Vehicle control device

Abstract

To provide a vehicular control device capable of suppressing deterioration in NV performance when continuing slip control.SOLUTION: A predetermined region where it is difficult to suppress an occurrence of NV is determined beforehand up to a low torque region of input torque to a lock-up clutch, and a high rotation region of an output rotation speed of an automatic transmission as an actual value of an input / output rotation speed difference of the lock-up clutch is smaller. When a duration time that a vehicle state is in the predetermined region continuously is within a predetermined time in the slip control, the slip control is maintained. Meanwhile, when the duration time exceeds the predetermined time, the slip control is finished. The predetermined time is determined beforehand to a shorter value as the input torque is higher, is determined beforehand to a shorter value as the output rotation speed is lower, and is determined beforehand to a shorter value as the actual value of the input / output rotation speed difference is smaller. Thereby, even when the actual value of the input / output rotation speed difference of the lock-up clutch is smaller than assumed, an occurrence of NV can be suppressed.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle that has a lock-up clutch in a power transmission path between an engine and an automatic transmission. [Background technology]

[0002] There is a well-known control device for a vehicle that includes an engine, an automatic transmission provided in a power transmission path between the engine and drive wheels, a hydrodynamic power transmission provided in the power transmission path between the engine and the automatic transmission, and a direct-coupled clutch that connects an input member and an output member of the hydrodynamic power transmission. For example, Patent Document 1 discloses a control device for a direct-coupled clutch for a vehicle. Patent Document 1 discloses that, during execution of slip control for the direct-coupled clutch, if the vehicle state enters the off-region of the slip control and then returns to the on-region of the slip control within a predetermined time, the slip control is continued without being stopped, and the predetermined time is determined using a throttle valve opening and a vehicle speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-175036 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the on-region of slip control is a region where, for example, NV is likely to occur when the direct-coupled clutch is engaged, and the direct-coupled clutch is put into a slip state to improve energy efficiency and drivability. The on-region of slip control is set taking into consideration the NV performance, i.e., NV performance, which suppresses NV. "NV" is a general term for noise and vibration generated in a vehicle and represents at least one of noise and vibration in a vehicle. By appropriately controlling the input / output rotational speed difference of the direct-coupled clutch through slip control, it is possible to achieve, for example, both improved energy efficiency and improved NV performance. However, during execution of slip control of the direct-coupled clutch, the actual value of the input / output rotational speed difference of the direct-coupled clutch may be smaller than an expected value (e.g., a target value). In this case, if slip control is continued, NV may be more likely to occur, even if the duration in the off-region is within a predetermined time, which may deteriorate NV performance.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle control device that can suppress deterioration of NV performance when slip control is continued. [Means for solving the problem]

[0006] The gist of a first invention is a control device for a vehicle including: (a) an engine; an automatic transmission provided in a power transmission path between the engine and drive wheels; a hydrodynamic power transmission provided in the power transmission path between the engine and the automatic transmission; and a direct-coupled clutch connecting an input member and an output member of the hydrodynamic power transmission, wherein (b) during execution of slip control for controlling the direct-coupled clutch to a slip state, a vehicle state indicated by an input torque to the direct-coupled clutch and an output rotation speed of the automatic transmission continues to be in a predetermined region in which it is difficult to suppress the generation of noise or vibration for a duration of less than a predetermined time. In this case, the slip control is maintained, while if the duration exceeds the predetermined time, the slip control is terminated and the direct-coupled clutch is controlled to a released state; (c) the smaller the actual value of the input / output rotational speed difference of the direct-coupled clutch, the more the predetermined region is predetermined to a low torque region of the input torque and a high rotational speed region of the output rotational speed; and (d) the predetermined time is predetermined to a shorter value as the input torque is higher, the output rotational speed is lower, and the smaller the actual value of the input / output rotational speed difference. [Effects of the Invention]

