JP6299666B2 - Power transmission device for vehicle - Google Patents

Description

  The present invention relates to a vehicle power transmission device, and more particularly to a technique for improving fuel consumption by engaging a lockup clutch while suppressing deterioration of NV (noise and vibration).

  (a) a fluid transmission device having a lock-up clutch, and (b) an automatic transmission capable of establishing a plurality of forward gears having different gear ratios, and (c) in a vehicle operating state. A vehicle power transmission device is known in which the lock-up clutch is engaged and released based on this and the automatic transmission is shifted. The device described in Patent Document 1 is one example, and the lock-up clutch is engaged even in an NV deterioration region (regions B, C, E, and F in FIGS. 8 and 9) in which a booming noise or the like may occur. (Including slip), and when traveling in the NV deterioration region continues for a certain time or more, the lockup clutch is released to improve the fuel efficiency while suppressing the deterioration of NV.

JP 2010-90958 A

  However, if the lock-up clutch is released uniformly when traveling in the NV deterioration region continues for a certain time or more in this way, the effect of improving the fuel consumption due to the engagement of the lock-up clutch is limited, so there is still room for improvement. It was.

  The present invention has been made against the background described above, and its object is to further improve fuel efficiency by engaging the lock-up clutch while suppressing the deterioration of NV.

  In order to achieve such an object, the present invention includes (a) a fluid transmission device provided with a lock-up clutch, and (b) an automatic transmission capable of establishing a plurality of forward gears having different gear ratios, (C) In the vehicle power transmission device in which the lockup clutch is engaged and released based on the driving state of the vehicle and the automatic transmission is shifted, (d) the lockup clutch is In the engaged state, when the driving state of the vehicle remains in a predetermined NV deterioration region, the lockup clutch is engaged when the gear ratio of the automatic transmission is small and the gear is at a predetermined high speed. The automatic transmission is downshifted while maintaining the state, and the lockup clutch is released when the automatic transmission is less than the high speed gear stage.

  In such a vehicle power transmission device, when the lockup clutch remains engaged and in the NV deterioration region, the lockup clutch remains held in the engaged state when the automatic transmission is at a high gear. Since the automatic transmission is downshifted, it is possible to suppress the deterioration of NV while maintaining the fuel efficiency improvement effect due to the engagement of the lockup clutch. That is, since the deterioration of NV generally occurs based on torque fluctuation, rotation fluctuation, etc. of the driving force source in the low rotation and high load region, if the rotational speed of the driving force source increases due to the downshift of the automatic transmission, the NV deterioration region Thus, the NV is prevented from deteriorating. There is a possibility that the fuel efficiency may deteriorate due to an increase in the rotational speed of the driving force source. However, since the NV deterioration region is a low speed, the rotational speed of the driving force source is relatively low even after the downshift, and the fuel efficiency deteriorates. The influence is small, and the fuel consumption can be improved by maintaining the engagement state of the lock-up clutch.

  On the other hand, when the lockup clutch is engaged and stays in the NV deterioration region, when the automatic transmission is at a low speed gear less than the high speed gear, the lockup clutch is released as in the conventional case and the NV deteriorates. Is suppressed. On the low-speed gear stage where the gear ratio is large, the interval between the shift lines is generally narrow, and if downshifting is forcibly performed, the shift associated with subsequent changes in the operating state may become a busy shift and the drivability may deteriorate. In the low-speed gear stage, the deterioration of NV is suppressed by releasing the lockup clutch without performing a downshift.

1 is a schematic configuration diagram of a vehicular power transmission device to which the present invention is applied, and also shows a main part of a control system. FIG. 2 is an operation table for explaining a plurality of gear stages of the automatic transmission of FIG. 1 and a friction engagement device for establishing the gear stages. 3 is a flowchart for specifically explaining the operation of the NV avoidance control unit of FIG. 1. It is an example of the map which defined the NV deterioration area used when determining whether it is NV deterioration area driving | running | working in FIG.3 S2. It is a figure explaining an example of the shift map changed by step S4 of FIG. It is a figure explaining an example of the lockup switching map changed by step S5 of FIG.

