 2, and rotates when supplied with electric power to start the engine 2.

[0015] The motor 3 is a motor generator that functions as an electric motor that generates driving force for the vehicle using power supplied from the battery 31 via the inverter 30, and as a generator that generates regenerative electricity using the rotational force (reverse driving force) input from the drive wheels 6 via the differential device 5.

[0016] Under the control of the ECU 10, the inverter 30 converts DC power supplied from the battery 31 into three-phase AC power and supplies it to the motor 3, and also converts three-phase AC power generated by the motor 3 into DC power to charge the battery 31. The battery 31 is formed of a secondary battery such as a lithium-ion battery.

[0017] The transmission 4 changes the speed of rotation input from the engine 2 to an input shaft 8 via a clutch 7 at a speed ratio corresponding to one of a plurality of gear positions and outputs the rotation from an output shaft 9. In this embodiment, the transmission 4 is an AMT (Automated Manual Transmission) that automates the gear shifting operation of a parallel shaft gear manual transmission. In more detail, the transmission 4 is a transmission that is based on the structure of a parallel shaft gear manual transmission and can either perform gear shifting automatically or allow the driver to perform gear shifting operation like a so-called manual transmission using a selector lever 40 (described later) or a clutch pedal (not shown). Hereinafter, for ease of explanation, the forward gear positions will be referred to as D range (1st / 2nd / 3rd / 4th / 5th / 6th gear positions), and the reverse gear position will be referred to as R range (reverse gear position).

[0018] The gears of the transmission 4 are changed by a shift actuator 44. The shift actuator 44 is connected to and controlled by the ECU 10. Specifically, the shift actuator 44 moves a gear change operation mechanism (not shown) to operate a synchronizer, thereby achieving and changing the gear. The gear change operation mechanism can use known technologies such as a shift fork or a shifter shaft. An output shaft 9 of the transmission 4 is connected to left and right drive wheels 6 via a differential device 5. Power output from the transmission 4 is transmitted to the drive wheels 6 via the differential device 5. Power output from the motor 3 is transmitted to the output shaft 9 via gears or the like, and is input together with the power output from the transmission 4 to the differential device 5. Therefore, the motor 3 applies power between the transmission 4 and the drive wheels 6. Note that the output shaft of the motor 3 may be integrally connected to the output shaft 9 of the transmission 4.

[0019] In this way, the vehicle 1 is configured as a hybrid vehicle that can run using the driving force of at least one of the engine 2 and the motor 3.

[0020] The transmission 4 is provided with a shift stroke sensor 42. The shift stroke sensor 42 is connected to the ECU 10. The shift stroke sensor 42 detects the gear position in the transmission 4. The shift stroke sensor 42 detects the position and amount of movement of a gear change operation mechanism such as a shift fork or a shifter shaft, and outputs a detection signal to the ECU 10.

[0021] The gears that can be established in the transmission 4 include, for example, forward gears (D range) ranging from a low 1st gear to a high 6th gear, and a reverse gear (R range). The number of gears for driving varies depending on the specifications of the vehicle 1 and is not limited to the above-mentioned 1st to 6th gears. The transmission 4 is equipped with synchronizers (synchromeshes) not only for the forward gears but also for the reverse gears.

[0022] The gears in the transmission 4 can be changed according to the operating position of a selector lever 40 operated by the driver. The operating position of the selector lever 40 is detected by a shift position sensor 41. The shift position sensor 41 is connected to the ECU 10 and transmits the detection result to the ECU 10.

[0023] In this embodiment, the select lever 40 has three operating positions: P range, which is a parking position; R range, which is a reverse position; N range, which is a neutral position; and D range, which is a forward position.

[0024] For example, when the driver sets the selector lever 40 to the D range, the ECU 10 drives the shift actuator 44 and the clutch actuator 70 in response to a detection signal from the accelerator opening sensor 91, etc., to shift between the first to sixth forward gears. The clutch actuator 70 operates the clutch 7 to switch between transmitting and cutting off power between the engine 2 and the transmission 4.

