FR3091568A1 - RELEASABLE CRANKSHAFT PULLEY WITH PASSIVE CONTROL SYSTEM - Google Patents

Abstract

The invention relates mainly to a disengageable pulley (12) intended to be mounted on a crankshaft, characterized in that it comprises: - a pulley body (24), - a permanent freewheel (21), and - a wheel disengageable freewheel (22) capable of taking an inactive state in which the freewheel (22) is uncoupled from the crankshaft and an active state in which the freewheel (22) is linked in rotation with the crankshaft, so as to allow the accessories front to turn faster than the heat engine and to transmit torque to the accessories front when the front turns slower than the heat engine or in a direction opposite to the heat engine, - said disengageable freewheel (22) being configured so that a The transition from inactive to active state occurs when a crankshaft rotational speed exceeds a speed threshold. Figure 3a

Description

Title of the invention: RELEASABLE CRANKSHAFT PULLEY WITH PASSIVE CONTROL SYSTEM

The present invention relates to a disengageable crankshaft pulley with passive control system.

The invention finds a particularly advantageous application with hybrid powertrains equipped with a mechanical air conditioning compressor operating in both directions of rotation and an electric machine mounted on the front of accessories capable of operating in engine mode and in alternator.

During the engine shutdown phases, the passenger compartment thermal performance must be ensured. To do this, it is possible to use an electric compressor which has the disadvantage of being much more expensive than a mechanical compressor.

It is also known to use the electric machine mounted on the accessories front to drive the mechanical compressor, while the heat engine is stopped. These systems require having a member compatible with the function of a conventional pulley to which a declutching function is added to allow the rotation of the facade while the engine is stopped.

Generally, known systems implement an external active actuation of the clutch type and / or a switch between several operating modes, as described in documents DE102014218114, DE102014214306, W02015014361, or WO2017032373.

Other systems include freewheels or one-way clutches provided with a torsion spring which expands or contracts according to the direction of torsion, which creates or not friction on the external diameter. Freewheels are known to have a behavior sensitive to the centrifugal force used for the definition of freewheels in so-called engaging cams (the torque capacity increases at high speed) or disengaging (the freewheel disengages at high speed).

However, known devices using clutches are bulky, generally limited in transmissible torque, in particular at low speed, and consume significant electrical power. In addition, these devices require external actuations and the development of a control system, which makes them expensive.

The invention aims to effectively remedy these drawbacks by proposing a disengageable pulley intended to be mounted on a crankshaft of a heat engine and comprising:

- a pulley body which can be selectively leading and / or led by a belt of an accessory facade,

- a permanent freewheel configured to permanently allow the belt of the accessory frontage to turn slower or in a direction of rotation opposite to a direction of rotation of the heat engine and to allow a drive of the heat engine by the belt of the accessory frontage as soon as said accessory front is driving, and - a disengageable freewheel capable of assuming an inactive state in which the disengageable freewheel is uncoupled from the crankshaft and an active state in which the disengageable freewheel is linked in rotation with the crankshaft, so to allow the accessory front to rotate faster than the thermal engine and to transmit a torque to the accessory front when the front turns less quickly than the thermal engine or in a direction opposite to the thermal engine,

- Said disengageable free wheel being configured so that a transition from the inactive state to the active state occurs when a speed of rotation of the crankshaft exceeds a speed threshold.

The invention thus allows, thanks to the use of the disengageable pulley, to ensure the drive of the electric compressor by the rotary electric machine while the engine is stopped, while providing a purely solution mechanical, compact, and easy to install. In addition, the invention does not require the use of external control because of its passive nature.

In one embodiment, the permanent freewheel and the disengageable freewheel are mounted in opposite directions of rotation relative to each other.

In one embodiment, the disengageable freewheel comprises a centrifugal chuck linked in rotation to the crankshaft, said centrifugal chuck being able to engage in order to pass the disengageable freewheel to the active state when said crankshaft rotates at a higher speed. at the speed threshold.

According to one embodiment, the disengageable freewheel comprises:

- an internal cam and an external cam rotatably mounted around an arm,

a return spring capable of keeping the internal cam and the external cam distant from an internal track and an external track respectively, and

- an eccentric mass capable of opposing the return spring to make the internal cam and the external cam cooperate respectively with the internal track and the external track so as to change the disengageable freewheel to the active state when the speed of the crankshaft exceeds the speed threshold.