  The present invention is suitably applied to an engine-driven vehicle including an engine that generates power by combustion of fuel such as an internal combustion engine as a driving force source, but is applied to a hybrid vehicle including an electric motor as a driving force source. Can also be applied. A torque converter is preferably used as the fluid transmission device, but a fluid coupling or the like can also be employed. The engagement of the lock-up clutch may be a slip engagement that allows predetermined relative rotation, even when the lock-up clutch is integrally engaged so that relative rotation is impossible. As the automatic transmission, a stepped automatic transmission such as a planetary gear type or a two-shaft meshing type is preferably used, but even a continuously variable transmission such as a belt type has a gear ratio as in a stepped transmission. The present invention can be applied when switching between the steps.

  The lock-up clutch engagement-release switching condition, the automatic transmission shift condition, and the NV deterioration region are all determined based on the driving state of the vehicle, for example, driving force source torque (accelerator operation amount or throttle valve opening degree). Etc.) and vehicle speed (output rotation speed corresponding to the vehicle speed, etc.) are determined as parameters. In addition, the lock-up clutch engagement-release switching condition, the automatic transmission shift condition, and the NV deterioration region can be determined based on common operating conditions, but can also be determined based on different operating conditions. It is. The downshift of the automatic transmission and the release of the lockup clutch while remaining in the NV deterioration region may be performed by temporarily changing a shift condition such as a shift map of the automatic transmission or by turning the lockup clutch ON / OFF ( It is appropriate to temporarily change the switching conditions such as the (engagement-release) switching map, but it is also possible to forcibly downshift or release the lockup clutch.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a vehicular power transmission device 10 according to an embodiment of the present invention, which shows a main part of a control system, and includes an automatic transmission 12. The automatic transmission 12 is suitably used for an FF vehicle or the like mounted in the left-right direction (horizontal) of the vehicle, and includes a single pinion type first planetary gear unit 14 and a double pinion type second planetary gear unit. 16 and a single pinion type third planetary gear unit 18 on the coaxial line, and the rotation of the input shaft 22 is shifted and output from the output gear 24. The input shaft 22 corresponds to an input member and is a turbine shaft of the torque converter 30 that is rotationally driven by the engine 28. The output gear 24 corresponds to an output member of the automatic transmission 12, and outputs a driving force to the left and right drive wheels via a differential gear device (not shown). The automatic transmission 12 is substantially symmetrical with respect to the center line, and the lower half of the center line is omitted in FIG.

  The engine 28 is a driving force source, for example, an internal combustion engine such as a gasoline engine that generates power by combustion of fuel, and in this embodiment, is provided with a turbocharger system such as an exhaust turbine type or a mechanical drive type. The torque converter 30 includes a pump impeller 30p connected to the crankshaft of the engine 28, a turbine impeller 30t connected to the input shaft 22 of the automatic transmission 12, and a housing (transmission case) via a one-way clutch. And a stator impeller 30 s connected to 26, and is a fluid transmission device that transmits the power generated by the engine 28 to the automatic transmission 12 via a fluid. Further, a lockup clutch 32, which is a direct coupling clutch, is provided between the pump impeller 30p and the turbine impeller 30t, and can be switched between an engaged state and a released state by hydraulic control. The lock-up clutch 32 is a pendulum damper type in this embodiment, and is integrally engaged so as not to be relatively rotatable in the engaged state, and the pump impeller 30p and the turbine impeller 30t are integrally rotated. .

