KR102448749B1 - Method for determining a bite point change of a hybrid separating clutch of a hybrid vehicle - Google Patents

Abstract

The present invention is operated by a hydrostatic clutch actuator (12) and the hybrid separation clutch (4) disconnects or connects the combustion engine (2) and the electric traction drive (3). , wherein the hybrid separation clutch (4) is moved starting from a position of the hybrid separation clutch at which the hybrid separation clutch (4) assumes a non-actuated state, for determining a contact point, and the hybrid vehicle starts operation The basic contact point of the hybrid disconnect clutch 4 is determined upon and/or during operation. Between the two sniffing processes of the hydrostatic clutch actuator 12, the contact point variation is determined from the pressure signal of the pressure sensor 21, and the basic contact point is matched based on this contact point variation.

Description

METHOD FOR DETERMINING A BITE POINT CHANGE OF A HYBRID SEPARATING CLUTCH OF A HYBRID VEHICLE

The present invention relates to a method for determining the contact point variation of a hybrid separation clutch of a hybrid vehicle operated by a hydrostatic clutch actuator and wherein the hybrid separation clutch disconnects or connects a combustion engine and an electric traction drive, wherein the hybrid separation clutch is the contact point For the determination of , the hybrid separation clutch is moved starting from the position of the hybrid separation clutch which assumes the non-actuated state, and the basic contact point of the hybrid separation clutch is determined at the start of operation and/or during operation of the hybrid vehicle.

In the case of a motor vehicle with a hybrid drivetrain, the running resistance can be overcome through conversion into mechanical energy from at least two independent energy sources: the fuel of the combustion engine and the electrical energy from the traction battery of the electric motor. According to DE 10 2008 030 473 A1, a method for determining the contact point of an automatic clutch in a hybrid drive train is known. The contact point of the hybrid separation clutch disposed between the combustion engine and the electric traction drive is determined by evaluating the effect of the closing clutch on the electric machine of the electric traction drive rotating at a set rotation speed with the clutch slowly closed, whereby the combustion engine is stopped. determined in case When the hybrid separation clutch is open, it enables purely electric driving of the vehicle, while in the closed state it transmits the torque of the combustion engine to the drive wheels.

Another challenge with the hybrid separation clutch is the starting of the combustion engine. To this end, the combustion engine is accelerated by intentionally raising the rotational torque of the electric motor and transferring energy to the combustion engine at rest by closing the hybrid disconnect clutch. In this case, with regard to driving comfort, in order to prevent unintentional vehicle acceleration, the rotational torque transmitted by the hybrid separation clutch must be accurately known, since the rotational torque of the electric motor is simultaneously transmitted to the drive wheels.

The rotational torque transmitted by the hybrid disconnect clutch is directly dependent on the position of the hydrostatic clutch actuator actuating the hybrid disconnect clutch. For the prediction of the transmitted clutch torque, on the one hand the position of the hydrostatic clutch actuator with respect to the possible travel path must be known, and on the other hand the clutch characteristic curve (clutch torque independent of the actuator position) is referenced for the actuator path. should be angry In this case, the contact point represents a sampling point of the clutch characteristic curve. The point of contact must be determined once for operation and must be matched to fluctuating clutch behavior during operation, for example due to various influencing factors such as wear of the clutch, subsequent adjustment and temperature as well as aging process. It is known to determine the contact point by means of a diagnostic service at the start of operation of the vehicle and to match it during operation of the vehicle.

A method for matching clutch parameters of a dual clutch transmission in a hydrostatic clutch system is known from DE 10 2012 204 940 A1. The hydrostatic clutch system is implemented with a clutch actuator device including a pressure sensor. The clutch actuator device is a so-called Hydrostatic Clutch Actuator (HCA). In fact, a hydrostatic clutch actuator of this type should be understood as an actuator with a hydrostatic transmission path, for example a pressure line with hydraulic fluid. The pressure in the pressure line is detected by a pressure sensor. For this determination of the contact point of the clutch, the clutch is opened or closed, during which the pressure trend is detected by the pressure sensor and the position of the clutch during closing and opening is detected. Then, parameters such as contact points for the clutch from the pressure trend are matched and the matched parameters are used for subsequent clutch operation. Determination of this point of contact is possible because in a dual clutch transmission the pressure monotonicly increases with the path.