In one embodiment, said pulley comprises an inertial ring and an elastomeric ribbon configured to limit torsional vibrations of the crankshaft.

In one embodiment, said pulley has a fixing interface with the crankshaft.

In one embodiment, said pulley has at least one bearing, such as a ball bearing, and stops in translation to ensure a pivot connection and a guide between the pulley body and the crankshaft.

According to one embodiment, the speed threshold causing the change of state of the disengageable pulley is of the order of 100 rpm.

The invention also relates to a heat engine for a motor vehicle comprising a crankshaft and a disengageable pulley as defined above mounted at one end of the crankshaft.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given only by way of illustration but in no way limit the invention.

[Fig.l]

Figure 1 shows a perspective view of an accessory front incorporating a disengageable crankshaft pulley according to the present invention;

[Fig.2]

Figure 2 is a functional schematic representation of the accessory facade of Figure 1;

[Fig.3a]

Figure 3a is a schematic representation of a disengageable crankshaft pulley according to the invention in the inactive state;

[Fig.3b]

FIG. 3b is a schematic representation of a disengageable crankshaft pulley according to the invention in the active state;

[Fig.4]

Figure 4 is a detailed sectional representation of the disengageable crankshaft pulley according to the invention;

[Fig.5a]

FIGS. 5a, 5b, 5c, 5d are schematic representations illustrating an operation of a disengageable freewheel with cams integrated in the crankshaft pulley according to the invention;

[Fig.5b]

FIGS. 5a, 5b, 5c, 5d are schematic representations illustrating an operation of a disengageable freewheel with cams integrated in the crankshaft pulley according to the invention;

[Fig.5c]

FIGS. 5a, 5b, 5c, 5d are schematic representations illustrating an operation of a disengageable freewheel with cams integrated in the crankshaft pulley according to the invention;

[Fig.5d]

FIGS. 5a, 5b, 5c, 5d are schematic representations illustrating an operation of a disengageable freewheel with cams integrated in the crankshaft pulley according to the invention;

[Fig.6]

Figure 6 is a schematic representation illustrating an alternative embodiment of the disengageable freewheel with cams integrated in the crankshaft pulley according to the invention.

Identical, similar, or analogous elements retain the same reference from one figure to another.

Figures 1 and 2 show an accessory facade 10 of a heat engine 14 of a motor vehicle comprising a belt 11, said accessories belt, cooperating with a disengageable pulley 12 according to the invention mounted on a crankshaft 13 of a heat engine 14 associated with a damper 15, as well as with a pulley 16 of a rotary electric machine 17 capable of operating in engine mode and in generator mode, and a pulley 18 of an air conditioning compressor 19.

The air conditioning compressor 19 is advantageously a mechanical compressor with axial pistons. The coupling of the compressor 19 is compatible with rotation in both directions of rotation of the accessory belt 11.

The disengageable pulley 12 comprises a permanent free wheel 21 and a disengageable free wheel 22.

More specifically, as can be seen in Figures 3a, 3b and 4, the disengageable pulley 12 of axis X mounted on the crankshaft 13 of the engine 14 includes a pulley body 24 which can be selectively driving and / or driven by the accessories belt 11. The belt 11 could for example be a toothed type belt. It is also possible to provide a drive zone 27 for a water pump.

An inertial ring 25 and an elastomeric strip 26 are configured to limit torsional vibrations of the crankshaft 13.

A bearing 28, constituted by one or more ball bearings, and stops 29 in translation make it possible to provide a pivot connection and the guide between the pulley body 24 and the crankshaft 13.

A fixing interface 31 with the crankshaft 13 is constituted for example by holes for fixing members, such as screws.

The permanent freewheel 21 allows the accessory front panel 10 to drive the crankshaft 13, in particular for starting and restarting the heat engine 14. For this purpose, the permanent free wheel 21 is configured to permanently authorize the front panel accessories 10 to rotate slower or in the direction of rotation opposite to the direction of rotation of the heat engine 14 and to allow a drive of the heat engine 14 by the accessories front 10 as soon as said accessories front is driven, that is to say when the speed of the accessory front 10 becomes higher than that of the heat engine 14 and therefore of the crankshaft 13. The permanent free wheel 21 is for example constituted by a conventional free wheel with rollers.