[0025] Furthermore, when the driver switches the select lever 40 from the D range to the R range, the ECU 10 drives the shift actuator 44 and the clutch actuator 70 to switch the gear from the forward gear to the reverse gear.

[0026] The transmission 4 is provided with a clutch 7 in a power transmission path between the transmission 4 and the engine 2. The clutch 7 may be, for example, a dry single-plate friction clutch. The transmission 4 is connected to the engine 2 via the clutch 7.

[0027] In this way, the transmission 4 is configured so that power is transmitted from the engine 2 to the input shaft 8 via the clutch 7, and the gear position can be changed by a shift operation. The clutch 7 is equipped with a clutch disc, and the clutch disc and the input shaft 8 of the transmission 4 are interconnected and rotate integrally. Therefore, the rotation speed of the clutch disc (hereinafter referred to as the rotation speed of the clutch 7) is equal to the rotation speed of the input shaft 8 of the transmission 4. Note that the rotation speed in this embodiment indicates the rotational speed (rpm).

[0028] The clutch 7 is operated by a clutch actuator 70 and can be switched between an engaged state in which power is transmitted between the engine 2 and the transmission 4, a disengaged state in which power is not transmitted, and a half-clutch state in which torque is transmitted with a rotational difference. The clutch actuator 70 is connected to and controlled by the ECU 10. The clutch 7 is a normally-stop type clutch that maintains the state (clutch stroke or degree of engagement) at the time of de-energization of the clutch actuator 70. The clutch actuator 70 is equipped with a hydraulic mechanism (not shown) and switches the clutch 7 via the hydraulic mechanism.

[0029] The clutch 7 is provided with a rotation speed sensor 43, which detects the rotation speed of the clutch 7. The rotation speed sensor 43 is connected to the ECU 10 and transmits the detection result to the ECU 10.

[0030] When switching the gear position, the ECU 10 controls the clutch actuator 70 to change the state of the clutch 7 .

[0031] The vehicle 1 is equipped with an accelerator pedal 90 that is operated by the driver. The amount of depression of the accelerator pedal 90 is detected by an accelerator opening sensor 91. The accelerator opening sensor 91 is connected to the ECU 10, detects the amount of depression of the accelerator pedal 90 as an accelerator opening, and transmits a signal corresponding to the accelerator opening to the ECU 10.

[0032] The vehicle 1 is equipped with a brake pedal 92 that is operated by the driver. The amount of depression of the brake pedal 92 is detected by a brake pedal sensor 93. The brake pedal sensor 93 is connected to the ECU 10 and transmits a signal corresponding to the amount of depression of the brake pedal 92 to the ECU 10.

[0033] The ECU 10 is composed of a computer unit having a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, etc., input ports, and output ports.

[0034] The ROM of the computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the ECU 10. That is, the CPU executes the program stored in the ROM using the RAM as a work area, causing the computer unit to function as the ECU 10 in this embodiment.

[0035] In addition to the above-mentioned sensors, a vehicle speed sensor 11 is connected to the ECU 10. The vehicle speed sensor 11 detects the speed of the vehicle 1 and transmits the detection result to the ECU 10.

[0036] The ECU 10 switches the control mode of the vehicle 1. In this embodiment, an EV mode and an HEV mode are set as the control modes.

[0037] The EV mode is a control mode in which the clutch 7 is in a disengaged state and the vehicle 1 is driven by the power of the motor 3. The HEV mode is a control mode in which the clutch 7 is in an engaged state and the vehicle 1 is driven by the power of the engine 2, or the engine 2 and the motor 3.

[0038] The ECU 10 switches between the EV mode and the HEV mode based on, for example, the accelerator opening and the engine speed.

[0039] For example, when the driver's requested torque determined by the accelerator opening exceeds the HEV transition threshold while the vehicle is running in the EV mode, the ECU 10 restarts the engine 2 and transitions to the HEV mode.

