JP2009257408A - Method for controlling automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method of an automatic transmission capable of smoothly performing shifting operation without generating an engine racing phenomenon or shock in a torque replacing process. <P>SOLUTION: The automatic transmission is equipped with a dual clutch comprising a first clutch part and a second clutch part, a first input shaft, a second input shaft, an output shaft, a plurality of gear trains, and an operation control part. The control method of the automatic transmission includes a gear train forming process for choosing and forming a gear train after shifting, the torque replacing process for replacing torque from one clutch part and one input shaft to the other clutch part and the other input shaft, and a synchronizing process for synchronizing rotation speed of a motor and rotation speed of the other input shaft. In the torque replacing process, rotation speed difference D between the motor and one input shaft, which is generated when torque Q1 transmitted in one clutch part is decreased or when torque Q2 transmitted in the other clutch part is increased, is obtained. At least one clutch part is operation-controlled for preventing the rotation speed difference D from being excessive. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for controlling an automatic transmission used in a vehicle or the like, and more particularly, to a method for controlling a dual clutch automatic transmission.

  One type of vehicle transmission is a dual clutch automatic transmission that includes a dual clutch having two clutch portions and a plurality of gear trains formed between two input shafts and an output shaft. This automatic transmission has the advantage that the shifting operation can be performed without interrupting the torque by performing a replacement operation with two clutch portions. As the dual clutch, for example, a friction clutch is used in which a friction disk on the driving side and a driven side frictionally connects and transmits torque. Each gear train that normally achieves a gear ratio of about 4 to 7 steps is selected and switched by a synchromesh mechanism, for example. Generally, the dual clutch and synchromesh mechanism are automatically controlled by an operation control unit including an electronic control device and an actuator.

  An example of a control device for such a dual clutch type automatic transmission is disclosed in Patent Document 1. The control device disclosed in Patent Document 1 can suppress a delay in the shift control by switching the shift control method according to the operating state of a drive device such as an engine. In a dual clutch type automatic transmission such as Patent Document 1, a gear train from one input shaft to an output shaft is formed while one clutch is engaged while the vehicle is running, and torque input from the prime mover is output. It is transmitted to the shaft and the speed is maintained. At this time, the other clutch portion is disengaged and no torque is transmitted to the other input shaft.

  The shift operation of this type of dual clutch type automatic transmission generally includes a gear train formation process, a torque replacement process, a synchronization process, and a gear train disengagement process. When a speed change operation command is issued, first, in the gear train formation step, another new gear train from the other input shaft to the output shaft is formed. Next, in the torque replacement step, one clutch portion is gradually released, and at the same time, the other clutch portion is gradually engaged, and the torque transmission destination is transferred from one input shaft to the other input shaft. . Then, in the synchronization step, the rotational speeds of the prime mover and the other input shaft are synchronized, and the other clutch portion can transmit torque without slipping. Finally, in the gear train disengagement step, the gear train before the gear transmission not transmitting torque is disengaged, and the gear shifting operation is completed.

Here, in order to perform the replacement smoothly in the torque replacement process, generally, the torque is estimated and control is performed based on the estimated value. Since it is difficult to measure the transmitted torque sequentially, estimation is performed based on various types of operation information. For example, in a configuration in which the prime mover is an engine, the output torque is estimated from information such as the engine speed, the fuel supply amount, and the intake air amount. In the friction clutch, the torque transmitted by the relative positional relationship between the friction disks on the driving side and the driven side is estimated. This estimation is generally performed using an arithmetic expression or a map inside the electronic control unit. Then, the engagement state of the two clutch portions is sequentially controlled so that the output torque of the engine branches without excess or deficiency, and the torque is gradually switched from one to the other.
JP 2006-226380 A

  By the way, since the estimated value of the torque in the torque replacement process varies, there is a problem that the switching operation is not always performed smoothly. For example, the output torque of the engine fluctuates depending on environmental conditions such as ambient temperature, and there is a limit in improving the estimation accuracy due to individual differences such as manufacturing tolerances in the clutch part. Due to variations in estimated values, the balance between the engine output torque and the sum of the torques transmitted by the two clutch parts is lost, and if the former is greater than the latter, the engine speed will increase rapidly, and on the contrary, Then, a shock occurred and none of them was preferable.

