Vehicle control device

Abstract

To provide a vehicle control device capable of appropriately suppressing vehicle vibration even when turning acceleration or lateral acceleration occurs.SOLUTION: An electronic control device 80 comprises: a vibration generation condition determination section 88 which determines whether all vibration generation conditions are satisfied; a resonance determination section 90 which determines whether an engine 12 and an automatic transmission 22 are in resonance when the vibration generation condition determination section 88 makes an affirmative determination; and a resonance suppression control section 94 which places an LU clutch 36 into a slip state to suppress resonance when the resonance determination section 90 makes an affirmative determination. The resonance suppression control section 94 corrects a required slip period Tst and a target differential rotation speed Nst in accordance with yaw acceleration Ryaw or lateral acceleration Gy of a vehicle 10. Accordingly, the slip state is decreased in response to turning acceleration and lateral acceleration of the vehicle 10, where vibration discomfort is reduced, thereby appropriately suppressing vehicle vibration and improving fuel efficiency.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a vehicle control device for suppressing vehicle vibration.

Background Art

[0002] Vehicles equipped with an engine, a transmission capable of selectively establishing a plurality of gear stages with different gear ratios, and a torque converter with a lock-up clutch for transmitting the torque of the engine to the transmission are well known. Patent Document 1 discloses a technique for suppressing vehicle vibration by controlling a lock-up clutch in a slip state for a short time when vehicle vibration caused by engine torque fluctuation is detected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the conventional slip control of the lock-up clutch for suppressing vehicle vibration, the control amounts such as the period of the slip state and the slip amount are determined by the engine rotational speed (vehicle speed) and torque. The control amount basically does not change even when vehicle turning G or left-right G is occurring. Due to the occurrence of turning G or left-right G, even when the discomfort with respect to vibration is small, the control amount in the slip state does not decrease, resulting in an excessive control amount and leading to the problem of deteriorated fuel efficiency.

[0005] The present invention has been made against the background of the above circumstances, and an object thereof is to provide a vehicle control device capable of appropriately suppressing vehicle vibration even when vehicle turning G or left-right G occurs.

Means for Solving the Problems

[0006] The gist of the present invention is a control device for a vehicle including (a) an engine, a transmission capable of selectively establishing a plurality of gear stages with different gear ratios, and a torque converter including a lock-up clutch that transmits the torque of the engine to the transmission, the control device including: (b) a vibration generation condition determination unit that determines whether all of the vibration generation conditions, which include the lock-up clutch being in an engaged state, a predetermined gear stage being established in the transmission, and an operating point determined according to the rotational speed and load of the engine belonging to a predetermined region, are satisfied; a resonance determination unit that determines whether the engine and the transmission resonate when an affirmative determination is made by the vibration generation condition determination unit; and a resonance suppression control unit that puts the lock-up clutch in a slip state to suppress resonance when an affirmative determination is made by the resonance determination unit, and (c) the resonance suppression control unit corrects the duration and the slip amount of the slip state according to the yaw acceleration or lateral acceleration of the vehicle.

Effect of the Invention

[0007] According to the present invention, the control device includes a vibration generation condition determination unit that determines whether all of the vibration generation conditions, which include the lock-up clutch being in an engaged state, a predetermined gear stage being established in the transmission, and an operating point determined according to the rotational speed and load of the engine belonging to a predetermined region, are satisfied; a resonance determination unit that determines whether the engine and the transmission resonate when an affirmative determination is made by the vibration generation condition determination unit; and a resonance suppression control unit that puts the lock-up clutch in a slip state to suppress resonance when an affirmative determination is made by the resonance determination unit, and the resonance suppression control unit corrects the duration and the slip amount of the slip state according to the yaw acceleration or lateral acceleration of the vehicle. Thereby, the duration and the slip amount are reduced according to the turning G or lateral G of the vehicle 10 in which the sense of incongruity with vibration is reduced, and by appropriately suppressing vehicle vibration, the fuel efficiency is improved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Examples

[0010] FIG. 1 is a diagram for explaining the schematic configuration of a vehicle 10 to which the present invention is applied, and is also a diagram for explaining the main part of the control functions for various controls in the vehicle 10. In FIG. 1, the vehicle 10 includes an engine 12 as a power source, drive wheels 14, and a power transmission device 16 provided in the power transmission path between the engine 12 and the drive wheels 14. The power transmission device 16 includes a torque converter 20, an automatic transmission 22, etc. inside a case 18 as a non-rotating member attached to the vehicle body. Further, the power transmission device 16 includes a propeller shaft 26 connected to the transmission output shaft 24 which is the output rotating member of the automatic transmission 22, a differential 28 connected to the propeller shaft 26, and left and right drive shafts 30 connected to the differential 28, etc.

