JP2008157317A - Viscous coupling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a viscous coupling capable of surely transmitting drive action to another side even in high speed continuous rotation, in other words, capable of surely transmitting necessary torque to another side. <P>SOLUTION: The viscous coupling 10 is provided with a housing 31 connected to one rotary shaft, a hub 21 connected to another rotary shaft, and a working chamber 11 comprising the housing 31 and the hub 21, has viscous fluid filled in the working chamber 11, has an outer plate 32 connected to the housing 31 and an inner plate 22 connected to the hub 21 alternately arranged, and can transmit power via viscous fluid. The coupling has a structure such that makes the outer plate 32 contacts the inner plate 33 when temperature of the viscous fluid in the working chamber 11 rises to predetermined temperature or higher. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a viscous coupling that transmits torque from one rotating member to the other rotating member via a viscous fluid.

  In the viscous coupling, the rotational speed difference between two rotating bodies that rotate relative to each other on the same axis is limited by a viscous fluid enclosed in a space formed by the two rotating bodies (hereinafter referred to as a working chamber). It is a device that makes it possible.

  A basic configuration of the conventional viscous coupling will be described with reference to a specific example shown in FIG. The viscous coupling 100 shown in the figure is arranged so as to be capable of relative rotation on the rotation axis C, and is alternately arranged to form a moving chamber 101. There are mainly two members, namely, a hub 102 that is a first rotating member and a housing 103 that is a second rotating member, and an inner plate 102A disposed in the working chamber 101 so as to be integrally rotatable with respect to the hub 102, And an outer plate 103 </ b> A disposed in the working chamber 101 so as to be integrally rotatable with respect to the housing 103.

  Further, the working chamber 101 is sealed with seal rings 104 and 105, and silicone oil which is a viscous fluid (not shown) is mixed and sealed in the working chamber 101. If this viscous coupling 100 is used, for example, as a device for transmitting power between front and rear axles of a power transmission system of a four-wheel drive vehicle, either the hub 102 or the housing 103 is connected to the four-wheel drive vehicle. The front wheel side shaft (not shown) is engaged, and the other side is engaged with the rear wheel side shaft (not shown) of the four-wheel drive vehicle.

  Since the hub 102 and the housing 103 can be rotated relative to each other, their rotational speeds are sometimes different. For example, when used in the above-described four-wheel drive vehicle, the front wheel and the rear wheel rotate at different speeds. When such a state occurs, the viscous coupling 100 causes the front wheel and the rear wheel (that is, the torque of the viscous coupling force acting between the plates 102A and 103A and the silicone oil in the working chamber 101 to be reduced. The rotational speed difference between the hub 102 and the housing 103) is limited, and power can be transmitted from the different rotational speeds of the front and rear wheels to the same rotational speed.

Such a viscous coupling not only transmits the driving force from one to the other but also has a function of transmitting the vibration while attenuating the vibration. Both the driving force transmission and the vibration attenuation are functionally Because of conflict, it is difficult to make both functions compatible. That is, in this viscous coupling, in order to transmit the driving force (transmitting force) efficiently, a viscous torque having a large linear output characteristic (high viscosity) is preferred. As the damper, a damper having a small viscous torque and a small output value (low viscosity) with respect to the input value is more preferable.
JP 2000-310254 A

  When the viscous coupling using this viscous fluid is used as the drive damper, the differential operation and the sliding operation are always acting. Therefore, especially when the input rotational speed increases and the viscosity decreases due to heat generation due to viscous friction due to the coupling operation, the viscous torque also decreases, so that the required driving force may not be maintained.

  For this reason, when this viscous coupling is used, for example, as a power transmission means for transmitting the driving force from the engine to the rear wheel side driving force together with the front wheel side driving force, when the high speed continuous rotation is performed, the second coupling coupled to the rear wheel side is performed. It is conceivable that the two-rotating member is idle and it is difficult to transmit the driving force to the rear wheel side.

