KR100561269B1 - Method for determining slip - Google Patents

Abstract

The present invention relates to a method and apparatus for determining a slip inside a clutch between a transmission of a drive train and an engine using a clutch input speed and a wheel speed, and using a mathematical model to explain the dynamic performance of the drive train. Changes are calculated and are considered when the slip is determined.

Description

Method for determining slip {METHOD FOR DETERMINING SLIP}

The present invention relates to a method for determining a slip (SLIP) inside a clutch mounted in a drive train of a vehicle.

The clutch mounted between the drive motor and the transmission in the drive train of the vehicle is incrementally automatically operated, and an actuator for operating the clutch in accordance with the operating conditions of the vehicle is controlled by the controller. Automatically actuated clutches of this type can also be mounted on the output side of the transmission. Automated clutches of this type on the one hand significantly improve the operational comfort of the vehicle. On the other hand, the fuel consumption is reduced by the clutches, especially with regard to automated transmissions, because the vehicle is driven more frequently by means of better energy saving gears. Thus, in order to reduce the fuel consumption of the actuator, the time required for operation and comfort is reduced, and the automated clutch is operated so that the clutch is closed only when necessary, resulting in an unacceptably large slip. Therefore, attention is paid to the slip of the clutch for various reasons.

By averaging the speeds of the driven wheels and doubling the gear input speed and the overall speed ratio in operation between the wheels, the clutch output speed equal to the speed change input speed is calculated, and the vibration action occurring in the drive train is ignored. (The drive train is essentially a vibration system). The result is a computerized difference between the measured engine speed (clutch input speed) and the calculated gear input speed (clutch output speed), and even if no slip actually exists, the action generated as a result of the vibration inside the drive train is slipped. It is evaluated as. In order to ensure the reliability of the above false evaluation on slip, the fixed slip limit has to be exceeded so far. The slip limit should be set very high, especially during severe vibrations occurring when operating at low speeds or starting with a jumper of torque. However, in normal driving operation, when no slip actually exists, the slip is still not recognized as a result, fuel consumption is unnecessarily large, and the service life of the clutch is reduced.

Accordingly, an object of the present invention is to determine the slip of a clutch mounted between an engine and a transmission inside a drive train of a vehicle, to measure the clutch output, and to reduce the slip generated in the clutch without considering the vibration of the drive train. It provides a way to be perceived.

A first solution to this problem is featured in claim 1.

According to the present invention, the speed changes generated by the dynamic behavior of the drive train are calculated in particular taking into account the torque change generated by the engine on the drive train. The difference must exceed the kinematically calculated speed changes so that the difference between the measured clutch output speed and the measured clutch input speed calculated from the measured vehicle wheel speed and the overall transmission ratio is evaluated as a slip.

The dependent claims of claims 2 to 5 relate to another embodiment of the method according to the main claim.

Claim 6 relates to a modification for solving the problem set by the present invention. By this method, the entire drivetrain is simulated in a mathematical model including measurable condition values and measurable generating torques. The clutch output speed is calculated from the mathematical model. The difference between the measured clutch input speed and the calculated clutch output speed is the slip actually present in the clutch.

Claim 7 relates to another advantageous embodiment of the method according to claim 6.

The invention furthermore relates to an apparatus for implementing a method for determining slip according to one of the claims above.

The invention is explained in more detail by the embodiments with reference to the drawings.

1 shows a drive train of a vehicle;

2 is a view showing a vibration model of the drive train.

3 shows vibrations appearing inside the drive train after a severe torque generation;

4 shows curves for explaining the crystallization of each operating engine torque;

5 shows the damped vibration of the gear input speed.

6 is a flowchart for explaining a calculation process of the dynamic slip limit value.

7 is a view of a drive train similar to FIG. 1 with additional sensors.

8 is a view for explaining a process of determining load torque.

9 is a flowchart for explaining determination of a gear input speed.

10 shows a vibration model of the drive train.

11 shows a vibration model of a drive train.