  The present invention has been made in view of the above background, and provides a control method for an automatic transmission that can smoothly perform a speed change operation without causing an engine blow-up phenomenon or a shock in a torque replacement process.

  The method for controlling an automatic transmission according to the present invention includes a dual clutch having a first clutch portion and a second clutch portion that selectively transmit torque output from a prime mover, and first torque transmitted from the first clutch portion. 1 input shaft, 2nd input shaft to which torque is transmitted from the second clutch portion, output shaft, the first input shaft and the torque from the second input shaft to the output shaft are selectively selected at different gear ratios. A gear train forming step for selectively forming a gear train after a shift, and an operation control unit for connecting and disconnecting the dual clutch and selecting and operating the gear train. A torque exchanging step of exchanging torque from the one clutch portion and the input shaft transmitting torque to the other clutch portion and the input shaft transmitting torque after shifting; And a synchronizing step for synchronizing the rotation speed of the other input shaft with the rotation speed of the other input shaft, wherein the torque replacement step includes a torque transmitted by the one clutch portion. A rotational speed difference between the prime mover and the one input shaft that occurs when the torque transmitted by the other clutch portion is increased or at least 1 is obtained so that the rotational speed difference does not become excessive. This is a step of operating and controlling the individual clutch portions.

  The present invention does not perform the conventional operation control based on the estimated torque value in the torque replacement process in the middle of the shifting operation of the dual clutch type automatic transmission, and focuses on the rotational speed difference between the engine and the input shaft. By engaging and disengaging the clutch part so that it does not become excessive, the engine output torque and the sum of the torques transmitted by the two clutch parts are balanced so that the engine blow-up phenomenon and shock do not occur. It is a summary. Performing a gear train forming step for selectively forming a gear train after shifting before the torque changing step, and performing a synchronizing step for synchronously rotating the motor and the input shaft for transmitting torque after the torque changing step. This is the same as in the prior art.

  The prime mover that inputs torque to the automatic transmission targeted by the control method of the present invention can be an engine. The dual clutch of the automatic transmission can be a friction clutch. Moreover, it can comprise so that the information of rotation speed may be transmitted to the operation control part from the rotation speed sensor which detects the rotation speed of an engine and two input shafts. The rotational speed sensor may be provided conventionally or may be newly provided. For example, an electronic control device and a hydraulic operation or an electric operation actuator may be used as the operation control unit, and a dual clutch disengagement operation and a gear train selection operation may be performed.

  In the torque replacement step, transmission is performed in the other clutch unit by controlling feedback of the difference in rotational speed between the prime mover and the one input shaft generated when the torque transmitted in the one clutch unit is reduced. It may be a step of increasing the torque to be performed.

  As an example of the control method of the torque replacement process according to the present invention, first, one clutch portion that is engaged and transmitting torque can be slightly opened. Then, the transmitted torque is reduced, the load seen from the engine is lightened, the engine speed is slightly increased, and a positive speed difference is generated with respect to one input shaft. The operation control unit can slightly engage the other clutch unit that is not transmitting torque so that this rotational speed difference does not become excessive. Then, the transmitted torque increases, the load seen from the engine becomes heavy, and the increase in the engine speed is suppressed. At the next timing, one of the clutch portions can be opened a little further to reduce the torque, and at the next timing, the other clutch portion can be connected a little more to further increase the torque. In this way, by performing feedback control so that the difference in rotational speed does not become excessive, the sum of the torques of the two clutch parts becomes substantially constant and maintains a state balanced with the engine output torque, while one clutch part is While disengaging, the other clutch can be engaged at the same time for replacement. In this example, a disengagement method of one clutch part, for example, a disengagement speed is determined in advance, and an engagement method of the other clutch part, for example, a method of sequentially controlling the disengagement speed can be used.

  In the torque replacement step, the one clutch portion is controlled by feedbacking the difference in rotational speed between the prime mover and the one input shaft generated when the torque transmitted by the other clutch portion is increased. This may be a step of reducing the torque transmitted in step.

