JP2012188023A - Brake control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make braking by the MG torque enforceable at low vehicle speed as much as possible, when the MG torque is transferred to the ECB torque immediately before the stop of the vehicle, while dividing the request braking torque by both the MG torque and the ECB torque.SOLUTION: Although the request braking torques are allotted by both the MG torque of the motor generator MG and the ECB torque by hydraulic brake 62, when the MG torque is transferred to the ECB torque immediately before the stop of the vehicle, while increasing the ECB torque gradually, the L/U clutch torque of lock-up clutch 30 is gradually decreased corresponding to an increase of the ECB torque, and gradually decreased while maintaining the MG torque more than the L/U clutch torque. Since the L/U clutch torque is gradually decreased in parallel with the transfer of the MG torque, the start time of transfer control of the MG torque can be made slow (low vehicle speed) that much and regenerative control of the MG torque comes to be enforceable even the low vehicle speed, and the energy recovery efficiency improves.

Description

  The present invention relates to a vehicle braking control device, and more particularly to a braking control device that shares a required braking torque by both a braking torque by a rotating machine and a braking torque by a mechanical brake.

  (a) a rotating machine that functions as at least a generator and can generate braking torque by regenerative torque, and (b) disconnects the rotating machine from the power transmission path and continuously engages the torque. A braking control device for a vehicle, comprising: a friction clutch that can be changed; and (c) a braking torque sharing control unit that shares a required braking torque by both the braking torque by the rotating machine and the braking torque by the mechanical brake. Are known. The device described in Patent Document 1 is an example, and a motor generator is used as a rotating machine, and a second clutch CL2 is provided as the friction clutch. When the braking torque by the generator is insufficient, the shortage is compensated by the braking torque by the mechanical brake (see paragraph 19). In Patent Document 2, a motor generator is used as a rotating machine, and the motor generator is connected to a power transmission path via a torque converter with a lock-up clutch as a friction clutch. A technique for regenerative control (also referred to as power generation control) of a motor generator by engaging a lock-up clutch in an operating state is described (see claim 1).

JP 2006-306328 A JP 2006-151307 A

  By the way, when the required braking torque is shared by both the braking torque by the rotating machine and the braking torque by the mechanical brake, immediately before stopping the vehicle, the braking torque by the rotating machine is gradually reduced and transferred to the braking torque by the mechanical brake. There is a need. In Patent Document 2, the oil pump is driven to rotate by an engine or a rotating machine. In order to generate a predetermined hydraulic pressure by the oil pump even when the vehicle is stopped, a friction clutch (lock-up clutch) is used. Need to be released. However, if the braking torque transfer control is to be performed prior to the friction clutch release control, it is necessary to start the braking torque transfer control earlier (at a higher vehicle speed), which reduces energy acquisition by regenerative control. Recovery efficiency is impaired.

  FIG. 7 shows the hybrid vehicle 10 shown in FIG. 1, in which the regenerative torque (MG torque) of the motor generator MG is the maximum regenerative torque tmgmx during braking by the brake depression operation, and the shortage is the braking torque (ECB torque) by the hydraulic brake 62. In the case of complementation, this is a case where regenerative return control for changing the braking torque is started at time t1 as the vehicle speed (corresponding to the output shaft rotational speed NOUT) decreases. The time t2 is a time when the transfer of the braking torque is completed and all the required braking torque can be obtained with the ECB torque, and the release control of the lockup clutch (L / U clutch) 30 starts at this time t2. The release control of the lockup clutch 30 is completed at time t3. In any of these transfer control and release control, it is necessary to smoothly change the torque so as not to generate shocks due to fluctuations in driving force or abnormal noise due to gear backlash, etc., so that the start time t1 of the regenerative recovery control is advanced. (High vehicle speed side) must be set. The graphs in the torque column are all converted to torque in the output shaft 22. The time t4 is a time when a shift output for downshifting the automatic transmission 20 to the first gear is made in preparation for the start after the vehicle stops, and the time t5 is for generating a predetermined creep torque. Is the time when the creep control of the motor generator MG is started. The oil pump 32 is rotationally driven by the creep control of the motor generator MG, so that the hydraulic pressure necessary to establish a predetermined gear stage of the automatic transmission 20 is ensured even when the vehicle is stopped.

  The present invention has been made against the background of the above circumstances. The purpose of the present invention is to share the required braking torque by both the braking torque by the rotating machine and the braking torque by the mechanical brake and immediately before stopping the vehicle. In addition, when the braking torque by the rotating machine is transferred to the braking torque by the mechanical brake, the energy recovery efficiency is improved by enabling the braking by the regenerative control of the rotating machine to be performed as low as possible.

  In order to achieve such an object, the first invention is as follows: (a) a rotating machine that functions as at least a generator and can generate braking torque by regenerative torque; and (b) the rotating machine with respect to a power transmission path. A friction clutch capable of continuously changing the engagement torque, (c) a brake control device for electrically controlling the braking torque of a mechanical brake provided on the wheel, and (d) And a braking torque sharing control means for sharing the required braking torque by both the braking torque by the rotating machine and the braking torque by the mechanical brake. (E) Immediately before the vehicle stops, Prior to the control by the torque sharing control means, the braking torque by the rotating machine is gradually reduced and transferred to the braking torque by the mechanical brake, and in parallel And (f) the transfer control means that gradually decreases the engagement torque of the friction clutch in response to an increase in braking torque by the mechanical brake. In addition, the regenerative torque of the rotating machine is gradually decreased while maintaining the frictional clutch engaging torque or more, and the braking torque by the mechanical brake is controlled while the braking torque by the rotating machine is controlled by the engaging torque of the friction clutch. It is characterized by being transferred to.