* Code Description

2 ... Internal combustion engine 4 ... Clutch

10 ... differential 12 ... wheel

20 ... lever 26 ... electronic control unit

28 ... speed sensor 30 ... position sensor

32,34 ... Wheel speed sensor 205 ... Vehicle

Referring to FIG. 1, the drive train of the vehicle has an internal combustion engine 2, which is connected to the transmission 6 via a clutch 4, followed by a cardan shaft 8 and a differential device. Via transmission 10 the transmission 6 is connected to the rear driven wheels 12. The front wheels 14 configured in the vehicle are not driven in the embodiment.

The structure of the clutch 4 is known per se, in particular comprising a clutch disc 16, the clutch disc 16 being fixedly connected to the crankshaft of the internal combustion engine 2, and also the pressure plate 18. The pressure plate 18 is fixedly connected to the input shaft of the transmission 6, and operates the lever 20 against the load of the leaf spring to release the pressure plate from the frictional connection with the clutch disk 16. do.                 

The transmission 6 is constituted by a manual transmission which is shiftable by the shift lever 22 and according to the prior art.

For example, an actuator 24, such as an electric step motor controlled by the electronic control device 26, is provided for operating the actuating lever 20.

According to a known method, the electronic control device 26 includes a microprocessor, a memory device, an interface, and the like. Speed sensor 28 for detecting the speed of the crankshaft or clutch disk 16 of the internal combustion engine 2, position sensor 30 for detecting the position of the operating lever 20 or the actor, wheel speed sensor 32 34 and, if necessary, signals of the sensor relating to operating parameters of the drive train, such as the position of the throttle flap of the internal combustion engine 2, are provided as input signals. Also provided to the controller 26 is the speed of the front wheels 14 not being driven.

The method and configuration of the device described so far is well known and therefore not described in further detail.

The speed of the pressure plate 18 equal to the speed of the gear pressure shaft is calculated so that the speeds of the rear wheels 12 are averaged and doubled by the overall speed ratio of the transmission 6 and the differential 10, and then the pressure plate 18. When the difference from the calculated speed of and the speed of the clutch disc 16 is considered as a slip, the problem that arises is as follows.

The entire drivetrain is a vibrating body, and the engine or internal combustion engine 2, which is smoothly mounted inside the vehicle, is supported in delay by the rear wheels 12 and has considerable inertia when the drivetrain acts as an elastic connecting element. Vibrate against the vehicle.                 

In figure 2 a vibration system is schematically shown. The moment of inertia of the engine is shown by J _M , the overall transmission ratio of the transmission is shown by i, and C is the spring constant of the drive train.

When the inertia of the engine is _excited by the torque change [Delta] M, vibrations are then formed in magnitude [Delta] M / C in the surge natural frequency [omega] _Rucked . According to the vibration shown in Fig. 3, the speed n is recorded on the longitudinal axis and the time t is recorded on the transverse axis.

=c*ω_Rucked에서 계산된다. 따라서The maximum angular velocity generated through the vibration

= c * ω _Rucked . therefore

Δn _dyn1 is the maximum speed change or speed difference generated by the engine torque change ΔM.

It is only evaluated as slip of the clutch when the difference from the measured speed and the gear input speed of the clutch disc 16 or the difference in the clutch speed calculated from the speed average value of the rear wheels 12 and the operating gear speed ratio is larger than Δn _dyn1 .

The surge frequency (ω _Ruckel ) depends on the associated gear transmission ratio. Surge frequencies can be determined from measurements or vehicle data for each gear. From the surge frequencies of the first gear, it is possible to determine the frequencies for another gear transmission ratio.

f _n = f ₁ *

Comparing the filtered engine torque signal with the engine torque signal, the engine torque change ΔM is determined. Engine torque signals are measured using, for example, the characteristics of the manifold pressure at which the engine torque is read by the engine speed and throttle valve position or engine speed and given values. Through a data bus, for example a CAN bus, engine torque can also be obtained directly from the engine control action. The filtered engine torque signal is calculated from the engine torque signal by the engine torque signal passing through the filter in a known manner by the filter time constant T _F. Since the filtered signal follows the unfiltered signal too quickly and the engine torque change ΔM cannot be determined accurately, the filter time constant T _F should not be selected too small. The filter time constant (T _F ), which is twice the period of surge vibration, is convenient. For this purpose, the engine torque change ΔM can be determined from the values of the engine torque at a previous time.

