Gear change controller for automatic transmission

Abstract

To provide a controller for automatic transmission capable of suppressing an increase in shift shock due to a torque return of an engine.SOLUTION: When up gear change is made from a current shift stage (first speed) to a next shift stage (second speed), a first shift actuator 56c is so actuated that a sleeve 56b of a first engagement clutch 56 separates from the gear (gear piece 38a) of the current shift stage while input torque from an engine 12 is being decreased, and when the sleeve 56b of another engagement clutch establishing the next shift stage and a gear piece 42a are engaged with each other, engine torque input to an automatic transmission 18 is returned from a temporary decrease at timing within a torque return range RT in which drive system torque decreases based upon a resonance period of a drive system of a vehicle 10. Consequently, an increase in shift shock due to the return of the engine torque is suppressed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a shift control device for an automatic transmission in which a gear shift stage is established by alternatively switching the engagement of a meshing clutch in a section where the input torque from the engine is reduced.

Background Art

[0002] There is known an automatic transmission including a plurality of meshing clutches operated by a shift actuator, and a gear shift stage is established by alternatively switching the engagement of the plurality of meshing clutches. For example, the parallel-axis constant-mesh type vehicle automatic transmission described in Patent Document 1 is such an example.

[0003] In such a vehicle automatic transmission, when upshifting from the current gear shift stage to the next gear shift stage, while reducing the input torque from the engine, the shift actuator is operated to disengage the meshing clutch from the gear of the current gear shift stage, and at the same time, shift control is performed such that the engagement of another meshing clutch establishing the next gear shift stage and the return of the torque input from the engine are carried out.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, when the engagement of the meshing clutch and the return of the engine torque are performed simultaneously, the return of the engine torque is performed synchronously with the torsional resonance of the drive system due to the fluctuation of the torque input by the engagement of the meshing clutch, so there has been a problem that a large shift shock occurs.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a control device for an automatic transmission that can suppress an increase in shift shock caused by engine torque return.

Means for Solving the Problems

[0007] The gist of the present invention is as follows: (a) having a plurality of meshing clutches respectively actuated by a shift actuator, and while temporarily reducing the torque input from the engine, releasing the meshing clutch that has established the previous gear stage, while engaging another meshing clutch that establishes a new gear stage to perform an upshift, a control device for an automatic transmission, and (b) after the engagement of the other meshing clutch, at the timing when the drive system torque decreases based on the resonance period of the drive system of the vehicle, returning the torque input from the engine from the temporarily reduced state.

Effects of the Invention

[0008] According to the control device for a vehicle of the present invention, at the timing when the drive system torque decreases based on the resonance period of the drive system of the vehicle, the engine torque is returned from the temporary decrease. As a result, the increase in torque due to the return of the engine torque from the temporary decrease and the decrease in the drive system torque based on the resonance period of the drive system of the vehicle cancel each other out, so an increase in shift shock caused by the return of the engine torque is suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment

[0011] In FIG. 1, in the power transmission path from the engine 12 of the vehicle 10 to the drive wheels 14, an automatic clutch 16, an automatic transmission 18, and a differential gear device 20 are sequentially provided. Further, an electric motor MG is connected to the differential gear device 20 via a speed reducer 22.

[0012] The electric motor MG is a motor generator, functions as a drive source during hybrid driving, and also functions as a generator during regenerative braking. Further, the electric motor MG controls the rotation of the meshing clutch to be synchronized by generating torque similar to the required torque, for example, during a temporary decrease period of the input torque of the automatic transmission 18 due to ignition retard of the engine 12 in order to mitigate the shift shock during the shift period of the power-on upshift of the automatic transmission 18, and the torque dropout feeling is suppressed.

[0013] Further, the vehicle 10 is provided with an engine control device (EG-ECU) 24 that controls the operation of the engine 12, a transmission control device (TM-ECU) 26 that controls the operations of the automatic clutch 16 and the automatic transmission 18, a motor control device (EG-ECU) 28 that controls the operation of the electric motor MG, and a hybrid control device (HV-ECU) 30. The engine control device 24, the transmission control device 26, the motor control device 28, and the hybrid control device 30 are electronic control devices including, for example, a microcomputer, and are connected to each other by a communication line or a data bus so that signals are exchanged between them. Further, some or all of the control devices 24, 26, 28, 30 may be configured as an integrated electronic control device.

