FR3060481A1 - VEHICLE POWERTRAIN - Google Patents

Abstract

The present invention relates to a powertrain for a vehicle comprising successively: - a heat engine (1), - a flywheel (9), - a clutch (2) comprising at least one clutch disk, - a gearbox (3). ) with manual control, - and a wheel (5) in which a freewheel device (20, 21, 22, 23, 24, 25, 26) authorizes the transmission of torque only from the engine (1) to the wheel and wherein the device (20, 21, 22, 23, 24, 25, 26) is disposed downstream or upstream of the clutch disk.

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number:

(to be used only for reproduction orders)

©) National registration number

060 481

62685

COURBEVOIE © IntCI ⁸ : B 60 K 17/26 (2017.01)

PATENT INVENTION APPLICATION

A1

©) Date of filing: 16.12.16. © Applicant (s): VALEO EMBRAYAGES Company by (© Priority: simplified actions - FR. @ Inventor (s): KRAEMER PHILIPPE. ©) Date of public availability of the request: 22.06.18 Bulletin 18/25. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): VALEO EMBRAYAGES Company by related: simplified actions. ©) Extension request (s): (© Agent (s): VALEO EMBRAYAGES Company by simplified actions.

(04 / VEHICLE DRIVE GROUP.

FR 3 060 481 - A1

The present invention relates to a powertrain for a vehicle comprising successively:

- a heat engine (1),

- a flywheel (9),

- a clutch (2) comprising at least one clutch disc,

- a gearbox (3) with manual control,

- And a wheel (5) in which a freewheel device (20, 21,22, 23, 24, 25, 26) authorizes the transmission of torque only from the motor (1) to the wheel and in which the device (20, 21,22, 23, 24, 25, 26) is arranged downstream or upstream of the clutch disc.

Vehicle powertrain

The invention relates to a vehicle powertrain implementing a freewheel as well as a method of driving the powertrain.

In the state of the art, systems and methods are known which decouple the heat engine from the wheels when the driver, for example, stops pressing the accelerator pedal. This type of system is frequently called by the terms in English, coasting and sailing. These systems and methods make it possible to decouple the engine during operating phases where the driver's torque demand is less than or equal to the torque that must be supplied to maintain the vehicle at constant speed or to accelerate it. In this case the internal friction and the pumping losses of the heat engine make the engine a braking element. Uncoupling the heat engine and even switching off the heat engine during these operating phases saves fuel.

The article R-2015-04-05, "Experimental validation of Stop & Start Sailing strategy for real-world driving cycles" published by the Society of Automotive Engineers presents the phases in which it is possible to decouple the heat engine vehicle wheels.

Document WO2014 / 094758A1 presents a decoupling of the heat engine and the wheels by means of a method for controlling a clutch. This process makes it possible to detect the conditions suitable for coasting and to disengage the clutch without the driver pressing the clutch pedal to disengage.

The application of such a method requires equipping the vehicle with a clutch actuation system comprising a clutch actuator, for example an electromechanical actuator, a computer, sensors as well as various means of interfacing between these elements. These different elements make the actuation system complex and expensive.

In all that follows, “upstream” and “downstream” are understood with respect to the direction of the transmission of torque from the engine of the vehicle to the wheels of the vehicle.

The object of the invention is to remedy all or part of these drawbacks by using a freewheel in the powertrain.

A powertrain for a vehicle according to the invention successively comprises:

a heat engine, a flywheel, a clutch comprising at least one clutch disc, a manual gearbox, and a wheel in which a freewheel device authorizes the transmission of torque only from the engine to the wheel , the device being arranged downstream or upstream of the clutch disc.

According to an additional characteristic of the invention, the flywheel is a double damping flywheel comprising a primary flywheel, a secondary flywheel and at least one elastic member between the primary flywheel and the secondary flywheel.

According to an additional characteristic of the invention, the freewheeling device is between two elements of the primary flywheel.

According to an additional characteristic of the invention, the secondary flywheel comprises two elements which are selectively movable relative to one another and the freewheel device is downstream from one of these two elements and upstream from the other of these elements.

According to an additional characteristic of the invention, the freewheel device is downstream of the engine and upstream of the flywheel.

