CN110799779A

CN110799779A - Control device for automatic transmission

Info

Publication number: CN110799779A
Application number: CN201880030279.4A
Authority: CN
Inventors: 下泽智启; 高野谅
Original assignee: Isuzu Motors Ltd
Current assignee: Isuzu Motors Ltd
Priority date: 2017-05-19
Filing date: 2018-05-18
Publication date: 2020-02-14
Anticipated expiration: 2038-05-18
Also published as: WO2018212313A1; JP6950277B2; CN110799779B; JP2018194132A

Abstract

The invention provides a control device for an automatic transmission, which can perform a shift control capable of preventing excessive heat generation of a friction engagement element when switching engagement of the friction engagement element and preventing a reduction in drivability. A control device for an automatic transmission is provided with: a shift condition satisfaction determination unit configured to determine whether or not a shift condition of a vehicle transmission that shifts in association with switching of engagement of a plurality of friction engagement elements is satisfied; and a transmission output torque reduction unit configured to reduce the output torque of the transmission by a predetermined amount before switching engagement of the plurality of friction engagement elements when the shift condition satisfaction determination unit determines that the shift condition is satisfied.

Description

Control device for automatic transmission

Technical Field

The present invention relates to a control device for an automatic transmission.

Background

Conventionally, various automatic transmissions are known which shift gears in accordance with engagement switching of a plurality of frictional engagement elements. For example, a Dual Clutch Transmission (DCT) is known, which has: a first clutch (frictional engagement element) provided between the engine and the odd-numbered stage gear train; and a second clutch (frictional engagement element) that is provided between the engine and the even-numbered gear train, and transmits the driving force from the engine to the output side via the first clutch or the second clutch. In addition, an Automatic Transmission (AT) is known, which has: a clutch (frictional engagement element) that stops relative rotation between elements constituting the planetary gear; and a brake (frictional engagement element) that stops rotation of the element, and transmits a driving force from the engine to the output side via the planetary gear.

In these automatic transmissions, switching between engagement of a plurality of frictional engagement elements, that is, releasing one frictional engagement element and engaging the other frictional engagement element, is performed in parallel with each other, so that frictional heat is generated in each frictional engagement element. The generation of excessive frictional heat causes damage to the frictional engagement elements. Therefore, some countermeasure against heat is required.

Therefore, various inventions for preventing damage to the friction engagement element at the time of switching engagement of the friction engagement element have been proposed so far.

For example, patent document 1 discloses an invention relating to a gear shift control method for a DCT vehicle. The method comprises the following steps: a gear shift command confirmation step for confirming whether an upshift gear shift command is generated during starting control of the DCT vehicle; a slip determination step of determining whether or not a difference in rotation number between the number of rotations of the input shaft to be synchronized with the engine and the number of rotations of the engine is within a predetermined reference rotation number (reference rotation number) when the shift instruction is generated during the start control as a result of confirmation in the shift instruction confirmation step; and a control switching step of ending the start control and switching to the shift control when the difference between the number of rotations of the input shaft and the number of rotations of the engine is within the reference number of rotations as a result of the determination in the slip determination step (claim 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2014-55666.

Disclosure of Invention

Problems to be solved by the invention

According to the method described in patent document 1, as shown in fig. 3 of patent document 1, the engine torque at the time of performing the engagement switching is reduced as compared with the engine torque before the engagement switching, but the amount of reduction is different for each gear shift. In addition, actually, the torque output from the transmission is not particularly noticed. Therefore, although the frictional engagement element may be prevented from being damaged, a different acceleration/deceleration feeling, that is, a feeling of incongruity may be given to the driver every time the gear is shifted.

An object of the present invention is to provide a control device for an automatic transmission capable of performing shift control capable of preventing excessive heat generation of a friction engagement element when switching engagement of the friction engagement element and preventing deterioration of drivability.

Means for solving the problems

A control device for an automatic transmission according to an aspect of the present invention includes: a shift condition satisfaction determination unit configured to determine whether or not a shift condition of a vehicle transmission that shifts in association with switching of engagement of a plurality of friction engagement elements is satisfied; and a transmission output torque reduction unit configured to reduce the output torque of the transmission by a predetermined amount before switching engagement of the plurality of friction engagement elements when the shift condition satisfaction determination unit determines that the shift condition is satisfied.

