CN105814332B - Contact point determination - Google Patents

Abstract

A transmission comprises an input shaft, a transmission shaft, a clutch for connecting the input shaft with the transmission shaft, an output shaft, a gear pair for coupling the transmission shaft with the output shaft in a torque-fit manner, and a motor connected with the transmission shaft. A method for determining a contact point of a clutch includes the steps of: the clutch is disengaged, the torque-matched coupling of the gearwheel pairs to the drive shaft or the output shaft is disengaged, a first speed gradient of the drive shaft in a first phase is determined, the clutch is partially closed, a second speed gradient of the drive shaft in a second phase is determined, and the contact point of the clutch is determined on the basis of the two gradients. In this case, the electric machine is controlled during these two phases in order to output a predetermined torque to the drive shaft.

Description

touch point determination

technical field

The present invention relates to determining the contact point of a clutch. In particular, the invention relates to a determination of the contact point of a clutch at a transmission in a hybrid powertrain.

Background technique

A hybrid motor vehicle comprises an internal combustion engine and an electric machine, which can alternatively or simultaneously be used to drive the motor vehicle. In one embodiment, a dual clutch transmission is provided in order to couple the internal combustion engine to a driven shaft connected to the drive wheels of the motor vehicle. The dual-clutch transmission comprises two drive shafts which are coupled to the internal combustion engine by means of associated clutches and which can be coupled to the output shaft by means of different gear pairs. If the internal combustion engine is running, only one of the clutches is always engaged. A range gear pair is engaged by torque-fitting connection of a range gear pair to the associated drive shaft and driven shaft on its clutch-disengaged propshaft; by disengaging the range gear pair from the driven shaft A torque fit connection between the gear pair or a torque fit connection between the range gear pair and the associated drive shaft enables the disengagement of the range gear pair. To do this, the gear pair that is active first is disengaged and the other gear pair is engaged. Shifting is performed by opening a closed clutch and simultaneously closing another clutch.

DE 10 2010 024 941 A1 shows such a transmission.

The clutches can each be actuated by means of an actuator. In particular, the actuator can include a hydraulic transmission line, possibly with an electromechanical transmitter. With this actuator or also with other types of actuators, for example wear or temperature influences can cause the contact points of the clutch to shift. The contact point corresponds to an operation of the clutch in which a preset torque is transmitted via the clutch.

In order to determine the contact point of a clutch, different approaches are known. In a variant, the rotational speed gradient of the propeller shaft is determined, the clutch of which is disengaged immediately after a gear pair has been disengaged. Subsequently, the clutch is partially engaged and a second rotational speed gradient of the propeller shaft is determined. Based on the first rotational speed gradient, the tractive torque of the propeller shaft can be evaluated and the clutch torque can be determined based on the second rotational speed gradient. The point of contact can then be precisely determined based on these two moments.

In a hybrid motor vehicle, the electric machine is connected to the first transmission shaft in a torque-locking manner. If the gear pair connected to the first transmission shaft is active, the electric machine can be used for acceleration or deceleration of the motor vehicle.

Of course, the determination of the contact point of the first clutch is difficult because the moment of inertia of the electric motor changes the speed gradient of the drive shaft. The electric machine acts as a rotational energy store, making it possible to reduce both speed gradients. This makes it difficult to determine the gradient with sufficient precision. One of the gradients can be so flat that an increased measurement time is required to observe the rotational speed of the first transmission shaft. The determination of the contact point at the first clutch can be time-consuming, so that rapid gear changes are prevented.

Contents of the invention

The invention is therefore based on the object of providing a method and a device for an improved determination of the contact point of a clutch on a transmission shaft with an electric machine.

The transmission includes an input shaft, a transmission shaft, a clutch for connecting the input shaft to the transmission shaft, an output shaft, a gear pair for torque-fit coupling the transmission shaft and the output shaft, and an electric motor connected to the transmission shaft. The method for determining the contact point of the clutch comprises the steps of: disengaging the clutch, decoupling the torque fit of the gear pair with the propeller shaft or the output shaft, determining a first rotational speed gradient of the propeller shaft in the first phase, Partially closing the clutch, determining a second rotational speed gradient of the propeller shaft in the second phase and determining the contact point of the clutch based on these two gradients. Here, the electric motor is controlled during these two phases in order to output a preset torque to the drive shaft.

