Control procedure for a dual-clutch transmission

Abstract

Method (300) for controlling a dual-clutch transmission (14), the method (300) comprising: providing a dual-clutch transmission (14) with a dual-clutch module, a first and a second input shaft (25, 27), a first and second countershaft (126, 128), a plurality of coplanar gear sets (140, 150, 160, 170, 180, 190) and a plurality of synchronizers (250, 252, 254, 256) capable of providing a plurality of forward gear torque ratios and a reverse gear torque ratio; Receiving (302) a command to engage the reverse gear torque ratio; the switching (304) of a first of the plurality of synchronizers (252) to engage a reverse gear (GR) of a first of the plurality of coplanar gear sets (190) with the first layshaft (126); the switching (304) of a second of the plurality of synchronizers (254) to engage a first gear (184) of a second of the plurality of coplanar gear sets (180) with the second countershaft (128), wherein the first gear (184) of the second of the plurality of coplanar gear sets (180) is able to provide a first torque ratio (G1) when engaged with the second countershaft (128); the engagement (304) of a first clutch (C2) of the dual clutch module; the detection (306) of a multitude of events indicating an unwanted noise, including the detection of a multitude of events indicating an unwanted noise, the detection of a multitude of accelerator pedal depressors and releasers, a multitude of brake pedal depressors and releasers, and a multitude of crossings of the torque zero point; the switching (308) of the second of the plurality of synchronizers (254) to disengage the first gear (184) of the second of the plurality of coplanar gear sets (180) from the second countershaft (128).

Description

TECHNICAL AREA

[0001] The present disclosure relates to a transmission, and in particular a compact dual-clutch multi-speed transmission with three axles for building up several gear ratios. BACKGROUND

[0002] The explanations in this section merely provide background information relating to the present disclosure and may or may not correspond to the current state of the art.

[0003] A dual-clutch transmission (DCT) uses two friction clutches to switch between its forward gear ratios. In operation, the DCT performs these shifts through the reciprocal engagement of the two friction clutches and the engagement of one of several coplanar gear sets with one of a pair of countershafts. One of the advantages of a DCT is its ability to make rapid gear ratio changes. This is achieved by engaging multiple gear ratios simultaneously with their respective countershafts.

[0004] Although current DCTs achieve their intended purpose, there is a need for new and improved transmission control methods that offer enhanced performance, particularly with regard to noise and vibration emissions, which are detrimental to the driver. Accordingly, there is a demand in the field for a transmission with improved noise and vibration performance, providing simultaneous gear ratios, torque ranges, and rapid gear ratio changes.

[0005] DE 10 2006 008 207 A1 discloses a method for reducing unwanted noise, comprising shifting the inactive sub-transmission into neutral when unwanted noise occurs. ROBERT BOSCH GmbH: Electronic Transmission Control EGS, 1st edition, Plochingen, company publication, 2004 (Yellow Series, Automotive Technology Expertise, Safety and Comfort Systems), pages 12-13, ISBN 3-7782-2027-6 discloses the design and operation of a dual-clutch transmission from ROBERT BOSCH GmbH. DE 10 2015105 847 A1 discloses a shift control method for a vehicle with a dual-clutch transmission, comprising determining whether rapid throttle release occurs during torque transfer control. SUMMARY

[0006] The present invention provides a method for controlling a dual-clutch transmission according to claim 1.

[0007] The aforementioned functions and advantages, as well as other functions and advantages of the present disclosure, will become apparent from the following detailed description of the best possible practical implementation of the presented disclosure in communication with the associated drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic representation of a vehicle with a dual-clutch transmission (DCT) according to the present invention; Fig. 2 is a set of time diagrams describing the change amplitudes of various vehicle performance values ​​according to the present invention; Fig. Figure 3 is an exemplary torque-to-position model that is used with the vehicle from Fig. 1 is usable according to the present invention; Fig. Figure 4 is a schematic cross-section of an embodiment of a seven-speed transmission according to the present invention; and Fig. 5 is a flowchart that illustrates an embodiment of a transmission control method for the [system / device] described in the Fig. Figures 1-4 describe the vehicle and the transmission according to the present invention. DESCRIPTION