Effects of the invention

According to the present invention, it is possible to provide a control device for an automatic transmission capable of performing a shift control capable of preventing excessive heat generation of a friction engagement element when switching engagement of the friction engagement element and preventing a reduction in drivability.

Drawings

Fig. 1 is a schematic configuration diagram showing a vehicle to which a control device for an automatic transmission according to the present invention is applied.

Fig. 2 is a functional block diagram of a control device of an automatic transmission of the present invention.

Fig. 3 is a flowchart showing a flow of control performed by the control device of the automatic transmission according to the present invention.

Fig. 4 is a timing chart when an upshift is performed.

Fig. 5 is a timing chart when a downshift is performed.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the drawings. The embodiments described below are examples, and the present invention is not limited to these embodiments.

First, the overall structure of the vehicle will be described with reference to fig. 1. As shown in fig. 1, a vehicle 1 includes: an engine 10; a DCT2 (automatic transmission) including the first clutch 20, the second clutch 30, the transmission portion 40, and the hydraulic circuit 90; and a control device 50. On the output side of the DCT2, drive wheels are coupled to enable power transmission via a propeller shaft and a differential gear, not shown.

The engine 10 is, for example, a diesel engine. The output rotation speed (hereinafter referred to as "engine rotation speed") and the output torque of the engine 10 are controlled based on the accelerator opening Acc of the accelerator pedal detected by the accelerator opening sensor 101. Further, an engine speed sensor 102 that detects the engine speed is provided on the engine output shaft 11.

The first clutch 20 is a hydraulically-operated wet multiple disc clutch having a plurality of first input-side clutch plates 21 and a plurality of first output-side clutch plates 22. The first input side clutch plate 21 rotates integrally with the engine output shaft 11 rotated by the engine 10. The first output clutch plate 22 rotates integrally with the first input shaft 41 of the transmission unit 40.

The first clutch 20 is biased in the disengagement direction by a return spring, not shown, and the first clutch 20 is engaged by moving the first piston 23 by the clutch operating hydraulic pressure supplied from the hydraulic circuit 90 to press-contact the first input-side clutch plate 21 and the first output-side clutch plate 22. By engaging the first clutch 20, the power of the engine 10 is transmitted to the first input shaft 41. The control device 50 controls the disengagement and engagement of the first clutch 20. The first clutch 20 may be a dry single-plate clutch.

The second clutch 30 is a hydraulically-operated wet multiple disc clutch having a plurality of second input-side clutch plates 31 and a plurality of second output-side clutch plates 32. The second input side clutch plate 31 rotates integrally with the engine output shaft 11. The second output side clutch plate 32 rotates integrally with the second input shaft 42 of the transmission unit 40.

The second clutch 30 is biased in the disengagement direction by a return spring, not shown, and the second clutch 30 is engaged by moving the second piston 33 by the clutch operating hydraulic pressure supplied from the hydraulic circuit 90 to press-contact the second input side clutch plates 31 and the second output side clutch plates 32. By engaging the second clutch 30, the power of the engine 10 is transmitted to the second input shaft 42. The control device 50 controls the disengagement and engagement of the second clutch 30. The second clutch 30 may be a dry single-plate clutch. Hereinafter, the first input side clutch plate 21, the second input side clutch plate 31, the first output side clutch plate 22, and the second output side clutch plate 32 will be referred to as "clutch plates" only as needed.

The second clutch 30 is disposed on the outer peripheral side of the first clutch 20. Further, the first input shaft 41 is provided with a not-shown lubricating oil passage constituted by an axial oil passage and one or more radial oil passages, and the first input shaft 41 is radially sprayed with lubricating oil, whereby the clutch plates of the first clutch 20 are cooled, and the clutch plates of the second clutch 30 are cooled. The lubricating oil that cools the clutch plates of the second clutch 30 flows out from the outer diameter side of the second clutch 30 and the like, and returns to an oil pan, not shown, provided in the hydraulic circuit 90. In the present embodiment, the case where the second clutch 30 is provided on the outer peripheral side of the first clutch 20 is described as an example, but the arrangement relationship between the first clutch 20 and the second clutch 30 is not limited to this. Specifically, for example, the second clutch 30 may be disposed on the rear side of the first clutch 20.