On the other hand, in the case of a closed clutch that is not actuated in connection with a lever spring, the pressure does not behave linearly, since the pressure increases to a pressure maximum during opening of the clutch and then decreases slightly again. Determination of the contact point for the electric motor in a hybrid vehicle can only be carried out if the combustion engine is open from the drivetrain. This is only possible in special circumstances where higher strategies must be allowed. If the sniffing process in the hydrostatic path is not allowed for a long time, the volume expansion of the hydraulic fluid can lead to very serious torque inaccuracies, as the volume expansion of the hydraulic fluid induces fluctuations in the contact point that cannot respond properly. For actuation of the hybrid separation clutch via a hydrostatic path, a piston in the master cylinder of the clutch actuator is adjusted by an electric motor, with hydraulic fluid in the system being pressurized against the other piston in the slave cylinder. The piston of the slave cylinder acts in this case on a lever spring which, during operation, stops the transmission of torque through the clutch by lifting the clutch plate away from the clutch disk. A preloaded lever spring deactivates the clutch.

An object of the present invention is to provide a method for determining the contact point variation of a hybrid separation clutch of a hybrid vehicle, wherein the clutch includes a lever spring and the contact point variation can be reliably determined even between sniffing processes of the hybrid separation clutch based on doing

According to the present invention, the contact point variation is determined from the pressure signal of the pressure sensor between two sniffing processes of the hydrostatic clutch actuator, and the basic contact point is matched based on the contact point variation. Thus, the contact point variation can be determined even during operation of the combustion engine and in the closed drivetrain, so that the current contact point present during operation of the hybrid vehicle can be determined, enabling accurate control of the hydrostatic actuator and, in addition, accurate control of the hybrid clutch. do.

Advantageously, the measurement of the pressure signal is carried out in a clear range of the pressure characteristic curve for the path of the hydrostatic clutch actuator in which the contact point variation is determined, whereby the measurement of the pressure signal is carried out. Due to the selection of the monotonic range of the pressure characteristic curve, the contact point variation can be determined without unreasonableness, because with this monotonic relationship between the pressure and the path of the hydrostatic actuator, the position of the hybrid separation clutch corresponding to the contact point variation is not reliable. because it can be determined.

Advantageously, the clear range of the pressure characteristic curve is parameterized by the equation. By these equations, the pressure trend is approximated over the selected monotonic range. In order to ensure the torque accuracy of the electric traction drive even between the two sniffing processes, the current contact point from the variation of the pressure characteristic curve can be matched after the sniffing process based on the basic contact point.

In one variant, the equation is formed as a first-order equation, wherein the intersection of the equation with the path axis gives the contact point variation at the base contact point. By determining the intersection point, the position corresponding to the current contact point is directly determined.

In one refinement, the initial parameters of the linear equation are stored from one sniffing pass to the next sniffing pass. Due to the learning process of the matching method, the initial parameter of the first equation does not need to be newly determined at every measurement, thereby reducing the time for determining the current contact point.

In one embodiment, the parameters of the first-order equation are learned from the initial parameters of the first-order equation by adjustments made under the use of a controlling descriptive observer. Each current parameter of the linear equation is conveniently implemented in determining the contact point variation between the two sniffing processes by adjusting from the ongoing initial parameters.

Preferably, a first point of contact variation is determined immediately after the sniffing process, said variation being added to the base point of contact to provide a current point of contact, with the path of the hydrostatic actuator relative to the previous point of contact variation being added to the previous current point of contact. By determining the deviation, one or more other contact point variances are determined without further sniffing. By simple addition, each current contact point can always be determined from the contact point variation and the basic contact point. Accordingly, exhaustive computational output can be omitted.

In one configuration, a clear range of the pressure characteristic curve passes during the period during which the volume expansion of the hydraulic fluid is inhibited. Since volume expansion changes the temperature in the hydraulic section and thus also the expansion of the component parts acting on the pressure set by the hydraulic fluid in the hydraulic section, it is ensured that the pressure measurement takes place only if no such change occurs. should be

In one variant, the measurement of the pressure signal is started after the minimum threshold pressure value has been exceeded. With this minimum critical pressure value, it is ensured that the pressure characteristic curve exists in the monotonic range of the pressure characteristic curve even during pressure measurement.