The disengageable freewheel 22 makes it possible to transmit torque to the accessory front panel 10 in particular during a regeneration phase during which the electric machine 17 operating in alternator mode supplies current during the braking phases. The disengageable freewheel 22 is oriented in the opposite direction to the normal direction of rotation of the heat engine 14. A screw 30 maintains the various elements of the pulley 12, as shown in FIG. 4.

The disengageable freewheel 22 is capable of assuming an inactive state in which the disengageable freewheel 22 is uncoupled from the crankshaft 13, as shown in FIG. 3a, and an active state in which the disengageable freewheel 22 is linked in rotation with the crankshaft 13 so as to allow the accessories front 10 to rotate faster than the engine 14 and to transmit a torque to the accessories front 10 when the front rotates slower than the engine 14 or in a direction opposite to the engine , as shown in Figure 3b.

The disengageable freewheel 22 is configured so that a transition from the disengaged state to the active state occurs when a speed of rotation of the crankshaft 13 exceeds a speed threshold. The speed threshold causing the change of state of the disengageable pulley 12 is of the order of 100 rpm. By of the order of, we mean a variation of plus or minus 10% around this value.

In other words, the change of state of the freewheel 22 depends on a centrifugal force related to the rotation of the crankshaft 13. When the crankshaft 13 does not rotate, this freewheel must be permanently disengaged, whatever the direction of rotation of the facade. As soon as the crankshaft 13 exceeds the speed threshold, the freewheel 22 changes to the active state.

Advantageously, the permanent free wheel 21 and the disengageable free wheel 22 are mounted in opposite directions of rotation relative to each other.

In the embodiment of Figures 3a and 3b, the disengageable freewheel 22 includes a centrifugal chuck 33 linked in rotation to the crankshaft 13. The chuck 33 is able to engage to pass the disengageable freewheel 22 to the active state when said crankshaft 13 rotates at a speed greater than the speed threshold, due to its movement along the arrow F1 under the effect of centrifugal force (see Figure 3b).

In the embodiment of Figure 5a, the disengageable freewheel 22 includes an internal cam 35 and an external cam 36 rotatably mounted around an arm 37 linked in rotation with the crankshaft 13. The internal cam 35 and the external cam 36 are able to cooperate respectively with an internal track 38 formed in the crankshaft 13 and an external track 39 formed in the pulley body 24.

A return spring 40 keeps the internal 35 and external 36 cams distant from the internal tracks 38 and external 39, respectively. An eccentric mass 41 associated with the cams 35, 36 is capable of opposing the return spring 40 for passing the freewheel 22 in the active state when the speed of rotation of the crankshaft 13 exceeds the speed threshold.

As can be seen in Figure 5b, when the crankshaft 13 does not rotate or has a speed below the speed threshold, the return spring 40 keeps the freewheel in the inactive state. The pulley 12 can then rotate freely in both directions of rotation (see arrows F2).

As can be seen in Figure 5c, when the crankshaft 13 starts to rotate, the force generated by the eccentric mass 41 manages to counteract the force of the return spring 40, so that the free wheel 22 goes to the active state by bringing the internal cam 35 and the external cam 36 into cooperation with the internal track 38 and the external track 39 respectively. The crankshaft 13 can then transmit torque according to arrow F3. Indeed, due to the rotation of the crankshaft 13, the freewheel 22 blocks the movement in one direction, as shown in FIG. 5d.

Alternatively, the assembly can be reversed, that is to say that the arm 37 can be linked in rotation with the body of the pulley, as illustrated in Figure 6. The position of the mass eccentric 41 and the return spring 40 is then adapted accordingly.

Advantageously, the disengageable freewheel 22 is never in a situation of significant sliding, except when it is disengaged or when the chuck 33 is in the released position.

We describe below the different operating phases of the accessory front 10 incorporating the disengageable pulley 12 according to the invention.

When the engine 14 is started, the disengageable freewheel 22 is in the active state. The two freewheels 21, 22 ensure the synchronization of the heat engine 14 and the belt 11 of the accessory front 10 whatever the direction of the torque.