The transmission unit 40 includes a first input shaft 41 connected to the output side of the first clutch 20, and a second input shaft 42 connected to the output side of the second clutch 30. The transmission unit 40 includes a counter shaft 43 disposed parallel to the first input shaft 41 and the second input shaft 42, and an output shaft 44 disposed coaxially with the first input shaft 41 and the second input shaft 42. A vehicle speed sensor 103 that detects a vehicle speed V, which is a speed of the vehicle 1, is provided on the rear end side of the output shaft 44.

The transmission unit 40 includes a first transmission unit 60, a second transmission unit 70, and a forward/backward movement switching unit 80. The first transmission unit 60 includes a first high-speed gear train 61, a first low-speed gear train 62, and a first link mechanism 63.

The first high-speed gear train 61 includes a first input gear 61a provided to be relatively rotatable with respect to the first input shaft 41, and a first counter gear 61b provided to mesh with the first input gear 61a and to rotate integrally with the counter shaft 43.

The first low-speed gear train 62 includes a second input gear 62a provided relatively rotatably with respect to the first input shaft 41, and a second counter gear 62b provided in mesh with the second input gear 62a and integrally rotatable with the counter shaft 43.

The first coupling mechanism 63 selectively rotates the first input gear 61a or the second input gear 62a integrally with the first input shaft 41 by moving the first sleeve 63a in the axial direction (the left-right direction in fig. 1) by a shift actuator (not shown).

The second transmission unit 70 includes a second high-speed gear train 71, a second low-speed gear train 72, and a second coupling mechanism 73. The second high-speed gear train 71 includes a third input gear 71a provided to be relatively rotatable with respect to the second input shaft 42, and a third counter gear 71b provided to mesh with the third input gear 71a and to rotate integrally with the counter shaft 43.

The second low-speed gear train 72 includes a fourth input gear 72a provided relatively rotatably with respect to the second input shaft 42, and a fourth counter gear 72b provided in mesh with the fourth input gear 72a and rotating integrally with the counter shaft 43.

The second coupling mechanism 73 alternatively rotates the third input gear 71a or the fourth input gear 72a integrally with the second input shaft 42 by moving the second sleeve 73a in the axial direction by a shift actuator, not shown.

The forward/backward switching unit 80 includes a forward gear train 81, a backward gear train 82, and a third coupling mechanism 83. The forward gear train 81 includes a first output gear 81a provided to be relatively rotatable with respect to the output shaft 44, and a fifth counter gear 81b provided to mesh with the first output gear 81a and to rotate integrally with the counter shaft 43.

The rear gear train 82 includes a second output gear 82a provided to be relatively rotatable with respect to the output shaft 44, and a sixth counter gear 82b provided to mesh with the second output gear 82a via an idle gear 82c and to rotate integrally with the counter shaft 43.

The third coupling mechanism 83 rotates the first output gear 81a or the second output gear 82a together with the output shaft 44 alternatively by moving the third sleeve 83a in the axial direction by a shift actuator, not shown.

Here, the power transmission path in the DCT2 will be briefly described. The 1 st speed is established by coupling the second input gear 62a and the first input shaft 41 with the first coupling mechanism 63, coupling the first output gear 81a and the output shaft 44 with the third coupling mechanism 83, and engaging the first clutch 20. Accordingly, the power of the engine 10 is transmitted from the first clutch 20 to the first input shaft 41, the first low-speed gear train 62, the counter shaft 43, the forward gear train 81, and the output shaft 44 in this order.

The 2-speed is established by coupling the fourth input gear 72a and the second input shaft 42 with the second coupling mechanism 73, coupling the first output gear 81a and the output shaft 44 with the third coupling mechanism 83, and engaging the second clutch 30. Accordingly, the power of the engine 10 is transmitted from the second clutch 30 to the second input shaft 42, the second low-speed gear train 72, the counter shaft 43, the forward gear train 81, and the output shaft 44 in this order.