[0040] For example, when the driver's requested torque, which is determined by the accelerator opening and the engine speed, falls below the EV transition threshold while the vehicle is running in the HEV mode, the ECU 10 stops the engine 2 and transitions to the EV mode.

[0041] When switching the internal gear position of the transmission 4, the ECU 10 drives the clutch actuator 70 to release the clutch 7, thereby changing the gear position of the transmission 4.

[0042] As shown in FIG. 2, the input shaft 8 and output shaft 9 of the transmission 4 are arranged in parallel.

[0043] A first-speed gear 8A, a second-speed gear 8B, a third-speed gear 8C, a fourth-speed gear 8D, a fifth-speed gear 8E, and a sixth-speed gear 8F are provided on an input shaft 8 of the transmission 4. The first-speed gear 8A and the second-speed gear 8B are fixed to the input shaft 8. The third-speed gear 8C, the fourth-speed gear 8D, the fifth-speed gear 8E, and the sixth-speed gear 8F are provided on the input shaft 8 so as to be rotatable relative to the input shaft 8.

[0044] A first-speed gear 9A, a second-speed gear 9B, a third-speed gear 9C, a fourth-speed gear 9D, a fifth-speed gear 9E, and a sixth-speed gear 9F are provided on an output shaft 9 of the transmission 4. The first-speed gear 9A and the second-speed gear 9B are provided on the output shaft 9 so as to be rotatable relative to the output shaft 9. The third-speed gear 9C, the fourth-speed gear 9D, the fifth-speed gear 9E, and the sixth-speed gear 9F are fixed to the output shaft 9.

[0045] The first gear 8A, second gear 8B, third gear 8C, fourth gear 8D, fifth gear 8E, and sixth gear 8F of the input shaft 8 are constantly in mesh with the first gear 9A, second gear 9B, third gear 9C, fourth gear 9D, fifth gear 9E, and sixth gear 9F of the output shaft 9.

[0046] A sleeve 13 of a synchronizer for switching between first and second gears is provided on the output shaft 9. The sleeve 13 is disposed between the first gear 9A and the second gear 9B on the output shaft 9 so as to be rotatable together with the output shaft 9 and movable in the axial direction.

[0047] The input shaft 8 is provided with a sleeve 14 of a synchronizer for switching between third and fourth gears, and a sleeve 15 of a synchronizer for switching between fifth and sixth gears. The sleeve 14 is disposed between the third gear 8C and the fourth gear 8D on the input shaft 8 so as to be rotatable integrally with the input shaft 8 and movable in the axial direction. The sleeve 15 is disposed between the fifth gear 8E and the sixth gear 8F on the input shaft 8 so as to be rotatable integrally with the input shaft 8 and movable in the axial direction.

[0048] In the transmission 4, the sleeve 13 moves axially on the output shaft 9 and engages with the first-speed gear 9A, thereby connecting the first-speed gear 9A to the output shaft 9 and forming a power transmission path for the first gear. The sleeve 13 moves axially on the output shaft 9 and engages with the second-speed gear 9B, thereby connecting the second-speed gear 9B to the output shaft 9 and forming a power transmission path for the second gear. When the sleeve 13 is in a neutral position where it is not engaged with either the first-speed gear 9A or the second-speed gear 9B, a neutral state is formed in which no power is transmitted through the first-speed gear 9A or the second-speed gear 9B. The sleeve 14 functions in the same way as the sleeve 13, thereby forming the power transmission paths for the third and fourth gears or the neutral state. The sleeve 15 functions in the same way as the sleeve 13, thereby forming the power transmission paths for the fifth and sixth gears or the neutral state.

[0049] The transmission 4 includes a reverse gear 8R fixed to the input shaft 8, a reverse gear 9R formed on the outer peripheral surface of a sleeve 13 on the output shaft 9, and a reverse idler gear 12R rotatably provided on the reverse shaft 12. When the reverse idler gear 12R moves axially on the reverse shaft 12 to the reverse position, the reverse gear 8R and the reverse idler gear 12R mesh together, and the reverse idler gear 12R and the reverse gear 9R mesh together, thereby forming a power transmission path for the reverse stage.

