An automobile, a control method for the coordinated starting of its gearbox and engine

Abstract

The present invention discloses an automobile and a cooperative starting control method for its gearbox and engine. The control method includes the following steps: judging the starting condition; the EMS calculates the ignition angle demand torque according to the rotational speed request value and the actual rotational speed, and calculates the intake air demand torque according to the driver demand torque; the TCU calculates the clutch engagement target torque according to the driver demand torque and the intake air torque of the engine. Applying this solution can effectively avoid the phenomena of rotational speed drop and unevenness, and can effectively reduce the influence of the clutch torque transmission deviation.

Description

Technical Field

[0001] The present invention relates to the technical field of starting control for DCT (dual clutch automatic transmission) vehicles, and particularly relates to an automobile, a gearbox thereof, and a cooperative starting control method for an engine. Background Art

[0002] In the prior art, for the starting control of a dual clutch automatic transmission (DCT), by means of a rotational speed request to intervene in the engine speed response, problems such as rotational speed fluctuations and uneven acceleration caused by inaccurate torque transmission of the clutch, low-temperature hydraulic follow-up, etc. can be improved. However, there are still the following problems:

[0003] 1) The rotational speed request control of the engine takes the transmission control module (TCU) sending a target rotational speed to the engine control system (EMS) as the response target, and performs PID control based on the difference between the target rotational speed and the actual rotational speed. At the same time, the intake air demand torque T AirReq (Airflow Request Torque) and the ignition angle demand torque T ActReq (Actual RequestTorque) are calculated. When the actuator performs an action, there is a lag in the intake air, which easily causes the actually output intake air torque T Air (Airflow Torque) not to match the intake air demand torque T AirReq , thus resulting in problems such as rotational speed drop and unevenness.

[0004] 2) The engine is targeted at rotational speed control. When the rotational speed request is reached, the increase in the engine torque mainly depends on the increase in the load torque at the clutch end and cannot well reflect the driving intention.

[0005] 3) When there is a deviation in the torque transmission of the clutch, the engine torque within the rotational speed request will be too large or too small. After the start is completed and the rotational speed request exits, the engine torque transitions from an intervention state to a non-intervention state, easily resulting in a torque transition problem.

[0006] In view of this, it is urgent to optimize the control of the existing DCT vehicle start to overcome the above technical defects. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides an automobile, a gearbox thereof, and a cooperative starting control method for an engine. By optimizing the control strategy, the phenomena of rotational speed drop and unevenness can be effectively avoided, and the influence of the torque transmission deviation of the clutch can be effectively reduced.

[0008] The cooperative starting control method for the gearbox and the engine provided by the present invention includes the following steps:

[0009] Judge the starting condition;

[0010] The EMS calculates the ignition angle demand torque based on the rotational speed request value and the actual rotational speed, and calculates the intake air demand torque based on the driver demand torque.

[0011] The TCU calculates the clutch engagement target torque based on the driver demand torque of the engine and the intake air torque.

[0012] Optionally, the formula for calculating the ignition angle demand torque is:

[0013] T ActReq = T PID + T C ;

[0014] In the formula, T ActReq is the ignition angle demand torque, Nm; T PID is the torque calculated by the slip PID, Nm; T c is the load torque at the clutch end, Nm;

[0015] Among them, the calculation formula of T PID is:

[0016] T PID = K pl *Δn + K Il *∫Δndt + K Dl *Δn';

[0017] In the formula, T PID is the ignition angle PID torque demand, Nm; K pl , K Il , K Dl are relevant calibration parameters; Δn' is the slip change rate, rpm / s;

[0018] Among them, the calculation formula of Δn is:

[0019] Δn = n tgt - n act ;

[0020] In the formula, Δn is the rotational speed difference, rpm; n tgt is the target rotational speed, rpm; n act is the actual rotational speed, rpm

[0021] Optionally, the formula for calculating the intake air demand torque is:

[0022] Among them, f(n eng , Pedal) is a look-up table related to the engine rotational speed and the throttle, Nm; n eng is the engine rotational speed, rpm; Pedal is the throttle opening, %.

