EP2324262A1

EP2324262A1 - Method for finding a clutch slip point of a hybrid vehicle

Info

Publication number: EP2324262A1
Application number: EP09741372A
Authority: EP
Inventors: Gaëtan ROCQ; Cédric LAUNAY
Original assignee: Peugeot Citroen Automobiles SA
Current assignee: PSA Automobiles SA
Priority date: 2008-09-05
Filing date: 2009-09-04
Publication date: 2011-05-25
Also published as: US20110153134A1; WO2010026348A1; CN102144109A; FR2935767B1; FR2935767A1; CN102144109B

Abstract

The present invention essentially relates to a method for finding a slip point of a hybrid vehicle (1) having an electrically towed rear axle. In said method, the electrical machine (17), when starting the vehicle, is actuated to provide the vehicle drive, the engine (7) being turned off, the clutch (10) being open, and the transmission (8) being in neutral. Once the speed of the main shaft has reached a threshold (K’1), the acceleration of said main shaft is measured and stored as a reference value, and the closing of the clutch (10) is gradually controlled. Once it has been detected that the change in acceleration (ΔWAP/Δt) of the main shaft relative to the reference value has reached a threshold (K’2), the position of the clutch (10) is stored in order to deduce therefrom the position of the slip point (PP).

Description

Method for learning a slip point of a clutch for a hybrid vehicle

[001]. The present invention relates to a method of learning a slip point of a clutch for a hybrid vehicle. Clutch slip point means the position of the clutch in which the two disks of the clutch begin to slip relative to each other to transmit torque.

[002]. The object of the invention is notably to enable the learning of the slip point while the engine is stopped.

[003]. The invention finds application in the field of hybrid vehicles with two types of energy, thermal and electrical, the combination ensures their traction while optimizing energy efficiency and thus reduce consumption and pollution. These vehicles are able to drive independently through the thermal energy of the internal combustion engine or electric through an electric traction machine.

[004]. More particularly, the invention finds an advantageous application in the field of hybrid vehicles combining the use of an electric traction system ensuring the electric traction of a vehicle trains and a thermal traction chain ensuring the thermal traction from the other vehicle train.

[005]. The power train has an internal combustion engine, and a gearbox coupled to the wheels. A clutch is connected on the one hand to said engine and on the other hand to the primary shaft of the gearbox, the secondary shaft of the gearbox being coupled to the wheels via a lowering bridge. Furthermore, a starting system independent of the engine by a controlled starter can be connected to the engine for its start.

[006]. The electric traction chain is formed by a machine an electric machine coupled to the wheels via a reducer, which electrical machine is connected to an energy storage device, such as a power battery, for supplying power when the machine is operating in motor mode or store it when the machine is running in generator mode.

[007]. Throughout the use of the vehicle, the position of the clutch corresponding to the slip point varies in particular according to the wear of the discs and the conditions of use of the clutch. It is therefore useful to establish a learning strategy of the clutch slip point to recalibrate the transfer function between the position of the clutch and the transmitted torque, in order to control the torque transmitted by the clutch. The purpose of this function is to gain reliability and consistency on the clutch torque transmission services during start-up and gear shifting.

[008]. There is known a learning method of the slip point adapted for hybrid vehicles comprising an electric machine connected in series with a heat engine via a clutch. This method makes it possible to detect the slip point by detecting a change in speed of the electric machine. This method, illustrated in Figure 1, is implemented at each start of the vehicle, when starting the engine, and before the driver has engaged a gear ratio.

[009]. More precisely, FIG. 1 shows in its upper part a diagram indicating the evolution of the WMTH speed of the thermal engine and the WMEL speed of the electric machine as a function of time and in its lower part the evolution of the position of the clutch. Pemb as a function of time. The position PO corresponds to the open position of the clutch, while the position PF corresponds to the closed position of the clutch.

[010]. In a first phase A, while the clutch is open to the maximum, the heat engine is started, and a regulation of the WMTH speed is carried out towards a given setpoint K1. [011]. In phase B, once the WMTH regime stabilized and the ratio to neutral, a slow closing of the clutch is performed in order to transmit a low torque to the electric machine and thus cause it to ramp up.

[012]. At the beginning of the phase C, at time t1 where a delta of speed ΔWMEL is detected higher than a calibratable threshold, the position of the clutch actuator is memorized and the position of the point of licking PP of the clutch is deduced therefrom. 'clutch.