[0014] The automatic clutch 16 includes an actuator (not shown) that is operated according to a command from the transmission control device 26, and is a dry or wet friction clutch that is automatically opened and closed by the actuator.

[0015] The automatic transmission 18 is a parallel-axis constant-mesh stepped automatic transmission that shifts the torque from the engine 12 at the gear ratios of a plurality of shift stages and outputs it to the differential gear device 20. The automatic transmission 18 includes an input shaft 32 and an output shaft 34 that are parallel to each other, and a pair of first-speed drive gears 36 and driven gears 38 that are fixed to one of the input shaft 32 and the output shaft 34 and supported so as to be relatively rotatable with respect to the other, and that mesh with each other, a pair of second-speed drive gears 40 and driven gears 42, a pair of third-speed drive gears 44 and driven gears 46, a pair of fourth-speed drive gears 48 and driven gears 50, and a pair of fifth-speed drive gears 52 and driven gears 54.

[0016] The automatic transmission 18 includes a first engagement clutch (dog clutch) 56 provided between the driven gear 38 and the driven gear 42 of the output shaft 34, a second engagement clutch (dog clutch) 58 provided between the drive gear 44 and the drive gear 48 of the input shaft 32, and a third engagement clutch (dog clutch) 60 provided between the drive gear 52 of the output shaft 34 and the shaft end of the input shaft 32.

[0017] The first engagement clutch 56 includes a sleeve 56b that is supported by the output shaft 34 so as to be movable in the rotational axis direction of the output shaft 34 and non-rotatable relative to the output shaft 34 via a clutch hub 56a, and a first shift actuator 56c that drives the sleeve 56b in the rotational axis direction of the output shaft 34 and selectively meshes the internal peripheral teeth (dog teeth) of the sleeve 56b with the external peripheral teeth (dog teeth) of the gear piece 38a of the driven gear 38 or the external peripheral teeth (dog teeth) of the gear piece 42a of the driven gear 42 to establish a first-speed gear stage or a second-speed gear stage. The first engagement clutch 56 is composed of a first-speed engagement clutch for establishing a first-speed gear stage and a second-speed engagement clutch for establishing a second-speed gear stage.

[0018] The second engagement clutch 58 includes a sleeve 58b that is supported by the input shaft 32 so as to be movable in the rotational axis direction of the input shaft 32 via a clutch hub 58a and non-rotatable relative thereto, and a second shift actuator 58c that drives the sleeve 58b in the rotational axis direction of the input shaft 32 and selectively engages the internal peripheral teeth (dog teeth) of the sleeve 58b with the external peripheral teeth (dog teeth) of the gear piece 44a of the drive gear 44 or the external peripheral teeth (dog teeth) of the gear piece 48a of the drive gear 48 to establish a third-speed gear stage or a fourth-speed gear stage. The second engagement clutch 58 is composed of a third-speed engagement clutch for establishing a third-speed gear stage and a fourth-speed engagement clutch for establishing a fourth-speed gear stage.

[0019] The third engagement clutch 60 includes a sleeve 60b that is supported by the input shaft 32 so as to be movable in the rotational axis direction of the input shaft 32 via a clutch hub 60a and non-rotatable relative thereto, and a third shift actuator 60c that drives the sleeve 60b in the rotational axis direction of the input shaft 32 and engages the internal peripheral teeth (dog teeth) of the sleeve 60b with the external peripheral teeth (dog teeth) of the gear piece 52a of the drive gear 52 to establish a fifth-speed gear stage.

[0020] Note that the reverse idler gear 62 engages with both the reverse drive gear 64 and the reverse driven gear 66 by a reverse actuator (not shown) to establish a reverse gear stage.