[0023] Optionally, the formula for calculating the target torque for clutch engagement is:

[0024] T ClchTat = filter(Min(T Air , T DrvIntd )) - T Iner :

[0025] In the formula, T ClchTgt is the target torque for clutch engagement, in Nm; T Air is the intake torque of the engine, in Nm; T DrvIntd is the driver demand torque, T Iner is the inertia torque, in Nm.

[0026] Optionally, when the actual torque transmitted by the clutch is too large, the clutch torque remains at the current torque or decreases.

[0027] Optionally, taking the difference between the engine speed and the target speed being less than the speed difference threshold or the engine speed change rate being greater than the speed change rate threshold as the judgment condition, it is determined that the actual torque transmitted by the clutch is too large.

[0028] Optionally, when the clutch torque has not reached the target torque for clutch engagement, the clutch torque is loaded at the engagement rate.

[0029] Optionally, when the clutch torque reaches the target torque for clutch engagement and the actual torque transmitted by the clutch is too small, the engine ignition angle is increased by increasing the clutch torque, so that the ignition angle torque reaches near the intake torque.

[0030] Optionally, taking the ignition angle torque being lower than the intake torque and exceeding the threshold range as the judgment condition, it is determined that the actual torque transmitted by the clutch is too small.

[0031] The present invention also provides an automobile, including an engine and a dual-clutch automatic transmission, and the automobile adopts the co-start control method of the transmission and the engine as described above.

[0032] Compared with the prior art, this solution proposes a collaborative control method for the gearbox and the engine during the starting process, so as to overcome the above-mentioned defects of the prior art. Specifically, after judging and entering the starting stage, the EMS calculates the ignition angle demand torque according to the rotational speed request value and the actual rotational speed, and calculates the intake air demand torque according to the driver demand torque. Here, the intake air demand torque responds to the driver demand torque and is not affected by the rotational speed request; that is to say, the engine intake air torque is the engine capacity torque output by the engine according to the actual response, and its magnitude is related to the current intake air volume, thus avoiding the rotational speed response fluctuation. At the same time, the TCU calculates the clutch engagement target torque according to the driver demand torque and the intake air torque of the engine, and the adjustment of the clutch torque enables the actual output torque of the engine to reach the capacity torque, covering the deviation of the vehicle acceleration caused by inaccurate torque transmission of the clutch; the torque output is smooth before and after starting to exit, improving the smoothness of the working condition transition. Description of the Drawings

[0033] Figure 1 It is a control signal interaction block diagram between the EMS and the TCU described in the specific embodiment;

[0034] Figure 2 It is an EMS control flow chart for the collaborative starting control of the gearbox and the engine described in the specific embodiment;

[0035] Figure 3 It is a TCU control flow chart for the collaborative starting control of the gearbox and the engine described in the specific embodiment;

[0036] Figure 4 It is a schematic diagram of rotational speed request control during the starting process described in the specific embodiment;

[0037] Figure 5 It is a schematic diagram of deep clutch torque deviation control described in the specific embodiment;

[0038] Figure 6 It is a schematic diagram of shallow clutch torque deviation control described in the specific embodiment. Specific Embodiment

[0039] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0040] For the starting rotational speed request control of a dual-clutch automatic transmission, this application proposes an independent calculation of rotational speed response requirements, that is, separately calculating the intake air demand torque and the ignition angle demand torque. At the same time, the TCU jointly controls the rotational speed form to solve the problem of unevenness during the starting of the DCT gearbox and the problem that the vehicle acceleration does not match the target.

[0041] The co - starting control method of the transmission and the engine described in this embodiment includes the judgment of the starting condition, the EMS speed control, and the TCU collaborative control.

[0042] 1) Judgment of the starting condition: The EMS judges whether it is a speed request for the starting condition through signals such as the speed request value, the speed request type, the speed request intervention method, the gear position, the throttle, and the speed overshoot situation. If it is, it enters the speed request control for the starting condition; if not, it enters the general control.

[0043] As Figure 1 shown, the EMS acquires the throttle, the gear position, the speed request value, the speed request type, the speed request intervention type at the TCU end, and the load torque signal of the clutch.