[0008] Referring to the drawings, in which the same reference symbols correspond to the same components in the different figures, it is stated in Fig. Figure 1 shows a schematic representation of a vehicle 10. The vehicle 10 includes an internal combustion engine 12 and a dry dual-clutch transmission (dDCT) 51, which is operationally connected to the engine 12. The dDCT includes two independently actuated drive clutches, i.e., the first and second input clutches C1 and C2 respectively, and is characterized by the absence of any circulation of cooling or lubricating fluids to the first and second drive clutches C1 and C2. The speed of the engine 12 responds to a received throttle request (arrow Th%), e.g., a force or a percentage of the travel of a throttle applicator 11, such as an accelerator pedal, a hand applicator, or another suitable device, which indicates a relative level of the requested engine torque. Such a force / movement can be detected by a sensor (not shown).In response to the reception of the throttle request (arrow Th%), the motor 12 generates a drive torque (arrow TI) for the dDCT arrangement 51 and provides the drive torque (arrow TI) via a rotatable drive element 15 for the dDCT assembly 51.

[0009] The vehicle 10 further includes a brake applicator 40 and a brake applicator position sensor (PS) 42 connected to the brake applicator 40. The brake applicator 40 is connected to the brakes (not shown) of the vehicle 10 and can be a brake pedal, a hand applicator, or any other suitable device. During operation of the vehicle 10, an operator can press the brake applicator 40 to apply the brakes of the vehicle 10, thereby reducing the speed of the vehicle 10. The brake applicator 40 can be released to increase the speed of the vehicle 10. The brake device position sensor 42 can detect the position of the brake applicator 40 and send a brake applicator position signal 44 to the ECM 30. The brake applicator position signal 44 indicates the position of the brake applicator 40.In response to the brake applicator position signal 44, the ECM 30 can determine or detect whether the brake applicator 40 is being applied or released. For example, the brake applicator position sensor 42 can send a brake applicator position signal 44 in response to the release of the brake applicator 40. Thus, the brake applicator position sensor 42 can communicate with the ECM 30. Although not shown in the drawings, it is intended that the brake applicator position sensor 42 can be in direct electronic communication with the TCM (transmission control module) 20. The TCM 20 can then receive the brake applicator position signal 44 directly from the brake applicator position sensor 42. In either case, the TCM 20 can receive the brake applicator position signal 44 directly from the brake applicator position sensor 42 or indirectly via the ECM 30. Therefore, the TCM 20 can detect or determine whether the brake applicator 40 is engaged or disengaged.

[0010] As already mentioned, vehicle 10 includes a DCT assembly 51. The DCT assembly 51 in turn includes a dDCT 14 and the TCM 20. The dDCT 14 is an automated, near-manual transmission with a gearbox 13 featuring two independently operated drive clutches, i.e., the respective first and second clutches C1 and C2, which are located in Fig. 1 are shown. Although in Fig. Figure 1, omitted for illustrative simplicity, shows that each drive clutch C1 and C2 can include a center plate containing any number of friction discs, friction plates, or other suitable friction materials. In the dDCT 14, the fluid (arrow F) can circulate only to the transmission 13. Instead of the dDCT 14, the vehicle 10 can include a wet DCT. In a wet DCT, fluid (arrow F) can be circulated to the drive clutches C1 and C2 by a motor-driven fluid pump 31. Therefore, instead of the dDCT 14, the vehicle 10 can include a wet DCT or any other suitable transmission. Associated electronic and hydraulic clutch control devices (not shown) ultimately control the shifting operation and vehicle start-up in response to commands from various onboard controls, as detailed below.In the present disclosure, the TCM 20 can also be described as a system for controlling the DCT assembly 51, the dDCT 14, or both.