[0021] The hybrid control device 30 calculates a required output based on the accelerator opening and the vehicle speed (the rotational speed of the second shaft 34) from a pre-stored relationship, and outputs a command to control the output torque of the engine 12 so that the required output can be appropriately obtained. The engine control device 24 controls the throttle opening and the fuel injection amount so that the engine output commanded by the hybrid control device 30 can be obtained.

[0022] The shift control device 26 determines a target shift stage based on the actual vehicle speed (the rotational speed of the second shaft 34) and the throttle opening from a pre-stored shift map, and controls either the first engagement clutch 56 of the automatic transmission 16, the second engagement clutch 58 provided between the drive gear 44 of the input shaft 32 and the drive gear 48, or the third engagement clutch 60 provided between the drive gear 52 of the output shaft 34 and the shaft end of the input shaft 32 so as to obtain the target shift stage.

[0023] Further, in order to mitigate shift shock associated with a change in the gear ratio, during the shift period at the time of power-on upshift of the automatic transmission 18, for example, in the upshift inertia phase, the shift control device 26 temporarily reduces the input torque from the automatic transmission 18 by ignition retard of the engine 12, releases the engagement clutch that has established the shift stage up to that point, and performs an upshift by engaging another engagement clutch that establishes a new shift stage. Also, after engaging another engagement clutch that establishes a new shift stage after the upshift, the shift control device 26 controls a torque return control unit 70 that controls the torque return from a temporary decrease in the input torque of the automatic transmission 18 by ignition retard of the engine 12 to occur at the return timing within the torque decrease section due to the torque fluctuation caused by the engagement of the other engagement clutch.

[0024] FIG. 2 is a time chart for explaining, for example, the torque fluctuation due to the engagement of the other meshing clutch in the upshift and the torque return timing from a temporary decrease in the input torque of the automatic transmission 18 due to the ignition retard of the engine 12 related to the torque fluctuation in the 1→2 power-up shift. For example, when a power-on 1→2 upshift command is issued from the hybrid control device 30 (at time t1), the shift control device 26 disengages the sleeve 56b from the gear piece 38a of the first-speed driven gear 38 using the first shift actuator 56c for the 1→2 upshift. Next, using the first shift actuator 56c, the inner peripheral teeth of the sleeve 56b are started to be moved to the side where they mesh with the outer peripheral teeth of the gear piece 42a of the second-speed driven gear 42, and at the same time, a decrease section of the input torque of the automatic transmission 18 is started by the retard of the ignition timing by the engine control device 24 (at time t2). Next, the engagement (meshing) of the sleeve 56b of the first meshing clutch 56 and the gear piece 42a of the driven gear 42 is started (at time t3).

[0025] When the engagement (meshing) of the sleeve 56b of the first meshing clutch 56 and the gear piece 42a of the second-speed driven gear 42 is started, as shown by the solid line in FIG. 2, conventionally, at this timing (time t3), the decrease section of the input torque ends, the torque from the engine 12 is transmitted to the output shaft 34, and when the transmitted torque to the output shaft 34 (the torsional torque of the drive system) is applied, the torsional torque of the drive system pulsates in synchronization with the torsional resonance period T of the drive system. This phenomenon is felt as an increase in the shift shock due to the return of the engine torque.

[0026] However, in this embodiment, from the time point t3 when the engagement (meshing) between the sleeve 56b of the engagement clutch 56 and the gear piece 42a of the driven gear 42 starts, and from the time point (time point t4) when half of the torsional resonance period T of the drive system has elapsed to the time point (time point t5) when one period of the resonance period T has elapsed, in the torque return range RT, the ignition timing retard by the engine control device 24 is returned to the value before the shift, and the input torque of the automatic transmission 18 is returned from the decreasing state. As a result, as shown by the broken line in FIG. 2, the pulsation synchronized with the torsional resonance period T of the torsional torque of the drive system is suppressed, and the shift shock caused by the return of the engine torque is alleviated.