According to an additional characteristic of the invention, the gearbox comprises an input shaft in two parts and the freewheel device is downstream from one of these parts and upstream from the other of these parts.

According to an additional characteristic of the invention, the gearbox comprises an output shaft in two parts and the freewheel device is downstream from one of these parts and upstream from the other of these parts.

According to an additional characteristic of the invention, the powertrain comprises a differential and the freewheeling device is downstream of the gearbox and upstream of the differential.

According to an additional characteristic of the invention, the powertrain comprises a differential and the freewheel device is downstream of the differential.

According to an additional characteristic of the invention, the freewheeling device can be locked.

According to an additional characteristic of the invention, the freewheel device comprises a damper and / or a torque limiter.

The use of a shock absorber or a torque limiter makes it possible to limit shocks when the driver of the vehicle accelerates in an operating phase where the freewheel device decouples the heat engine and the wheels. In fact during this acceleration the speed of the input element of the freewheel device increases until reaching the speed of the output element of the freewheel device. A shock can occur due to the difference in acceleration between the input element and the output element of the freewheel device. The use of a shock absorber for example a spring or a limiter makes it possible to limit this shock and therefore to improve the comfort of the vehicle and to protect the powertrain upstream and downstream of the freewheel device.

According to an additional characteristic of the invention, the powertrain comprises an engine control system. The engine control system is configured so that if the difference between the speed of the input element and the speed of the output of the freewheel device is less than a predefined value, the motor is checked for that the speed of the input element gradually reaches the speed of the output element.

The subject of the invention is also a method of driving a powertrain for a vehicle comprising successively:

a heat engine, an engine flywheel, a clutch comprising at least one clutch disc, a manual gearbox, and a wheel, and comprising a freewheel device allowing the transmission of torque only from the engine to the wheel, the device being arranged downstream or upstream of the clutch disc in which:

determining the speeds of the input element and the output element of the freewheel device and whether the difference between the speed of the input element and the speed of the output element of the wheel device free is less than a predefined value, the motor is controlled so that the speed of the input element gradually reaches the speed of the output element.

The predefined value of difference between the speed of the input element and the speed of the output of the freewheel device can preferably be less than 500 rpm and preferably about 300 rpm.

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given by way of illustration and not limitation, with reference to the appended figures.

In these figures:

Figure 1 schematically shows the powertrain according to a first embodiment of the invention;

FIG. 2 schematically represents the powertrain according to a second embodiment of the invention;

FIG. 3 schematically represents the powertrain according to a third embodiment of the invention;

FIG. 4 schematically represents the powertrain according to a fourth embodiment of the invention;

FIG. 5 schematically represents the powertrain according to a fifth embodiment of the invention;

FIG. 6 schematically represents the powertrain according to a sixth embodiment of the invention;

FIG. 7 schematically represents the powertrain according to a seventh embodiment of the invention;

Figure 8 is a graph schematically showing the state of components of the powertrain according to the embodiment of Figure 2 equipped or not with a damper; Figure 9 is a graph schematically showing the state of components of the powertrain according to the embodiment of Figure 2 with or without engine control strategy so that the speed of the input element of the freewheeling device reaches gradually the speed of the output element of the freewheel device.

In all the figures, identical elements or ensuring the same function bear the same reference numbers.

FIG. 1 schematically represents a vehicle powertrain according to a first embodiment of the invention. The powertrain includes a heat engine 1 equipped with an output shaft. The heat engine 1 is controlled by the driver of the vehicle by means of an accelerator control, not shown. A freewheel device 20 is mounted on the output shaft upstream of a flywheel 9. The flywheel can be a double damping flywheel as shown in the figure but can also be a flywheel of another type such a simple flywheel. An input shaft of a gearbox 3 is connected to the flywheel 9 via a clutch 2. Conventionally, the transmission of torque between the flywheel 9 and the input shaft 8 of the manual gearbox 3 is ensured when the clutch 2 is in a engaged position and this torque transmission is interrupted when the clutch 2 is in a disengaged position. The manual gearbox 3 comprises an output shaft 7 which transmits the torque to a differential 4. The differential 4 transmits the torque to the wheels 5 via shafts 10. While remaining within the scope of the invention the transmission of the torque between the differential 4 and the wheels 5 can be provided by another device such as a chain or a belt. In another variant not shown, the torque is transmitted to only one wheel by the manual gearbox via a transmission device such as a chain, a belt or a shaft. Variants of the second, third and fourth embodiments in which the powertrain transmits torque to only one wheel are also possible according to the invention.