According to the top view of FIG. 4, the difference between the engine torque signal M _B and the filtered engine torque signals M _{E and F} is shown. The curves at the bottom are the same as the curves at the top, and the filter time constants T _F are shown. The smaller the filter time constants T _F , the faster the filtered torque signals M _{E, F} approach the actual engine torque M _E. The torque change ΔM is determined by comparing the surge signal M _E with the filtered signals M _{E and F} , and the fading regarding the time of the drive train vibration is shown.

Due to the attenuation inside the drive train, the magnitude of surge vibration Δn decreases with time. The above procedure for describing the fading of vibration through the time reduction of the torque change ΔM is generally not accurate enough. From the magnitude of the surge oscillation, for this reason, the magnitude of the next time step at which the fading of the vibration is taken into account is determined by the damping constant (D).

For the new size it is applied to the next procedure.

During the period of surge oscillation, the control p-fold is called and the speed D-fold is read out so that the following relationship is made to the fade constant k (which is the fade constant for control stop).

In order to simply calculate the fade constant (k), the term is made with backwater evolution. So for example the first approximation is:

(1-ｘ) ^m = 1-mx-...

However, if accuracy needs to be increased, additional links of backwater forwarding can be used.

Therefore, the following relationship applies to the dynamic slip threshold from the damping effect.

Equation 2

Δn = Δn _{dyn2 dyn} * K

By this method, two parts can be used to determine the slip limit value, ie the slip limit value Δn _dyn1 calculated from the engine torque change ΔM on the one hand and the slip limit value Δn _dyn2 calculated on the other hand as the damping effect. The maximum value of the two parts is used as the slip limit value.

Δn _dyn1 = MAX (Δn _dyn1 , Δn _dyn2 )

In contrast to the prior art in which a fixed slip limit set very high is used to suppress the influence of vibration inside the drive train, the present invention is operable by an actual slip limit adapted to actual drive train vibrations.

According to FIG. 5, a method for determining slip as a flowchart is provided.

The slip Δn is calculated by the conventional method in which the gear input speed determined from the wheel speed measured in step 100 and the total speed ratio is subtracted from the measured engine speed.

In step 102, the engine torque change ΔM is calculated as described with reference to FIG.

In step 104, the slip limit value Δn _dyn1 is calculated from the engine torque change ΔM according to equation (1).

In step 106, the slip limit value Δn _dyn2 is calculated from the damping effect according to equation (2).

In step 108, it is determined whether the slip limit value Δn _dyn1 is greater than the slip limit value Δn _dyn2 . If large, in step 110 the slip limit value Δn _dyn1 is set to the dynamic slip limit value Δn _dyn . If not, the slip limit value Δn _dyn2 forms a dynamic slip limit value Δn _dyn at step 112. In step 114, whether the slip Δn determined according to the prior art is larger than the slip limit Δn _dyn is set. If large, this is assessed as the occurrence of clutch slip. If it is not large, it is evaluated that no slip occurs in the clutch.

As an alternative embodiment of the method, it is possible to at least approximately reconstruct the overall condition vector of the dynamic system "drive train" from the measurements. For this purpose, the mathematical simulation of the drivetrain is loaded by a kinetic model with input engine torque M _E and load M _L , and the measurements are compared with the corresponding values of the mathematical model. For this purpose, the difference between the measurements of the drive train and the values determined from the mathematical model is changed to the input of the mathematical model by appropriate evaluation. Therefore, the mathematical model is excited so that the mathematical model vibrates in the same rhythm as the driving train. According to this method, numerical values measurable from a mathematical model cannot be measured. In the special case of determining slip, an unmeasurable value of gear input speed or clutch output speed is selected. The presence of slip can be determined by the comparison.