[013]. This strategy has the advantage of being simple but poses a problem in the case of hybrid vehicles electrically towed rear train. Indeed, with this type of architecture, we no longer find the life situation at a standstill in which the engine running, the clutch is open and the gearbox in neutral, since the vehicle is started by the electric machine at the back of the vehicle.

[014]. For hybrid architectures electrically towed rear train, there is therefore the need for a skate point learning strategy using otherwise the vehicle organs.

[015]. The invention fills this need by proposing a method in which the slip point of the clutch is deduced from the measurement of the variation of the acceleration of the primary shaft of the gearbox performed during a progressive closure. of the clutch, while the vehicle is traveling in electric mode.

[016]. More specifically, in the method according to the invention, the vehicle is started and rolls in electric mode, the clutch being open and the gearbox being in neutral, that is to say in neutral. The engine is stopped and the gearbox is neutral for the duration of the process.

[017]. The rotation of the front wheels drives the primary shaft of the gearbox to a non-zero speed depending on the speed of the vehicle and the internal friction of the gearbox. Once the speed of the primary shaft exceeds a calibrated threshold, it calculates and stores its acceleration as a reference value.

[018]. Then a controlled closing of the clutch is carried out in order to transmit clutch torque to the primary shaft of the gearbox and thus to disrupt its change in speed.

[019]. As soon as an acceleration variation of the primary shaft is detected relative to the reference acceleration greater than a second calibratable threshold, the position of the clutch actuator is memorized so as to deduce the slip point of the clutch actuator. the clutch.

[020]. The invention thus makes it possible to reset the slip point of the coupling system throughout the life of the vehicle, in particular during each pure electric driving phase. It is recalled that these phases of electric taxiing generally occur in the city when the vehicle is traveling at a speed below a threshold speed.

[021]. The invention therefore relates to a method for learning a slip point for a hybrid vehicle provided with a thermal traction chain ensuring the traction of one of the vehicle trains and an electric traction chain ensuring the traction of the vehicle. other train of the vehicle, - the thermal traction chain comprising an internal combustion engine, a gearbox coupled to the wheels, and a clutch connected on the one hand to said engine and on the other hand to the primary shaft of the gearbox,

- the electric traction chain comprising in particular an electric machine coupled to the wheels, characterized in that,

when the vehicle is started, the electric machine is actuated to ensure traction of the vehicle, the engine being off, the clutch being open, and the gearbox being in neutral,

the acceleration of said primary shaft is measured and stored as a reference value, and the closing of the clutch is progressively controlled, and - as soon as an acceleration variation of the gearbox primary shaft is detected greater than a threshold, the variation in acceleration being equal to the variation between the acceleration of the measured primary shaft and the value reference, the position of the clutch is memorized to deduce the position of the slip point.

[022]. According to one implementation, the acceleration variation threshold is calibrated and is for example 0.5 m. s ^"2 .

[023]. According to one implementation, the acceleration reference value is measured and calculated as soon as it is detected that the speed of the primary shaft of the gearbox is greater than a threshold.

[024]. According to one implementation, the speed threshold is calibrated and is for example 500trs / min.

[025]. According to one embodiment, the position of the clutch is measured at the concentric stop of the fork of the clutch.

[026]. According to one implementation, once the position of the skid point memorized, it re-opens the clutch.

[027]. According to one implementation, the acceleration variation threshold corresponds substantially to the position of the slip point.

[028]. According to one embodiment, the thermal traction chain ensures traction of the front axle of the vehicle and the electric traction system ensures the traction of the rear axle of the vehicle.

[029]. The invention further relates to a hybrid vehicle implementing the learning method of the slip point according to the invention.

[030]. The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given for illustrative purposes but in no way limitative of the invention. They show : [031]. FIG. 1 (already described): time diagrams of the evolution of the parameters of the vehicle components during the implementation of a method of learning the skidding point according to the state of the art;

[032]. Figure 2 is a schematic representation of a hybrid vehicle according to the invention with electrically towed rear axle implementing the method according to the invention;

[033]. 3: time diagrams of the evolution of the parameters of the vehicle components during the implementation of the learning method of the slip point according to the invention.

[034]. Identical elements retain the same reference from one figure to another.