In one refinement, upon stopping the combustion engine, the primary contact point is rotated by slow actuation of the hybrid separation clutch starting from the position of the hybrid separation clutch in which the hybrid separation clutch assumes a non-actuated state when a prescribed torque rise is detected. The speed is determined by observing the torque of the electric traction drive operating during controlled operation. Accordingly, the basic contact point of the hybrid separation clutch can be basically determined, in which the current contact point determined between sniffing processes of the hydrostatic actuator occurs in the range of the basic contact point. Thus, upon the determination of the current contact point and upon the determination of the contact point variation, the hybrid disconnect clutch can already approach the range of the basic contact point in order to derive the correct current contact point.

The present invention allows for multiple embodiments. One of these is explained in more detail based on the embodiment shown in the drawings.

1 is a basic principle diagram of a hybrid driving unit;
2 is a basic principle diagram of a hydrostatic clutch operating system having a hydraulic transmission path;
3 is a pressure-path characteristic curve of a hydrostatic actuator.

Identical features are denoted by like reference numerals.

1 illustrates a basic principle diagram of a drive train of a hybrid vehicle. This drive train 1 comprises a combustion engine 2 and an electric motor 3 . A hybrid disconnect clutch 4 is arranged between the combustion engine 2 and the electric motor 3 immediately behind the combustion engine 2 . The combustion engine 2 and the hybrid separation clutch 4 are connected to each other via a crankshaft 5 . The electric motor 3 has a rotatable rotor 6 and a fixed stator 7 . The output shaft 8 of the hybrid separation clutch 4 is connected with a transmission 9 , the transmission being a coupling element not shown in detail, for example a second clutch arranged between the electric motor 3 and the transmission 9 or It includes a rotation torque converter. The transmission 9 transmits the torque generated by the combustion engine 2 and/or the electric motor 3 to the drive wheels 10 of the hybrid vehicle. The electric motor 3 and the transmission 9 in this case form a transmission system 11 driven by a hydrostatic actuator 12 .

The hybrid decoupling clutch 4 arranged between the combustion engine 2 and the electric motor 3 is for starting or boosting the combustion engine 2 during running of the hybrid vehicle with a torque generated by the electric motor 3 . It is fastened for travel with a combustion engine 2 and an electric motor 3 running during operation. The hybrid disconnect clutch 4 in this case is actuated by an electrostatic clutch actuator. Upon restart of the combustion engine by the electric motor 3 , sufficient torque to substantially start the combustion engine 2 as well as to move the vehicle via the drive wheels 10 while maintaining driving comfort is generated by the electric motor 3 ), an accurate perception of the clutch characteristic curve of the hybrid separation clutch 4 to which the clutch torque is mapped through the actuator path is required. A node of this clutch characteristic curve is a contact point, and the contact point may be understood as a position of the hybrid separation clutch where the friction surfaces of the input side and the output side of the hybrid separation clutch 4 come into frictional contact with each other.

Since this point of contact is particularly important for the control of the hybrid disconnect clutch, it is determined during the first operation of the hybrid vehicle and matched during the driving operation of the hybrid vehicle. The determination of the basic contact point is made at standstill of the combustion engine 2 . It also starts from the fact that the hybrid disconnect clutch 4 is an engaged clutch (normally closed) not actuated by a lever spring. For the determination of the basic contact point, the clutch target torque applied to the hybrid separation clutch 4 is gradually increased until the electric motor 3 can detect a drive torque that can be assigned to the clutch target torque. Accordingly, the hybrid separation clutch 4 is closed until the frictional engagement surfaces of the input side and the output side of the hybrid separation clutch 4 are in frictional contact and a minimum torque is transmitted to the electric motor 3, wherein the minimum torque is the electric It is determined through the corresponding reaction of the motor 3 . Said corresponding reaction consists in that a prescribed torque rise is provided by the electric motor 3 . A prerequisite for this is that the hybrid disengagement clutch is in an open state and then slowly closed while observing the torque of the electric motor 3 , wherein the electric motor 3 is in an operating state in which the rotational speed is controlled.