  In addition, for example, when this viscous coupling is used as a driving force transmission means for transmitting the driving force from the engine to the alternator for rotation and power generation, for example, if the high-speed continuous rotation is performed, the driving force is transmitted to the alternator side. It is conceivable that power generation is not sufficient and the vehicle cannot travel. In other words, if the engine continues at a high speed, the viscous damper generates heat by repeatedly snapping (differential), so the drive torque decreases (oil viscosity decreases), the alternator causes a charging failure, and the vehicle cannot run It may be possible to stop.

  An object of the present invention is to provide a viscous coupling that can reliably transmit a drive operation to the other side even when rotating at a high speed continuously, in other words, can reliably transmit a necessary number of torques to the other side. It is to provide.

  In order to achieve the above object, the viscous coupling of the present invention forms a working chamber by an outer rotating member connected to one rotating shaft and an inner rotating member connected to the other rotating shaft, and a viscous fluid is formed in the working chamber. A viscous cup that alternately disposes an outer plate connected to the outer rotating member and an inner plate connected to the inner rotating member, and enables power transmission between the two plates via the viscous fluid. A ring, wherein when the working fluid in the working chamber rises to a predetermined temperature or more, the outer plate and the inner plate are brought into contact with each other and are integrally coupled.

  In the viscous coupling of the present invention, it is desirable that the outer plate and the inner plate are brought into contact with each other when the temperature of the viscous fluid in the working chamber falls within a range of 160 ° C to 250 ° C.

  In the viscous coupling of the present invention, it is desirable that the filling ratio of the viscous fluid with respect to the empty volume in the working chamber is in a range of 70% to 90% at normal temperature and normal pressure.

  According to the viscous coupling of the present invention, it is possible to reliably transmit the driving operation to the other side even when rotating at high speed continuously, in other words, it is possible to reliably transmit the necessary number of torques to the other side. A viscous coupling can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The viscous coupling 10 is arranged so as to be capable of relative rotation about an axis C, and is a hub that forms a working chamber 11 that is an annular space filled with a viscous fluid (not shown) by being combined with each other. (Front wheel side) 21, housing (rear wheel side) 31, inner plate 22 arranged in the working chamber 11 so as to be integrally rotatable with respect to the hub 21 which is an inner rotating member, and an outer rotating member. An inner plate 22 and an outer plate 32 arranged alternately in the working chamber 11 are provided so that the housing 31 can rotate integrally.

  The hub (front wheel side) 21 has an engaging protrusion 21A for engaging with the inner plate 22 at a portion constituting the part of the working chamber 11 on the outer peripheral surface, that is, a portion facing the working chamber 11, with an axis C A plurality are formed in parallel along the direction. The housing 31 is formed in a cylindrical shape having an annular hollow space therein, and an engagement protrusion 33A for engaging with the outer plate 32 on an inner peripheral surface constituting a part of the working chamber 11. Are formed in plural and in parallel along the direction of the axis C.

  The inner plate 22 has a thin plate substantially disk (substantially donut) shape with an opening hole in the center, and an engagement groove (Y) in the thickness (Y) direction along the inner peripheral surface of the opening hole on the center side. It has a structure provided with a number of (not shown). In addition, the inner plate 22 is formed to have a predetermined outer diameter so as to avoid being locked to an engaging protrusion 33A (described later) of the cylindrical portion 33 on the housing 31 side. Further, the inner plate 22 may be provided with slits, holes and the like in order to increase viscous friction.

  As a result, the inner plate 22 is serrated or spline engaged with the engaging protrusion 21A of the hub 21, and rotates around the shaft center integrally with the hub 21 via the engaging protrusion 21A. Although it operates, the (Y) direction parallel to the direction of the axis C is not constrained and can be slid.

  Similar to the inner plate 22, the outer plate 32 has a thin plate substantially disk (substantially donut) shape with an opening hole 32 </ b> A provided in the center, but unlike the inner plate 22, the outer plate 32 is thicker along the outer peripheral surface thereof. In this structure, a large number of engagement grooves (not shown) are provided in the direction (Y). Further, the outer plate 32 is formed so that the opening hole 32 </ b> A is slightly larger than the opening hole of the inner plate 22 so as not to engage with the engaging protrusion 21 of the hub 21. Further, the outer plate 32 may be provided with a slit (not shown).