[0011] The engine 12 is controlled such that the engine torque Te which is the output torque of the engine 12 is controlled by the engine control device 40 provided in the vehicle 10 being controlled by an electronic control device 80 described later.

[0012] The torque converter 20 is disposed in the power transmission path between the engine 12 and the automatic transmission 22, and is connected to the engine 12 via the crankshaft 32. The torque converter 20 includes a pump impeller 20p, a turbine impeller 20t, etc., and further includes a lock-up clutch (hereinafter referred to as the LU clutch) 36 that connects the pump impeller 20p and the turbine impeller 20t.

[0013] The automatic transmission 22 is connected to the torque converter 20 via the input shaft 34. The automatic transmission 22 is a known planetary gear type stepped transmission that can selectively establish a plurality of gear stages with different gear ratios, and includes, for example, a plurality of sets of planetary gear devices and a plurality of hydraulic engagement devices CB such as clutches and brakes.

[0014] The vehicle 10 includes an electronic control unit 80 as a controller of the vehicle 10.

[0015] Various signals etc. (for example, engine rotational speed Ne (rpm), turbine rotational speed Nt (= AT input rotational speed Ni), AT output rotational speed No (rpm) corresponding to vehicle speed V, accelerator opening pap (%), longitudinal acceleration Gx and lateral acceleration Gy of the vehicle 10, yaw acceleration Ryaw which is the rotational angular velocity around the vertical axis of the vehicle 10, etc.) based on the detection values by the engine rotational speed sensor 60, turbine rotational speed sensor 62, output rotational speed sensor 64, accelerator opening sensor 66, G sensor 70, yaw acceleration sensor 72, etc. provided in the vehicle 10 are respectively supplied to the electronic control unit 80. The accelerator opening pap corresponds to the required driving torque of the driver for the vehicle 10. The longitudinal acceleration Gx, lateral acceleration Gy, and yaw acceleration Ryaw respectively indicate the longitudinal G, lateral G, and turning G generated in the vehicle 10.

[0016] From the electronic control unit 80, various command signals (for example, engine control command signal Se for controlling the engine 12, hydraulic control command signal Sat for controlling the operating state of the engagement device CB, hydraulic control command signal Slu for controlling the operating state of the LU clutch 36, etc.) are output to the engine control unit 40, the hydraulic control circuit 50, etc. provided in the vehicle 10, respectively.

[0017] The electronic control unit 80 functionally includes an engine control unit 82, a shift control unit 84, an LU clutch control unit 86, a vibration generation condition determination unit 88, and a resonance determination unit 90. Further, the LU clutch control unit 86 functionally includes a resonance suppression control unit 94.

[0018] The engine control unit 82 controls the engine 12 so as to obtain the required engine torque Te. The engine control unit 82 calculates the required drive torque Tdem by applying the accelerator opening pap and the vehicle speed V to a predetermined drive force map. The engine control unit 82 outputs an engine control command signal Se for obtaining the engine torque Te for realizing the required drive torque Tdem to the engine control unit 40.

[0019] The shift control unit 84 executes the shift control of the automatic transmission 22. For example, the shift control unit 84 determines the gear position POSsh of the automatic transmission 22 using, for example, a shift map which is a predetermined relationship. The shift control unit 84 outputs a hydraulic control command signal Sat for switching the operating state of the engagement device CB so as to form the determined gear position POSsh to the hydraulic control circuit 50.

[0020] The LU clutch control unit 86 applies the vehicle driving state represented by the required driving torque Trdem calculated from the actual vehicle speed V and the accelerator opening pap to a pre-determined lock-up operation area map, determines which operation area it is, and outputs a hydraulic control command signal Slu to the hydraulic control circuit 50 so that the operation state of the LU clutch 36 corresponding to the determined operation area is realized. The operation state of the LU clutch 36 is an open state in which the LU clutch 36 is released, a slip state in which the LU clutch 36 is slipped to a set slip amount, and an engaged state in which the LU clutch 36 is engaged.

[0021] Figure 2 is a flowchart for explaining the main part of the control operation for suppressing vibrations of the vehicle 10 performed by the vibration generation condition determination unit 88, the resonance determination unit 90, and the resonance suppression control unit 94, which are functionally provided in the electronic control unit 80. Figure 3 is an example of a time chart corresponding to the control operation of Figure 2. Hereinafter, the control operation will be described with reference to Figure 3 along the processing steps of Figure 2.