  In this example, since the torque of the clutch portion first increases, the engine speed decreases, and a negative speed difference occurs with respect to one input shaft. In the case of a negative rotational speed difference, it is the same that the two clutch sections are operated and controlled so that this does not become excessive. For example, it is possible to use a method in which the engagement method of the other clutch portion is determined in advance and the release method of one clutch portion is sequentially controlled.

  The connection control method of the two clutch portions is not limited to the above-described two examples, and for example, the sum of torque transmitted and the rotational speed difference may be maintained by sequentially controlling both clutch portions. Further, the rotational speed difference may be either positive when the engine side is large or negative when the engine side is small. Further, different control methods may be used for the upshift operation during acceleration and the downshift operation during deceleration.

  In the torque replacement step, it is preferable that operation control is performed so that the difference in rotational speed between the prime mover and the one input shaft is constant.

  The target value for maintaining the rotational speed difference between the prime mover and one input shaft is preferably a constant value. For example, when the rotational speed of the engine greatly exceeds that of one input shaft and the rotational speed difference exceeds a certain value, the operation control section quickly engages the other clutch section that is engaged. Can do. As a result, the load seen from the engine becomes heavy, an increase in the engine speed is suppressed, and the speed difference approaches a constant value. Conversely, when the rotational speed difference is less than a certain value, the operation control unit can slowly engage the other clutch unit being engaged. As a result, the load seen from the engine is reduced, the increase in the engine speed is promoted, and the speed difference approaches a constant value.

  Further, in the torque replacement process, operation control may be performed so that the rotational speed difference between the prime mover and the one input shaft increases in the first half of the process and decreases in the second half of the process.

  Instead of setting the target value of the rotational speed difference to a constant value, it can be a mountain-shaped curve that changes with time. The operation control unit can store this mountain-shaped curve and control the operation so that the rotational speed difference changes on the curve. That is, when the rotational speed difference begins to deviate from the curve, the rotational speed difference can be returned to the curve by adjusting the sum of the torques of the two clutch portions.

  In the aspect in which the target value of the rotational speed difference is a mountain-shaped curve, the engine rotational speed has a certain rate of change at the end of the torque replacement process. On the other hand, in the next synchronization step, it is necessary to change the engine speed and synchronize with the other input shaft. Here, if the rate of change of the engine speed in the torque replacement process is a value close to that of the synchronous process, the process can be smoothly transferred, and the time required for the synchronous process can be shortened. .

  In the control method for an automatic transmission according to the present invention, a difference in rotational speed between the engine and one input shaft is obtained in the torque replacement step, and at least one clutch unit is operated and controlled so that the rotational speed difference does not become excessive. I did it. Therefore, the balance of torque is maintained between the engine output and the two clutch portions, and the speed change operation can be performed smoothly without causing the engine blowing-up phenomenon or shock.

  The best mode for carrying out the present invention will be described with reference to FIGS. FIG. 1 is a skeleton diagram showing a dual clutch type automatic transmission 1 targeted by a control method according to an embodiment of the present invention. The dual-clutch automatic transmission 1 according to the embodiment includes a dual clutch 2, a first input shaft 31 and a second input shaft 32, an output shaft 33, a first counter shaft 34 and a second counter shaft 35, forward 7 speed and reverse 1 Speed gear trains 41 to 47 and 4R, four synchromesh mechanisms 51 to 54, two clutch actuators 61 and 62, four actuators 65 to 68 of the four synchromesh mechanisms, three rotation speed sensors 70 to 72, an electronic control unit 8 for transmission. In addition, the broken line arrow in the figure shows the flow of transmission of the information on the rotation speed and the operation control.

  The dual clutch 2 has a first clutch portion C1 that transmits the torque of the crankshaft 91 connected to the engine to the first input shaft 31, and a second clutch portion C2 that transmits the torque to the second input shaft 32. is doing. Both clutch parts C1 and C2 are friction clutches, and are engaged and disengaged by first and second clutch actuators 61 and 62, respectively.