The freewheel device 20 does not transmit the torque from the heat engine 1 to the flywheel 9 if the heat engine 1 receives a torque setpoint lower than the torque setpoint which would allow it to reach a speed of rotation equal to that of the flywheel 9. Such a torque setpoint is notably sent to the heat engine 1 when the driver stops pressing the accelerator control. This absence of torque transmission between the heat engine 1 and the flywheel 9 makes it possible to avoid subjecting the vehicle to the engine brake. In known manner, the engine brake is due to internal friction and pumping losses of the heat engine 1. The absence of an engine brake makes it possible to reduce the consumption of the vehicle. If the driver stops pressing the accelerator control, the engine speed decreases to its idle speed. To further reduce vehicle consumption, it is possible to stop the engine under certain driving conditions.

The freewheel device 20 again transmits the torque from the heat engine 1 to the flywheel 9 if the heat engine 1 receives a torque setpoint greater than the torque setpoint which enables it to reach the speed of rotation of the engine flywheel 9.

The freewheel device 20 can be associated with a locking system which makes it possible, if activated, to transmit the torque between the output shaft of the heat engine 1 and the flywheel 9 even if, for example, the driver stops pressing the accelerator control. The lock can be used in particular during long descents to avoid prolonged use of the vehicle's brakes.

FIG. 2 schematically represents a vehicle powertrain according to a second embodiment of the invention. In this embodiment, the flywheel is linked in rotation to the heat engine 1. The flywheel 9 is a double damping flywheel. It comprises a primary flywheel 91, a secondary flywheel 92 and a damping element 93, for example a helical spring, which transmits the torque between the primary flywheel 91 and the secondary flywheel 92. The primary flywheel 91 consists of a first element and of a second element interconnected by a freewheel device 21. This second embodiment is also similar to the first embodiment.

The freewheel device 21 does not transmit the torque of the heat engine 1 from the first element of the primary flywheel 91 to the second element of the primary flywheel 91 if the heat engine 1 receives a torque setpoint lower than the torque setpoint which would allow it to reach a speed of rotation equal to that of the second element of the primary flywheel 91. Such a torque setpoint is notably sent to the heat engine 1 when the driver stops pressing the accelerator control. This absence of torque transmission between the first element of the primary flywheel 91 and the second element of the primary flywheel 91 makes it possible to avoid subjecting the vehicle to the engine brake and therefore to reduce the fuel consumption of the vehicle as for the first embodiment.

The freewheel device 21 can be associated with a locking system which makes it possible, if activated, to transmit the torque between the first element and the second element of the primary steering wheel 91 even if, for example, the driver stops pressing on the throttle control. The lock can be used in particular during long descents to avoid prolonged use of the vehicle's brakes.

FIG. 3 schematically represents a vehicle powertrain according to a third embodiment of the invention. In this embodiment, the flywheel is also linked in rotation to the heat engine 1 and the flywheel 9 is also a double damping flywheel. It comprises a primary flywheel 91, a secondary flywheel 92 and a damping element 93, for example a helical spring, which transmits the torque between the primary flywheel 91 and the secondary flywheel 92. The secondary flywheel 92 consists of a first element and of a second element linked together by a freewheel device 22. This third embodiment is also similar to the first embodiment.

The freewheel device 22 does not transmit the torque of the heat engine 1 from the first element of the secondary flywheel 92 to the second element of the secondary flywheel 92 if the heat engine 1 receives a torque setpoint lower than the torque setpoint which would allow it to reaching a speed of rotation equal to that of the second element of the secondary flywheel 92. Such a torque setpoint is notably sent to the heat engine 1 when the driver stops pressing the accelerator control. This absence of torque transmission between the first element and the second element of the secondary flywheel 92 makes it possible to avoid subjecting the vehicle to the engine brake and therefore to reduce the fuel consumption of the vehicle as for the first embodiment.