This makes it possible to determine the contact point of the clutch without having to provide a mechanical device, such as a further clutch between the electric machine and the transmission shaft. This procedure can also be used to determine other parameters on the first drive shaft, into which the moment of inertia of the electric machine is incorporated.

In a preferred embodiment, the transmission further includes: another transmission shaft, another clutch for connecting the input shaft with the other transmission shaft, and a clutch for torque-fit coupling the other transmission shaft with the output shaft Another gear gear pair. In this case, during the method described above, the further clutch is engaged and the further gear pair is coupled torque-lockingly to the drive shaft and the output shaft.

In other words, the method is preferably executable on a dual clutch transmission with a flanged electric machine. In principle, two different variants for controlling the electric machine are conceivable.

In a first variant, the predetermined torque corresponds to the moment of inertia of the electric machine. As a result, the effect of the moment of inertia of the electric machine can be compensated practically, so that the determination method for determining the contact point of the clutch does not have to be changed. This enables a modular construction of the transmission, optionally with or without an electric machine, without having to change the method for determining the contact point. The moment of inertia of the electric machine can be related to the rotational speed of the drive shaft. This can be taken into account when controlling the electric machine in order to compensate the moment of inertia of the electric machine with improved accuracy.

In a second variant, the absolute value of the predetermined torque is constant during the two phases, wherein the contact point is additionally determined on the basis of the predetermined torque.

Thereby, the control of a motor can be designed more simply. The torque applied by the motor must then be taken into account in sign and absolute value when determining the contact point. The information on which torque the electric motor applies can be transmitted from the control device for the electric motor to the control device for determining the contact point. The moment of inertia of the shaft together with the motor is thus taken into account when determining the contact point.

In both variants, if the output shaft accelerates during the method, the preset torque is negative during the first phase to decelerate the transmission shaft and positive during the second phase to decelerate the transmission Axis acceleration. If, for example, the motor vehicle comprises a drive train with a dual clutch transmission, acceleration of the output shaft can take place during the acceleration phase of the motor vehicle, wherein the torque is transmitted via another clutch, another drive shaft and another gear pair . The sign change between the two phases ensures that the two rotational speed gradients can be determined more quickly or with improved accuracy.

In the above variant, if the output shaft is decelerated during the method, the preset torque is negative during these two phases in order to decelerate the propeller shaft. If, as described above, a dual-clutch transmission is present, the reduction can again take place, for example, by means of a torque via another gear pair, another drive shaft and another clutch.

In both cases, however, the acceleration or deceleration of the output shaft can also be brought about by other effects, especially if there is no double clutch transmission. For example, the described motor vehicle is capable of driving or coasting on a ramp.

The transmission according to the present invention includes an input shaft, a transmission shaft, a clutch for connecting the input shaft to the transmission shaft, an output shaft, a gear pair for torque-fit coupling the transmission shaft and the output shaft, and the transmission shaft A connected electric machine and a control device for controlling the transmission by means of the method described above.

Description of drawings

The invention will now be described in more detail with reference to the accompanying drawings, in which

FIG. 1 shows a section of a drive train for a motor vehicle;

Figure 2 shows the speed and torque diagram and

FIG. 3 shows the rotational speed and torque diagram during an upshift.

Detailed ways

FIG. 1 shows a section of a drive train 100 , in particular for a motor vehicle. The drive train 100 includes an input shaft 105 for connection to an internal combustion engine 110 and an output shaft 115 , which is used in particular for connection to drive wheels (not shown) of a motor vehicle. A first transmission shaft 125 is coupled to the input shaft 105 by means of a first clutch 120 and a second transmission shaft 135 is coupled to the input shaft 105 by means of a second clutch 130 . The electric motor 140 is rigidly connected to the first transmission shaft 125 .