When the engine 14 goes to a standstill, the disengageable freewheel 22 goes to the inactive state because the centrifugal force no longer maintains the chop 33 or the cams 35, 36 engaged in the tracks 38, 39. The vibrations at standstill participate in the loosening of the system. We can then rotate the belt 11 of the accessory front 10 upside down and thus drive the compressor 19 by the electric machine 17.

When it is necessary to restart the heat engine 14, it then suffices to rotate the electric machine 17 in the direction of the heat engine 14 or to start by braking it if the belt 11 of the front panel accessories 10 drives the compressor 19 for air conditioning and therefore turned upside down.

When the belt 11 of the accessories front 10 starts to rotate faster than the heat engine 14 (and the direction of rotation is reversed), the permanent freewheel 21 is activated and begins to drive the heat engine 14.

As soon as the speed of the crankshaft 13 reaches the speed threshold, then the disengageable freewheel 22 is activated and the belt 11 of the accessory front panel 10 is synchronized with the heat engine 14 via the two freewheels 21, 22. Advantageously , the activation is carried out in the phase where the crankshaft 13 driven by the facade is synchronized with the latter. The possible shocks linked to the speed differential are therefore lower.

Claims (1)

Claims [Claim 1] Releasable pulley (12) intended to be mounted on a crankshaft (13) of an engine (14), characterized in that it comprises: - a pulley body (24) which can be selectively driving and / or led by a belt (11) of an accessory front (10), - a permanent freewheel (21) configured to permanently allow the belt (11) of the accessory front (10) to rotate slower or in a direction of rotation opposite to a direction of rotation of the heat engine (14) and to allow a drive of the heat engine (14) by the belt (11) of the accessory front (10) as soon as said accessory front (10) is driven, and - a disengageable free wheel (22) capable of assuming an inactive state in which the disengageable free wheel (22) is uncoupled from the crankshaft (13) and an active state in which the disengageable free wheel (22) is linked in rotation with the crankshaft (13), so as to allow the accessories facade (10) to rotate faster than the heat engine (14) and to transmit a torque to the accessories facade (10) when the facade rotates slower than the heat engine (14) or in a direction opposite to the heat engine (14), - Said disengageable free wheel (22) being configured so that a transition from the inactive state to the active state occurs when a speed of rotation of the crankshaft (13) exceeds a speed threshold. [Claim 2] Pulley according to claim 1, characterized in that the permanent free wheel (21) and the disengageable free wheel (22) are mounted in opposite directions of rotation relative to each other. [Claim 3] Pulley according to claim 1 or 2, characterized in that the disengageable freewheel (22) comprises a centrifugal chuck (33) linked in rotation to the crankshaft (13), said centrifugal chuck (33) being able to engage to pass the disengageable freewheel (22) in the active state when said crankshaft (13) rotates at a speed greater than the speed threshold. [Claim 4] Pulley according to claim 1 or 2, characterized in that the disengageable freewheel (22) comprises: an internal cam (35) and an external cam (36) rotatably mounted around an arm (37), a return spring (40) capable of keeping the internal cam (35) and the external cam (36) distant from an internal track (38) and an external track (39) respectively, and - an eccentric mass (41) capable of opposing the return spring (40) to make the internal cam (35) and the external cam (36) cooperate with the internal track (38) and the external track (39) respectively so as to change the disengageable freewheel (22) to the active state when the speed of the crankshaft (13) exceeds the speed threshold. [Claim 5] Pulley according to any one of claims 1 to 4, characterized in that it comprises an inertial ring (25) and an elastomer strip (26) configured to limit torsional vibrations of the crankshaft (13). [Claim 6] Pulley according to any one of claims 1 to 5, characterized in that it comprises a fixing interface (31) with the crankshaft (13). [Claim 7] Pulley according to any one of claims 1 to 6, characterized in that it comprises at least one bearing (28), such as a ball bearing, and stops (29) in translation to ensure a connection pivot and a guide between the pulley body (24) and the crankshaft (13). [Claim 8] Pulley according to any one of Claims 1 to 7, characterized in that the speed threshold for the change of state of the disengageable pulley (12) is of the order of 100 rpm. [Claim 9] Heat engine (14) for a motor vehicle, characterized in that it comprises a crankshaft (13) and a disengageable pulley as defined according to any one of the preceding claims mounted at one end of the crankshaft (13). 1/5