The drive train shown in FIG. 7 corresponds to the drive train of FIG. 1, but additionally sensors such as throttle valve position sensor 36, cardan speed sensor 38, and the like are provided. The additional sensors are connected to an electronic controller 26 in which a mathematical model is processed.

In view of the problem of the calculation method by the observer, in the special case of the vehicle, the load torque M _L is not known (running resistance, slope, etc.). Therefore, it is necessary to determine the load moment M _L in anticipation of the break-down value. For this purpose, measurable values and engine speed can be used, such as driving speed (from wheel speed). With regard to the wheel speed, the speeds of the wheels 14 in front are advantageously taken into account, and in all cases the speeds are detected from the ABS sensor provided, so that there is no additional cost. By the known inertia of the engine and the vehicle it is possible to determine the expected value of the load moment M _L by the model shown in FIG. 8 and very simplified.

The following relationship applies:

M _L = M _E -J _M * ω _M -J _KFZ * ω _KFZ

Where J _M is the mass moment of inertia of the engine, J _KFZ is the mass moment of inertia of the vehicle that is reduced at the engine side, ω _M is the rotational speed of the engine, and ω _KFZ is the rotational speed of the vehicle projected from the engine side.

The mathematical dynamics model of the vehicle can be expressed as

ｘ = Ax + Bu

The vector ｘ is the state value (torsion angle, angular velocities), and the vector U connects the excited torque (engine torque, load torque). The system is described by the conditional matrix A. Through the control matrix B, the individual excited torques are projected on the individual condition coordinates.

A flowchart for the determination of slip from the complete mathematical model is shown in FIG. The input value engine torque measured on (eg from the load of bearings that block the engine on the vehicle) and calculated (eg from speed and throttle valve angle or engine control data) acts on the vehicle 120. The values measured on the vehicle 120 are determined by the sensors 122. In addition, the load torque is determined 124 as described with reference to FIG. 8. Load torque and engine torque are input into the dynamic vehicle model 126 as input values. Measurements 122 are mathematically read 128 from the dynamic vehicle model 126. The difference between the mathematically determined measurement 128 and the directly measured measurement is evaluated kinetically 130 and input into the kinetic model 126 126. With the appropriate choice of kinetic evaluation, the kinetic model is excited so that the kinetic model vibrates in line with the vehicle, so that the gear input speed or clutch output speed can be calculated and compared with the engine speed or clutch input speed. .

An embodiment for model formation is as follows. For the clutch in which slip is occurring, the following relationship applies according to FIG.                 

Known inertia of the engine 201, transmission 203, vehicle 205 and clutch 202, transferable torque and stiffness of the drivetrain 204 form a dynamic module of the vehicle from the model of FIG. Can be.

The following relation is applied not only by the condition matrix B but also by the condition vector (ｘ), the condition vector (u) and the condition matrix (A).

In another embodiment of FIG. 11, a model can be set for a clutch without slips. The rotation angles of the clutch input and output are the same. Thus, the rotational inertia of the engine and transmission are combined and the following relationship applies.

The following relationship is applied by the condition vector (ｘ), the inspection vector (u), the condition matrix (A) and the condition matrix (B).

Basically, a method and apparatus for carrying out the method according to the invention are described, in which a slip calculated from the difference between the engine speed and the transmission or at least the output speed of the wheel of the individual vehicle is actually present in the clutch, and the gear input and The speed difference formed from the dynamics of the transfer size (torsional vibration of the output shaft between the gearbox and the vehicle wheels) between the wheels can be differentiated into actual slips.

When a vehicle reaction or clutch operation performed as a function of slip is introduced, the vehicle reaction or clutch operation is introduced by the actual clutch slip, and the vehicle reaction or clutch operation is prevented by the actual slip. For example, the part where the clutch is closed when slip is detected is included in the control / adjustment action.

With the vehicle running properly, there may be clutch slips that form a controlled closure of the clutch. For example, through a load change repeatedly introduced on the other hand, the actual slip can be reached as the speed difference between the output speed and the gear input speed applied to the entire transmission.