A first gear set 145 , a second gear set 150 and a third gear set 155 are provided for coupling the drive shafts 125 , 135 to the output shaft 115 . In this case, the first gear set 145 and the third gear set 155 are associated with the first transmission shaft 125 and the second gear set 150 is associated with the second transmission shaft 135 . This association is purely exemplary and more or fewer gear pairs 145 to 155 can also be provided. Each range gear pair 145-155 is capable of being engaged and disengaged. When engaged, a torque-fit connection is established with the associated propeller shaft 125, 135 and output shaft 115, and when disengaged, a torque-fit connection is established with the associated propeller shaft 125, 135 or with the output shaft 115, or both. Moment fit connections. Engagement and disengagement of range gear pairs 145 - 155 occur during disengagement of the associated clutch 120 , 130 . Without limiting generality, the following is based on the following: If the associated clutch 120, 130 is closed, then in order to achieve the same rotational speed on the output shaft 115, a high rotational speed on the input shaft 105 is combined with an engaged The first gear 145 on the input shaft 105 connects the medium speed on the input shaft 105 with the engaged second gear 150 and connects the low speed on the input shaft 105 with the engaged third gear 155 . Reference can therefore also be made here to first gear 145 , second gear 150 and third gear 155 .

Control device 160 is designed to control a part of drive train 100 , in particular to control transmission 165 . The transmission 165 includes at least an input shaft 105 , a first clutch 120 , a first transfer shaft 125 , one of range gear pairs 145 , 155 , and an output shaft 115 . Preferably, the transmission 165 is a dual clutch transmission which additionally includes a second clutch 130 , a second drive shaft 135 and a second range gear pair 150 as described above. Control device 160 is connected to a device for determining the rotational speed of first transmission shaft 125 . Whether gears 145 , 155 are engaged or disengaged can be determined by means of further sensors or controlled by means of corresponding actuators. In a corresponding manner, the degree of disengagement of first clutch 120 can be determined or controlled by control device 160 . Corresponding sensors or actuators are preferably also provided for the second transmission shaft 135 , the second gear set 150 and the second clutch 130 . In another specific embodiment, the control device 160 can also be designed to control the torque output by the electric machine 140 . For this purpose, the control device 160 can directly control the torque of the electric machine 140 or be connected to a control device for the torque of the electric machine 140 .

FIG. 2 shows a rotational speed and torque diagram 200 during an upshift of transmission 165 from FIG. 1 . Here, the described variant of the dual clutch transmission is based. Time is additionally plotted horizontally. The rotational speed (N), operating stroke (s), torque (M) and gear (G) are plotted in the vertical direction. Diagram 200 shows the shift from third gear 155 to first gear 145 at first transmission shaft 125 and the determination of the contact point for first clutch 120 during the reduction of the rotational speed of output shaft 115 . The braking of the output shaft 115 can be determined in particular by the braking torque of the internal combustion engine 110 , which is transmitted by means of the second clutch 130 , the second transmission shaft 135 and the second gear 150 .

A first curve 205 relates to the rotational speed of the first transmission shaft 125 , a second curve 210 shows the rotational speed of the second transmission shaft 135 in dashed lines. A third curve 215 shows the engaged gears 145 , 155 on the first transmission shaft 125 and a fourth curve 220 shows the engaged gears on the second transmission shaft 135 in dashed lines. An engaged gear of 0 means that no gear pair 145 to 155 is torque-fittingly connected to the corresponding drive shaft 125 , 135 . This state is also referred to as idling. A fifth curve 225 shows the degree of operation of the first clutch 120 . The higher the value shown, the more engaged the first clutch 120 and thus the higher the torque that can be transmitted via the first clutch 120 .

During a first step 240 the first clutch 120 is disengaged. The third gear set 155 is then disengaged, so that the gear sets 145 , 155 are not torque-transmittingly connected to the first drive shaft 125 ; the first drive shaft 125 is freewheeling. In a subsequent step 245, the transmission shaft 125 is desynchronized. When the torque engagement between the third gear set 155 and the first transmission shaft 125 is completely eliminated, the first transmission shaft 125 , as can be understood from the first curve 205 , only begins to decelerate freely to a standstill. After a preset time or when the rotation speed decreases by a preset value or to a preset degree, the gradient of the rotation speed of the first transmission shaft 125 is determined. Step 250 is also referred to as the first stage.