[0011] In the exemplary dDCT 14 from Fig. Within the individual gear sets 24 and 29, additional clutches, such as hydraulically actuated rotary or brake clutches, can be engaged or disengaged as needed to establish the desired gear position. The reverse gear position can be controlled via the first drive clutch C1. With this type of gear arrangement, the dDCT 14 can be quickly shifted through its available gears without completely interrupting the power flow from the motor 12. The arrangement of the gear sets 24 and 29 of the dDCT 14 is described in more detail below.

[0012] The in Fig. The vehicle control systems 10 shown in Figure 1 include at least one transmission control module (TCM) 20 and one engine control module (ECM) 30. As further below with reference to Fig. As described in detail in Figures 2-4, the TCM 20 interacts with the ECM 30 during the creeping of the vehicle 10 to implement engine acceleration-based closed-loop position control via any actuators of the designated drive clutch, e.g., clutch pistons. For a dry DCT, the present transmission control approach can help address the basic variations for improving creep performance. Although this variant is generally widespread with dry DCTs, a creeping vehicle with a wet DCT can also benefit from the present transmission control due to the lack of cooling at the friction interfaces of the drive clutches.

[0013] In the case of the exemplary vehicle 10 of Fig. The dDCT 14 also includes an output shaft 21 connected to a set of drive gears (not shown). The output shaft 21 ultimately transmits output torque (arrow) to the drive gears to propel the vehicle 10. The dDCT 14 may include a first shaft 25 connected to the first drive clutch C1, a second shaft 27 connected to the second drive clutch C2, and respective odd and even gear sets 24, 29 (GSO, GSE) positioned within the transmission 13. Both gear sets can be cooled and lubricated by circulating transmission fluid from an oil pan 35 via a motor-driven main pump 31, e.g., via a pump shaft 37, or alternatively via an additional pump (not shown).

[0014] Within the dDCT 14, the first shaft 25 is connected only to and drives the odd-numbered gear sets 24 (GSO). The second shaft 27 is connected only to and drives the even-numbered gear sets 29 (GSE), including a reverse gear set. The dDCT 14 also includes upper and lower main shafts 17 and 19, respectively, which are connected to final drive (F / D) gear sets 34 and 39. The final drive gear sets 34 and 39, in turn, are connected to the output shaft 21 of the dDCT 14 and are configured to provide any required final gear reduction.

[0015] With reference to the controls of the vehicle 10, the TCM 20 and the ECM 30 can be configured as a microprocessor-based device with elements such as processors 22, 32, which are tangible non-transient memories 23, 33, including but not necessarily limited to a solid-state memory (ROM), working memory (RAM), electronically erasable programmable write-protected memory (EEPROM), flash memory, etc., and circuits including but not limited to a high-speed clock, analog-to-digital (A / D) circuit, digital-to-analog (D / A) circuit, a digital signal processor or DSP, transceivers 26, 36, and the necessary input / output (I / O) devices and other signal-conditioning and / or buffering circuits.

[0016] The TCM 20 and ECM 30 are programmed to execute the necessary steps of the transmission control procedure 300, an example of which is shown in Fig. Figure 5 shows that the TCM 20 provides, in particular, proportional integral derivative (PID) position control over the operation of a named first and second clutch C1, C2 during the entire duration of a creep of the vehicle 10. Within the framework of the present transmission control method, the ECM 30 can generate various control values, including an engine speed request for controlling the engine 12 and an engine inertial torque (arrow Iα), the latter of which is transmitted to the TCM 20 for use in a calculation by the TCM 20, which is hereinafter referred to as the calculated clutch torque.Ultimately, the TCM 20 uses the motor inertial torque (arrow Iα) as a feedback value when maintaining position control via the first and second clutches C1, C2, and outputs a position control signal (arrow PX) to the designated first and second clutches C1, C2, in order to control the position of the designated first and second clutches C1, C2 in the manner described below.