  A second aspect of the invention is the vehicle braking control apparatus according to the first aspect of the invention, wherein the transfer control means has a predetermined target rotational speed at which the rotational speed difference before and after the friction clutch is lower than the rotational speed on the rotating machine side. It is characterized by having a rotation control means that gradually reduces the regenerative torque of the rotating machine while maintaining the regenerative torque of the rotating machine at or above the engagement torque of the friction clutch by feedback control of the regenerative torque of the rotating machine so as to achieve a speed difference. To do.

  A third aspect of the invention is the vehicle braking control apparatus according to the second aspect of the invention, wherein the rotation control means adds a correction value by the feedback control to a feedforward value determined based on an engagement torque command value of the friction clutch. And controlling the regenerative torque of the rotating machine.

  The fourth invention comprises (a) a rotating machine that functions as at least a generator and can generate braking torque by regenerative torque; and (b) disconnects the rotating machine from the power transmission path and engages it. A friction clutch capable of continuously changing the torque, (c) a brake control device for electrically controlling a braking torque of a mechanical brake provided on the wheel, and (d) a required braking torque by the rotating machine. And a braking torque sharing control unit that shares both braking torque and braking torque by the mechanical brake. (E) Immediately before the vehicle stops, the control by the braking torque sharing control unit has priority. Then, the braking torque by the rotating machine is gradually reduced and transferred to the braking torque by the mechanical brake, and the engagement torque of the friction clutch is gradually increased in parallel. And (f) the transfer control means gradually reduces the regenerative torque of the rotating machine in response to an increase in braking torque by the mechanical brake and engages the friction clutch. It is characterized in that the torque is gradually reduced while maintaining the torque higher than the regenerative torque of the rotating machine.

  In the vehicle braking control apparatus according to the first aspect of the present invention, when the required braking torque is shared by both the braking torque by the rotating machine and the braking torque by the mechanical brake, the braking torque by the rotating machine is mechanical before the vehicle is stopped. When switching to the braking torque by the brake, the engagement torque of the friction clutch is gradually reduced in response to the increase of the braking torque by the mechanical brake, and the regenerative torque of the rotating machine (depending on the rotational resistance of the rotating machine itself generated by the regeneration control). Torque) is gradually reduced while maintaining the friction clutch engagement torque or more, and the braking torque by the rotating machine is transferred to the braking torque by the mechanical brake while being controlled by the engagement torque of the friction clutch. The braking torque can be smoothly transferred without causing a shock. In this case, since the engagement torque of the friction clutch is gradually reduced in parallel with the transfer of the braking torque, it is possible to delay the start time of the transfer control of the braking torque and to apply the braking torque by the rotating machine. It becomes possible to carry out even at a low vehicle speed, and energy recovery efficiency is improved by increasing energy acquisition by regenerative control of the rotating machine. In addition, since the engagement torque of the friction clutch is gradually reduced in the same manner as the transfer of the braking torque, the generation of abnormal noise due to gear backlash or the like is suppressed.

  In the second aspect of the invention, the regenerative torque of the rotating machine is feedback-controlled so that the difference between the rotational speeds before and after the friction clutch becomes a predetermined target rotational speed difference. Since it gradually decreases while maintaining the torque or more, it is possible to prevent the rotational speed of the rotating machine from being extremely lowered while appropriately securing the braking torque obtained based on the regenerative control of the rotating machine. Thereby, for example, when an oil pump is connected to the rotating machine, insufficient hydraulic pressure due to a decrease in the rotational speed is avoided.

  In the third aspect of the invention, since the regenerative torque of the rotating machine is controlled by adding a correction value by feedback control to the feedforward value determined based on the engagement torque command value of the friction clutch, the rotational speeds before and after the friction clutch are controlled. The regenerative torque of the rotating machine is quickly controlled so that the difference becomes the target rotational speed difference. As a result, the regenerative torque of the rotating machine becomes smaller than the engaging torque of the friction clutch and the braking torque is insufficient, and the rotation speed of the rotating machine is prevented from being extremely reduced, while appropriately preventing the friction clutch. The regenerative torque of the rotating machine is decreased following the decrease in the engagement torque.

  In the vehicle braking control apparatus according to the fourth aspect of the invention, when the required braking torque is shared by both the braking torque by the rotating machine and the braking torque by the mechanical brake, the braking torque by the rotating machine is mechanically set immediately before the vehicle is stopped. When switching to the braking torque by the brake, while gradually reducing the regenerative torque of the rotating machine in response to the increase of the braking torque by the mechanical brake, while maintaining the engagement torque of the friction clutch more than the regenerative torque of the rotating machine Since it gradually decreases, the braking torque can be smoothly transferred without causing a shock such as a fluctuation in driving force. In this case, since the engagement torque of the friction clutch is gradually reduced in parallel with the transfer of the braking torque, it is possible to delay the start time of the transfer control of the braking torque and to apply the braking torque by the rotating machine. It becomes possible to carry out even at a low vehicle speed, and energy recovery efficiency is improved by increasing energy acquisition by regenerative control of the rotating machine. In addition, since the engagement torque of the friction clutch is gradually reduced in the same manner as the transfer of the braking torque, the generation of abnormal noise due to gear backlash or the like is suppressed.