Subsequently, first clutch 120 is partially actuated in step 255 , which is also referred to as the second phase, as can be derived from fifth curve 225 . As a result, the rotational speed of the first transmission shaft 125 is increased to the level of the rotational speed of the second transmission shaft 135 . If the rotational speeds of the transmission shafts 125 , 135 match each other, a second gradient is determined which represents the change in the rotational speed of the first transmission shaft 125 during step 225 . The contact point of first clutch 120 can then be determined based on these two determined gradients.

Then in step 260 the actuation of the first clutch 120 is withdrawn again, so that the first clutch 120 is disengaged. Subsequently, the first gear 145 is engaged as shown by the third curve 215 . During engagement of the first gear 145, the rotational speed of the first transmission shaft 125 is increased so that the first gear 145 can be smoothly engaged. This process is called synchronization. Subsequently, in step 265 the first clutch 120 can be engaged while the second clutch 130 is disengaged. The gear lying in the line of force of drive train 100 changes here from second gear 150 to first gear 145 .

In order to keep the gradient of first curve 205 sufficiently high during steps 250 and 255 , it is provided that electric machine 140 is controlled so that first transmission shaft 125 is acted upon with a predetermined torque during steps 250 and 255 . Curves 230 and 235 show different variants.

According to a first variant, according to sixth curve 230 , electric machine 140 outputs a negative torque during first phase 250 and a positive torque during second phase 255 . In this case, the torques respectively correspond to the moments of inertia of the electric machine 140 . Preferably, a negative torque builds up continuously during step 245 . In this embodiment, the gradient is so large during steps 250 and 255 that it appears that the motor 140 is not present. The device or method for determining the gradient or determining the contact point of the first clutch 120 based on the gradient does not have to be adjusted.

According to the second variant, a constant negative torque is output to first transmission shaft 125 during step 235 and a constant positive torque is output to first transmission shaft 125 during step 255 according to seventh curve 235 . Preferably, a negative torque has been output during step 245 . In this variant, the moment of inertia of the unit formed by the first transmission shaft 125 and the electric machine 140 is reduced by a constant value corresponding to the torque of the electric machine 140 . When making further determinations based on the first or second gradient, in particular the contact point of the first clutch 120 , the entire moment of inertia of the first transmission shaft 125 , the electric machine 140 and the torque exerted by it are taken into account.

FIG. 3 shows a view corresponding to FIG. 2 during the opposite shifting process. The reference numerals and axis designations of FIG. 2 are used. In contrast to the illustration in FIG. 2 , the acceleration phase of output shaft 115 is based on diagram 300 . During the engagement of the second range gear set 150 on the second drive shaft 135 , on the first drive shaft 125 the first range set 145 is disengaged in step 240 and the third set 155 is engaged in step 265 . During a step 250 —during a first phase—the first transmission shaft 125 is decelerated to a standstill and a first gradient of its rotational speed can be determined. During step 255 , the second phase, the rotational speed of the first transmission shaft 125 is reduced to the rotational speed of the second transmission shaft 135 by partially closing the first clutch 120 to a greater extent than by merely slowing down. In this case a second gradient is determined.

Curve 330 , which corresponds to sixth curve 230 in FIG. 2 and relates to the first variant described above, shows the torque output by electric machine 140 to first transmission shaft 125 , which corresponds to the moment of inertia of electric machine 140 . During steps 250 and 255, the output torque is always negative, but the absolute value is different in these two phases. Preferably, a negative torque has been continuously built up during step 245 .

In a curve 335 , which corresponds to the curve 235 in FIG. 2 and relates to the second variant described above, a constant negative torque is provided by the electric machine 140 . Preferably, a negative torque has been built up during step 245 .

The determination of the contact point in both variants takes place as described above with regard to deceleration when the output shaft 115 is accelerating.