[0007] According to the first aspect of the present invention, the predetermined region in which noise or vibration generation is difficult to suppress is predetermined to extend up to a low torque region of the input torque to the direct-coupled clutch and a high rotational speed region of the output rotational speed of the automatic transmission, as the actual value of the input / output rotational speed difference of the direct-coupled clutch decreases. During slip control, if the vehicle state indicated by the input torque and output rotational speed continuously remains within the predetermined region for a predetermined time or less, slip control is maintained. On the other hand, if this duration exceeds the predetermined time, slip control is terminated and the direct-coupled clutch is controlled to a disengaged state. This predetermined time is predetermined to be shorter as the input torque increases, as the output rotational speed decreases, and as the actual value of the input / output rotational speed difference decreases. In other words, the predetermined time is calculated taking into account the actual value of the input / output rotational speed difference of the direct-coupled clutch. This allows NV to be suppressed even if the actual value of the input / output rotational speed difference of the direct-coupled clutch is smaller than expected. Therefore, deterioration of NV performance can be suppressed when slip control is continued. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and control systems for various controls in the vehicle. [Figure 2] FIG. 10 is a diagram showing an example of an LU slip limited region determination map. [Figure 3] FIG. 10 is a diagram illustrating an example of a predetermined time map. [Figure 4] 1 is a flowchart illustrating a main part of the control operation of the electronic control device, and is a flowchart illustrating the control operation for suppressing deterioration of NV performance when LU slip control is continued. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied, and also illustrates the main parts of the control functions and control systems for various controls in the vehicle 10. In FIG. 1, the vehicle 10 includes an engine 12, drive wheels 14, and a power transmission device 16 provided in a power transmission path between the engine 12 and the drive wheels 14.

[0011] The engine 12 is a known internal combustion engine, and the engine torque Te of the engine 12 is controlled by an electronic control device 80 described later, which controls an engine control device 50 including a fuel injection device and the like provided on the vehicle 10.

[0012] The power transmission device 16 includes, within a case 18, which is a non-rotating member, a torque converter 20 connected to the engine 12, an automatic transmission 22 connected to the torque converter 20, and the like. The power transmission device 16 also includes, within a case 18, a propeller shaft 26 connected to a transmission output shaft 24, a differential gear 28 connected to the propeller shaft 26, a pair of drive shafts 30 connected to the differential gear 28, and the like. The transmission output shaft 24 is an output rotating member of the automatic transmission 22. The power transmission device 16 also includes, within a case 18, an engine connecting shaft 32 that connects the engine 12 and the torque converter 20, and the like.

[0013] The torque converter 20 includes a pump wheel 20a connected to an engine connecting shaft 32 and a turbine wheel 20b connected to a transmission input shaft 34. The transmission input shaft 34 is an input rotating member of the automatic transmission 22. The pump wheel 20a is an input member of the torque converter 20, and the turbine wheel 20b is an output member of the torque converter 20. The torque converter 20 is a fluid-type power transmission device provided in a power transmission path between the engine 12 and the automatic transmission 22. The torque converter 20 includes an LU clutch 36 as a direct-coupled clutch that connects the pump wheel 20a and the turbine wheel 20b. The LU clutch 36 is a known lock-up clutch, such as a hydraulic friction engagement device. The control state of the LU clutch 36 is switched by changing the LU torque Tlu, which is a torque capacity, using an LU oil pressure PRlu supplied from a hydraulic control circuit 52 provided in the vehicle 10. The control states of the LU clutch 36 include a released state (which also means a fully released state), a slip state in which the LU clutch 36 is engaged with slippage, and an engaged state (which also means a fully engaged state).

[0014] The automatic transmission 22 is, for example, a known planetary gear automatic transmission. The automatic transmission 22 is configured to have one of a plurality of gear stages with different gear ratios γ (=AT input rotation speed Nin / AT output rotation speed Nout). The AT input rotation speed Nin is the rotation speed of the transmission input shaft 34, which is the input rotation speed of the automatic transmission 22, and is equivalent to the turbine rotation speed Nt, which is the output rotation speed of the torque converter 20. The AT output rotation speed Nout is the rotation speed of the transmission output shaft 24, which is the output rotation speed of the automatic transmission 22.