[0050] The sleeves 13, 14, and 15 are operated by a shift actuator 44 to form either a forward or reverse power transmission path for one of the first to sixth gears. The sleeves 13, 14, and 15 are components of a synchronizer. When the sleeves 13, 14, and 15 engage with the gear to be shifted, the synchronizer uses friction to eliminate the difference in rotational speed with the gear to be shifted, thereby synchronizing the rotational speeds. When the synchronizer of the sleeves 13, 14, and 15 functions during gear shifting, kinetic energy is transmitted between the input shaft 8 and the output shaft 9. This transmission of kinetic energy acts to slow down the rotation of the faster rotating shaft (higher rotational speed) and to speed up the rotation of the slower rotating shaft (slower rotational speed).

[0051] In a vehicle 1 equipped with a transmission 4 consisting of an AMT, the transmission 4 is controlled to a gear position corresponding to the vehicle speed. When the vehicle 1 decelerates and stops, the transmission 4 downshifts from second gear to first gear in preparation for starting. During this downshift just before stopping, the engine 2 is stopped using the idle stop function, and running noise, road noise, and vibration from the tires and other components are low, making the vehicle quiet. For this reason, noises such as gear rattles generated by the transmission 4 are easily noticeable to the driver and passengers. The gear rattles generated by the transmission 4 during a downshift just before stopping are caused by backlash between gears inside the transmission 4, and are a hammering sound on the tooth surfaces due to torque reversal. When the rotational fluctuations of the output shaft 9 increase, the hammering sound on the tooth surfaces due to torque reversal also increases. Furthermore, when the rotational fluctuations of the output shaft 9 increase, the fluctuations in the vehicle speed also increase.

[0052] More specifically, when the transmission 4 is downshifted from second gear to first gear, the sleeve 13 moves from the second gear position through the neutral position toward the first gear position, and first gear is established by the action of the synchronizer.

[0053] During synchronization from the neutral position to first gear, the input shaft 8, which had been rotating at a gear ratio of second gear relative to the output shaft 9 until then, needs to be rotated at a gear ratio of first gear relative to the output shaft 9, so kinetic energy is transmitted from the output shaft 9 to the input shaft 8. As a result, the rotational speed of the input shaft 8 increases, and the rotational speed of the output shaft 9 and the vehicle speed decrease. At this time, the input shaft 8, whose rotational speed is increasing, is fitted with the clutch 7 (more specifically, a clutch disc) which has a large inertial mass and rotates integrally therewith, so a large amount of kinetic energy is required to increase the rotational speed of the input shaft 8. As a result, the rotational speed of the output shaft 9 decreases. As the rotational speed of the output shaft 9 decreases, the speed of the vehicle 1 decreases suddenly compared to the gradual deceleration that had been occurring up until then, which may cause the driver to feel uncomfortable.

[0054] Furthermore, because the input shaft 8 has the inertial mass described above, the increased rotational speed of the input shaft 8 becomes faster than the rotational speed of the input shaft 8 rotating at the gear ratio of first gear relative to the rotation of the output shaft 9 decelerating toward a stop. In other words, during the process of downshifting the transmission 4 from second gear to first gear, the direction of torque transmission in the transmission 4 reverses from the direction from the output shaft 9 to the input shaft 8 to the direction from the input shaft 8 to the output shaft 9. As a result, a rattle noise (crash noise) occurs due to the torque reversal between the first gear 8A of the input shaft 8 and the first gear 9A of the output shaft 9. Therefore, it is desirable to suppress rotational fluctuations (drop in rotation) of the output shaft 9 during the period when the transmission 4 downshifts from second gear to first gear during coasting.