[0017] With reference to Fig. Figure 2 shows a series of curves 50 to illustrate various performance characteristics of the vehicle 10 of Fig. Figure 1 describes a reverse driving maneuver. In each of the curves, the amplitude (A) is plotted on the vertical axis, and the time (t) is plotted on the horizontal axis. At time t0, the driver depresses the brake applicator 40 and positions the transmission in reverse (R). The TCM 20 signal sends a basic clutch command to the first or second clutch C1, C2. Specifically, at time t0, when the brake applicator 40 is at least partially depressed, the TCM 20 sends a kissing point position signal to the designated first or second clutch C1, C2, thereby controlling the designated first or second clutch C1, C2 to be at its kissing point position Pk. At the kissing point position Pk, the designated first or second clutch C1, C2 begins to transmit torque from the engine 12.Therefore, the kissing point position Pk is defined as the clutch position at which the designated first or second clutch C1, C2 begins to transmit torque from the motor 12.

[0018] At or near time t1, the driver releases the brake applicator 40, and the brake device position sensor 42 sends the brake applicator position signal 44 to the ECM 30, indicating that the brake applicator 40 has been released. At time t2, the creep mode of the dDCT 14 transmission is activated. For this purpose, the TCM 20 can send a creep mode activation signal (trace 49) to the dDCT 14. In creep mode, the dDCT 14 allows the vehicle 10 to move. Fig. 2 is the creep mode signal (curve 49) shown as a step signal.

[0019] Another of the in Fig. The curve 50 shown in Figure 2 represents the controlled clutch torque (curve Tc), which rises rapidly at the beginning of the vehicle's creep and then begins to stabilize at approximately time t4, when the TCM 20 makes necessary adjustments. The controlled clutch torque (curve Tc), extracted as a calibration value from the TCM 20, for example, from the lookup table or a torque model recorded in memory 23, may differ from the engine torque. In one embodiment, the controlled clutch torque (curve Tc) may correspond to an output engine torque. As used herein, "controlling clutch torque" refers to the clutch torque required to creep the vehicle 10 after the brake applicator 40 has been released but before the throttle applicator 11 has been actuated.

[0020] Fig. Figure 2 also illustrates a calculated clutch torque (Tcc), which can correspond to the sum of the actual engine torque and the product of the engine inertia (I) and the acceleration (α) of the engine 12. The calculated clutch torque difference (Δ) between the controlled clutch torque (curve Tc) and the calculated controlled clutch torque (curve Tcc) is used by the TCM 20 to precisely determine when and by how much to increase or decrease a clutch position signal, with the basic clutch position signal as curve Px and the modified clutch position signal as curve Pf. In other words, the TCM 20 monitors the engine and the engine inertia (Iα) to determine how much load is applied to the first or second clutch C1, C2 of the dDCT 14 during vehicle creep and then adjusts the position signal (curve Px) as needed over time.

[0021] With further reference to Fig. 2. The basic coupling position signal (curve Px) is generated by the TCM 20. Fig. 1 is generated and goes to the first or second coupling C1, C2 of Fig. 1 is transmitted, which is used to control the vehicle so that it creeps. As used herein, an "increased" clutch position signal is any position signal or command that results in movement of the clutch actuating piston or other actuator in the direction of the first or second clutch C1, C2, and is thus a signal that results in an increase in clutch torque. Likewise, a "decreased" clutch position signal results in movement of a clutch actuating piston or other actuator in the disengagement direction, and is thus a signal that results in a decrease in clutch torque. The designated first or second clutch C1, C2 reaches its base bite point Pt at approximately time t3.As used herein, the bite point refers to a clutch position in which the clutch transmits sufficient torque to move the vehicle 10 when the brake applicator 40 and the throttle applicator 11 are not depressed. In other words, the bite point is a clutch position in which the clutch transmits sufficient torque to move the vehicle 10 when the brake applicator 40 is not actuated and the engine 12 is idling. The basic bite point Pt can be obtained from a recorded torque-to-position (TTP) table 60, as shown in . Fig. 4 shown.