[0044] Here, the "speed request type" can include Max (not exceeding the request value), Min (not less than the request value), MaxAndMin (equal to the request value); the "speed request intervention type" can include two intervention types: stable response and fast response. In other specific applications, the speed request type and the speed request intervention type are not limited to the foregoing type settings and can be determined according to the actual product design requirements.

[0045] Please refer to Figure 2 together, which is the EMS control flow chart of the co - starting control of the transmission and the engine described in this embodiment.

[0046] As Figure 2 shown in step S21 of

[0047] If the throttle is depressed, and the gear position is in the 1st gear or 2nd gear or R gear, and the speed request value at the TCU end > 0, and the speed request type is 3 (equal), and the speed request intervention type is 3 (stable response), it is determined to enter the starting speed request control.

[0048] 2) EMS speed control:

[0049] After entering the starting speed request control, the EMS calculates the ignition angle demand torque by doing PID control according to the difference between the speed request value and the actual speed. The formula is:

[0050] T ActReg = T PID + R C

[0051] Among them, T ActReg is the ignition angle demand torque, Nm; T PID is the torque calculated by the slip PID, Nm; T c is the load torque at the clutch end, Nm.

[0052] Here, asFigure 2 As shown in step S22 in

[0053] First, calculate the rotational speed difference: Δn = n tgt - n act .

[0054] where Δn is the rotational speed difference, rpm; n tgt is the target rotational speed, rpm; n act is the actual rotational speed, rpm.

[0055] Then, calculate the PID torque demand based on the rotational speed difference Δn:

[0056] T PID = K pl *Δn + K Il *∫Δndt + K Dl *Δn';

[0057] In the formula, T PID is the ignition angle PID torque demand, Nm; K pl , K Il , K Dl are relevant calibration parameters; Δn' is the slip change rate, rpm / s.

[0058] In this solution, the engine ignition angle torque T Act is the actual torque obtained by the engine by controlling the ignition angle, and its magnitude is limited by the current intake air volume and is related to the minimum ignition angle and the basic ignition angle.

[0059] Here, the load torque T c at the clutch end is determined based on the relationship between the clutch pressure or position and the transmitted torque, and can be specifically obtained through bench tests and written into the TCU controller. During application, according to the pressure or position collected by the clutch pressure sensor or position sensor, the corresponding load torque can be obtained by looking up the corresponding relationship table written by the TCU.

[0060] Different from the original strategy, the intake air demand torque is not affected by the rotational speed request at this time, but responds to the driver demand torque (T DrvIntd ), and its formula is:

[0061] T AirReq = T DrvIntd = f(n eng , Pedal)

[0062] where f(n eng , Pedal) is a look-up table related to the engine rotational speed and throttle, Nm; n eng is the engine rotational speed, rpm; Pedal is the throttle opening, %.

[0063] In this solution, the engine intake torque T Air is the engine capacity torque actually output in response to T AirReq , and its magnitude is related to the current intake air volume.

[0064] Furthermore, as shown in step S23 of Figure 2 , the intake demand torque T AirReg is judged and calculated.

[0065] If Δn < the threshold value, the engine speed has a serious overshoot, and it may not be possible to pull the speed into the target range only by the method of ignition angle control. At this time, the calculation of the intake demand torque T AirReg is the same as the calculation of the ignition angle torque T Act , and it also needs to respond to the speed request control, which is a PID control related to Δn.

[0066] If Δn > the threshold value, it means that the method of single ignition path adjustment can avoid speed overshoot. At this time, the calculation of the engine intake demand torque is different from the calculation of the ignition angle demand torque T ActReg , and it is not affected by the speed request. It directly responds to the driver demand torque (T DrvIntd ), and this torque is the target torque set according to the vehicle acceleration demand, which is related to the engine speed and throttle.

[0067] Furthermore, as shown in step S24 of Figure 2 , the engine controls the ignition angle magnitude to output the ignition angle torque T ActReg according to the ignition angle demand torque T ACT , and the engine controls the throttle opening, supercharging and other intake mechanisms to output the intake torque T AirReq according to the intake demand torque T AIR .

[0068] Please also refer to Figure 3 , and this figure is the TCU control flow chart of the coordinated start control of the transmission and the engine described in this embodiment.