It is the schematic block diagram which showed the principal part of the control system | strain in addition to the main point figure of the hybrid vehicle to which this invention is applied suitably. It is a flowchart explaining the operation | movement of the transfer control means with which the electronic controller of FIG. 1 is provided functionally. It is a control block diagram explaining MG rotation speed control of step S5 of FIG. It is an example of the time chart which shows the torque change of each part at the time of braking torque transfer control being performed according to the flowchart of FIG. 2, a rotational speed change, etc. FIG. It is a figure explaining another aspect of the transfer control means with which the electronic controller of FIG. 1 is equipped functionally, and is a flowchart corresponding to FIG. It is an example of the time chart which shows the torque change of each part, rotation speed change, etc. when braking torque transfer control is performed according to the flowchart of FIG. It is an example of the time chart which shows the torque change of each part, a rotational speed change, etc. in case the release control of a lockup clutch is performed after the braking torque transfer control is completed.

  As a rotating machine that functions as at least a generator, a motor generator that can also function as an electric motor and generate power running torque is preferably used, but a generator that does not provide a function as an electric motor should be adopted. The generator and the electric motor may be provided separately. The present invention is preferably applied to an electric vehicle that travels using a motor generator as a driving force source, and is a hybrid vehicle including an engine such as an internal combustion engine that generates power by combustion of fuel in addition to the motor generator. Also good. The engine is connected to the motor generator via a connection / disconnection device such as a hydraulic friction engagement device. The hydraulic friction engagement device is a single-plate or multi-plate friction clutch or friction brake that is frictionally engaged by a hydraulic cylinder. The engine is connected to a power transmission path in which a motor generator is disposed, and is configured to rotationally drive a common drive wheel. For example, the engine is disposed so as to be directly connected to the motor generator by a connecting / disconnecting device. You may arrange | position in the power transmission path (for example, front-wheel drive side) different from the power transmission path (for example, rear-wheel drive side) by which the motor generator was arrange | positioned.

  As the friction clutch for connecting and disconnecting the rotating machine from the power transmission path, a single-plate or multi-plate hydraulic friction clutch that is frictionally engaged by a hydraulic cylinder as in the above-described hydraulic friction engagement device is preferably used. An electromagnetic friction clutch can also be employed. The friction clutch may be, for example, a lock-up clutch of a torque converter with a lock-up clutch, but the present invention can also be applied to an electric vehicle that does not include a torque converter. As a mechanical brake provided on a wheel, for example, a hydraulic brake that generates a braking torque by a friction force by a hydraulic cylinder is widely used, and the braking torque is controlled by a brake control device having an electromagnetic hydraulic control valve or the like. However, a mechanical brake such as an electric type may be employed.

  The braking torque sharing control means is configured to supplement the shortage with the braking torque by the mechanical brake when the braking torque by the regenerative torque of the motor generator reaches the maximum value, for example, but the braking torque by the regenerative torque of the motor generator Various modes are possible, for example, such that the braking torque by the mechanical brake may be shared at a predetermined ratio such as 50%. The required braking torque is, for example, the braking torque required by the driver's braking operation, but may be the required braking torque for automatically braking the vehicle, and includes the regenerative torque for charging the battery. You can leave. When the required braking torque is distributed to the front and rear wheels at a predetermined ratio, if the braking torque due to the regenerative torque of the motor generator acts on only one of the front and rear wheels, only the required braking torque for the one wheel side is targeted. The share amount may be controlled as follows. The regenerative torque of the motor generator is a torque generated by regenerative control due to the rotational resistance of the motor itself, and a predetermined braking torque is applied to the wheels via a power transmission path such as an automatic transmission based on the regenerative torque.

  When a stepped or continuously variable automatic transmission is disposed in a power transmission path to which a rotating machine is connected via a friction clutch, the automatic transmission is, for example, after the friction clutch is released immediately before the vehicle stops. The speed is changed to the starting speed state such as the first gear stage having the largest speed ratio or the maximum speed ratio. In addition, when a motor generator is used as a rotating machine and the creep torque is generated by the motor generator, the regenerative torque is reduced to 0 by the switching of the braking torque immediately before the vehicle stops and the friction clutch is released. It is desirable to control the motor generator so as to generate a predetermined creep torque by performing power running control. This creep torque itself can be generated even with the friction clutch engaged, but for example, when the vehicle is stopped in order to generate a predetermined hydraulic pressure by rotating an oil pump mechanically connected to the motor generator. However, when the motor generator is rotated at a predetermined rotational speed, the friction clutch is controlled by slip control to transmit creep torque, or the friction clutch is released and creep torque is transmitted via a fluid power transmission device such as a torque converter. Therefore, the present invention in which the friction clutch is released immediately before the vehicle stops is preferably applied to such a case. When shifting the transmission to the starting shift state after releasing the friction clutch, or generating creep torque with the motor generator, increase the start time of the braking torque transfer control in consideration of such time. Will be set to.