  The automatic transmission 12 has clutches C1 and C2 and brakes B1, B2 and B3 (hereinafter simply referred to as clutch C and brake B unless otherwise specified) as a plurality of friction engagement devices. It is a stepped transmission that establishes one of a plurality of gear stages by selective engagement of the device. The clutch C and the brake B are hydraulic friction engagement devices that are controlled by a hydraulic actuator such as a multi-plate clutch or brake. The clutch C and the brake B are electromagnetic switching valves of a hydraulic control circuit 34 provided in the vehicle power transmission device 10. The engaged / released state is switched by a hydraulic control valve or the like. FIG. 2 summarizes the relationship between the gears of the automatic transmission 12 and the operating states of the clutch C and the brake B. “◯” indicates engagement, “◎” indicates engagement only during engine braking, and blanks indicate Each represents a release. In this embodiment, six gear stages from the first speed gear stage “1st” to the sixth speed gear stage “6th” are established as the forward gear stages, and the first speed gear stage “1st” to the sixth speed gear stage “ The gear ratio (the rotational speed of the input shaft 22 / the rotational speed of the output gear 24) decreases stepwise as it goes to "6th". “F1” in FIGS. 1 and 2 is a one-way clutch that is engaged when the first gear stage “1st” is established, and is engaged only during driving, and is idling when driven. It becomes a state. Further, “R” in FIG. 2 is a reverse gear, and “N” is a neutral that interrupts power transmission.

  The vehicle power transmission device 10 includes an electronic control unit 40 as a controller for performing shift control of the automatic transmission 12 and engagement / release control of the lockup clutch 32. The electronic control unit 40 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM, and signals according to a program stored in the ROM in advance. The process includes a shift control unit 42 that performs shift control of the automatic transmission 12 and a lockup (L / U) control unit 44 that performs engagement-release control of the lockup clutch 32. The electronic control unit 40 includes an accelerator pedal operation amount (accelerator operation amount) Acc, a throttle valve opening θth of the engine 12, a rotational speed (engine rotational speed) NE of the engine 28, a turbine rotational speed NT of the torque converter 30, Various signals necessary for control, such as the rotational speed (output rotational speed) Nout of the output gear 24 of the automatic transmission 12, are supplied from each sensor. The turbine rotation speed NT is the same as the rotation speed of the input shaft 22, and the output rotation speed Nout corresponds to the vehicle speed V.

  The shift control unit 42 switches the six forward gear stages “1st” to “6th” according to a shift map set in advance with the vehicle operating conditions such as the output rotation speed Nout and the throttle valve opening θth as parameters. FIG. 5 shows a case where a shift map is determined with the output rotational speed Nout and the throttle valve opening θth as parameters, and the solid line is an upshift from the fourth speed gear stage “4th” to the fifth speed gear stage “5th”. → 5 is an example of an upshift line, and an alternate long and short dash line is an example of a downshift line that downshifts from the fifth speed gear stage “5th” to the fourth speed gear stage “4th”. Hysteresis is provided. This shift map is set based on the output characteristics, driving force performance, etc. of the engine 28, and the intervals between the shift lines of the plurality of forward gear stages (intervals of the upshift lines, intervals of the downshift lines) are smaller than the gear ratio. The higher the gear speed side, the wider.

  The lockup control unit 44 switches between the engagement and disengagement states of the lockup clutch 32 according to a lockup switching map set in advance with the vehicle operating state such as the output rotational speed Nout and the throttle valve opening θth as parameters. FIG. 6 shows a case where the lockup switching map is determined with the output rotational speed Nout and the throttle valve opening θth as parameters, and the solid line is an OFF → ON switching line for switching the lockup clutch 32 from the released state to the engaged state. An alternate long and short dash line is an example of an ON → OFF switching line for switching the lockup clutch 32 from the engaged state to the released state, and a predetermined hysteresis is provided to prevent hunting. This lockup switching map is set for each gear stage based on the output characteristics of the engine 28, fuel consumption, and the like.