  For this reason, on the inner peripheral surface of the cylindrical portion 33 formed inside the housing 31, the engagement groove of the outer plate 32 is serrated or spline engaged with the engagement protrusion 33 </ b> A formed on the inner peripheral surface. It is supposed to be. Accordingly, the housing 31 rotates integrally with the housing 31 via the engaging protrusion 33A. However, like the inner plate 22, the (Y) direction parallel to the axis C direction is restricted. Not slidable.

  The working chamber 11 is sealed by seal rings (O-rings) 12 and 13, and silicone oil is sealed in the working chamber 11 as the viscous fluid described above. Further, the working chamber 11 is provided with a check valve 14 having a ball 14A to serve as an inlet for silicone oil into the working chamber 11 and to prevent leakage of the silicone oil to the outside of the working chamber 11. Yes.

  The working chamber 11 of the viscous coupling 10 is filled with silicone oil (not shown). The silicone oil of this embodiment has a viscosity of 100 [cSt] to 1 million [cSt] at normal temperature and normal pressure, and the filling rate of the silicone oil with respect to the empty volume in the working chamber 11 at this normal temperature and normal pressure is In consideration of the thermal expansion of silicone oil, it is set within the range of 70% to 90% at room temperature.

A viscous coupling 50 according to an embodiment of the present invention will be described with reference to the drawings.
The viscous coupling 50 according to the present embodiment includes an engine (crankshaft) (not shown) side (provided on the right side of this) and an alternator (not shown) (provided on the left side of the viscous coupling 50). As in the first embodiment, basically, a hub 61 that is an inner rotating member, a housing 71 that is an outer rotating member, and a hub 61 and a housing 71 are provided. A working chamber 51 that is an annular space formed between them, and an inner plate 62 disposed on the hub 61 and an outer plate 72 disposed on the housing 71 are provided alternately in the working chamber 51. In the figure, reference numerals 52 and 53 denote seal rings (O-rings).

  The hub 61 is rotatably supported with respect to a drive shaft 70 that constitutes a substantial rotor drive unit of an alternator (not shown) provided on the left side of the viscous coupling 50 in FIG. Presents. As in the first embodiment, the hub 61 is provided with a large number of engaging protrusions 61A along the axis (Y) direction on the outer peripheral surface, and the inner plate 62 is held by the engaging protrusions 61A.

  As in the first embodiment, the inner plate 62 has a thin plate-like substantially ring shape with a large hole opened in the center portion, and is engaged in the thickness (Y) direction along the inner peripheral surface of the opening hole on the center side. It has a structure in which a number of grooves (not shown) are provided. As a result, the inner plate 62 is serrated or spline engaged with the engagement protrusion 61A of the hub 61 and rotates integrally with the hub 61. However, the inner plate 62 is in the (Y) direction parallel to the axis C direction of the drive shaft 70. Is possible to slide. The hub 61 is fixed integrally with the driven gear 63 via a tightening bolt 64. The driven gear 63, which is not shown, is an accessory driving gear that rotates integrally with the crankshaft on the engine side. Mesh. Reference numeral 63 </ b> A indicates a tooth portion of the driven gear 63.

  On the other hand, in the housing 71, on the inner peripheral surface of the cylindrical portion 73 formed in a cylindrical shape, as in the first embodiment, the engaging protrusion 73A in which the engaging groove of the outer plate 72 engages with serration or spline is provided. Provided. Therefore, the outer plate 72 rotates integrally with the housing 71 via the engaging protrusion 73A (centering on the axis of the drive shaft 70), but is parallel to the axis C direction (like the inner plate 62) ( In the Y) direction, sliding (sliding) is possible. The drive shaft 70 is press-fitted and fitted into the housing 71, and when the rotational drive force from the hub 61 side is transmitted to the housing 71, the drive shaft 70 rotates integrally with the housing 71. Further, as described above, the drive shaft 70 constitutes a substantial rotor drive unit of the alternator, and generates electric power by generating an induced current by rotating with the stator inside the alternator.