  In the case of gradually decreasing the engagement torque of the friction clutch in response to the increase of the braking torque due to the mechanical brake and gradually decreasing the regenerative torque of the rotating machine while maintaining the engagement torque of the friction clutch or more, for example, As described above, it is desirable to feedback control the regenerative torque of the rotating machine so that the difference between the rotational speeds before and after the friction clutch becomes a predetermined target rotational speed difference. The regenerative torque control of the rotating machine may be performed with a torque value that is larger than the engagement torque command value of the friction clutch by a predetermined value. The target rotational speed difference of the second invention is such that the regenerative torque of the rotating machine does not become smaller than the engagement torque of the friction clutch, resulting in insufficient braking torque, and the rotating speed of the rotating machine does not extremely decrease. For example, a constant value within a range of several tens to several hundreds rpm is set. The feedforward value of the third aspect of the invention may be the same torque value as the engagement torque command value of the friction clutch, but in order to avoid that the regenerative torque of the rotating machine becomes smaller than the engagement torque of the friction clutch. A torque value obtained by adding a predetermined value to the engagement torque command value of the friction clutch may be used.

  In the fourth aspect of the invention, the regenerative torque of the rotating machine is gradually reduced in response to the increase of the braking torque by the mechanical brake, and the engagement torque of the friction clutch is gradually reduced while being maintained above the regenerative torque of the rotating machine. For example, the engagement torque control value of the friction clutch may be controlled by setting the engagement torque command value of the friction clutch to a torque value larger than the regenerative torque command value of the rotating machine by a predetermined value.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram including a skeleton diagram of a drive system of a hybrid vehicle 10 to which the present invention is preferably applied. The hybrid vehicle 10 includes an engine 12 that is an internal combustion engine such as a gasoline engine or a diesel engine that generates power by combustion of fuel, and a motor generator MG that functions as an electric motor and a generator as driving power sources. The outputs of the engine 12 and the motor generator MG are transmitted from the torque converter 14 which is a fluid transmission device to the automatic transmission 20 via the turbine shaft 16 and the C1 clutch 18, and further to the output shaft 22 and the differential gear. It is transmitted to the left and right drive wheels 26 via the device 24. The torque converter 14 includes a lock-up clutch (L / U clutch) 30 that directly connects the pump impeller and the turbine impeller, and an oil pump 32 is integrally connected to the pump impeller, and the engine. 12 and motor generator MG are mechanically driven to rotate. The motor generator MG corresponds to a rotating machine. The lock-up clutch 30 corresponds to a friction clutch that disconnects the motor generator MG from the power transmission path, and is disengaged by an electromagnetic hydraulic control valve, a switching valve, or the like provided in the hydraulic control device 28. At the same time, the engagement torque (L / U clutch torque) is continuously changed.

  A K0 clutch 34 is provided between the engine 12 and the motor generator MG via a damper 38 to directly connect them. The K0 clutch 34 is a single-plate or multi-plate friction clutch that is frictionally engaged by a hydraulic cylinder, and is disposed in the oil chamber 40 of the torque converter 14 in an oil bath state from the viewpoint of cost, durability, and the like. . The K0 clutch 34 is a hydraulic friction engagement device, and functions as a connection / disconnection device that connects or disconnects the engine 12 to / from the power transmission path. Motor generator MG is connected to battery 44 via inverter 42. Further, the automatic transmission 20 is a stepped automatic transmission such as a planetary gear type in which a plurality of gear stages having different gear ratios are established depending on the disengagement state of a plurality of hydraulic friction engagement devices (clutch and brake). The shift control is performed by an electromagnetic hydraulic control valve, a switching valve or the like provided in the hydraulic control device 28. The C1 clutch 18 functions as an input clutch of the automatic transmission 20 and is similarly subjected to engagement / release control by the hydraulic control device 28.

  The driving wheel 26 and the driven wheel (not shown) are each provided with a hydraulic brake 62 that mechanically generates a braking torque (hereinafter also referred to as ECB (electronic control brake) torque) by a hydraulic cylinder. The braking torque is controlled by 60. The hydraulic brake control device 60 includes an electromagnetic hydraulic control valve, a switching valve, and the like, and electrically controls the braking torque of the hydraulic brake 62 in accordance with a brake control signal output from the electronic control device 70. The hydraulic brake 62 corresponds to a mechanical brake.

  The electronic control unit 70 includes a so-called microcomputer having a CPU, a ROM, a RAM, an input / output interface, and the like, and performs signal processing according to a program stored in advance in the ROM while using a temporary storage function of the RAM. Do. The electronic control device 70 is supplied with a signal representing an accelerator pedal operation amount (accelerator operation amount) Acc from the accelerator operation amount sensor 46 and represents a brake pedal depression force (brake depression force) Brk from the brake pedal force sensor 48. A signal is supplied. Further, from the engine speed sensor 50, the MG speed sensor 52, the turbine speed sensor 54, and the vehicle speed sensor 56, the rotational speed (engine speed) NE of the engine 12 and the rotational speed (MG speed) NMG of the motor generator MG, respectively. The rotational speed of the turbine shaft 16 (turbine rotational speed) NT and the rotational speed of the output shaft 22 (corresponding to the vehicle speed V in the output shaft rotational speed) NOUT are supplied. In addition, various types of information necessary for various types of control are supplied.