  The first input shaft 31 has a rod shape, and the second input shaft 32 has a cylindrical shape and is arranged on the inside and outside of the same axis. The left side of the first input shaft 31 in the drawing is connected to the first clutch portion C1 of the dual clutch 2, and the left side of the second input shaft 32 in the drawing is connected to the second clutch portion C2 of the dual clutch 2. Torque is independently transmitted between the first input shaft 31 and the second input shaft 32, and the first input shaft 31 and the second input shaft 32 can rotate at different rotational speeds. The output shaft 33 shares the axis with the first input shaft 31 and is arranged on the right side of the first input shaft 31 in the figure. Further, in parallel with these three shafts 31 to 33, a first auxiliary shaft 34 is arranged on the lower side in the drawing, and a second auxiliary shaft 35 is arranged on the upper side in the drawing.

  The gear trains 41 to 47 and 4R of the seventh forward speed and the first reverse speed are formed with the first input shaft 31 or the second input shaft 32 as a starting point and the output shaft 33 as an end point. On the first input shaft 31, odd-numbered gears are provided, and a third speed gear train 43, a first speed gear train 41, a reverse gear train 4R, a seventh speed gear train 47, and a fifth speed gear train 45 are formed in order from the left side. . The third speed gear train 43 and the first speed gear train 41 reach the output shaft 33 via the first countershaft 34. The seventh speed gear train 47 reaches the output shaft 33 via the second auxiliary shaft 35. The fifth speed gear train 45 is formed at the right end of the first input shaft 31 so as to be directly coupled to the output shaft 33. The reverse gear train 4R starts from the drive gear 48 common to the first speed and reaches the output shaft 33 via the reverse idler gear 49 and the second countershaft 35. Further, an even-numbered speed stage is provided on the second input shaft 32, and a second speed gear train 42, a fourth speed gear train 44, and a sixth speed gear train 46 are formed in order from the left side. The second speed gear train 42 and the fourth speed gear train 44 reach the output shaft 33 via the first countershaft 34. The sixth speed gear train 46 reaches the output shaft 33 via the second countershaft 35.

  Each of the gear trains 41 to 47 and 4R is selected and switched by four synchromesh mechanisms 51 to 54. That is, the fifth to seventh speed synchromesh mechanism 51 provided at the right end of the first input shaft 31 selects the fifth speed gear train 45 by moving the sleeve S to the right, and the sleeve S is moved to the left. The seventh speed gear train 47 is selected by moving, and a neutral state is selected in which neither is selected at an intermediate position. Similarly, the first to third speed synchromesh mechanism 52 provided on the right side of the first countershaft 34 can select the first speed gear train 41 and the third speed geartrain 43, and is provided on the left side of the first countershaft 34. The second-fourth speed synchromesh mechanism 53 is configured so that the second-speed gear train 42 and the fourth-speed gear train 44 can be selected. The sixth speed-reverse synchromesh mechanism 54 provided on the second countershaft 35 is configured to be able to select the sixth speed gear train 46 and the reverse gear train 4R. The sleeves S of the synchromesh mechanisms 51 to 54 are operated by the actuators 65 to 68, respectively.

  In order to detect the engine speed (not shown), an engine speed sensor 70 is provided in the vicinity of the crankshaft 91. Similarly, a first input shaft rotational speed sensor 71 that detects the rotational speed of the first input shaft 31 is provided, and a second input shaft rotational speed sensor 72 that detects the rotational speed of the second input shaft 32 is provided. .

  The operation control unit of the present invention includes the above-described two clutch actuators 61 and 62, four actuators 65 to 68, and the transmission electronic control device 8. The electronic control device 8 includes a calculation unit, a storage unit, an input / output unit, etc. (not shown), and the control method of the present invention is executed by software. The electronic control device 8 is connected to rotational speed sensors 70 to 72 so that information on the detected rotational speed is inputted. Further, the electronic control unit 8 outputs control commands to the clutch actuators 61 and 62 and the actuators 65 to 68.

  Next, the control method of the embodiment of the present invention performed for the automatic transmission 1 configured as described above will be described with reference to FIG. FIG. 2 is a diagram for explaining the control method of the embodiment by taking upshift operation from the third speed to the fourth speed as an example. The horizontal axis is time, the upper half of the vertical axis is the rotation speed, and the vertical axis The lower half shows the torque. Time T1 is a transition timing from the gear train formation process to the torque replacement process, time T2 is a transition timing from the torque replacement process to the synchronization process, and time T3 is a transition timing from the synchronization process to the gear train dissociation process.