[0055] Therefore, on the condition that the transmission 4 is downshifted during coasting, in which the vehicle is decelerating by inertia with the accelerator pedal 90 released, the ECU 10 causes the motor 3 to generate motor torque so as to suppress rotation fluctuations in the transmission 4 and the motor 3 during the downshift. More specifically, when downshifting during deceleration, particularly from second gear to first gear, the ECU 10 applies driving force from the motor to the output shaft 9 so as to suppress a drop in rotation of the output shaft 9 (a sudden drop in vehicle speed). In other words, rather than causing the motor 3 to spin freely, the motor 3 is caused to generate motor torque, which suppresses rotation fluctuations. It is preferable that the rotation speed of the motor 3 be controlled so that the rate of decrease in vehicle speed (deceleration) is constant.

[0056] Furthermore, ECU 10 controls motor 3 to generate motor torque so as to suppress rotation fluctuations in transmission 4 and motor 3 during the downshift, under the additional conditions that the vehicle speed is less than a predetermined vehicle speed and the downshift is a change from a predetermined higher gear to a predetermined lower gear. In this embodiment, the predetermined higher gear is second gear, and the predetermined lower gear is first gear. Note that even in this case, it is preferable to control the rotation speed of motor 3 so as to maintain a vehicle speed deceleration appropriate for the predetermined deceleration.

[0057] Furthermore, under the additional condition that the motor 3 is not generating regenerative torque, the ECU 10 causes the motor 3 to generate motor torque so as to suppress rotation fluctuations in the transmission 4 and the motor 3 during the downshift. In detail, when the rotation speed of the input shaft 8 is increased by the synchronizer, the ECU 10 causes the motor 3 to generate motor torque so as to increase the rotation speed of the input shaft 8, thereby helping to increase the rotation speed of the input shaft 8, which requires a large amount of kinetic energy, and suppressing a drop in rotation of the output shaft 9 (a sudden drop in vehicle speed).

[0058] The control by the ECU 10 will be described with reference to Fig. 3. This control is repeatedly executed at predetermined intervals.

[0059] The ECU 10 determines whether a gear change is in progress (step S1). If a gear change is not in progress (NO in step S1), the ECU 10 ends the current operation. In step S1, the ECU 10 determines that a gear change is in progress if the clutch 7 is not fully engaged or if the actual gear position differs from the target gear position.

[0060] If a gear shift is in progress (YES in step S1), the ECU 10 determines whether the accelerator opening is less than a predetermined opening (step S2). If the accelerator opening is not less than the predetermined opening (NO in step S2), the ECU 10 ends the current operation.

[0061] If the accelerator opening is less than the predetermined opening (YES in step S2), the ECU 10 determines whether or not a predetermined shift is occurring (step S3). If the predetermined shift is not occurring (NO in step S3), the ECU 10 ends this operation. In this embodiment, the predetermined shift is a downshift from second gear to first gear.

[0062] If the shift is a predetermined one (YES in step S3), the ECU 10 determines whether the vehicle speed is less than a predetermined vehicle speed (step S4). If the vehicle speed is not less than the predetermined vehicle speed (NO in step S4), the ECU 10 ends the current operation.

[0063] If the vehicle speed is less than a predetermined vehicle speed (YES in step S4), the ECU 10 determines whether the absolute value of the motor torque calculated using normal control logic is equal to or less than a predetermined torque (step S5). If the absolute value of the motor torque is not equal to or less than the predetermined torque (NO in step S5), the ECU 10 ends the current operation. In step S5, the predetermined torque is a minimum value close to 0 Nm. Therefore, in step S5, the ECU 10 determines whether the motor torque is approximately 0 Nm (motor torque ≈ 0 Nm). Therefore, if the motor 3 is not powering or regenerating and is spinning so as not to affect the running of the vehicle 1, the ECU 10 determines YES in step S5.