  The electronic control unit 70 functionally includes a hybrid control means 72, a shift control means 74, a creep control means 76, and a braking control means 80. The hybrid control means 72 controls the operation of the engine 12 and the motor generator MG, for example, an engine travel mode in which the engine 12 travels using only the engine 12 as a driving force source, or a motor travel mode that travels using only the motor generator MG as a drive power source. Switching between a plurality of predetermined driving modes, such as an engine that uses both of them and a motor driving mode, according to driving conditions such as the amount of accelerator operation (driver's required driving force) Acc and vehicle speed V And run. Further, the shift control means 74 controls the automatic hydraulic shift by switching the engagement / disengagement state of the plurality of hydraulic friction engagement devices by controlling the electromagnetic hydraulic control valves, switching valves and the like provided in the hydraulic control device 28. The plurality of gear stages of the machine 20 are switched according to a predetermined shift map with the operating state such as the accelerator operation amount Acc and the vehicle speed V as parameters.

  The creep control means 76 performs creep control for operating the motor generator MG with a predetermined creep power running torque tcreep (see FIG. 4) with the lockup clutch 30 released at a predetermined low vehicle speed including a vehicle stop state. By executing, a predetermined creep torque is generated via the torque converter 14. The creep power running torque tcreep is determined such that, for example, the MG rotational speed NMG is substantially the same as the idle rotational speed of the engine 12, and thereby the K0 clutch 34 is disconnected and the engine 12 is disconnected. Also, it is possible to generate the same creep torque as when the engine is idle in the engine running mode. Further, the oil pump 32 is rotationally driven by this creep control, so that a predetermined gear stage (first speed gear stage, etc.) of the automatic transmission 20 is established as in the case of engine idling in the engine running mode. A predetermined hydraulic pressure required for the operation is ensured.

  The braking control means 80 controls the motor generator MG and the hydraulic brake control device 60 so as to obtain the required braking torque according to the required braking torque due to the depression operation of the brake pedal or the like. That is, the entire required braking torque obtained according to the brake pedaling force Brk is distributed to the drive wheel 26 side and the driven wheel side (not shown), and the required braking torque for the drive wheel 26 side is applied to the regeneration control (power generation control) of the motor generator MG. The amount of such control is controlled so as to be shared by both the braking torque by the hydraulic brake 62 and the braking torque by the hydraulic brake 62, and the braking torque sharing control means 82 and the transfer control means 84 are functionally provided. . For example, the braking torque sharing control means 82 brakes only with the braking torque by the motor generator MG until the regenerative torque of the motor generator MG reaches the maximum regenerative torque tmgmx, and does not reach the required braking torque only with the braking torque by the motor generator MG. In addition, the shortage is supplemented with a braking torque (ECB torque) by the hydraulic brake 62. Thus, battery 44 can be efficiently charged while generating a predetermined braking torque by regenerative control of motor generator MG when the vehicle is decelerated. The initial state (before time t1) of the time chart of FIG. 4 is a case where the motor generator MG is set to the maximum regenerative torque tmgmx and the shortage is supplemented with the ECB torque. Note that the braking torque on the driven wheel side where the braking torque by the motor generator MG cannot be obtained is controlled by the hydraulic brake 62 so as to obtain a predetermined braking torque.

  The transfer control unit 84 prioritizes the sharing control by the braking torque sharing control unit 82 immediately before stopping the vehicle, gradually reduces the braking torque by the motor generator MG and transfers it to the braking torque by the hydraulic brake 62, and in parallel. The engagement torque of the lockup clutch 30 is gradually reduced, and signal processing is executed according to the flowchart of FIG. In the flowchart of FIG. 2, steps S3 to S6 correspond to the transfer control means 84, and step S5 therein corresponds to the rotation control means.

In step S1 of FIG. 2, it is determined whether or not the regeneration control execution flag is ON, that is, whether or not the regeneration control of the motor generator MG is being executed by the sharing control by the braking torque sharing control means 82. If the regenerative control is not being executed, the process is terminated. If the regenerative control is being executed, step S2 and subsequent steps are executed. In step S2, it is determined whether or not the regeneration return control execution flag is ON. If the regeneration return control execution flag is ON, step S3 and subsequent steps are executed, but if the regeneration return control execution flag is not ON, step S9 is executed. Then, the regeneration control of the motor generator MG is executed according to the sharing control by the braking torque sharing control means 82. The regeneration return control execution flag is turned ON, for example, when the output shaft rotational speed NOUT satisfies the following expression (1).
NOUT <Tima × ΔNOUT + NOUTs (1)