[0022] In step S10 of Figure 3 (hereinafter, steps are omitted), the vibration generation condition determination unit 88 determines whether or not all of the "vibration generation conditions" under which the vehicle 10 vibrates due to resonance detected by the resonance determination unit described later are satisfied. The "vibration generation conditions" are: (A) the LU clutch 36 is in the engaged state; (B) the gear position POSsh of the automatic transmission 22 is within a pre-determined gear position range POSshA; (C) the operating point determined by the engine rotational speed Ne and the engine load belongs to a pre-determined area Ae; (D) the accelerator opening pap is equal to or greater than a pre-determined predetermined opening papA; and (E) the vehicle speed V is equal to or less than a pre-determined predetermined speed Va. Note that depending on the vehicle conditions, the conditions (D) and (E) are not essential and are preferably selected according to the target vehicle.

[0023] If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, that is, if the "vibration generation condition" is determined to be satisfied by the vibration generation condition determination unit 88, then in S20 corresponding to the resonance determination unit 90, it is determined whether the engine 12 and the automatic transmission 22 resonate. When the LU clutch 36 is in the engaged state, the crankshaft 32 of the engine 12 and the input shaft 34 of the automatic transmission 22 are fastened. In this state, if the frequency of the torque fluctuation of the engine 12 coincides with the torsional first natural frequency of the automatic transmission 22, the engine 12 and the automatic transmission 22 resonate. The resonance determination unit 90 calculates the rotational speed difference Ndt, which is the difference between the engine rotational speed Ne, the multiplication value of the AT output rotational speed No and the reduction ratio of the gear stage POSsh, and determines whether resonance has occurred based on whether the absolute value of the rotational speed difference Ndt is equal to or greater than a predetermined threshold value Nlt. When resonance occurs, the resonance occurrence flag VF is set to ON (VF = 1).

[0024] If the determination in S20 is negative, this routine is terminated. If the determination in S20 is positive, that is, if resonance is determined to have occurred by the resonance determination unit 90 and the resonance occurrence flag is ON (VF = 1), then in S30 corresponding to the resonance suppression control unit 94, the LU clutch 36 is put into a slip state, and resonance suppression control for suppressing resonance is started, and the suppression control flag SF is set to ON (SF = 1).

[0025] In FIG. 3, the period from time t0 to time t1 shows the control operation up to the above S30. Vehicle vibration occurs at time t0, and since the absolute value of the rotational speed difference Ndt becomes equal to or greater than the threshold value Nlt at time t1, resonance is determined to have occurred by the resonance determination unit 90 (resonance occurrence flag VF = 1), and in response to this, the resonance suppression control by the resonance suppression control unit 94 is started (suppression control flag SF = 1).

[0026] Also, the operation from time t1 to time t3 in FIG. 3 corresponds to the control operation of resonance suppression control executed by the resonance suppression control unit 94. During the period from time t2 to time t3 after a predetermined delay period Tdl determined in advance design-wise or experimentally from time t1 in FIG. 3, the LU clutch 36 is put into a slip state, thereby suppressing vehicle vibration. The duration of the slip state of this LU clutch 36 is set as the required slip period Tst. Also, the actual differential rotational speed Ns (= engine rotational speed Ne - turbine rotational speed Nt), which is the difference in rotational speeds between the input and output of the LU clutch 36 in the slip state, i.e., the slip amount between the input and output, is controlled by outputting a hydraulic control command signal Slu from the resonance suppression control unit 94 to the hydraulic control circuit 50 so as to become the set target differential rotational speed Nst. In FIG. 3, the engine rotational speed Ne is shown by a solid line, and the turbine rotational speed Nt is shown by a dashed line with one dot.

[0027] The aforementioned required slip period Tst is calculated by the following formula (1) including a correction coefficient αt smaller than 1, for example, and the target differential rotational speed Nst is calculated by the following formula (2) including a correction coefficient αn smaller than 1, for example. Required slip period Tst = Optimal required slip period Tsta × αt ···(1) Target differential rotational speed Nst = Optimal target differential rotational speed Nsta × αn ···(2) Here, the optimal required slip period Tsta and the optimal target differential rotational speed Nsta are the optimal values of the duration and differential rotational speed of the slip state required for suppressing vehicle vibration, and are obtained in advance design-wise or experimentally from, for example, the estimated acceleration calculated from the transition of the engine torque Te and the vehicle speed V, respectively. Also, the correction coefficient αt and the correction coefficient αn are coefficients provided for appropriately correcting the slip period and differential rotational speed according to other conditions.