[0022] With reference to Fig. 3 is a torque-to-position (TTP) model from Table 60, which is recorded in memory 23 of the TCM 20 ( Fig. 1) is used by the TCM 20 to accurately determine how much torque (T) to apply for a given clutch position (P), and vice versa. The TTP table 60 may include one or more TTP curves 62a, 62b, and 62c for different clutch temperature ranges (Temp). The TTP table includes a vertical axis representing a clutch torque and a horizontal axis representing a clutch position P according to a clutch temperature Temp. Each TTP curve 62a, 62b, and 62c includes points of the respective calibrated bite points 63a, 63b, and 63c, and respective torque zero points (ZTP) 65a, 65b, and 65c derived from the bite points 63a, 63b, and 63c. The calibrated bite points 63a, 63b, 63c can correspond to a single calibrated bite point torque Tb and the respective bite point coupling positions Pa, Pb or Pc in each TTP curve 62a, 62b, 63c.ZTP 65a, 65b, and 65c correspond to clutch positions Pd, Pe, and Pf, respectively, where the clutch's zero-torque engagement is transmitted from the engine at these points. For each specific ZTP engaging the clutch 1 mm above or 1 mm below Pd, Pe, or Pf, the torque transmitted by the engine is reversed to a load applied to the first or second clutch, C1 or C2, by the transmission. This reversal of torque flow indicates that the operator is passing through a torque strain zone, which will produce an audible rattle or vibration.

[0023] Now let's move on to... Fig. 4, an example of a dDCT transmission, which is generally found in Fig. 1 is shown, and is now presented in more detail and is usually indicated by reference numeral 14, when reference numerals are used. Fig. 1 for similar components. The transmission 14 also includes a drive element 15 and an output element or gear 14. In the present embodiment, the input shaft 15 is a shaft and the output shaft 21 is a gear; however, those skilled in the field will recognize that the input shaft 15 can be a component other than a shaft and the output shaft 21 can be a component other than a gear, such as a shaft. For example, the input element 15 can be a clutch housing connected to a flywheel and receiving drive torque from it.

[0024] The input element 15 is continuously connected to a motor 12 ( Fig. 1) or another torque-generating device to provide a drive torque to the input element 15. The output element 21 drives a differential assembly 16. The differential assembly 16 ultimately transmits the torque of the output element 14 to a pair of vehicle wheels (not shown).

[0025] Gearbox 14 includes a housing 118 that at least partially encloses a gearbox assembly 120. Gearbox assembly 120 comprises various shafts or elements, coplanar meshing gear sets, a dual-clutch assembly, and synchronizers, which, as will be described below, can be selectively engaged. For example, gearbox assembly 120 includes a first shaft or element 25, a second shaft or element 27, a first countershaft 126, and a second countershaft 128. The second shaft or element 27 is a sleeve (hollow shaft) that is concentric with and located above the first shaft or element 25. The first countershaft 126 and second countershaft 128 are installed at a distance from and parallel to the first and second shafts 25 and 27, respectively.The first and second shafts 25, 27 define a first axis of rotation, the first countershaft 126 defines a second axis of rotation and the second countershaft 128 defines a third axis of rotation.

[0026] A dual-clutch assembly 132 is connected between the input element 15 and the first and second shaft elements 25, 27. The dual-clutch assembly 132 includes a clutch housing 134, which is connected to the input element 15 for common rotation. Therefore, the clutch housing 134, which is supported within the transmission housing 118, provides the driving torque for the transmission gear sets, as described in more detail below. Furthermore, the dual-clutch assembly 132 has a first and second clutch C1, C2. Thus, the selective engagement of the first clutch C1 connects the input element 15 to the first shaft element 25 for common rotation. The selective engagement of the second clutch C2 connects the input element 15 to the second shaft element 27 for common rotation.

[0027] The gear arrangement 120 also comprises a plurality of coplanar, meshing gear sets 140, 150, 160, 170 and 180. The present invention provides that the plurality of coplanar, meshing gear sets 140, 150, 160, 170 and 180 are arranged axially along the first and second shaft elements 25, 27 in a different order than in Fig. 4 can be arranged and yet does not deviate from the scope of the invention. The coplanar gear set 140 comprises gear 142 and gear 144. Gear 142 is connected to the second shaft element 27 for common rotation. Gear 144 is selectively connectable to the second countershaft element 128 for common rotation and meshes with gear 142. It should be noted that gear 142 may have a separate gear structure attached to the second shaft element 27 or teeth / internal teeth on an outer surface of the second shaft element 27 without deviating from the scope of the present invention. Gear set 140 is arranged adjacent to a wall 148 of the transmission housing 118, which is located on a front or side of the transmission 14 near the dual-clutch assembly 132.