The 3-speed is established by coupling the first input gear 61a and the first input shaft 41 by the first coupling mechanism 63, coupling the first output gear 81a and the output shaft 44 by the third coupling mechanism 83, and engaging the first clutch 20. Accordingly, the power of the engine 10 is transmitted from the first clutch 20 to the first input shaft 41, the first high-speed gear train 61, the counter shaft 43, the forward gear train 81, and the output shaft 44 in this order.

The 4-speed is established by coupling the third input gear 71a and the second input shaft 42 with the second coupling mechanism 73, coupling the first output gear 81a and the output shaft 44 with the third coupling mechanism 83, and engaging the second clutch 30. Accordingly, the power of the engine 10 is transmitted from the second clutch 30 to the second input shaft 42, the second high-speed gear train 71, the counter shaft 43, the forward gear train 81, and the output shaft 44 in this order.

The control device 50 includes a CPU (Central Processing Unit) 51, a memory 52, and an interface (not shown) connected to various sensors and devices to transmit and receive signals. The CPU51 controls the engine 10 by executing programs stored in the memory 52 and controls the DCT2 by controlling the hydraulic circuit 90. Specifically, the CPU51 executes the program stored in the memory 52, and functions as the shift condition satisfaction determining unit 53, the transmission output torque reducing unit 54, and the executing unit 55, as shown in fig. 2.

The shift condition satisfaction determination unit 53 determines whether or not the shift condition is satisfied based on the accelerator opening Acc, the vehicle speed V, the shift map stored in the memory 52, and the like.

The transmission output torque reduction portion 54 reduces the output torque of the DCT2 by a certain amount before the engagement switching starts at each gear shift.

The actuator 55 performs the disconnection and engagement of the first clutch 20, the disconnection and engagement of the second clutch 30, and the movement of the first sleeve 63a, the second sleeve 73a, and the third sleeve 83a via the hydraulic circuit 90. Thereby, the shift of the upshift or the downshift is performed.

It is not necessary that all of the above-described functional units be realized by the control device 50, and one or more of the above-described functional units may be realized by another control device different from the control device 50. For example, the control device 50 may be configured to function as the shift condition satisfaction determination unit 53 and the transmission output torque reduction unit 54. It is needless to say that any one of the above-described functional units may be configured to have the function of another functional unit.

Next, the shift control performed by the transmission control device according to the present embodiment will be described in detail with reference to the flowchart of fig. 3.

First, the shift condition satisfaction determination unit 53 checks whether or not the shift condition for upshift or downshift is satisfied (S1). Whether or not the shift condition is established is determined based on the accelerator opening Acc, the vehicle speed V, the shift map, and the like. While it is determined that the shift condition is not satisfied (no at S1), the determination as to whether the shift condition is satisfied is repeated until it is determined that the shift condition is satisfied (yes at S1).

If it is determined that the shift condition is satisfied, the transmission output torque reduction unit 54 reduces the output torque of the DCT2 (transmission output torque) (S2). The reduction amount is a constant value predetermined according to an experiment, a use method of the vehicle 1, a vehicle type, and the like.

When the output torque of the DCT2 is reduced by the transmission output torque reduction unit 54, the execution unit 55 executes the shift of the upshift or the downshift determined by the shift condition satisfaction determination unit 53 as satisfaction of the condition (S3). Thus, the shift control is ended.

Next, referring to fig. 4 showing a timing chart at the time of executing the gear shift, how the gear shift advances will be specifically described. Here, it is assumed that an upshift from the 3-speed to the 4-speed is performed.

When the shift condition establishment determination unit 53 determines that the shift condition for upshift is established, first, as shown in the lower graph, the transmission output torque reduction unit 54 reduces the transmission output torque by a constant value from the value up to this point (the driver-requested output torque).