2 shows a clutch actuation device 13 with a hydrostatic actuator 12 . The clutch actuation device 13 includes a control device 15 for driving the hydrostatic actuator 12 on the master side 14 . When the position of the actuator 12 is changed, the piston 16 is displaced to the right along the actuator path in the master cylinder 17 to pressurize the hydraulic fluid 18 in the master cylinder 17, so that in the master cylinder 17 A pressure p is created, by which the hydraulic fluid 18 is delivered to the slave cylinder 20 by the hydraulic line 19 . The hydraulic line 19 is matched to the assembly space situation of the hybrid vehicle in relation to the length and shape of the hydraulic line.

The pressure p of the hydraulic fluid 18 in the slave cylinder 20 causes a path change that is transmitted to the hybrid separation clutch 4 to actuate the hybrid separation clutch 4 . The pressure p in the master cylinder 17 is detected by the pressure sensor 21 , while the path section moved along the actuator path by the hydrostatic actuator 12 is determined by the path sensor 22 .

The master cylinder 17 has a sniffing bore 23 through which the master cylinder 17 is connected with a storage tank 24 for the hydraulic fluid 18 . In this case, the piston 16 passes the sniffing bore 23 when the hydrostatic actuator 12 operates, thereby interrupting the connection between the storage tank 24 and the master cylinder 17 . However, when the piston 16 of the master cylinder 17 moves to the left in the opposite direction, the sniffing bore 23 is released and the volumetric equilibrium of the hydraulic fluid 18 is achieved between the hydraulic transmission section and the storage tank 24 . This is referred to as the sniffing process. This volume equilibration results in temperature fluctuations in the hydraulic transmission section, which act on the hybrid separation clutch 4 which will likewise be actuated by the hydrostatic actuator 12 . Based on this, the basic contact point should be matched even between the two sniffing processes. This consists in determining the contact point variation, which is added to the basic contact point, from which the current contact point is provided.

As shown in Fig. 3, using the pressure sensor 21 and the path sensor 22, a pressure characteristic curve is recorded in which the pressure p for the path s of the hydrostatic actuator 12 is plotted. Looking at the upper branching curve of the hysteresis curve of the pressure characteristic curve going from left to right during the opening of the non-actuated closed hybrid separation clutch 4, it is almost linear in the range where the pressure p exceeds 3 bar and less than 10 bar. rising can be seen. After that, again a clearly flat maximum pressure is reached. When the hydrostatic actuator 12 is gradually closed, the pressure drop after the maximum becomes smaller and smaller.

From the variation of the pressure characteristic curve, the contact point variation between the two sniffing processes must now be determined. Immediately after the sniffing process, the current contact point is the same as the basic contact point.

Under the assumption that the hybrid separation clutch 4 is opened after the sniffing process, the upper branching curve of the pressure characteristic curve proceeds from left to right. At this time, the measurement process by the pressure sensor 21 starts when the pressure characteristic curve is located at a positive pressure gradient between 3 bar and 10 bar. From the pressure data thus measured, a first-order equation is parameterized, and the first-order equation approximates the pressure trend in a selected range. When measuring the pressure, it must be ensured that the stated pressure range passes in a short time in order to prevent the volume expansion of the hydraulic fluid 18 during the measuring time. In addition, it should be ensured that the evaluation starts when the pressure falls within the monotonic range of the pressure characteristic curve.

Therefore, immediately after the sniffing process, the intersection of the path axis of the pressure characteristic curve and the linear equation can be assigned to the basic contact point.

For all other openings of the hybrid disengagement clutch 4 made without sniffing, since the pressure characteristic curve is displaced, the first-order equation is newly calculated and a new intersection point with the path axis is determined. The intersection of the linear equations immediately after the sniffing process and the deviation of the intersection determined from the further transition between the two sniffing processes gives a direct contact point deviation and, by said contact point deviation, the basis which was advantageously determined at the initial start-up of the vehicle. The current point of contact must be displaced with respect to the point of contact. Since the pressure characteristic curve is displaced after the sniffing process, the current contact point from the variation of the pressure characteristic curve can be determined on the basis of the basic contact point, so that each another point of intersection with the path axis is determined in each new measuring cycle. do.

Alternatively, the constraint of starting the pressure measurement at a minimum pressure of 3 bar can be replaced by constraining the range for the recognition of the linear equation so that the pressure is clear in the open branching curve.