[0028] Returning to FIG. 2, following S30, in S40 corresponding to the resonance suppression control unit 94, the correction coefficient αt and the correction coefficient αn corresponding to the turning G or the lateral G generated in the vehicle 10 are calculated. As shown in the blowing on the right side of the drawing of FIG. 2, in the case of the correction corresponding to the turning G, for example, the yaw acceleration Ryaw from the yaw acceleration sensor 72 is applied to the yaw acceleration slip period correction coefficient map MAP1 and the yaw acceleration target difference rotational speed correction coefficient map MAP2, and thereby, the correction coefficient αt and the correction coefficient αn, which become smaller as the yaw acceleration Ryaw increases, are calculated respectively. Further, in the case of the correction corresponding to the lateral G, for example, the lateral acceleration Gy from the G sensor 70 is applied to the lateral acceleration slip period correction coefficient map MAP3 and the lateral acceleration target difference rotational speed correction coefficient map MAP4, and thereby, the correction coefficient αt and the correction coefficient αn, which become smaller as the lateral acceleration Gy increases, are calculated respectively.

[0029] Next, in S50 corresponding to the resonance suppression control unit 94, the optimum required slip period Tsta and the optimum target difference rotational speed Nsta are obtained, and these and the correction coefficient αt and the correction coefficient αn calculated in S40 are applied to equations (1) and (2) to calculate the required slip period Tst and the target difference rotational speed Nst.

[0030] Then, resonance suppression control is implemented from S60 to S80 corresponding to the resonance suppression control unit 94 (corresponding to the time points from t1 to t3 in FIG. 3). At the time point t2 after a predetermined delay period Tdl from the time point t1 in FIG. 3, the LU clutch 36 is shifted to the slip state. Next, in the determination of S70, it is determined whether or not the required slip period Tst has ended. If the determination in S70 is negative, the process returns to S60 and the resonance suppression control is continued. If the determination in S70 is positive, the resonance suppression control ends, that is, the LU clutch 36 is shifted from the slip state to the engaged state, the suppression control flag SF is turned OFF (SF = 0), and this routine ends (see t3 in FIG. 3).

[0031] As described above, according to this embodiment, the electronic control device 80 includes a vibration generation condition determination unit 88 that determines whether all of the vibration generation conditions, which consist of the LU clutch 36 being in an engaged state, the gear position POSsh of the automatic transmission 22 being within a predetermined gear position range POSshA, and the operating point determined by the engine rotational speed Ne and the engine torque Te belonging to a predetermined region Ae, are all satisfied; a resonance determination unit 90 that determines whether the engine 12 and the automatic transmission 22 resonate when an affirmative determination is made by the vibration generation condition determination unit 88; and a resonance suppression control unit 94 that, when an affirmative determination is made by the resonance determination unit 90, sets the LU clutch 36 in a slip state to suppress resonance. The resonance suppression control unit 94 corrects the required slip period Tst and the target differential rotational speed Nst according to the yaw acceleration Ryaw or the lateral acceleration Gy of the vehicle 10. As a result, the required slip period Tst and the target differential rotational speed Nst are reduced according to the turning G or the left-right G of the vehicle 10 where the discomfort of the vibration itself is reduced, and the vehicle vibration is appropriately suppressed, thereby improving the fuel efficiency.

[0032] Note that the above description is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0033] 10: Vehicle 12: Engine 20: Torque converter 22: Automatic transmission (transmission) 36: LU clutch (lock-up clutch) 80: Electronic control device (control device) 88: Vibration generation condition determination unit 90: Resonance determination unit 94: Resonance suppression control unit Gy: Lateral acceleration Ne: Engine rotational speed Nst: Target differential rotational speed POSsh: Gear position Te: Engine torque Tst: Required slip period (duration) Ryaw: Yaw acceleration

Claims

【Claim 1】 A control device for a vehicle, comprising: an engine; a transmission capable of selectively establishing a plurality of gear stages with different gear ratios; and a torque converter including a lock-up clutch that transmits the torque of the engine to the transmission, a vibration generation condition determination unit that determines whether all of the vibration generation conditions, which include that the lock-up clutch is in an engaged state, that a predetermined gear stage is established in the transmission, and that an operating point determined according to the rotational speed and load of the engine belongs to a predetermined region, are satisfied; a resonance determination unit that determines whether the engine and the transmission resonate when an affirmative determination is made by the vibration generation condition determination unit; and a resonance suppression control unit that, when an affirmative determination is made by the resonance determination unit, puts the lock-up clutch in a slip state to suppress resonance, wherein the resonance suppression control unit corrects the duration and the slip amount of the slip state according to the yaw acceleration or lateral acceleration of the vehicle. A control device for a vehicle, characterized by the above.

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