Specifically, the transmission output torque reduction unit 54 determines the amount of reduction in the engine torque based on the 3-speed gear ratio, which is the gear position before the gear shift is performed, and the engine torque when it is determined that the gear shift condition is satisfied, so as to reduce the transmission output torque by a predetermined constant value. When the reduction amount is obtained, as shown in the middle graph, the transmission output torque reduction unit 54 reduces the engine torque by the reduction amount, and reduces the torque capacity of the engaged first clutch 20 during the 3-speed execution so as to be equal to the reduced engine torque.

Further, it is preferable to reduce the transmission output torque by a constant value so as not to give a sense of incongruity to the driver. That is, it is preferable that the reduction of the transmission output torque before the engagement switching of the two clutches is performed at the following change rate: the jerk of the vehicle 1, which is reducing the transmission output torque, is not set to a change rate that gives the driver a sense of incongruity. For example, the transmission output torque reduction unit 54 reduces the transmission output torque so as to satisfy the following expression (1). The jerk referred to herein is a forward jerk, which is a jerk in the traveling direction of the vehicle 1.

[ numerical formula 1]

In formula (1), r_wIs the radius of the tire, i_fIs a final drive ratio, m with a mark ^ is the weight of the vehicle, F with a mark ^_aeroIs an air resistance estimate, F marked ^_rollIs the rolling resistance estimate, g is the gravitational acceleration, and θ, marked "^", is the slope estimate. These parameters may be determined in advance or determined by a method known in the art at the time of application. Thus, detailed description is omitted.

In the formula (1), the symbol "·" means 1-order time differential, and the symbol "·" means 2-order time differential. T is_oiIs the transmission output torque. Thus, T_oiThe 1 st order time differential value of (d) means the speed of change of the transmission output torque. In addition, v_xIs the front speed of the vehicle 1. Thus, the 2 nd order time differential value thereof means the forward jerk of the vehicle 1.

As v _x2 order time ofThe range of the optimum value of the differential value (the forward jerk of the vehicle 1) is obtained in advance through experiments, and is stored in the memory 52. Therefore, by changing the transmission output torque at the change speed within the numerical range obtained by substituting such a value into equation (1), the transmission output torque can be reduced before the engagement switching of the clutch without giving a sense of incongruity to the driver.

Next, as shown in the middle diagram, the execution unit 55 gradually decreases the torque capacity of the first clutch 20 and gradually increases the torque capacity of the second clutch 30. That is, the engagement switching of the clutch is performed.

As a result, as shown in the following figures, the first clutch system output torque, which is the torque transmitted to the output shaft 44 via the first clutch 20 and the first transmission unit 60, gradually decreases. Further, the second clutch system output torque, which is the torque transmitted to the output shaft 44 via the second clutch 30 and the second transmission unit 70, gradually increases. The torque output from the output shaft 44, i.e., the transmission output torque, is the sum of the first clutch system output torque and the second clutch system output torque. The execution unit 55 controls the torque capacities of the clutches while maintaining a state in which the transmission output torque is reduced by a predetermined constant value with respect to the driver-requested output torque.

When the first clutch system output torque is 0 and the transmission output torque is equal to the second clutch system output torque, the execution unit 55 performs control as follows. That is, as shown in the middle diagram, the execution unit 55 maintains the torque capacity of the second clutch 30 at the engine torque at the time of switching the engagement of the clutch for a predetermined time, and reduces the engine torque by a predetermined amount. As a result, as shown in the above-described graph, the engine speed is shifted from the speed of the first input shaft 41 to the speed of the second input shaft 42. When the engine speed matches the speed of the second input shaft 42, slip is not generated in any of the clutches.

When the engine speed matches the speed of the second input shaft 42, the execution unit 55 increases the torque capacity of the second clutch 30 by a predetermined amount so as not to generate slip, as shown in the middle graph. In addition, the engine torque is restored to the driver-requested engine torque. Thereby, 4-speed shift is achieved.