[0064] If the absolute value of the motor torque is equal to or less than the predetermined torque (YES in step S5), the ECU 10 executes noise suppression control (step S6) and ends this operation. In the noise suppression control in step S6, the ECU 10 controls the motor 3 so that the motor torque becomes the set torque. More specifically, in the noise suppression control, the ECU 10 adds torque to the normal control torque to suppress noise (clack noise of the transmission gears) generated from the transmission 4 during gear shifting.

[0065] More specifically, when the rotation speed of the input shaft 8 is increased by the synchronizer, a powering torque is applied in the direction of increasing the rotation speed of the input shaft 8, accelerating the vehicle 1, thereby suppressing a drop in rotation of the output shaft 9 (a sudden drop in vehicle speed) that occurs when the rotation speed of the input shaft 8 is increased. This makes it possible to maintain a smooth deceleration state of the vehicle 1 and reduce the energy of the reversing torque generated by the increase in rotation speed of the input shaft 8 and the drop in rotation of the output shaft 9, thereby reducing gear rattle noise.

[0066] In this way, the ECU 10 executes the noise suppression control in step S6 on the condition that it has determined in step S1 that a gear shift is in progress, so that it can determine the timing when a torque command is required in response to noise during a gear shift, thereby minimizing adverse effects on fuel economy and other drivability, etc.

[0067] Furthermore, ECU10 executes noise suppression control only in the coasting deceleration region with the accelerator off and in the low vehicle speed region, where the driver is likely to perceive noise during gear changes relatively loudly, thereby effectively suppressing the noise perceived by the driver while minimizing adverse effects on fuel economy and other drivability.

[0068] Here, in steps S5 and S6, a set torque value of several Nm is required on the output shaft of the motor 3 to suppress noise from the transmission 4 during gear changes. The ECU 10 outputs the set torque in step S6 after completing the calculation of the normal motor torque. Furthermore, when the torque command amount during gear changes falls below a predetermined value in absolute value under normal control, the minimum torque at which the driver does not feel a sense of acceleration or deceleration is determined as the set torque. This makes it possible to eliminate backlash in the transmission 4 during gear changes, regardless of other control states, and to suppress noise from the transmission 4.

[0069] With reference to Figure 4, the transition of the vehicle state during control by the ECU 10 will be described. In Figure 4, the vertical axis represents the shift stroke, G sensor detection signal, input rotation speed, vehicle speed, and motor rotation speed. The horizontal axis represents time. The shift stroke is the gear position detected by the shift stroke sensor 42 based on the position of the synchronizer sleeve and the position of a gear change operating member such as a shift fork. Figure 4 shows the process of the shift stroke being downshifted from second gear to first gear via the neutral position. The G sensor detection signal represents the detection signal of a G sensor (acceleration sensor) not shown. The input rotation speed is the rotation speed (rotational speed) of the input shaft 8 of the transmission 4. The motor rotation speed is the rotation speed of the motor 3.

[0070] At time t0, the vehicle 1 is coasting and decelerating by inertia with the accelerator pedal released. At this time t0, the vehicle speed, input rotation speed, and motor rotation speed are decreasing. Also, the shift stroke is set to second gear.

[0071] At time t1, a downshift from second gear to first gear is initiated. At this time t1, the shift stroke changes from the second gear position to the neutral position. In other words, the sleeve 13, which was engaged with the second gear 9B, moves axially on the output shaft 9, and the engagement between the sleeve 13 and the second gear 9B is released. Note that a downshift (gear change) requires the release of the clutch 7, but because the vehicle 1 is traveling at a low speed, the clutch 7 is already released at time t0. In other words, the transmission 4 is disconnected from the engine 2.

[0072] At time t3, the downshift from second gear to first gear is completed. At this time t3, the shift stroke changes to the position of first gear, and first gear is established. In other words, the sleeve 13 engages with the first gear 9A, connecting the first gear 9A to the output shaft 9 so that it rotates integrally with the output shaft 9.