  When traveling at the third speed, the first clutch portion C1 of FIG. 1 is engaged, the sleeve S of the first to third speed synchromesh mechanism 52 moves to the left, and the third speed gear train 43 is selectively formed. ing. The crankshaft 91 and the first input shaft 31 connected to the engine transmit torque Q1 at the rotational speed N1, and the torque Q1 is transmitted to the output shaft 33 via the first countershaft 34. At this time, since the second clutch portion C2 is disengaged, torque is not transmitted, and the second input shaft 32 is not restrained by other members, so the rotational speed is uncertain.

  When a command for shifting to the fourth speed is issued, first, the electronic control unit 8 controls and executes the gear train formation process. That is, the electronic control unit 8 outputs a control command to the actuator 67 and moves the sleeve S of the second-fourth speed synchromesh mechanism 53 to the right. Then, the fourth speed gear train 44 is selectively formed, and the second input shaft 32 is driven while being constrained to the output shaft 33 side. Since the gear ratio is different between the third speed and the fourth speed, the rotational speed N2 of the second input shaft 32 is smaller than the rotational speed N1 of the first input shaft 31.

  Next, the electronic control unit 8 controls and executes the torque replacement process. That is, at time T1 in FIG. 2, the electronic control unit 8 outputs a control command to the first clutch actuator 61, and gradually opens the first clutch portion C1. As a result, the torque Q1 transmitted due to the weak engagement of the first clutch portion C1 decreases, the load seen from the engine becomes lighter, and the engine speed NE slightly increases as indicated by point A in the figure. . Since the vehicle can be regarded as traveling at a constant speed, the rotational speed N1 of the first input shaft 31 does not change. Based on the information on the engine speed NE and the speed N1 of the first input shaft 31, the electronic control unit 8 sequentially performs calculations for subtracting the latter from the former to obtain the speed difference D.

  When the rotational speed difference D reaches a predetermined constant value, a control command is output to the second clutch actuator 62, and the second clutch portion C2 is gradually engaged. Then, as shown after the point B in the figure, the coupling of the second clutch portion C2 is strengthened and the transmitted torque Q2 increases, the load seen from the engine becomes heavy, and the increase in the engine speed NE stops. . Further, the rotational speed difference D remains at a constant value. Thereafter, even if the torque Q1 transmitted by the first clutch portion C1 is gradually reduced, feedback control for keeping the rotational speed difference D at a constant value can be performed. That is, in order to make the rotation speed difference D constant, the torque Q2 transmitted by the second clutch portion C1 can be increased. Eventually, the sum (Q1 + Q2) of the torque transmitted by the two clutch portions C1, C2 automatically balances with the engine output torque.

  The above feedback control is repeated until time T2 when the first clutch part C1 reaches the final disengagement position and the second clutch part C2 reaches the final engagement position. At time T2, the torque Q2 is transmitted from the crankshaft 91 only to the second input shaft 32 at a different rotational speed. That is, the second clutch portion C2 slips.

  Next, in order to eliminate the slip of the second clutch part C2, the electronic control unit 8 controls and executes the synchronization process. At time T2 in FIG. 2, the electronic control unit 8 requests an engine electronic control unit (not shown) to reduce the engine speed NE to the speed N2 of the second input shaft 32. Then, the engine rotational speed NE gradually decreases, and the synchronization process ends at time T3 that coincides with the rotational speed N2 of the second input shaft 32. After this, in the gear train disengaging step, the sleeve S of the first to third speed synchromesh mechanism 52 is generally returned to the intermediate position, and the third speed gear train 43 is generally dissociated.

  Since the control method of the upshift operation at other gear stages can be performed in the same manner, the description thereof is omitted. Moreover, in the downshift operation, the magnitude relationship between the rotational speeds is reversed, but a similar control method can be used.

  Next, as a control method according to another embodiment of the present invention, a mode in which the target value of the rotational speed difference D is not a constant value but a mountain-shaped curve will be described with reference to FIG. The control method shown in FIG. 3 is the same control method as in FIG. 2 except that the automatic transmission 1 described in FIG. 1 is the target and the target value of the rotational speed difference D in the torque replacement process is different. In the embodiment of FIG. 3, the rotational speed difference D obtained by subtracting the rotational speed N1 of the first input shaft 31 from the engine rotational speed NE is gradually increased in the first stage of the torque replacement process and gradually decreased in the second half of the process. The operation is controlled so as to obtain a shape.