[035]. Figure 2 shows a hybrid vehicle 1 according to the invention provided with a chain 2 of thermal traction ensuring traction of the train 3.1 before the vehicle and an electric traction chain 4 ensuring the traction of the rear axle 3.2 of the vehicle. The wheels of the vehicle bear the reference 5.

[036]. The thermal traction chain 2 comprises in particular an internal combustion engine 7, gasoline, diesel or other equipped with a flywheel and an 8 speed gearbox N reports discrete manual type controlled, automatic or other wheel connected 5.

[037]. A clutch 10 is connected on the one hand to said thermal engine 7 and on the other hand to the primary shaft of the gearbox 8. The clutch 10 may be a clutch of dry type, wet, or other. The secondary shaft of the box 8 is coupled to the wheels 5 via a lower deck (not shown).

[038]. Furthermore, a starting system 13 independent of the engine 7 is connected to said motor 7 via a coupling system 14 to ensure its startup. This starting system 13 can be achieved by a controlled starter formed by a small electrical machine or other; while the coupling system 14 may take the form of a belt system.

[039]. The electric traction chain 4 is formed in particular by an electric machine 17 coupled to the wheels 5 by means of a gear unit 19. Moreover, this electrical machine 17 is in connection with an energy storage device 20, such as a power battery, making it possible to supply energy when the machine 17 is operating in motor mode or to store it when the machine 17 operates in generator mode.

[040]. Each member 7, 8, 10, 13, 17, 20 is controlled by a close-up computer 7.1, 8.1, 10.1, 13.1, 17.1 and 20.1 which is itself controlled by a single computer, said supervisory computer 23, which takes the decisions and synchronizes the actions of the various members 7, 8, 10, 13, 17, 20 to respond to the will of the driver.

[041]. This calculator 23, depending on the life situations and the state of the vehicle, drives the 2 and electric traction chains 4, decides the driving mode, coordinates all the transient phases and chooses the operating points of the various organs, to optimize fuel consumption and depollution.

[042]. Thus, the computer 23 controls the members 7, 8, 10, 13, 17, 20 so that the vehicle operates in electric mode when the vehicle speed is below a threshold speed. While the computer 23 controls the members 7, 8, 10, 13, 17, 20 so that the vehicle operates in thermal mode when the vehicle is traveling at a speed greater than the threshold speed. In the recovery phases, which occur during braking, it ensures in particular that the machine 17 operates in generator mode to transform the kinetic energy of the vehicle into electrical energy and store it in the storage device 20.

[043]. Figure 3 shows, from top to bottom, a diagram indicating the evolution of the speed V of the vehicle 1 (in kilometers per hour km / h) in according to the time, the evolution of the ratio R of the gearbox 8 as a function of time, the evolution of the speed WAP of the primary shaft of the gearbox 8 (in revolutions per minute rpm) as a function of the time, and the evolution of the position of the clutch 10 (in millimeters) as a function of time, the position PO corresponding to the open position of the clutch 10, the position PF corresponding to the closed position of the clutch 10 .

[044]. During a first phase A ', the vehicle 1 is started and runs in pure electric mode, that is to say that the electric machine 17 is actuated and the thermal engine 7 is off. The clutch 10 is open and the gearbox 8 is in neutral. Note that the engine 7 remains off and the gearbox 8 remains neutral throughout the learning procedure of the slip point of step A 'to step D'.

[045]. The rotation of the front wheels 5 drives the primary shaft of the gearbox 8 at a non-zero speed depending on the speed V of the vehicle and the internal friction of the gearbox 8. Indeed, even if the primary shaft and the secondary shaft of the gearbox 8 are not coupled by interconnection, the gearbox 8 being in neutral, the rotation of the front axle and therefore the secondary shaft of the Gearbox 8 drives the rotation of the primary shaft of the gearbox 8 because of the internal friction between the different gears of the ratios of the gearbox 8.

[046]. Phase B 'constitutes the continuity of phase A'. However, at the end of the phase B ', at time t'1, as soon as the computer 23 detects that the speed WAP of the primary shaft of the gearbox 8 is greater than a first calibrated threshold K'1 , the computer 23 calculates and stores the acceleration of this primary shaft as reference acceleration.

[047]. This first threshold K'1 depends in particular on the type of gearbox 8 and the type of clutch 10 used. In one example, for a vehicle comprising a dry disc type clutch 10 and a robotic manual gearbox 8, the first threshold K'1 is 500 rpm. This first threshold K'1 is for example determined on engine bench or by simulation.