[0015] The vehicle 10 is equipped with a mechanical oil pump 54. The oil pump 54 is connected to the pump impeller 20a and is rotationally driven by the engine 12 to discharge hydraulic oil OIL, which is supplied to the hydraulic control circuit 52. The hydraulic control circuit 52 supplies an LU hydraulic pressure PRlu and the like that is adjusted based on the hydraulic oil OIL discharged by the oil pump 54.

[0016] The vehicle 10 further includes an electronic control device 80 as a controller including a control device for the vehicle 10. The electronic control device 80 includes, for example, a so-called microcomputer equipped with a CPU, RAM, ROM, an input / output interface, etc. The CPU executes various controls of the vehicle 10 by performing signal processing according to a program stored in advance in the ROM while utilizing, for example, the temporary storage function of the RAM.

[0017] The electronic control device 80 is supplied with various signals (e.g., engine rotation speed Ne, which is the rotation speed of the engine 12; AT input rotation speed Nin (= turbine rotation speed Nt); AT output rotation speed Nout, which corresponds to the vehicle speed V; accelerator opening θacc, which is the driver's accelerator operation amount, which indicates the magnitude of the driver's acceleration operation; and throttle valve opening θth, which is the opening of the electronic throttle valve) based on detection values ​​from various sensors provided on the vehicle 10 (e.g., engine rotation speed sensor 60, input rotation speed sensor 62, output rotation speed sensor 64, accelerator opening sensor 66, throttle valve opening sensor 68, etc.).

[0018] The electronic control unit 80 outputs various command signals (e.g., engine control command signal Se, LU hydraulic control command signal Slu for controlling the LU clutch 36, etc.) to each device (e.g., engine control unit 50, hydraulic control circuit 52, etc.) provided in the vehicle 10.

[0019] The electronic control device 80 includes an LU clutch control unit 82. The LU clutch control unit 82 determines the control region using, for example, a lockup region diagram, which is a predetermined relationship, and controls the LU clutch 36 so as to achieve a control state (released state, slip state, engaged state) corresponding to the determined control region. The lockup region diagram is a predetermined relationship, for example, on a two-dimensional coordinate system using the AT output rotation speed Nout and the LU input torque Tinlu as variables, with a release region corresponding to the released state, a slip region corresponding to the slip state, and a lockup region corresponding to the engaged state. The LU input torque Tinlu is the input torque to the LU clutch 36 and is equivalent to, for example, the engine torque Te. The engine torque Te is, for example, an estimated engine torque Tee, which is an estimated value of the engine torque Te. The LU clutch control unit 82 calculates the estimated engine torque Tee by, for example, applying the throttle valve opening θth and the engine rotation speed Ne to a predetermined engine torque map.

[0020] When the LU clutch control unit 82 determines that the control region is the lock-up region, it sets the LU oil pressure PRlu to obtain the LU torque Tlu capable of transmitting the LU input torque Tinlu, and controls the LU clutch 36 to an engaged state. The LU torque Tlu capable of transmitting the LU input torque Tinlu is, for example, a torque value obtained by multiplying the LU input torque Tinlu by a safety factor (>1). On the other hand, when the LU clutch control unit 82 determines that the control region is the release region, it sets the LU oil pressure PRlu to zero, and puts the LU clutch 36 into a released state.

[0021] On the other hand, if the LU torque Tlu is small relative to the LU input torque Tinlu, slippage occurs in the LU clutch 36. When the LU clutch control unit 82 determines that the control region is the slip region, it controls the LU clutch 36 to a slip state, i.e., executes LU slip control CNlusp. The LU slip control CNlusp is slip control of the LU clutch 36, which controls the LU clutch 36 to a slip state by setting the LU hydraulic pressure PRlu to achieve a target LU slip amount Nslplut, which is a target value of the LU slip amount Nslplu, relative to the LU input torque Tinlu. The LU slip amount Nslplu is the slip amount of the LU clutch 36 and is the input / output rotational speed difference of the LU clutch 36, i.e., the rotational speed difference (= Ne - Nt) between the LU input rotational speed (= engine rotational speed Ne) and the LU output rotational speed (= turbine rotational speed Nt). The target LU slip amount Nslplut is a predetermined input / output rotational speed difference that is set in advance. In the lock-up region diagram, the slip region is the ON region of the LU slip control CNlusp, and is set to a low vehicle speed region compared to the lock-up region, for example.