During the shifting operation, slip occurs in the first clutch 20 and the second clutch 30 in the engagement switching process of the first clutch 20 and the second clutch 30. In the process of shifting the engine speed, the second clutch 30 generates slip. However, the torque capacity of each clutch decreases during these processes. Therefore, the energy absorbed by each clutch decreases, and the amount of heat generated by each clutch also decreases. That is, according to the control device of the transmission of the present embodiment, excessive heat generation in each clutch can be prevented. Further, since the engagement switching process of the clutches and the transition process of the engine rotational speed are performed in a state where the transmission output torque, which is the output torque of the DCT2, is reduced, the amount of heat generation in each clutch can be more reliably reduced.

Before the engagement switching, the transmission output torque is reduced by a predetermined constant value, and this state is continued in the engagement switching step and the engine speed transition step. Therefore, the occurrence of unexpected variation in the vehicle jerk by the driver during one shift is prevented.

Further, according to the transmission control device of the present embodiment, the amount of reduction in the transmission output torque with respect to the driver-requested output torque is not always constant, but is always constant, rather than varying every time the transmission is shifted. Therefore, the degree of change in the acceleration of the vehicle given to the driver at the time of shifting can be equalized. That is, it is possible to prevent a reduction in drivability due to different acceleration/deceleration feeling given to the driver at each gear shift.

The transmission control device according to the present embodiment may be applied to downshifting. Fig. 5 is a timing chart when a downshift from 3-speed to 2-speed is performed.

When executing a downshift, the transmission output torque is reduced by a constant value from the value up to this point (driver-requested output torque) before the engagement of the clutch is switched, as in the case of executing an upshift. The engine speed transition step and the engagement switching step are executed in this state. Thus, as in the case where the upshift is performed, excessive heat generation in each clutch can be prevented, and a decrease in drivability can be prevented.

The automatic transmission may be a DCT that has more gear trains and can perform more-stage gear changes, or may be an automatic transmission that includes a clutch that stops relative rotation between elements constituting the planetary gear and a brake that stops rotation of the elements.

The present application is based on japanese patent application published on 5/19/2017 (japanese patent application 2017-099983), the contents of which are incorporated herein by reference.

Industrial applicability

According to the present invention, it is possible to provide a control device for an automatic transmission capable of performing shift control capable of preventing excessive heat generation of a friction engagement element when switching engagement of the friction engagement element and preventing deterioration of drivability. Thus, its industrial applicability is large.

Description of the reference numerals

1 vehicle

2 DCT

10 engines

11 output shaft of engine

20 first clutch

21 first input side clutch plate

22 first output side clutch plate

23 first piston

30 second clutch

31 second input side clutch plate

32 second output side clutch plate

33 second piston

40 speed changing part

41 first input shaft

42 second input shaft

43 auxiliary shaft

44 output shaft

50 control device

51 CPU

52 memory

53 Gear Change Condition satisfaction judging section

54 transmission output torque reducing section

55 executive part

60 first transmission part

61 first high speed gear train

61a first input gear

61b first pinion

62 first Low speed Gear train

62a second input gear

62b second pinion

63 first connecting mechanism

63a first sleeve

70 second transmission part

71 second high speed gear train

71a third input gear

71b third pinion

72 second Low speed Gear train

72a fourth input gear

72b fourth pinion

73 second connecting mechanism

73a second sleeve

80 forward and backward switching part

81 forward gear train

81a first output gear

81b fifth pinion

82 rear-wheel gear train

82a second output gear

82b sixth pinion

82c idler

83 third connecting mechanism

83a third sleeve

101 accelerator opening sensor

102 engine speed sensor

103 vehicle speed sensor

90 hydraulic circuit

Claims

1. A control device for an automatic transmission, comprising:

a shift condition satisfaction determination unit configured to determine whether or not a shift condition of a vehicle transmission that shifts in association with switching of engagement of a plurality of friction engagement elements is satisfied; and

and a transmission output torque reduction unit configured to reduce the output torque of the transmission by a predetermined amount before switching the engagement of the plurality of friction engagement elements when the shift condition satisfaction determination unit determines that the shift condition is satisfied.

2. The control apparatus of an automatic transmission according to claim 1,

the transmission output torque reduction unit reduces the output torque of the transmission at a change speed within a predetermined range that is predetermined so that a jerk of the vehicle, which is reducing the output torque of the transmission, has a value that does not give a sense of incongruity to a driver of the vehicle.