[0028] The coplanar gear set 150 comprises gear 152, gear 154, and gear 156. Gear 152 is rotatably fixed and connected to the second shaft element 27 for common rotation, and meshes with gear 154 and gear 156. Gear 154 can be selectively connected to the second countershaft element 128 for common rotation. Gear 156 can be selectively connected to the first countershaft element 126 for common rotation. Gear set 150 is positioned adjacent to gear set 140.

[0029] The coplanar gear set 160 comprises gear 162, gear 164, and gear 166. Gear 162 is rotatably fixed and connected to the first shaft element 25 for common rotation, and meshes with gear 164 and gear 166. Gear 164 can be selectively connected to the second countershaft element 128 for common rotation. Gear 166 can be selectively connected to the first countershaft element 126 for common rotation. Gear set 160 is arranged adjacent to gear set 150.

[0030] The coplanar gear set 170 comprises gear 172 and gear 174. Gear 172 is rotatably fixed and connected to the first shaft element 25 for common rotation, and meshes with gear 174. Gear 174 can be selectively connected to the first countershaft element 126 for common rotation. Gear set 170 is positioned adjacent to gear set 160.

[0031] The coplanar gear set 180 comprises gear 182 and gear 184. Gear 182 is rotatably fixed and connected to the first shaft element 25 for common rotation, and meshes with gear 184. Gear 184 can be selectively connected to the second countershaft element 128 for common rotation. Gear set 180 is positioned between gear set 170 and an end wall 188 of the gearbox housing 118.

[0032] The reverse gear 190 can optionally be connected to the first countershaft element 126 for common rotation and meshes with a reverse gear section 192 of the stepped gear 144. The reverse gear section 192 of the gear 144 is fixed for common rotation with the gear 144 and can, if necessary, have a different gear inclination than the gear inclination of the gear 144 in order to achieve a reverse gear speed. The reverse gear 190 is positioned between the gear set 150 and the end wall 148.

[0033] Furthermore, a first countershaft transmission gear 200 is fixed and connected to the first countershaft element 126 for common rotation. A second countershaft transmission gear 210 is rotatably mounted and connected to the second countershaft element 128 for common rotation. The first countershaft transmission gear 200 is configured to engage with the output element 21, and the second countershaft transmission gear 210 is configured to engage with the output element 21. However, the first countershaft transmission gear 200 and the second countershaft transmission gear 210 are not engaged with each other. The first countershaft transmission gear 200 is located between the reverse gear 190 and the end wall 148 of the transmission housing 118.The second countershaft transmission gear 210 is arranged between the reverse gear 144 and the end wall 148 of the gearbox housing 118. The output element 21 is coplanar to the first and second countershaft transmission gears 200 and 210.

[0034] The transmission 14 further includes a plurality of selectively activatable synchronization assemblies 250, 252, 254, and 256. The synchronizers 250, 252, 254, and 256 are double-sided synchronizers and generally include a shift fork (not shown) which is bidirectionally actuated by an actuator (not shown) into at least two engaged positions and a neutral or disengaged position. In the present embodiment, the synchronizer 250 can be selectively actuated to engage gear 144 for common rotation with the second countershaft element 128, and the synchronizer 250 can be selectively actuated to engage gear 154 for common rotation with the second countershaft element 128.The synchronizer 252 can be selectively actuated to connect the reverse gear 190 to the first countershaft 126 for common rotation, and can be selectively actuated to connect the gear 156 to the first countershaft 126 for common rotation. The synchronizer 254 can be selectively actuated to connect the gear 164 to the second countershaft element 128 for common rotation, and can be selectively actuated to connect the gear 184 to the second countershaft 128 for common rotation. The synchronizer 256 can be selectively actuated to connect the gear 166 with the first countershaft element 126 for the purpose of common rotation and can be selectively actuated to connect the gear 174 with the first countershaft element 126 for the purpose of common rotation.