  Here, if the lock-up clutch 32 is in an engaged state and stays in an operating region of a low rotation and high load on an uphill road or the like, there is a possibility that a booming noise or the like is generated due to resonance or the like. In order to suppress this, the electronic control unit 40 of the present embodiment includes an NV avoidance control unit 46, and executes signal processing according to the flowchart of FIG. In step S1 of FIG. 3, it is determined whether or not the lock-up clutch 32 is in an ON state, that is, in an engaged state. Whether or not the lockup clutch 32 is in an engaged state can be determined, for example, based on whether or not the engine rotational speed NE and the turbine rotational speed NT substantially match, but the information on the switching state by the lockup control unit 44 is read, Various modes are possible, such as determination using the same lockup switching map as the lockup control unit 44.

  In step S2, it is determined whether or not the vehicle is traveling in the NV deterioration region, that is, whether or not the vehicle has continued in a predetermined NV deterioration region for a predetermined time or longer. The NV deterioration region is an operation region in which there is a possibility that a booming noise or vibration may occur due to resonance or the like. Specifically, the NV deterioration region is an operation region with a low rotation and high load. Determined. This NV worsening area is not a problem because it passes quickly due to an increase in the vehicle speed V on a flat road, but the vehicle speed V is balanced on an uphill road or the like and stays for a long time without passing through the NV worsening area. Problems such as giving a feeling of unpleasantness due to the occurrence of a booming sound or vibrations occur. In the present embodiment, as shown in FIG. 4, the output rotation speed Nout and the throttle valve opening θth are set as parameters for each gear step in the same manner as in the shift map and the lockup switching map. In FIG. 4, the lower rotation and higher throttle valve opening side (high load side) than the NV determination line are determined as the NV deterioration region, but the NV deterioration region is determined based only on the rotational speed or only the load. You can also.

  If the determination in step S2 is YES (affirmative), that is, if the vehicle is traveling in the NV deterioration region, step S3 is executed. In step S3, it is determined whether or not the gear stage of the automatic transmission 12 is a predetermined high speed gear stage. If the gear stage is a high speed gear stage, a shift map is set so that the automatic transmission 12 is downshifted in step S4. On the other hand, if the speed is not high, the lockup switching map is changed so that the lockup clutch 32 is released in step S5. That is, step S3 is a step of determining whether the deterioration of NV is suppressed by downshifting of the automatic transmission 12 or whether the deterioration of NV is suppressed by releasing the lockup clutch 32 according to the gear stage of the automatic transmission 12. The downshift does not cause a busy shift feeling, whether or not a downshift is possible for each of the plurality of gear stages, whether or not the lockup clutch 32 can be disengaged, and whether the influence (deterioration allowance) on fuel consumption is small. For example, at a high speed gear stage greater than or equal to the fourth speed gear stage “4th”, step S4 is executed, and at a lower gear stage less than or equal to the third speed gear stage “3rd”, step S4 is executed. S5 is executed.

  In step S4, for example, the downshift region downshifted by the 5 → 4 downshift line in FIG. 5 is expanded as indicated by a broken line, and an upshift permission determination value indicated by a two-dot chain line is set. Limiting is performed so that a 4 → 5 upshift is performed on the higher rotation speed side than the shift permission determination value. When the shift control is performed by the shift control unit 42 according to the changed shift line (shift map), a 5 → 4 downshift is performed to increase the engine rotational speed NE, and the deterioration of NV is suppressed. In addition, hunting that repeats up and down is prevented by the upshift permission determination value. The enlarged portion of the downshift area indicated by hatching is set based on the NV worsening area in FIG. 4, and if it is determined that the vehicle is traveling in the NV worsening area in step S2, the result is obtained by changing the shift map in step S4. Accordingly, the automatic transmission 12 is downshifted. As described above, the deterioration of NV is suppressed by the downshift of the automatic transmission 12, so that the fuel efficiency improvement effect by the engagement of the lockup clutch 32 is maintained. If the engine speed NE is increased due to the downshift of the automatic transmission 12, the fuel consumption may be deteriorated. However, since the NV deterioration region is a low speed, the engine speed NE is relatively low even after the downshift. The influence of the deterioration of the fuel consumption is small, and the fuel consumption can be improved by maintaining the engagement state of the lockup clutch 32. Further, on the high-speed gear stage side, since the interval between the shift lines is relatively wide, there is little possibility of causing a busy shift feeling due to the shift due to the change of the driving state after the downshift. The change of the shift map in step S4 is released when a certain release condition is satisfied, such as an upshift is performed according to the changed shift map.