In another configuration, the pressure characteristic curve can be modulated and the displacement can be determined on both sides of the pressure maximum. For this purpose, the position (pos_max) of the maximum pressure value must be reliably determined. Accordingly, the characteristic curve at the safety distance s can be matched in the range less than pos_max - s and in the range greater than pos_max + s. This has the advantage that a reliable determination of the contact point is possible during longer periods of no sniffing and during periods in which the safety distance s has to be chosen correspondingly larger since it is not known where the pressure characteristic curve is directly located.

The proposed solution allows the determination of the point of contact between two sniffing processes using a pressure sensor. For this purpose, the pressure characteristic curve is evaluated in a linear range, and the contact point variation is derived from the displacement of the pressure characteristic curve caused by the volume expansion of the hydraulic fluid 18 .

1 drive train
2 combustion engine
3 electric motor
4 Hybrid Separation Clutch
5 crankshaft
6 rotor
7 stator
8 output shaft
9 gearbox
10 drive wheel
11 transmission system
12 hydrostatic actuator
13 Clutch Actuator
14 Master side
15 control unit
16 piston
17 master cylinder
18 hydraulic fluid
19 hydraulic line
20 slave cylinder
21 pressure sensor
22 path sensor
23 sniffing bore
24 storage tank

Claims (10)

In a method for determining the contact point variation of a hybrid separation clutch of a hybrid vehicle operated by a hydrostatic clutch actuator (12) and in which the hybrid separation clutch (4) isolates or connects a combustion engine (2) and an electric traction drive (3) wherein the hybrid separation clutch (4) is moved starting from a position of the hybrid separation clutch at which the hybrid separation clutch (4) assumes a non-actuated state, for determination of the point of contact, upon initiation of operation of the hybrid vehicle and/or A method for determining the contact point variation of a hybrid separation clutch of a hybrid vehicle, wherein the basic contact point of the hybrid separation clutch (4) is determined during operation, the method comprising:
The contact point variation is determined from the pressure signal of the pressure sensor 21 between the two sniffing processes of the hydrostatic clutch actuator 12, and the basic contact point is matched based on this contact point variation,
Immediately after the sniffing process, a first contact point variation is determined, said variation being added to the basic contact point to provide a current contact point, with the path of the hydrostatic clutch actuator 12 relative to the immediately preceding contact point variation being added to the previous current contact point. A method for determining a contact point variation of a hybrid disengagement clutch of a hybrid vehicle, characterized in that the variation is determined, whereby at least one other contact point variation is determined without another sniffing process. Determining the contact point variation of a hybrid separation clutch of a hybrid vehicle according to claim 1, characterized in that the measurement of the pressure signal is made in a clear range of the pressure characteristic curve for the path of the hydrostatic actuator (12) on which the contact point variation is determined. how to do it. Method according to claim 2, characterized in that the distinct range of the pressure characteristic curve is parameterized by the equation. 4. The contact point variation of the hybrid separation clutch of a hybrid vehicle according to claim 3, wherein the equation is formed as a first-order equation, wherein the intersection of the first-order equation with the path axis provides the contact point variation for the basic contact point. How to decide. 5. The method according to any one of claims 2 to 4, characterized in that the initial parameters of the linear equation are stored from one sniffing process to the next sniffing process. Way. 5. A hybrid vehicle according to any one of claims 2 to 4, characterized in that the parameters of the linear equation are learned from the initial parameters of the linear equation through adjustment proceeding under the use of a control technical observer. A method for determining the contact point variation of a disconnect clutch. 5. The pressure characteristic curve of the hydrostatic clutch actuator (12) according to any one of the preceding claims, characterized in that a definite pressure range of the pressure characteristic curve of the hydrostatic clutch actuator (12) passes in the period during which the volume expansion of the hydraulic fluid (18) is inhibited. , a method for determining a contact point variation of a hybrid disconnect clutch of a hybrid vehicle. Method according to one of the preceding claims, characterized in that the measurement of the pressure signal starts after the minimum threshold pressure value is exceeded. 5. The hybrid separation clutch according to any one of claims 1 to 4, wherein the basic contact point at the stop of the combustion engine (2) is that if a prescribed torque rise is detected, the hybrid separation clutch (4) assumes an inoperative state. by the slow operation of the hybrid separation clutch (4) starting from the position of A method for determining contact point variation. delete

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