[0073] The period between time t1 and time t3 is when the transmission 4 is in the middle of a downshift. A look at the shift stroke in Figure 4 reveals a change in the situation. The shift stroke is the movement of the sleeve 13. From time t1, the sleeve 13 moves quickly on the output shaft 9, disengaging from the second-speed gear 9B. However, just before time t2, the movement of the sleeve 13 slows down. This indicates that the movement of the sleeve 13 has begun to activate the synchronizer. The sleeve 13 begins to press the synchronizer ring (not shown) of the synchronizer against the first-speed gear 9A, and is waiting for the friction of the synchronizer ring to eliminate (synchronize) the relative rotational speed between the first-speed gear 9A and the sleeve 13. To synchronize the first-speed gear 9A and the sleeve 13, it is necessary to synchronize the rotating parts associated with each. In other words, synchronizing with the first-speed gear 9A means adjusting (increasing) the rotational speed of not only the first-speed gear 9A but also the members on the first-speed gear 9A side, including the input shaft 8, first-speed gear 8A, second-speed gear 8B, and clutch 7 (clutch disc) attached to the input shaft 8. Similarly, synchronizing with the sleeve 13 means adjusting and synchronizing the rotational speed of not only the sleeve 13 but also the members on the sleeve 13 side, including the output shaft 9, third-speed gear 9C, fourth-speed gear 9D, fifth-speed gear 9E, sixth-speed gear 9F, and drive wheels 6.

[0074] As a result, a large amount of kinetic energy is transferred from the member on the sleeve 13 side to the member on the first-speed gear 9A side. This state is reflected in the changes in "vehicle speed," "motor rotation speed," and "input rotation speed" at time t2 shown in the comparative example in Figure 4.

[0075] In other words, the drop in "vehicle speed (comparative example)" at time t2 is the result of kinetic energy being used to increase the rotation of the member on the first-speed gear 9A side, resulting in a state similar to that of braking, and the driver feels a sudden deceleration, especially since the vehicle is inertial traveling at low speed. The drop in "vehicle speed (comparative example)" also causes a drop in "motor rotation speed (comparative example)." In contrast, the "input rotation speed" at time t2 increases suddenly. Then, when the first-speed gear 9A and the sleeve 13 are synchronized, the sleeve 13 moves to the first-speed position (the position where the sleeve 13 and the first-speed gear 9A are engaged), achieving the state at time t3, and the downshift is completed.

[0076] When the first-speed gear 9A and sleeve 13 synchronize, the rotational speed of the components on the first-speed gear 9A side increases rapidly to a rotational speed corresponding to the first-speed gear ratio relative to the rotation of the sleeve 13 at that moment, and the inertial mass of these components causes them to rotate in an attempt to maintain that rotational speed. In contrast, the rotational speed of the sleeve 13 decreases rapidly, so the relationship between the rotational speeds of the components on the first-speed gear 9A side and the sleeve 13 side is reversed before and after synchronization. That is, the rotational speed of the sleeve 13 side is higher before synchronization, and the rotational speed of the components on the first-speed gear 9A side (strictly speaking, after synchronization, the first-speed gear 9A becomes the component on the sleeve 13 side due to engagement, so the rotational speed of the first-speed gear 8A taking into account the first-speed gear ratio) increases after synchronization. This sudden reversal of rotational speed changes the tooth contact surface at the meshing position of the first-speed gears (first-speed gear 9A, first-speed gear 8A), causing a strong collision between the teeth. For this reason, in the present invention, during such a downshift, the conditions for executing noise suppression control are met, and the motor 3 generates motor torque to suppress rotation fluctuations in the transmission 4 and the motor 3. As described above, at time t2 during the downshift, the shift stroke gradually moves from the neutral position to the first gear position to perform synchronization. During this synchronization, the transfer of kinetic energy from the output shaft 9 to the input shaft 8 acts to reduce the rotation speed of the output shaft 9. However, in this embodiment, the motor torque generated by the motor acts on the output shaft 9, suppressing rotation fluctuations in the transmission 4 and the motor 3. As a result, sudden changes in the vehicle speed and motor rotation speed are suppressed, and the vehicle speed and motor rotation speed decrease smoothly at a roughly constant rate.