[0035] The transmission 14 is capable of transmitting torque from the input shaft 15 to the output gear element 21 in at least seven forward torque gears and at least one reverse torque gear. Each of the forward torque gears and the reverse torque gear is achieved by selectively engaging the dual-clutch assembly 132 and one or more synchronizers 250, 252, 254, and 256. Experts in the field will readily recognize that each speed ratio corresponds to a different torque ratio.

[0036] It should be noted that each individual gear set 140, 150, 160, 170 and 180, when the synchronizing arrangements 250, 252, 254 and 256 are selectively engaged, provides one or more forward and / or reverse gear ratios. Furthermore, it should be noted that a specific forward or reverse gear can be achieved by various combinations of synchronizers and associated gear sets without deviating from the scope of the present invention.

[0037] To establish the reverse gear torque ratio, for example, the second clutch C2 is engaged and the synchronizer 252 is activated. The second clutch C2 connects the input element 15 to the second shaft element 27. The synchronizer 252 connects the reverse gear 190 to the first countershaft 126. More precisely, the input torque is transmitted from the input shaft 15 through the dual-clutch assembly 132 to the second shaft element 27, via gear 142 to gear 144, through gear 144 to reverse gear 190, from reverse gear 190 to the first countershaft element 126, via the synchronizer 252 to the first countershaft transmission gear 200, and from the first countershaft transmission gear 200 to the output element 21.

[0038] To establish a first forward gear torque ratio (i.e., a 1st gear), the first clutch C1 is engaged and the synchronizer 254 is activated. The first clutch C1 connects the input element 15 to the first shaft element 25. Synchronizer 254 connects the gear 184 to the second countershaft element 128. The drive torque from the input element 15 is transmitted through the dual-clutch assembly 132 to the first shaft element 25 and then to gear 182. Gear 182 transmits the torque to gear 184, which transmits the torque via synchronizer 254 to the second countershaft element 128 and to the second countershaft transmission gear 210, and then from the second countershaft transmission gear 210 to the output element 21.

[0039] Similar system engagements are pursued for the remaining torque ratios. In addition to the ability to arrange seven forward gear torque ratios and one reverse gear torque ratio in a compact and lightweight assembly, the transmission 14 is also capable of making rapid gear ratio changes. For example, if a second torque ratio is engaged by activating the second clutch C2 and the engagement of synchronizer 250 with gear 192, the synchronizer of the next gear ratio, in this case synchronizer 256, would engage gear 174 with, or is also engaged by, the first countershaft 126. This enables rapid gear changes simply by alternately engaging the second clutch C2 and the first clutch C1.

[0040] A similar operating procedure is used to change the gear ratios from the reverse gear torque ratio to the forward gear or first gear torque ratio. When the operator moves the gear selector switch to reverse, the TCM instructs the transmission 14 to engage the synchronizer 252 with the reverse gear 190. Simultaneously, the synchronizer 254 shifts to engage the gear 184 with the second countershaft 128, which is necessary to engage the first forward gear torque ratio. This allows for a rapid transition from the reverse gear torque ratio to the first forward gear torque ratio simply by disengaging the second clutch C2 and engaging the first clutch C1.