  In the above equation (1), Time A is a predetermined regenerative recovery time, which is t1 to t2 in FIG. ΔNOUT is a deceleration of the output shaft rotation speed NOUT. NOUTs is a predetermined regenerative recovery rotational speed, which is the output shaft rotational speed NOUT at time t2 in FIG. FIG. 4 is an example of a time chart showing torque and rotation speed change of each part when regenerative recovery control, that is, braking torque transfer control is executed according to the flowchart of FIG. 2, and satisfies the above equation (1) at time t1. Thus, the regeneration return control execution flag is turned ON, and the regeneration return control is started. In this way, it is desirable to determine whether or not to start the regenerative return control based on the vehicle deceleration ΔNOUT. However, the starting condition for the regenerative return control is to change the braking torque and lock up at least before the vehicle stops. It is set as appropriate so that the clutch 30 can be released. The graphs in the torque column of FIG. 4 are all converted to torque in the output shaft 22, and the regeneration torque (MG torque) of the motor generator MG at the start of regeneration return control t1 and the ECB at the completion of regeneration return control t2. The torque is substantially the same, and at the time t1 when the regenerative recovery control starts, the braking torque is larger by the ECB torque, but this is added with the regenerative torque for charging the battery 44 in addition to the required braking torque by the brake operation. Because. This additional regenerative torque is gradually reduced at the time of regenerative return control (t1 to t2) and becomes 0 at time t2. The same applies to the time charts of FIGS. However, in the following description, this additional regenerative torque is assumed to be zero.

  In step S3 of FIG. 2, the ECB torque required for the hydraulic brake control device 60 is gradually increased at a predetermined rate of change. As a result, the ECB torque controlled by the hydraulic brake control device 60 is gradually increased. The change rate of the ECB torque is obtained by dividing the MG torque (the maximum regenerative torque tmgmx in FIG. 4) at the start of regenerative recovery control t1 by the regenerative recovery required time Tima. However, a constant rate of change obtained by dividing the maximum regenerative torque tmgmx by the regenerative recovery required time Tima regardless of the magnitude of the MG torque at the time t1 when the regenerative return control is started may be determined in advance.

  In step S4, the engagement torque (L / U clutch torque) of the lockup clutch 30 is gradually reduced. Specifically, the L / U clutch torque command value iTLU is obtained by subtracting the ECB required torque obtained in step S3 from the required braking torque, and the L / U clutch torque is controlled according to the L / U clutch torque command value iTLU. To do. Therefore, the L / U clutch torque is gradually reduced so as to decrease substantially symmetrically with respect to the ECB torque gradually increasing. In the next step S5, the MG torque of the motor generator MG is gradually reduced while being maintained at or above the L / U clutch torque (large in the regeneration direction). That is, the braking torque obtained based on the MG torque of the motor generator MG is transferred to the ECB brake by the hydraulic brake 62 while being controlled by the L / U clutch torque smaller than the MG torque.

FIG. 3 is a control block diagram for explaining the signal processing in step S5. The plant 92 to be controlled is the motor generator MG, and the rotational speed difference ΔN before and after the lock-up clutch 30, specifically the MG rotation. A rotational speed difference (NMG-NT) between the speed NMG and the turbine rotational speed NT is detected as a control amount. Further, the adjustment unit 90 determines a predetermined deviation (tΔN−ΔN) between a predetermined target rotational speed difference tΔN and an actual rotational speed difference ΔN that causes the MG rotational speed NMG to be lower than the turbine rotational speed NT. Is multiplied by a gain k1 to obtain a feedback value fb. A predetermined feedforward value ff is added to the feedback value fb to obtain an MG torque command value iTMG, and the motor generator MG is controlled according to the MG torque command value iTMG. Torque control is performed. Thereby, the MG torque is controlled so that the rotational speed difference ΔN becomes a predetermined target rotational speed difference tΔN, and the MG rotational speed NMG becomes a rotational speed lower than the turbine rotational speed NT by the target rotational speed difference tΔN. In addition, the MG torque is maintained at or above the L / U clutch torque, the lockup clutch 30 is held in the slip state, and the braking torque obtained based on the MG torque is defined by the L / U clutch torque. The following expression (2) is an arithmetic expression of the MG torque command value iTMG, and k1 × {tΔN− (NMG−NT)} corresponds to the feedback value fb. This feedback value fb is a correction value for feedback control for controlling the MG torque so that the rotational speed difference ΔN becomes a predetermined target rotational speed difference tΔN.
iTMG = k1 × {tΔN− (NMG−NT)} + ff (2)

  Here, the target rotational speed difference tΔN is, for example, such that the MG torque does not become smaller than the L / U clutch torque so that the braking torque is not insufficient, and the MG rotational speed NMG does not extremely decrease. A constant value within a range of about several tens to several hundred rpm is predetermined. Further, as the feedforward value ff, the MG torque is quickly controlled so that the rotational speed difference ΔN becomes the target rotational speed difference tΔN, the MG torque is set to the L / U clutch torque or more, and the lockup clutch 30 is in the slip state. Is preferably set based on the L / U clutch torque command value iTLU. Specifically, for example, the L / U clutch torque command value iTLU is set as it is as the feedforward value ff, but it is avoided that the MG torque becomes smaller than the L / U clutch torque and the braking torque becomes insufficient. Thus, a torque value obtained by adding a predetermined value to the L / U clutch torque command value iTLU can also be used as the feedforward value ff.