In another embodiment, a temperature model / load model for determining the clutch temperature / clutch load is formed in the control / adjustment action of the automatically operated clutch. From the vehicle data, the frictional force introduced into the clutch or the temperature of the clutch is calculated. According to the control action, the formed reaction appears in the vehicle and the clutch is operated when the limit temperature / limit load is exceeded. The control action from the determination and micronization between slip and actual slip can control the introduction or prevention of changes in clutch operation.

By means of the method for determining the slip inside the clutch, the clutch input speed or engine speed is measured and the clutch output speed is calculated from the speed of at least one vehicle wheel and the total speed ratio acting between the clutch output and the vehicle wheel. In the first embodiment of implementing the method, using a mathematical model representing the dynamic behavior of the drive train, it rises depending on the change of the operating parameters of the drive train, and / n _k1 -n _ka / -Δn _dyn > The velocity change Δn _dyn , which is evaluated as slip when zero, is calculated.

An apparatus for determining slip according to the above description is also related to the present invention.

The claims of the present application are the claims proposed without the intention of seeking broader patent protection. Applicant reserves the right to claim features disclosed to date only in the description and / or in the drawings.

The descriptions of the dependent claims refer to the subject matter of the main claim through the features of each relevant dependent claim. The above descriptions should not be considered unnecessary to seek independent subject protection with respect to the features of the described dependent claims.

However, the subject matter of the dependent claims also forms an independent invention, which has a design independent of the subject matter of the preceding claims.

In addition, the present invention is not limited to the embodiments of the detailed description. Within the scope of the present invention, there are advances to the combination or modification of the individual features or elements or process steps described and contained in the figures, in particular in connection with the somewhat different modifications and variations, in particular in connection with the general description and the embodiments and claims, Combinable features enable the above modifications, elements and combinations and / or materials to form new subjects, new steps or sequences of process steps as far as manufacturing, testing and workflow are concerned.

Claims (8)

The clutch input speed (n _ki ) is measured, the clutch output speed (n _ka ) is calculated from the speed of at least one vehicle wheel, the clutch output and the total speed ratio acting between the vehicle wheels, and the engine and transmission inside the vehicle's drivetrain. In the method for determining the slip inside the clutch mounted in between, For the mathematical model to explain the dynamic behavior of the drive train, the method is characterized in that / n _ki -n _ka / -Δn _dyn is evaluated in which the rising speed change (Δn _dyn ) in response to the change of operating parameters of the drive train is evaluated. . The formula according to claim 1, wherein ΔM = engine torque change, J _M = moment of inertia of the engine, f _R = surge frequency.

From the speed change Δn _dyn is determined. 3. The method according to claim 2, wherein the engine torque change ΔM is determined by comparing the filtered engine torque with the engine torque signal. The method according to claim 1, wherein D = attenuation constant of the surge vibration and T _R = time duration of the surge vibration. Δn (t + T _R ) _dyn2 = Δn (t) * e ^-δTR only,

Accordingly, the speed change Δn _dyn is determined. The method according to claim 2 or 4, wherein the speed change Δn _dyn is the larger of Δn _dyn1 and Δn _dyn2 . The clutch input speed or engine speed n _ki is measured, the clutch output speed n _ka is calculated by measuring at least one wheel speed, and the slip inside the clutch mounted between the engine and the transmission in the drive train of the vehicle. In the method for determining When x is the condition value of the drive train, u is the excited torque, and A is the condition matrix and B is the condition matrix, x = Ax + Bu The entire drivetrain is simulated by a mathematical model and the clutch output speed is calculated from the mathematical model. 7. The method of claim 6, wherein M _E = engine torque, J _M = moment of inertia of the engine, ω _M = angular velocity of the engine, J _KFZ = total moment of inertia at the vehicle wheels, ω _KFZ = angular velocity of the vehicle wheels. M _L = M _E -J _M * ω _M -J _KFZ * ω _KFZ Obtained according to the method. delete

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