The freewheel device 22 can be associated with a locking system which makes it possible, if activated, to transmit the torque between the first element of the secondary steering wheel 92 and the second element of the secondary steering wheel 92 even if, for example, the driver stops pressing the accelerator control. The lock can be used in particular during long descents to avoid prolonged use of the vehicle's brakes.

FIG. 4 schematically represents a vehicle powertrain according to a fourth embodiment of the invention. In this embodiment, the flywheel 9 is also linked in rotation to the heat engine 1. The input shaft 8 of the gearbox 3 comprises first and second parts connected by a freewheel device 23.This fourth embodiment is also similar to the first embodiment.

The freewheel device 23 does not transmit the torque from the heat engine 1 from the first part of the input shaft 8 of the gearbox 3 to the second part of the input shaft of the gearbox 3 if the heat engine 1 receives a torque setpoint lower than the torque setpoint which would allow it to reach a speed of rotation equal to that of the second part of the input shaft of the gearbox 3. Such a setpoint torque is notably sent to the heat engine 1 when the driver stops pressing the accelerator control. This absence of torque transmission between the first and second parts of the input shaft 8 of the gearbox 3 makes it possible to avoid subjecting the vehicle to the engine brake and therefore to reduce the fuel consumption of the vehicle as for the first embodiment.

The freewheel device 23 can be associated with a locking system which makes it possible, if activated, to transmit the torque between the first part of the input shaft 8 and the second part of the input shaft of the gearbox 3 even if, for example, the driver stops pressing the accelerator control. The lock can be used in particular during long descents to avoid prolonged use of the vehicle's brakes.

FIG. 5 schematically represents a vehicle powertrain according to a fifth embodiment of the invention. In this embodiment, the flywheel 9 is also linked in rotation to the heat engine 1. The output shaft 7 of the gearbox 3 includes first and second parts connected by a freewheel device 24. This fifth mode embodiment is also similar to the first embodiment.

The freewheel device 24 does not transmit torque from the first part of the output shaft 7 of the gearbox 3 to the second part of the output shaft of the gearbox 3 if the heat engine 1 receives a torque setpoint lower than the torque setpoint which would allow the first part of the gearbox output shaft to reach a speed of rotation equal to that of the second part of the gearbox output shaft of speeds 3. Such a torque set point is notably sent to the heat engine 1 when the driver stops pressing the accelerator control. This absence of torque transmission between the first and second parts of the output shaft 7 of the gearbox 3 makes it possible to avoid subjecting the vehicle to the engine brake and therefore to reduce the fuel consumption of the vehicle as for the first embodiment.

The freewheel device 24 can be associated with a locking system which makes it possible, if activated, to transmit the torque between the two parts of the output shaft even if, for example, the driver stops pressing the throttle control or if the reverse gear of gearbox 3 is selected.

FIG. 6 schematically represents a vehicle powertrain according to a sixth embodiment of the invention. In this embodiment, the flywheel 9 is also linked in rotation to the heat engine 1. A freewheel device 25 is mounted downstream of the gearbox 3 and upstream of the differential 4. This sixth embodiment is also similar to the first embodiment.

The freewheel device 25 does not transmit torque from the gearbox 3 to the second part of the output shaft of the gearbox 3 to the differential if the heat engine 1 receives a torque setpoint lower than the setpoint. torque which would allow the output shaft of the gearbox to reach a speed of rotation equal to that of the input of the differential. Such a torque setpoint is notably sent to the heat engine 1 when the driver stops pressing the accelerator control. This absence of torque transmission between the gearbox 3 and the differential 4 makes it possible to avoid subjecting the vehicle to the engine brake and therefore to reduce the fuel consumption of the vehicle as in the first embodiment.

The freewheel device 25 can be associated with a locking system which makes it possible, if activated, to transmit the torque between the gearbox 3 and the differential 4 even if, for example, the driver stops pressing the throttle control or if the reverse gear of gearbox 3 is selected.