List of reference signs

100 Power Train

105 input shaft

110 Internal combustion engines

115 output shaft

120 first clutch

125 First drive shaft

130 Second clutch

135 Second drive shaft

140 motor

145 First gear gear pair

150 Second gear gear pair

155 Third gear gear pair

160 Controls

165 transmission

200 charts

205 The first curve: the rotational speed of the first transmission shaft 125

210 The second curve: the rotational speed of the second transmission shaft 135

215 Third Curve: Engaged Gears of First Drive Shaft 125

220 Fourth Curve: Engaged Gears of Second Drive Shaft 135

225 fifth curve: operate the first clutch 120

230 Sixth curve: first preset torque (first variant)

235 Seventh curve: second preset torque (second variant)

240 disengage the first clutch, disengage the third gear

245 out of sync

250 Phase 1: Determine the first gradient

255 Second stage: Determining the second gradient

260 Engage first gear

265 Close the first clutch

300 Charts

330 corresponds to the sixth curve (first variant)

335 corresponds to the seventh curve (second variant)

Claims (9)

CLAIMS 1. A method (200, 300) for determining a contact point of a clutch (120) on a transmission (165), wherein the transmission (165) comprises the following: - input shaft (105); - transmission shaft (125); - a clutch (120) for connecting said input shaft (105) with said transmission shaft (125); - output shaft (115); - range gear pairs (145, 155) for torque-fit coupling said drive shaft (125) with said output shaft (115) and - an electric motor (140) connected to said transmission shaft (125), Wherein said method (200,300) comprises the steps of: - disconnecting (240) said clutch (120); - decoupling (240) the torque fit of said gear pair (145, 155) with said transmission shaft (125) or said output shaft (115); - determining (250) a first rotational speed gradient of said transmission shaft (125) in a first phase; - partially close (255) said clutch (120); - determining (255) a second rotational speed gradient of said transmission shaft (125) in a second phase, and - determining (255) the contact point of said clutch (120) based on these two gradients, It is characterized in that, The motor (140) is controlled during two phases (250, 255) such that a preset torque is output to the drive shaft (125). 2. The method (200, 300) according to claim 1, wherein said preset torque corresponds to a moment of inertia of said electric machine (140). 3. The method (200, 300) according to claim 1, wherein the absolute value of said preset torque during said two phases (250, 255) is constant and is additionally based on said preset to determine (255) the contact point. 4. The method (200, 300) of claim 1, wherein the transmission (165) further comprises the following: - another transmission shaft (135); - a further clutch (130) for connecting said input shaft (105) with said further transmission shaft (135), and - a further gear pair (150) for torque-fit coupling said further transmission shaft (135) with said output shaft (115); and wherein during said method (200, 300) - closing said further clutch (130), and - said further range gear pair (150) is coupled in torque fit with said further transmission shaft (135) and said output shaft (115). 5. The method (200, 300) according to claim 4, wherein said preset torque corresponds to a moment of inertia of said electric machine (140). 6. The method (200, 300) according to claim 4, wherein said preset torque is constant in absolute value during said two phases (250, 255) and is additionally based on said preset to determine (255) the contact point. 7. The method (200, 300) according to any one of claims 1-6, wherein during said method (200, 300) said output shaft (115) is accelerated and said preset torque Negative during the first phase (250) to decelerate the drive shaft (125) and positive during the second phase (255) to accelerate the drive shaft (125). 8. The method (200, 300) according to any one of claims 1-6, wherein during said method (200, 300) said output shaft (115) is decelerated and said preset torque Negative during the two phases (250, 255) to decelerate the drive shaft (125). 9. A transmission (165), comprising the following elements: - input shaft (105); - transmission shaft (125); - a clutch (120) for connecting said input shaft (105) with said transmission shaft (125); - output shaft (115); - a range gear pair (145, 155) for torque-fit coupling said transmission shaft (125) with said output shaft (115); - an electric motor (140), said electric motor being connected to said transmission shaft (125), and - A control device (160) for controlling the transmission (165) by means of a method (200, 300) according to any one of the preceding claims.