  Returning to FIG. 2, in the next step S6, it is determined whether or not the L / U clutch torque has become 0, and steps S1 to S5 are repeatedly executed until the L / U clutch torque = 0. The ECB torque is gradually increased and the L / U clutch torque is gradually decreased, and the MG torque is gradually decreased as the L / U clutch torque decreases. When L / U clutch torque = 0, the braking torque generated by the motor generator MG is entirely transferred to the ECB torque generated by the hydraulic brake 62, and a series of transfer control is completed. Steps S7 and S8 are executed following step S6. By doing this, both the regeneration control execution flag and the regeneration return control execution flag are turned OFF.

  A time t2 in FIG. 4 is a time when all braking torques by the motor generator MG are transferred to ECB torques by the hydraulic brake 62 by the transfer control unit 84. Thereafter, when the output shaft rotational speed NOUT further decreases, a shift command (3 in the figure) for downshifting the automatic transmission 20 to the start-time shift state such as the first speed gear stage at time t3 in preparation for the start after the vehicle stops. (→ 1 shift) is output, and the automatic transmission 20 is downshifted accordingly, and at the time t4, the creep control by the creep control means 76 is started, and the MG torque is increased smoothly to the creep power running torque tcreep. It is done.

  Thus, in the hybrid vehicle 10 of the present embodiment, the required braking torque is shared by both the braking torque due to the MG torque of the motor generator MG and the ECB torque due to the hydraulic brake 62 by the braking torque sharing control means 82. When the braking torque based on the MG torque is transferred to the ECB torque immediately before the stop of the engine, the ECB torque is gradually increased, and the engagement torque (L / U clutch torque) of the lockup clutch 30 is increased corresponding to the increase in the ECB torque. It gradually decreases and gradually decreases while maintaining the MG torque of the motor generator MG at or above the L / U clutch torque. In other words, the braking torque obtained based on the MG torque is transferred to the ECB torque while being controlled by the L / U clutch torque, and the braking torque by the regenerative control of the motor generator MG is smoothly generated without causing a shock such as a fluctuation in driving force. It can be transferred to ECB torque.

  In that case, since the L / U clutch torque of the lockup clutch 30 is gradually reduced in parallel with the transfer of the braking torque, the start time of the transfer control of the braking torque can be delayed by that much (low vehicle speed). The braking torque can be applied by regenerative control of the motor generator MG up to a low vehicle speed, energy acquisition by the regenerative control of the motor generator MG is increased, and energy recovery efficiency is improved. Further, the L / U clutch torque of the lock-up clutch 30 is also gradually reduced in the same manner as the braking torque transfer, so that the generation of noise due to gear backlash and the like is suppressed.

  Further, in this embodiment, the MG torque of the motor generator MG is feedback-controlled so that the rotational speed difference ΔN before and after the lock-up clutch 30 becomes a predetermined target rotational speed difference tΔN. Since the torque gradually decreases while being maintained above the / U clutch torque, it is possible to prevent the MG rotational speed NMG from being extremely lowered while appropriately securing the braking torque obtained based on the MG torque. As a result, the hydraulic pressure output of the oil pump 32 that is mechanically driven to rotate by the motor generator MG is appropriately maintained, and insufficient hydraulic pressure due to a decrease in the rotational speed is avoided.

  In this embodiment, the MG torque command value iTMG is calculated by adding the feedback value fb to the feedforward value ff determined based on the L / U clutch torque command value iTLU of the lockup clutch 30, and the MG torque Since the MG torque is controlled according to the command value iTMG, the MG torque is quickly controlled so that the rotational speed difference ΔN before and after the lockup clutch 30 becomes the target rotational speed difference tΔN. This appropriately prevents the MG torque from becoming smaller than the L / U clutch torque and the braking torque from being insufficient, or the MG rotational speed NMG from being extremely lowered to impair the hydraulic output of the oil pump 32. Meanwhile, the MG torque is decreased following the decrease in the L / U clutch torque.

  Next, another embodiment of the present invention will be described. In the following embodiments, parts that are substantially the same as those in the above embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 5 is a diagram for explaining another aspect of the transfer control means 84, and is a flowchart implemented instead of FIG. Steps R1 to R3 and R6 to R9 in the flowchart of FIG. 5 are the same as steps S1 to S3 and S6 to S9 in the flowchart of FIG. 2, respectively, and only steps R4 and R5 are different. FIG. 6 is an example of a time chart showing torque changes, rotation speed changes, and the like of each part when regenerative recovery control, that is, braking torque transfer control is performed according to the flowchart of FIG. 5, and corresponds to FIG. FIG.

  Step R4 in FIG. 5 performs gradual decrease processing of the MG torque of the motor generator MG in response to the gradual increase processing of ECB required torque in step R3. Specifically, the ECB required torque obtained in step R3 from the required braking torque. Is subtracted to obtain an MG torque command value iTMG, and the MG torque of the motor generator MG is controlled in accordance with the MG torque command value iTMG. Therefore, the MG torque is gradually reduced so as to decrease substantially symmetrically with respect to the ECB torque gradually increasing. Further, in the next step R5, the L / U clutch torque of the lockup clutch 30 is gradually decreased while being maintained at or above the MG torque. Specifically, a predetermined value α is added to the MG torque command value iTMG to obtain the L / U clutch torque command value iTLU, and the L of the lockup clutch 30 is determined according to the L / U clutch torque command value iTLU. / U clutch torque is controlled. That is, in this embodiment, the MG torque and the L / U clutch torque are gradually reduced while the lock-up clutch 30 is completely engaged, and the braking torque is transferred. Is fixed in advance so that can be maintained in the fully engaged state.