[0022] Here, if the vehicle state indicated by the LU input torque Tinlu and the AT output rotation speed Nout transitions from the slip region to a region exceeding the NV limit while the LU slip control CNlusp is being executed, the LU slip control CNlusp is terminated. A temporary change in the vehicle state due to accelerator operation, etc., may cause the vehicle state to return to the slip region in a short period of time. In such a case where the vehicle temporarily leaves the slip region, it is preferable that the LU slip control CNlusp be continued without being stopped. The region exceeding the NV limit is, for example, a predetermined region where it is difficult to suppress the occurrence of NV (noise or vibration) even if the LU slip control CNlusp is executed.

[0023] If the vehicle state enters a predetermined region while the LU slip control CNlusp is being executed, the LU clutch control unit 82 sets the duration of the LU slip control CNlusp to a finite value, and terminates the LU slip control CNlusp after the predetermined time TMfldly has elapsed. If the vehicle state returns to the slip region before the predetermined time TMfldly has elapsed after entering the predetermined region while the LU slip control CNlusp is being executed, the LU clutch control unit 82 continues the LU slip control CNlusp. The predetermined time TMfldly is, for example, a predetermined threshold value at which the occurrence of NV is unlikely to become a problem even if the vehicle state enters the predetermined region. The predetermined region is, for example, a release region, which is an LU slip finite region in which the duration of the LU slip control CNlusp is set to a finite value. Regions other than the LU slip finite region are, for example, an LU slip permitted region in which execution of the LU slip control CNlusp is permitted. In this embodiment, the duration during which the vehicle state continuously remains in the LU slip finite region is referred to as the LU slip finite region duration TMfllim.

[0024] If the LU slip finite region duration TMfllim is within the predetermined time TMfldly while the LU slip control CNlusp is being executed, the LU clutch control unit 82 maintains the LU slip control CNlusp. On the other hand, if the LU slip finite region duration TMfllim exceeds the predetermined time TMfldly while the LU slip control CNlusp is being executed, the LU clutch control unit 82 ends the LU slip control CNlusp and controls the LU clutch 36 to a released state.

[0025] During the execution of the LU slip control CNlusp, the actual value of the LU slip amount Nslplu, i.e., the actual LU slip amount Nslplur, may be smaller than the expected value. If this occurs, NV may be more likely to occur even if the LU slip finite region duration TMfllim is within the predetermined time TMfldly.

[0026] Therefore, in this embodiment, the LU slip finite region and the predetermined time TMfldly are determined in advance in consideration of the actual LU slip amount Nslplur.

[0027] FIG. 2 shows an example of an LU slip finite region determination map used to determine the LU slip finite region. In FIG. 2, the LU slip finite region determination map is a predetermined relationship on a two-dimensional coordinate system with the AT output rotation speed Nout and the LU input torque Tinlu as variables, with a boundary between the LU slip finite region and the LU slip allowance region. In this embodiment, this boundary is referred to as the finite region determination line. The finite region determination line LNp shown in dashed line is a comparative example of this embodiment, and a single finite region determination line is used to determine the LU slip finite region. In contrast, in this embodiment, finite region determination lines are set for each actual LU slip amount Nslplur, such as the finite region determination lines LNa, LNb, and LNc shown in solid line, and the LU slip finite region is determined according to the actual LU slip amount Nslplur. Referring to FIG. 2, in this embodiment, the LU slip finite region is predetermined to extend to a low torque region of the LU input torque Tinlu as the actual LU slip amount Nslplur decreases. Furthermore, in this embodiment, the LU slip finite region is predetermined to extend up to a high rotation region of the AT output rotation speed Nout as the actual LU slip amount Nslplur becomes smaller.