[0077] On the other hand, if motor torque is not generated in the motor 3 during a downshift of the transmission 4, the motor 3 simply spins idle. In this case, as shown as a comparative example in FIG. 4, the motor rotation speed and vehicle speed fluctuate (decrease) at time t2 during synchronization. Note that at time t2, the increase in input rotation speed is small in the comparative example and large in this embodiment. This is because, in this embodiment, the decrease in rotation speed of the output shaft 9 is suppressed by being supported by the motor torque, and the increase in rotation speed of the input shaft 8 increases accordingly.

[0078] As described above, in this embodiment, the ECU 10 generates motor torque in the motor 3 to suppress rotational fluctuations in the transmission 4 and the motor 3 during the downshift, provided that the transmission 4 is downshifted during coasting, in which the vehicle is decelerating by inertia with the accelerator pedal 90 released.

[0079] As a result, when the transmission 4 is downshifted during coasting, the rotational fluctuation of the motor 3 is suppressed, thereby suppressing the rotational fluctuation of the transmission 4, thereby suppressing the generation of noise such as tooth rattle caused by reversal of the gear tooth contact surfaces of the transmission 4. Furthermore, because the rotational fluctuation of the motor 3 is suppressed, fluctuations in vehicle speed can be suppressed. As a result, when the transmission 4 is downshifted during coasting, noise generated from the transmission 4 and fluctuations in vehicle speed can be suppressed.

[0080] Furthermore, in this embodiment, ECU 10 causes motor 3 to generate motor torque so as to suppress rotational fluctuations in transmission 4 and motor 3 during the downshift, under the further condition that the vehicle speed is less than a predetermined vehicle speed and the downshift is a change from a predetermined higher speed gear to a predetermined lower speed gear.

[0081] This suppresses the rotational fluctuations of the motor 3 in vehicle conditions where noise caused by reversal of the tooth contact surface of the transmission 4 is more noticeable, thereby effectively suppressing noise and vehicle speed fluctuations associated with downshifting of the transmission 4.

[0082] Furthermore, in this embodiment, the ECU 10 causes the motor 3 to generate motor torque so as to suppress rotational fluctuations of the transmission 4 and the motor 3 during the downshift period, with the further condition that the motor 3 is not generating regenerative torque.

[0083] As a result, in a vehicle state in which the motor 3 is not generating regenerative torque and noise is likely to occur due to reversal of the tooth contact surface of the transmission 4, rotational fluctuations of the transmission 4 are suppressed, thereby effectively suppressing noise and fluctuations in vehicle speed associated with downshifting of the transmission 4.

[0084] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0085] 1 vehicle 2 engines 3 motors 4-speed 6 drive wheels 10 ECU (control unit) 90 Accelerator pedal

Claims

1. The engine and a transmission comprising an AMT that automates the gear shifting operation of a parallel shaft gear type manual transmission, to which power is transmitted from the engine; drive wheels to which power is transmitted from the transmission; a motor that applies power between the transmission and the drive wheels, A vehicle control device including a control unit that controls the transmission and the motor, The control unit generates a motor torque in the motor so as to suppress rotation fluctuations of the transmission and the motor during the downshift, on the condition that the transmission is downshifted during coasting in which the vehicle is decelerating by inertia with the accelerator pedal released.

2. 2. The vehicle control device according to claim 1, wherein the control unit generates motor torque in the motor so as to suppress rotation fluctuations of the transmission and the motor during the downshift, under the further condition that the vehicle speed is less than a predetermined vehicle speed and the downshift is a change from a predetermined higher-speed gear stage to a predetermined lower-speed gear stage.

3. The control unit 3. The vehicle control device according to claim 1, wherein the motor generates a motor torque so as to suppress rotation fluctuations of the transmission and the motor during the downshift, with the further condition that the motor is not generating regenerative torque.

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