  Also in this embodiment, when the braking torque based on the MG torque is transferred to the ECB torque immediately before the vehicle stops, the ECB torque is gradually increased and the MG torque of the motor generator MG is gradually decreased in response to the increase in the ECB torque. In addition, since the L / U clutch torque of the lockup clutch 30 is gradually decreased while maintaining the MG torque or more, the generation of the motor generator MG is prevented while preventing the generation of noise due to shocks such as fluctuations in the driving force and backlash of the gear The braking torque by the regenerative control can be smoothly transferred to the ECB torque. In that case, since the L / U clutch torque of the lockup clutch 30 is gradually reduced in parallel with the transfer of the braking torque, the start time of the transfer control of the braking torque can be delayed by that much (low vehicle speed). The same effect as in the above-described embodiment, in which the braking torque can be applied by the regeneration control of the motor generator MG up to a low vehicle speed, the energy acquisition by the regeneration control of the motor generator MG is increased, and the energy recovery efficiency is improved. Is obtained.

  In this embodiment, since the L / U clutch torque has a predetermined value α even when the MG torque becomes zero, the L / U clutch torque changes until then even after MG torque = 0. The lock-up clutch 30 is released by gradually decreasing it to 0 at substantially the same rate of change as the rate. For this reason, the regenerative recovery required time Tima becomes longer than the above-described embodiment by the L / U clutch release time TimB required to change the L / U clutch torque from the predetermined value α to zero.

  As mentioned above, although the Example of this invention was described in detail based on drawing, these are one Embodiment to the last, This invention is implemented in the aspect which added the various change and improvement based on the knowledge of those skilled in the art. be able to.

10: Hybrid vehicle (vehicle) 30: Lock-up clutch (friction clutch) 60: Hydraulic brake control device (brake control device) 62: Hydraulic brake (mechanical brake) 70: Electronic control device 80: Braking control means 82: Braking torque Sharing control means 84: Transfer control means MG: Motor generator (rotating machine) ff: Feed forward value fb: Feedback value (correction value) ΔN: Rotational speed difference tΔN: Target rotational speed difference Step S5: Rotational control means

Claims (4)

A rotating machine that functions as at least a generator and can generate braking torque by regenerative torque;
A friction clutch capable of continuously disconnecting the engagement torque from the power transmission path and continuously changing the engagement torque;
A brake control device for electrically controlling the braking torque of a mechanical brake provided on the wheel;
Braking torque sharing control means for sharing the required braking torque by both the braking torque by the rotating machine and the braking torque by the mechanical brake;
In a braking control device for a vehicle having
Immediately before the stop of the vehicle, the braking torque by the rotating machine is gradually reduced and transferred to the braking torque by the mechanical brake in preference to the control by the braking torque sharing control means, and at the same time, the engagement torque of the friction clutch Is provided with transfer control means for gradually decreasing
The transfer control means gradually reduces the engagement torque of the friction clutch in response to an increase in braking torque by the mechanical brake, and holds the regenerative torque of the rotating machine at or above the engagement torque of the friction clutch. The braking control device for a vehicle is characterized in that the braking torque of the vehicle is gradually reduced and the braking torque by the rotating machine is transferred to the braking torque by the mechanical brake while being controlled by the engagement torque of the friction clutch. The transfer control means feedback-controls the regenerative torque of the rotating machine so that the rotational speed difference before and after the friction clutch becomes a predetermined target rotational speed difference that is lower than the rotational speed on the rotating machine side. The vehicle braking control device according to claim 1, further comprising: a rotation control unit that gradually decreases the regenerative torque of the rotating machine while maintaining the regenerative torque of the rotating machine equal to or higher than the engagement torque of the friction clutch. The rotation control means controls the regenerative torque of the rotating machine by adding a correction value by the feedback control to a feedforward value determined based on an engagement torque command value of the friction clutch. Item 3. The vehicle braking control device according to Item 2. A rotating machine that functions as at least a generator and can generate braking torque by regenerative torque;
A friction clutch capable of continuously disconnecting the engagement torque from the power transmission path and continuously changing the engagement torque;
A brake control device for electrically controlling the braking torque of a mechanical brake provided on the wheel;
Braking torque sharing control means for sharing the required braking torque by both the braking torque by the rotating machine and the braking torque by the mechanical brake;
In a braking control device for a vehicle having
Immediately before the stop of the vehicle, the braking torque by the rotating machine is gradually reduced and transferred to the braking torque by the mechanical brake in preference to the control by the braking torque sharing control means, and at the same time, the engagement torque of the friction clutch Is provided with transfer control means for gradually decreasing
The transfer control means gradually reduces the regenerative torque of the rotating machine in response to an increase in braking torque by the mechanical brake, and holds the engagement torque of the friction clutch at or above the regenerative torque of the rotating machine. The braking control device for a vehicle is characterized in that it gradually decreases.

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