  In step S5, for example, the lockup OFF region in which the lockup clutch 32 is released by the lockup ON → OFF switching line in FIG. 6 is expanded as indicated by a broken line, and the lockup OFF → ON switching line is a solid line. It changes from the normal switching line shown to the switching line at the time of NV shown with a dashed-two dotted line. Then, when lockup switching control is performed by the lockup control unit 44 according to the changed lockup switching line (lockup switching map), the lockup clutch 32 is released, and the deterioration of NV is suppressed, and Hunting that repeatedly engages and disengages is prevented by the lockup OFF → ON switching line at NV. The enlarged portion of the lock-up OFF area indicated by hatching is set based on the NV deterioration area in FIG. 4, and if it is determined that the NV deterioration area travels in step S2, the lock-up switching map is changed in step S5. As a result, the lockup clutch 32 is released. Thus, in the low speed gear stage in which the determination in step S3 is NO (negative), the deterioration of NV is suppressed by the release of the lockup clutch 32, so that the fuel efficiency improvement effect by the engagement of the lockup clutch 32 is limited. The Even at a low gear, the downshift can suppress the deterioration of NV. However, on the low gear stage side, the interval between the shift lines is narrow, and if a downshift is forcibly performed, a shift associated with a change in the driving state thereafter is performed. Since there is a possibility that the drivability deteriorates due to a busy shift, the deterioration of NV is suppressed by releasing the lockup clutch 32 without performing a downshift at a low gear. The change of the lockup switching map in step S5 is released when a certain release condition is satisfied, such as the lockup clutch 32 being engaged according to the changed switching map.

  Thus, in the vehicle power transmission device 10 of the present embodiment, when the lockup clutch 32 is engaged and the driving state of the vehicle remains in the NV deterioration region, the automatic transmission 12 has a high gear stage. In some cases, the shift map is changed in step S4, so that the automatic transmission 12 is downshifted while the lockup clutch 32 is maintained in the engaged state, so that the fuel efficiency improvement effect by the engagement of the lockup clutch 32 is maintained. However, the deterioration of NV can be suppressed. When the automatic transmission 12 is in the low gear stage, the lockup switching map is changed in step S5, so that the lockup clutch 32 is released as in the conventional case to suppress the deterioration of NV. Compared to downshifting, there is no risk that the drivability will deteriorate due to busy shifting.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

  DESCRIPTION OF SYMBOLS 10: Vehicle power transmission device 12: Automatic transmission 30: Torque converter (fluid transmission device) 32: Lock-up clutch 40: Electronic control device 42: Shift control unit 44: Lock-up control unit 46: NV avoidance control unit

Claims (1)

A fluid transmission with a lock-up clutch;
An automatic transmission capable of establishing a plurality of forward gears with different gear ratios;
In the vehicle power transmission device in which the lockup clutch is engaged and released based on the driving state of the vehicle and the automatic transmission is shifted.
When the lock-up clutch is engaged and the driving state of the vehicle remains in a predetermined NV deterioration region, the lock is applied when the gear ratio of the automatic transmission is a predetermined high-speed gear stage with a small speed. The vehicle power transmission device, wherein the automatic transmission is downshifted while the up clutch is held in an engaged state, and the lockup clutch is released when the automatic transmission is less than the high speed gear.

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