[0069] 3) TCU coordinated control:

[0070] As Figure 3 shown in step S31 of, the TCU calculates the clutch engagement target torque according to the driver demand torque and the intake torque of the engine. To avoid target fluctuations caused by excessive demand torque and torque fluctuations in the initial stage, it is necessary to take the smaller value of the two torques and perform filtering processing. The inertia torque is the torque related to the engine speed increase rate.

[0071] That is to say, the clutch engagement rate is determined by the vehicle acceleration target, and the clutch engagement target torque is the difference between the filtered torque after taking the smaller value of the intake torque and the driver demand torque and the inertia torque, which can be expressed as:

[0072] T ClchTgt = filter(Min(T Air , T DrvIntd )) - T Iner

[0073] Wherein, T ClchTgt is the target torque for clutch engagement, Nm; T Air is the intake torque of the engine, Nm; T DrvIntd is the driver demand torque, T Iner is the inertia torque, Nm.

[0074] The relationships of each torque are as shown Figure 4 in the figure.

[0075] As shown in S32, if the difference between the engine speed and the target speed is still large or the engine speed change rate is small at this time, the actual torque transmitted by the clutch may be too large, and the clutch torque needs to maintain the current torque or even decrease, in order to avoid possible difficulties in speed increase or speed drop. The judgment of the clutch torque behavior is mainly related to the settings of the speed difference and the speed change rate related thresholds.

[0076] As shown in S33, if the clutch torque at this time has not reached the target torque calculated in S31, the clutch torque is loaded at the given engagement rate. The setting of the engagement rate should be related to the acceleration curve required by the vehicle, and at the same time, relevant factors such as the throttle, impact degree, and environment need to be considered.

[0077] As shown in S34, if the clutch torque at this time has reached the target torque calculated in S31, it is necessary to judge whether the ignition angle torque of the engine is consistent with the intake torque. If the ignition angle torque is lower than a certain threshold of the intake torque, it is judged that the actual torque transmitted by the clutch is too small at this time, and it is necessary to increase the clutch torque to guide the engine to increase the ignition angle so that the ignition angle torque reaches near the intake torque.

[0078] As shown in S35, if the difference between the engine speed and the shaft speed of the clutch gradually decreases and is less than a certain value, it is judged that the speed is synchronized, the speed request exits, and the starting control is completed.

[0079] It should be noted that since the intake torque no longer responds to the speed request, even if the ignition angle demand torque is larger after the ignition angle torque reaches the intake torque, torque increase cannot be achieved. Therefore, based on the following possible working conditions, this embodiment further proposes optimization processing means:

[0080] Working condition 1: Overshoot of speed caused by slow clutch loading.

[0081] In order to avoid initial impact during the clutch engagement process, the clutch is generally engaged slowly. At this time, the engine torque is large, which often causes speed overshoot. At this time, the EMS can respond to the speed request to calculate the ignition angle torque demand closed-loop control to reduce the actual engine torque output and avoid speed overshoot.

[0082] Working condition 2: Excessive speed overshoot due to excessive intake torque and shallow clutch torque.

[0083] Due to the excessive intake torque, the engine ignition angle has been adjusted to the minimum through working condition 1, but the speed cannot be controlled within the target range. At this time, the intake torque is required to respond to the speed request to avoid excessive speed overshoot.

[0084] Working condition 3: Speed drop due to excessive clutch torque.

[0085] Since the actual torque transmitted by the clutch is higher than the representative torque of the clutch, the engine speed is pulled down. At this time, the engine's ignition angle torque reaches the intake torque. Since the engine intake torque (capacity torque) does not respond to the speed request, torque increase cannot be achieved. At this time, the clutch torque reduction method is needed to increase the speed. The clutch torque reduction control is a PID control based on the difference between the target speed and the actual speed. As shown in the figure Figure 5 shown.

[0086] Working condition 4: The engine ignition angle torque output is too small due to insufficient clutch torque transmission.