FIG. 7 schematically represents a vehicle powertrain according to a seventh embodiment of the invention. In this embodiment, the flywheel 9 is also linked in rotation to the heat engine 1. A freewheel device 26 is mounted on the transmission shaft between the differential 4 and each of the wheels 5. This sixth embodiment is by elsewhere similar to the first embodiment.

The freewheel devices 26 do not transmit torque from the differential 4 to the wheels 5 if the heat engine 1 receives a torque setpoint lower than the torque setpoint which would allow the output of the differential to reach a rotation speed equal to that wheels. Such a torque setpoint is notably sent to the heat engine 1 when the driver stops pressing the accelerator control. This absence of torque transmission between the differential 4 and the wheels makes it possible to avoid subjecting the vehicle to the engine brake and therefore to reduce the fuel consumption of the vehicle as for the first embodiment.

The freewheeling devices 26 can be associated with a locking system which makes it possible, if activated, to transmit the torque between the differential 4 and the wheels even if, for example, the driver stops pressing the control d accelerator or if the reverse gear of gearbox 3 is selected.

In another variant not shown, the torque is transmitted to only one wheel by the manual gearbox via a transmission device such as a chain, a belt or a shaft. This variant does not include a differential. In this variant, the freewheel device 26 is downstream of the gearbox and upstream of the wheels.

The freewheel devices 20, 21, 22, 23, 24, 25 and 26 can be fitted with a damper, for example with coil springs.

Figure 8 shows, schematically, the state of components of the powertrain according to the embodiment of Figure 2 equipped or not with the damper.

The abscissa of the graphs in Figure 8 represents time. Time marks 200 and 201 indicate the succession of events of the process according to the invention. The reference 200 corresponds to the moment when the driver begins to re-accelerate, for example by pressing the accelerator control. The reference 201 corresponds to the moment when the speed of an input element of the freewheel device 21 becomes equal to the speed of the output element of the freewheel device 21.

Curve 100 represents the state of the accelerator control. When the curve coincides with the x-axis, the driver does not press the accelerator control. Curve 101 represents the torque on the output element of the freewheel device. Curve 102 represents the speed of rotation of the input shaft 8 of the gearbox 3. Curve 103 represents the speed of rotation of the output shaft of the heat engine 1. Curve 104 represents the acceleration d 'A vehicle equipped with a variant of the powertrain comprising a freewheel device 21 without shock absorber. Curve 105 represents the acceleration of a vehicle equipped with a variant of the powertrain comprising a freewheel device 21 with shock absorber.

At time marker 200, the driver presses the accelerator control. Between the time mark 200 and the time mark 201, the speed of rotation 103 of the output shaft of the heat engine 1 increases until it becomes equal to the speed of rotation 102 of the input shaft 8 of the gearbox 3 at the time mark 201. At this time the torque 101 transmitted by the freewheeling device increases suddenly causing a variation in the acceleration 104, 105 of the vehicle. This variation in acceleration is a source of discomfort for vehicle users. It should therefore be limited. The use of a shock absorber in the freewheel device makes it possible to limit the variation in vehicle acceleration. Curve 105 shows for example a decrease of about 20% of the acceleration compared to curve 104. We also note that the amplitude of the oscillation of the acceleration reduces more quickly with the use of a damper in the freewheeling device.

FIG. 9 shows the state of components of the powertrain during the implementation of the method according to the invention in which the heat engine 1 is controlled so that the speed of the input element of the freewheel device 21 reaches the speed of the output element of the freewheel device 21 progressively.

The graphs in FIG. 9 are similar to those in FIG. 8. The elements in FIG. 9 bearing the same references as the elements in FIG. 8 relate to the same powertrain comprising a freewheel device 21 without damper and without control specific to the heat engine.

The curve 101 ′ represents the torque on the output element of the freewheel device of a variant of the powertrain comprising a freewheel device 21 without damper and with control of the heat engine 1. It is noted that the curve 101 ′ does not have the sudden increase in curve 101. Curve 103 ′ represents the speed of rotation of the output shaft of the heat engine 1 of this same variant of the powertrain. The curve 105 ′ represents the acceleration of a vehicle equipped with this same variant of the powertrain.