[0028] FIG. 3 is a diagram showing an example of a predetermined time map used to calculate or select the predetermined time TMfldly. In FIG. 3, the predetermined time map shows a predetermined relationship between the predetermined time TMfldly and each of the parameters LU input torque Tinlu, AT output rotation speed Nout, and actual LU slip amount Nslplur. Referring to FIG. 3, the predetermined time TMfldly is predetermined to be shorter as the LU input torque Tinlu increases and longer as the LU input torque Tinlu decreases. The predetermined time TMfldly is predetermined to be shorter as the AT output rotation speed Nout decreases and longer as the AT output rotation speed Nout increases. The predetermined time TMfldly is predetermined to be shorter as the actual LU slip amount Nslplur decreases and longer as the actual LU slip amount Nslplur increases.

[0029] Figure 4 is a flowchart explaining the main parts of the control operation of the electronic control unit 80, and is a flowchart explaining the control operation for suppressing deterioration of NV performance when LU slip control CNlusp is continued, and is executed repeatedly, for example, while LU slip control CNlusp is being executed.

[0030] In FIG. 4, each step of the flowchart corresponds to a function of the LU clutch control unit 82. First, in step (hereinafter, "step" will be omitted) S10, it is determined whether the vehicle state is within the LU slip finite region corresponding to the actual LU slip amount Nslplur. If the determination in S10 is affirmative, the LU slip finite region duration TMfllim is calculated in S20. Next, in S30, a predetermined time TMfldly is selected based on the LU input torque Tinlu, the AT output rotation speed Nout, and the actual LU slip amount Nslplur. Next, in S40, it is determined whether the LU slip finite region duration TMfllim is within the predetermined time TMfldly. On the other hand, if the determination in S10 is negative, the LU slip finite region duration TMfllim is set to zero in S50. If the determination in S40 is affirmative, or following S50, the LU slip control CNlusp is continued in S60. If the determination in S40 is negative, the LU slip control CNlusp is turned off in S70, and the LU clutch 36 is controlled to be in a released state.

[0031] As described above, according to this embodiment, the LU slip finite region and the predetermined time TMfldly are set taking into consideration the actual LU slip amount Nslplur, so that the occurrence of NV can be suppressed even if the actual LU slip amount Nslplur is smaller than expected. Therefore, when the LU slip control CNlusp is continued, it is possible to suppress the deterioration of NV performance.

[0032] The above describes in detail an embodiment of the present invention based on the drawings, but what has been described above is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0033] 10: Vehicle 12: Engine 14: Drive wheels 20: Torque converter (fluid-type power transmission) 20a: Pump impeller (input member of fluid-type power transmission) 20b: Turbine impeller (output member of fluid-type power transmission) 22: Automatic transmission 36: LU clutch (direct coupling clutch) 80: Electronic control device (control device)

Claims

[Claim 1] A control device for a vehicle including an engine, an automatic transmission provided in a power transmission path between the engine and drive wheels, a fluid type power transmission provided in the power transmission path between the engine and the automatic transmission, and a direct coupling clutch that connects an input member and an output member of the fluid type power transmission, During execution of slip control for controlling the direct-coupled clutch to a slip state, if the vehicle state indicated by the input torque to the direct-coupled clutch and the output rotation speed of the automatic transmission continues to be in a predetermined region in which it is difficult to suppress the generation of noise or vibration for a duration of less than a predetermined time, the slip control is maintained, but if the duration exceeds the predetermined time, the slip control is terminated and the direct-coupled clutch is controlled to a released state, the predetermined region is predetermined to be a low torque region of the input torque and a high rotation region of the output rotation speed as the actual value of the input / output rotation speed difference of the direct coupling clutch becomes smaller, a predetermined time period that is predetermined to be shorter as the input torque increases, a predetermined time period that is predetermined to be shorter as the output rotational speed decreases, and a predetermined time period that is predetermined to be shorter as the actual value of the input / output rotational speed difference decreases.

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