  Then, at the end of the torque replacement process, as indicated by a point X in the figure, the engine speed NE has a rate of change corresponding to a downward slope. If this rate of change is maintained and the process proceeds to the next synchronization step, the change in the engine speed NE becomes continuous, and since the refraction is not performed as shown in FIG. 2, the process can be smoothly shifted. Furthermore, the time TW required for the synchronization process can also be shortened compared to FIG.

  In the control method of the automatic transmission of the embodiment shown in FIGS. 2 and 3, the engine speed NE and the speed N1 of the first input shaft 31 are measured in the torque replacement step, and the speed difference D between the two is successively measured. Therefore, the dual clutch 2 is operated and controlled so as not to be excessive. Therefore, the speed-up operation can be performed smoothly without causing the phenomenon of sudden increase in engine speed NE or shock.

It is a skeleton figure which shows the dual clutch type automatic transmission which the control method of the Example of this invention makes object. FIG. 2 is a diagram for explaining an example of an upshift operation performed by the control method of the embodiment of the present invention for the automatic transmission of FIG. 1. It is a figure explaining the control method of another Example of this invention which made object the automatic transmission of FIG.

Explanation of symbols

1: Dual clutch type automatic transmission 2: Dual clutch C1: First clutch portion C2: Second clutch portion 31: First input shaft 32: Second input shaft 33: Output shaft 34: First countershaft 35: Second Subshafts 41-47: 1st to 7th gear train 4R: Reverse gear train 51: 5-7th synchromesh mechanism 52: 1st-3rd synchromesh mechanism 53: 2nd-4th synchromesh Mechanism 54: 6th speed-reverse synchromesh mechanism 61: 1st clutch actuator 62: 2nd clutch actuator 65-68: Actuator 70: Engine speed sensor 71: 1st input shaft speed sensor 72: 2nd input shaft Speed sensor 8: Electronic control unit for transmission

Claims (6)

A dual clutch having a first clutch portion and a second clutch portion that selectively transmit torque output from the prime mover, a first input shaft to which torque is transmitted from the first clutch portion, and a second clutch portion; A second input shaft to which torque is transmitted, an output shaft, a plurality of gear trains that selectively transmit torque at different speed ratios from the first input shaft and the second input shaft to the output shaft, and the dual clutch And an operation control unit that selectively operates the gear train, and a gear train forming step that selectively forms the gear train after the shift, and one clutch unit that transmits torque before the shift And a torque changing process for transferring the torque from the input shaft to the other clutch portion and the input shaft that transmits torque after shifting, and the rotational speed of the prime mover and the rotation of the other input shaft. A control method for an automatic transmission having a, a synchronization step of synchronizing the number,
The torque replacement step is a rotation of the prime mover and the one input shaft that occurs when the torque transmitted by the one clutch part is decreased or when the torque transmitted by the other clutch part is increased. A method for controlling an automatic transmission, characterized in that it is a step of obtaining a number difference and controlling the operation of at least one clutch portion so that the difference in rotational speed does not become excessive.   In the torque replacement step, transmission is performed in the other clutch unit by controlling feedback of the difference in rotational speed between the prime mover and the one input shaft generated when the torque transmitted in the one clutch unit is reduced. The method for controlling an automatic transmission according to claim 1, wherein the torque is increased.   In the torque exchanging step, transmission is performed in the one clutch unit by control for feeding back the difference in rotational speed between the prime mover and the one input shaft generated when the torque transmitted in the other clutch unit is increased. The method for controlling an automatic transmission according to claim 1, which is a step of reducing torque to be generated.   The method for controlling an automatic transmission according to any one of claims 1 to 3, wherein in the torque replacement step, operation control is performed so that the difference in rotational speed between the prime mover and the one input shaft is constant.   4. The operation control is performed so that, in the torque replacement step, operation is controlled so that the rotational speed difference between the prime mover and the one input shaft increases in the first half of the process and decreases in the second half of the process. The control method of the automatic transmission as described in the item.   The method for controlling an automatic transmission according to claim 1, wherein the dual clutch is a friction clutch.

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