[0027] FIG. 3 is a flowchart for explaining the main part of the control operation of the electronic control device of this embodiment. In step S1 (hereinafter, steps are omitted) in FIG. 3, it is determined whether or not the power-on upshift of the vehicle 10 is determined. If the determination in S1 is negative, this routine is terminated, but if it is affirmative (time point t1), in S2, the torque down of the engine 12 is started by ignition timing retard, ignition cut, fuel cut, etc. (time point t2). In S3, the output torque of the engine 12 is decreased, and in S4, the sleeve 56b is disengaged from the meshing with the gear piece 38a of the first-speed driven gear 38 by the first shift actuator 56c. In S5, the sleeve 56b is engaged with the gear piece 42a of the second-speed driven gear 42 by the first shift actuator 56c to achieve the target gear stage.

[0028] Subsequently, in S6, the inner peripheral teeth of the sleeve 56b and the outer peripheral teeth of the gear piece 42a of the second-speed driven gear 42 are engaged and the play therebetween is clogged, and the torsion of the drive system is started (time point t3). Next, in S7, it is waited until half of the torsional resonance period T of the power transmission system has elapsed from the start of engagement between the inner peripheral teeth of the sleeve 56b and the outer peripheral teeth of the gear piece 42a of the second-speed driven gear 42, that is, until the maximum value of the torsional torque vibration of the power transmission system arrives.

[0029] Next, in S8, from the start of engagement between the internal teeth of the sleeve 56b and the external teeth of the gear piece 42a of the two-speed driven gear 42, when half of the torsional resonance period T of the power transmission system has elapsed until the entire resonance period T has elapsed, within the torque recovery range RT, torque recovery from a temporary decrease in the input torque of the automatic transmission 18 due to ignition retard, ignition cut, fuel cut, etc. of the engine 12 is started. The torque recovery range RT is a torque decrease section from the maximum value to the minimum value of the torsional torque vibration of the power transmission system. Then, in S9, torque recovery from a temporary decrease in the input torque of the automatic transmission 18 due to ignition retard, ignition cut, fuel cut, etc. of the engine 12 is performed.

[0030] As described above, according to the electronic control device (torque recovery control unit 70) of the present embodiment, when upshifting from the current gear stage (first speed) to the next gear stage (second speed), while reducing the input torque from the engine 12, the first shift actuator 56c is operated so that the sleeve 56b of the first engagement clutch 56 is disengaged from the gear (gear piece 38a) of the current gear stage. On the other hand, when engagement between the sleeve 56b of the other engagement clutch that establishes the next gear stage and the gear piece 42a, and recovery of the torque input from the engine 12 to the torque before the torque decrease are performed, at the timing within the torque recovery range RT where the drive system torque decreases based on the resonance period of the drive system of the vehicle 10, the engine torque input to the automatic transmission 18 is recovered from a temporary decrease. As a result, the increase in shift shock caused by the recovery of the engine torque is suppressed because the torque increase due to the recovery of the engine torque from the temporary decrease and the decrease in the drive system torque based on the resonance period of the drive system of the vehicle 10 cancel each other out.

[0031] As described above, the embodiments of the present invention have been described in detail based on the drawings, but the present invention is also applicable in other aspects.

[0032] For example, the vehicle 10 of the above-described embodiment was equipped with the electric motor MG, but it does not necessarily have to be equipped with the electric motor MG.

[0033] In the above-described embodiment, the first meshing clutch 56, the second meshing clutch 58, and the third meshing clutch 60 do not include a synchronizer (synchronization mechanism), but they may include a synchronizer (synchronization mechanism).

[0034] Note that the above 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

[0035] 10: Vehicle, 18: Automatic transmission, 26: Shift control device (control device), 56: First meshing clutch, 58: Second meshing clutch, 60: Third meshing clutch, 70: Torque return control unit

Claims

【Claim 1】 A control device for an automatic transmission having an engagement clutch actuated by a shift actuator, which releases an engagement clutch that has established the previous gearshift stage while temporarily reducing the torque input from the engine, and performs an upshift by engaging another engagement clutch that establishes a new gearshift stage, after the engagement of the other engagement clutch, the torque input from the engine is restored from a state where it has been temporarily reduced at a timing when the drive system torque decreases based on the resonance period of the drive system of the vehicle. A control device for an automatic transmission, characterized by the above.

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