[048]. As soon as the computer 23 has detected that this value K'1 has been exceeded and the acceleration of the primary shaft has been memorized, it proceeds to the phase C in which the computer 23 controls the progressive closing of the clutch 10, so as to the torque is transmitted via the clutch 10 to the primary shaft of the box 8 and thus disrupt its evolution WAP regime.

[049]. At the end of the phase C, at the moment t'2, as soon as the computer 23 detects a variation of acceleration ΔWAP / Δt of the primary shaft, corresponding to the variation between the acceleration of the primary shaft measured and the reference acceleration, greater than a second calibratable threshold K'2, the position of the clutch actuator is memorized to deduce the slip point PP of the clutch 10.

[050]. Here, the detected second threshold K'2 substantially corresponds to the position of the slip point PP, that is to say that when the computer 23 detects that the acceleration variation reaches this second threshold K'2, the computer 23 Known that the clutch 10 is substantially at the position of the slip point PP. As a variant, the second threshold K'2 corresponds to a position remote from the slip point PP from which the computer 23 knows, a priori, to find the position of the slip point PP, for example from a map of acceleration variation. of the primary shaft / position of the clutch 10.

[051]. The second threshold K'2 corresponding to the slip point PP depends, of course, on the type of gearbox 8 and the type of clutch used. For example, for a hybrid vehicle 1 having a dry disk-type clutch 10 and a robotic manual type gearbox 8, the second threshold K'2 is equal to 0.5 ms- ^{2, which} second threshold K'2 is for example determined on engine bench or simulation.

[052]. The storage of the clutch position can for example be performed at the concentric stop of the fork of the clutch 10 moved by an actuator.

[053]. Once the position of the slip point PP memorized, one goes to phase D ', in which the clutch 10 is reopened to complete the procedure.

[054]. Alternatively, the chain 2 of thermal traction ensures traction of the rear axle of the vehicle; while the chain 4 of electric traction ensures the traction of the front axle of the vehicle.

Claims

A method of learning a slip point for a hybrid vehicle (1) equipped with a chain (2) of thermal traction ensuring the traction of one of the trains (3.1) of the vehicle and a chain electric traction (4) ensuring the traction of the other train (3.2) of the vehicle,

the thermal traction chain comprising an internal combustion engine, a gearbox coupled to the wheels, and a clutch connected to said engine and on the other hand to the primary shaft of the gearbox (8),

- the electric traction chain (4) including in particular an electric machine (17) coupled to the wheels (5), characterized in that,

- When starting the vehicle, the electric machine (17) is actuated to ensure traction of the vehicle, the motor (7) being off, the clutch (10) being open, and the gearbox (8) being neutral ,

the acceleration of said primary shaft is measured and stored as a reference value, and the closing of the clutch (10) is progressively controlled, and

- as soon as an acceleration variation (ΔWAP / Δt) of the primary shaft of the gearbox (8) of speeds greater than a threshold (K'2) is detected, the acceleration variation being equal to the variation between the acceleration of the measured primary shaft and the reference value, the position of the clutch is memorized to deduce the position of the slip point (PP).

2. Method according to claim 1, characterized in that the threshold

(K'2) acceleration variation is calibrated and is for example 0.5 m. s ^"2 .

3. Method according to claim 1 or 2, characterized in that the acceleration reference value is measured and calculated as soon as it is detected that the speed (WAP) of the primary shaft of the gearbox (8) is greater than a threshold (K'1).

4. Method according to claim 3, characterized in that the speed threshold (K'1) is calibrated and is for example 500trs / min.

5. Method according to one of claims 1 to 4, characterized in that the position of the clutch (10) is measured at the concentric stop of the fork of the clutch (10).

6. Method according to one of claims 1 to 5, characterized in that once the position of the slip point (PP) stored, re-opens the clutch (10).

7. Method according to one of claims 1 to 6, characterized in that the threshold (K'2) acceleration variation corresponds substantially to the position of the slip point (PP).

8. Method according to one of claims 1 to 7, characterized in that the chain (2) of thermal traction ensures the traction of the front axle (3.1) of the vehicle and the electric traction chain (4) ensures the traction of the train rear (3.2) of the vehicle.