[0041] Under certain operating conditions or due to the driver's driving behavior, the driver may experience unintended torque reversals at rotating components of the transmission, which can lead to rattling or vibrations. With reference to Fig. 5 begins a procedure 300 to control the in Fig.Figure 1 shows the dDCT 14 in a first step 302, in which the vehicle operator engages the reverse gear torque ratio. A second step 304 engages the synchronizer 252 with the reverse gear gear 190, causing the reverse gear 190 and the first countershaft 126 to rotate together. Simultaneously, the synchronizer 254 engages the gear 184 of the first forward gear torque ratio, causing the gear 184 and the second countershaft 128 to rotate together. Finally, to complete the reverse gear engagement, the second clutch C2 is engaged to transmit torque from the input shaft 15 through the transmission 14 to the output element 21.Next, a third step 306, after obtaining a speed target for a specific duration, detects a multitude of events indicating that the second countershaft 128 is passing through a strain zone and thus entering an audible rattling or vibration state. The speed target can be 2 km / h, but can be a similarly higher or lower speed without deviating from the scope of the invention. Once the TCM 20 detects several events indicating that the audible rattling or vibration state has occurred, a fourth step 308 disengages the synchronizer 254 from the gear 184. The number of events that occur before executing step 308 can be 2 to 5 events, with 3 being the most probable number.In this way, the gear 184, the gear 182 and the first shaft 25 no longer rotate with the second countershaft 128 and thus no longer cause the system to rattle or vibrate during subsequent events.

[0042] Regarding the third step 306, there are several types of events that can cause crossing the tug zone and the subsequent vibrations. A first event involves pressing and releasing the accelerator pedal 11. At low speeds, this can cause the engine 12 to place a load on the transmission 14 when the operator presses the accelerator pedal 11, and cause the wheels and differential 16 to place a load on the transmission 14 with opposite rotation when the operator releases the accelerator pedal 11. Additional loads can be caused by uneven road surfaces or ground, leading the operator to attempt to overcome driving or drifting by using the accelerator pedal 11.

[0043] A second event involves applying and releasing the brake pedal 40. Like the accelerator pedal event, the braking event can lead to a crossing of the tug zone, which is a reason for an audible rattling or vibration.

[0044] A third event involves the detection of multiple crossings of the zero torque point (ZTP) by the TCM 20. The detection of the ZTP crossing most likely indicates that the operator perceives audible rattling or vibrations. The audible rattling or vibrations are negated as soon as the synchronizer 254 is disengaged from the first gear 184 in the fourth step 308 of the procedure 300.

[0045] A fifth step 310 of the procedure resets the counter of the third step 306 if the operator shifts the transmission out of reverse gear R or if the vehicle's speed falls below the target speed before the specified time duration is reached.

[0046] Although the best ways of carrying out the invention have been described in detail, those skilled in the art who are familiar with the technology described herein will recognize various alternative configurations and embodiments with which the invention can be carried out within the scope of the added claims.

Claims

[1] Method (300) for controlling a dual-clutch transmission (14), the method (300) comprising: providing a dual-clutch transmission (14) having a dual-clutch module, first and second input shafts (25, 27), first and second countershafts (126, 128), a plurality of coplanar gear sets (140, 150, 160, 170, 180, 190), and a plurality of synchronizers (250, 252, 254, 256) capable of providing a plurality of forward gear torque ratios and a reverse gear torque ratio; receiving (302) a command to engage the reverse torque ratio; switching (304) a first of the plurality of synchronizers (252) to engage a reverse gear (GR) of a first of the plurality of coplanar gear sets (190) with the first countershaft (126); switching (304) a second of the plurality of synchronizers (254) to engage a first gear (184) of a second of the plurality of coplanar gear sets (180) with the second countershaft (128), wherein the first gear (184) of the second of the plurality of coplanar gear sets (180) is capable of providing a first torque ratio (G1) when engaged with the second countershaft (128); engaging (304) a first clutch (C2) of the dual clutch module; detecting (306) a plurality of events indicating an undesirable noise, wherein detecting a plurality of events indicative of an undesirable noise comprises detecting a plurality of accelerator pedal depressions and releases, a plurality of brake pedal depressions and releases, and a plurality of torque zero crossings; switching (308) the second of the plurality of synchronizers (254) to disengage the first gear (184) of the second of the plurality of coplanar gear sets (180) from the second countershaft (128). [2] A method (300) for controlling a dual clutch transmission (14) according to claim 1, wherein detecting a plurality of events indicative of an undesirable noise further comprises detecting a vehicle speed of a predetermined threshold. [3] A method (300) for controlling a dual-clutch transmission (14) according to claim 2, wherein detecting a vehicle speed of a predetermined limit further comprises detecting a vehicle speed of at least 2 km / h.

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