The control of the heat engine may include a step of detecting the relative speed between the input element and the output element of the freewheel device 21. If this relative speed is less than about 500 rpm, it is checked the motor so that the acceleration of the input element of the freewheel device 21 is slightly greater than the acceleration of the output element of the freewheel device 21. The acceleration of the element input of the freewheel device may for example be limited to a value greater by a maximum of 20% than that of the output element of the freewheel device 21.

The comparison of curve 104 and curve 105 ′ makes it possible to highlight a very significant limitation of the variation in acceleration of the vehicle with the control of the heat engine 1.

Curve 105 ′ shows, for example, an approximately 50% decrease in acceleration compared to curve 104.

This type of control of the heat engine 1 can be used with the various other embodiments of the invention.

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Claims (15)

Claims 1. Powertrain for a vehicle comprising successively: a heat engine (1), a flywheel (9), a clutch (2) comprising at least one clutch disc, a gearbox (3) with manual control, and a wheel (5) characterized in that it includes a freewheel device (20, 21, 22, 23, 24, 25, 26) authorizing the transmission of torque only from the motor (1) to the wheel (5), the freewheel device (20, 21, 22, 23, 24, 25, 26) being arranged downstream or upstream of the clutch disc 2. Powertrain for vehicle according to the preceding claim characterized in that the flywheel (9) is a double damping flywheel comprising a primary flywheel (91), a secondary flywheel (92) and at least one elastic member (93) between the primary flywheel (91) and secondary flywheel (92). 3. Powertrain for a vehicle according to claim 2 characterized in that the freewheeling device (21) is between two elements of the primary flywheel (91). 4. Powertrain for vehicle according to claim 2 characterized in that the secondary flywheel (92) comprises two elements selectively movable relative to each other and that the freewheel device (22) is downstream of the one of these two elements and upstream of the other of these elements. 5. Powertrain for a vehicle according to claim 1 or 2 characterized in that the freewheel device (20) is downstream of the engine and upstream of the flywheel. 6. Powertrain for vehicle according to claim 1 or 2 characterized in that the gearbox (3) comprises an input shaft (8) in two parts and the freewheeling device (23) is downstream of the 'one of these parts and upstream of the other of these parts. 7. Powertrain for vehicle according to claim 1 or 2 characterized in that the gearbox (3) comprises an output shaft (7) in two parts and the freewheeling device (24) is downstream of the one of these parts and upstream of the other of these parts. 8. Powertrain for vehicle according to claim 1 or 2 characterized in that it comprises a differential (4) and in that the freewheeling device (25) is downstream of the gearbox (3) and in upstream of the differential (4). 9. Powertrain for vehicle according to claim 1 or 2 characterized in that it comprises a differential (4) and in that the freewheeling device (26) is downstream of the differential (4). 10. Powertrain for a vehicle according to one of the preceding claims, characterized in that the freewheel device (20, 21, 22, 23, 24, 25, 26) can be locked. 11. Powertrain for a vehicle according to one of the preceding claims, characterized in that the freewheel device (20, 21, 22, 23, 24, 25, 26) comprises a damper and / or a torque limiter. 12. Powertrain for vehicle according to one of the preceding claims, characterized in 5 that it includes a motor control system, the motor control system being configured so that, if the difference between the speed of the input element and the speed of the output of the wheeled device free is less than a predefined value, the motor is controlled so that the speed of the input element reaches the speed of the output element gradually. 13. Method for driving a powertrain for a vehicle, comprising successively: 10 - a heat engine (1), a flywheel (9), a clutch (2) comprising at least one clutch disc, a gearbox (3) with manual control, and a wheel (5) 15 and comprising a freewheel device (20, 21, 22, 23, 24, 25, 26) authorizing the transmission of torque only from the motor (1) to the wheel (5), the device (20, 21, 22, 23, 24, 25, 26) being arranged downstream or upstream of the clutch disc in which the speeds of the input element and of the output element of the freewheel device (20, 21, 22, 23, 24, 25, 26), 20 - and if the difference between the speed of the input element and the speed of the output of the freewheel device (20, 21, 22, 23, 24, 25, 26) is less than a value predefined, the motor (1) is controlled so that the speed of the input element gradually reaches the speed of the output element. 1/6