[0047] The technical solutions of the present invention will be described in detail by the following examples. The following examples are only exemplary, and can only be used to explain and illustrate the technical solutions of the present invention, but cannot be construed as limitations on the technical solutions of the present invention.
[0048] A wet dual-clutch automatic transmission micro-slip control method, such as figure 1 shown, including initialization control, torque drop control, torque rise control and micro-slip control.
[0049] Before the transmission is controlled, it is first judged whether the transmission meets the micro-slip control conditions. The micro-slip control conditions include that the transmission is not creeping, not starting, not shifting, and the clutch is not Open and not in failure mode.
[0050] After judging, if it matches, then proceed to the initialization control stage.
[0051] Under the initial control condition, it is judged whether the slip meets the first set threshold. In an embodiment of the present application, the first set threshold is 20 rpm, that is, if it is judged that the slip is less than or equal to 20 rpm.
[0052] The slip calculation method, such as figure 2 shown, including the following steps:
[0053] Determine whether the driving gear in gear is an odd-numbered gear,
[0054] If it is an odd-numbered gear, judge whether the difference between the engine speed and the input shaft speed is less than or equal to the first set speed threshold, and whether the engine torque is less than or equal to the first engine torque set threshold. If so, then slip = input one. Shaft speed - engine speed; if not, slip = engine speed - input shaft speed, in this embodiment, the first set speed threshold is 10rpm (preferred value), and the first engine torque set threshold is 5nm.
[0055] If it is a non-odd gear, judge whether the difference between the engine speed and the input two-shaft speed is less than or equal to the second set speed threshold, and whether the engine torque is less than or equal to the second engine torque set threshold, if so, then slip = input Two-shaft speed - engine speed; if not, slip = engine speed - input two-shaft speed. The second set rotational speed threshold is 10 rpm (preferred value), and the second engine torque set threshold is 5 nm.
[0056] If the first set threshold is met, the gearbox performs torque drop control; if the first set threshold is not met, the gearbox performs slip control.
[0057]Under the torque drop control condition, it is judged whether the first control condition is met. If the first control condition is met, the gearbox performs slip control; if the first control condition is not met, the second control condition is judged. If the second control condition is not met, the torque increase control is performed, and if the second control condition is not met, the transmission performs the torque decrease control.
[0058] The first control condition is: slip ≤ the second set threshold. In this embodiment, the second set threshold is 15 rpm, and the non-slip time is less than the first set time. In this embodiment, The first set time is 1000ms, and the clutch request torque ≤ the first set torque, in this embodiment, the first set torque is 2.5nm, the slip change
[0059] The calculation logic of slip change is as follows image 3 As shown, the slip change = current slip - previous sample slip.
[0060] The second control condition is: the slippage time ≈=0ms, and the severe slippage time is the second set time. In this embodiment, the second set time is 500ms, and the slip change
[0061] Under the torque increase control, it is determined whether the second control condition is met. If the second control condition is met, the transmission maintains the torque increase control. If the second control condition is not met, the transmission The transmission has slip control.
[0062] Under the sliding friction control, it is judged whether the third control condition is met. If the third control condition is met, the gearbox performs torque reduction control; if the third control condition is not met, it is judged whether the third control condition is met. The second control condition, if the second control condition is met, the transmission enters the torque rise control, and if the second control condition is not met, the transmission maintains the slip control.
[0063] The third control condition is: non-slip time≥first set time, clutch request torque>first set torque, and slip change
[0064] The calculation method of the slippage time, such as Figure 5 shown, including the following steps:
[0065] It is judged that the slip is less than or equal to the absolute value of the third set threshold. If it matches, the slip time is 0ms. If not, the slip time is the previous slip time + 10ms, and the third set threshold is re-judged. is 15rpm.
[0066] The calculation method of the serious skid time, such as Figure 4 shown, including the following steps:
[0067] It is judged whether the severe slippage time is greater than the fourth set threshold value, if so, the severe slippage time = the previous severe slippage time + 10ms, if not, the severe slippage time is 0ms, and the fourth set threshold value is 100rpm.
[0068] The initialization control is desired torque=open-loop partial torque+first corrected partial torque;
[0069] The open-loop part torque=expected torque*0.5+engine actual torque*0.5;
[0070] The first corrected partial torque=expected torque at the previous moment-open-loop partial torque.
[0071] The torque drop control is desired torque=open-loop partial torque+second modified partial torque;
[0072] The open-loop part torque=expected torque*0.5+engine actual torque*0.5;
[0073] The second correction part torque is controlled as follows, such as Image 6 As shown, the basic idea of the modified partial torque control is to use a larger gradient descent when the torque is not too small; when the torque is a smaller value, use a smaller gradient descent or torque maintenance.
[0074] The control method for the second modified partial torque includes the following steps:
[0075] Judging whether the expected torque is less than the minimum torque limit, the minimum torque value is preferably 2.5nm, if so, the second corrected partial torque maintains the torque at the previous moment, if not, judge whether the second corrected partial torque < the corrected torque limit , or desired torque
[0076] The torque rise control is desired torque=open-loop partial torque+third modified partial torque;
[0077] The open-loop part torque=expected torque*0.5+engine actual torque*0.5;
[0078] The third modified partial torque control method, such as Figure 7 shown, including the following steps;
[0079] start, rise torque = 0nm;
[0080] It is judged that the rising torque < the maximum limit of the rising torque, if yes, the third correction torque = the third correction torque at the previous moment + Rate3, the rising torque = the rising torque + Rate3; if not, the third correction torque and the rising torque remain unchanged.
[0081] The preferred value of the maximum limit value of the rising torque is 50 nm, and the preferred value of the Rate3 is 1 nm.
[0082] The micro-slip control is feedforward torque = open-loop part torque = (expected torque * 0.5 + engine actual torque * 0.5);
[0083] Correction torque = correction torque at the previous moment + PID.
[0084] Desired torque = open loop partial torque + corrected partial torque.
[0085] P = P term coefficient * slip change.
[0086] I=I coefficient * (current slip - target slip), the preferred value of target slip is 35rpm.
[0087] D=D item coefficient*slip change rate-previous time (D item coefficient*slip change rate).
[0088] The P-term coefficient is preferably 2, the I-term coefficient is preferably 0.2, and the D-term coefficient is preferably 1.
[0089] The present application discloses a micro-slip control system for a wet dual-clutch automatic transmission. The micro-slip control is performed on the transmission, and the goal is to make the actual slip of the transmission reach the target slip. Vibration isolation of the engine, the control should not only consider the ability to isolate vibration, but also consider clutch wear and fuel consumption. The goal of the control is to avoid too low slip, resulting in clutch jamming, which cannot achieve the purpose of isolating vibration; Avoid excessive slip, causing the clutch to heat up too quickly.
[0090] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and variations, the scope of the present invention is defined by the appended claims with full equivalents.