[0087] If the clutch base point is shallow, the actual torque transmission is lower than the representative torque of the clutch. EMS can reach the target speed through ignition angle adjustment, but at this time the engine's ignition angle has not reached the vicinity of the basic ignition angle, and there is still reserve torque. At this time, the clutch torque increase method is required to increase the actual engine torque to achieve the intake torque. The clutch torque increase control is a closed-loop control of the difference between the intake torque and the actual torque. By controlling the clutch torque to combine at a certain rate, the actual engine torque follows the intake torque. This can avoid the torque jump when the ignition angle torque transitions to the intake torque after the speed request is exited, and also improves economy. Control as shown in the diagram Figure 6 shown.

[0088] In summary, after the EMS and TCU control implement this strategy, the speed response fluctuation problem can be effectively avoided; the actual output torque of the engine reaches the capacity torque through the adjustment of the clutch torque, covering the acceleration deviation of the whole vehicle caused by inaccurate clutch torque transmission; the torque output before and after starting and exiting is smooth, which improves the smoothness of the working condition transition.

[0089] In addition to the aforementioned co-start control method for the gearbox and the engine, this embodiment also provides a vehicle, which includes an engine and a dual-clutch automatic transmission, and adopts the aforementioned co-start control method for the gearbox and the engine to achieve the aforementioned technical effects. It should be understood that the other functional components of this vehicle are not the core inventive points of this application. For example, but not limited to, the engine and the dual-clutch automatic transmission, etc., and those skilled in the art can implement them based on the prior art, so they will not be elaborated herein.

[0090] Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing relevant hardware through a program, and this program can be stored in a computer-readable storage medium. The storage medium can include: ROM, RAM, magnetic disk or optical disk, etc.

[0091] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A cooperative starting control method for a gearbox and an engine, characterized in that, Including the following steps: Judge the starting condition; The EMS calculates the ignition angle demand torque according to the rotational speed request value and the actual rotational speed, and calculates the intake air demand torque according to the driver demand torque; The TCU calculates the clutch engagement target torque according to the driver demand torque and the intake air torque of the engine; The formula for calculating the ignition angle demand torque is: ； Wherein, is the ignition angle demand torque, Nm; is the torque calculated by the rotational speed difference PID, Nm; is the load torque at the clutch end, Nm; Among them, The calculation formula is: ; Wherein, , , are relevant calibration parameters; is the rate of change of rotational speed difference, rpm / s; Among them, The calculation formula is: ； Wherein, is the rotational speed difference, in rpm; is the target rotational speed, in rpm; is the actual rotational speed, in rpm.

2. The co-start control method of the gearbox and the engine according to claim 1, characterized in that, The calculation formula for the intake air demand torque is: Among them, is a look-up table related to engine speed and throttle, Nm; is the engine speed, rpm; is the throttle opening, %.

3. The co-start control method of the gearbox and the engine according to claim 1 or 2, characterized in that, The formula for calculating the clutch engagement target torque is: ； Wherein, is the target torque for clutch engagement, Nm; is the intake torque of the engine, Nm; is the driver demand torque, is the inertia torque, Nm.

4. The co-start control method for a gearbox and an engine according to claim 3, characterized in that, When the actual torque transmitted by the clutch is too large, the clutch torque remains the current torque or reduces the torque.

5. The co-start control method of the gearbox and the engine according to claim 4, characterized in that Taking that the difference between the engine rotational speed and the target rotational speed is less than the rotational speed difference threshold or the engine rotational speed change rate is greater than the rotational speed change rate threshold as the judgment condition, it is determined that the actual torque transmitted by the clutch is too large.

6. The co-start control method for a gearbox and an engine according to claim 3, wherein When the clutch torque has not reached the clutch engagement target torque, the clutch torque is loaded at the engagement rate.

7. The method for controlling the coordinated start of a gearbox and an engine according to claim 3, characterized in that, When the clutch torque reaches the clutch engagement target torque and the actual torque transmitted by the clutch is too small, the engine ignition angle is increased by increasing the clutch torque, so that the ignition angle torque reaches near the intake air torque.

8. The co-start control method of the gearbox and the engine according to claim 7, characterized in that, Taking that the ignition angle torque is lower than the intake air torque and exceeds the threshold range as the judgment condition, it is determined that the actual torque transmitted by the clutch is too small.

9. An automobile, comprising an engine and a dual clutch automatic transmission, characterized in that, The vehicle adopts the transmission and engine coordinated starting control method according to any one of claims 1 to 8.

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