  Further, in the working chamber 51 of the present embodiment, silicone oil is sealed as a viscous fluid and sealed by seal rings 52 and 53 as in the first embodiment. Further, the working chamber 51 is also provided with a check valve 54 having a ball 54A in order to prevent leakage of silicone oil to the outside.

  The viscous coupling 50 has the above-described configuration, and the operation of driving the above-described alternator (generator) by the crankshaft in which the viscous coupling 50 is interposed will be simply described with reference to FIGS. I will explain.

  In FIG. 3, when the auxiliary machine drive gear attached to the end of the crankshaft rotates as a result of the rotation of the crankshaft by the operation of an engine (not shown) provided on the right side of the viscous coupling 50, the auxiliary drive gear is rotated. The rotational force is transmitted to the driven gear 63 that meshes with the machine drive gear. The hub 61 that rotates integrally with the driven gear 63 is provided with an inner plate 62 in the working chamber 51, and the outer plate 72 is rotated by the viscous torque of silicone oil generated along with the rotation of the inner plate 62. Rotate. For this reason, the housing 71 provided with the outer plate 72 and the drive shaft 70 integrated therewith rotate. In this way, power can be generated by rotating the drive shaft 70 of the alternator.

Next, the operation of the viscous coupling 50 according to this embodiment will be described.
Even in the present embodiment, for example, when performing high-speed continuous operation or winding road operation on an expressway, the same action as in the first embodiment occurs. That is, in the viscous coupling 50, when the inner plate 62 side continuously rotates at high speed following the rotation of the crankshaft on the engine side, the viscosity between the inner plate 62 and outer plate 72 in the working chamber 51 and the silicone oil. Heat is generated by friction, the internal temperature of the working chamber 51 rises rapidly, and the silicone oil undergoes thermal expansion. Then, due to the increase in pressure in the working chamber 51 due to the increase in the volume of the silicone oil, the inner plate 62 and the outer plate 72 are brought into close contact with each other as shown by arrows in FIG. Gather together into one. As a result, the viscous coupling 50 is humped and the engine side and the alternator side are directly connected.

  When the plates are gathered in this way, as described in the first embodiment, the generation of heat due to viscous friction is greatly suppressed, and the internal temperature of the working chamber 51 and the internal pressure are reduced. As a result, each inner plate 62 and outer plate 72 return to the original separated state again. Therefore, when the high-speed continuous operation ends here, the state returns to the snapping state in which a differential can be generated between the engine side and the alternator side (relative rotation is possible).

  On the other hand, when high-speed continuous operation or winding road operation continues, as described in the first embodiment, by repeating the direct connection state (bumping) by the collective action and the differential state (snapping) by the separation action, A significant increase in internal pressure due to an increase in temperature in the working chamber 51 and extreme expansion of the silicone oil can be avoided, and troubles such as leakage of silicone oil to the outside can be avoided. As described above, even in this embodiment, when a long distance is continuously operated at high speed for a long time, the engine-side drive can be reliably transmitted to the alternator side by the viscous coupling 50, so that the engine is stopped due to the inability to generate power in the alternator. Troubles such as these can be reliably prevented, and safety and reliability can be ensured even in high-speed continuous operation.

Next, examples will be described.
In this example, the viscous coupling 10 according to the first embodiment is used, and the correlation between the filling rate of the viscous fluid into the working chamber 11 and the surface temperature of the viscous coupling 10 (temperature in the working chamber) is examined. I tried the experiment. In this experiment, silicone oil having three different viscosity coefficients (viscosity) μ1 to μ3 [cTs] is used as the viscous fluid, and the hub (front wheel side) 21 is rotated at a high speed of ΔN = 500 rpm. The temperature change was measured. However, the viscosity coefficient of each silicone oil used here is as follows.
μ1 = 50000 [cSt]
μ2 = 2000 [cSt]
μ3 = 1000 [cSt]

As a result, a result as shown in FIG. 5 was obtained.
In FIG. 5, the effect of the present invention (proactively using the hump to lower the temperature in the working chamber) cannot be expected so much in the hump-prohibited region (α). The viscous surface temperature (the temperature inside the working chamber) is required to be 160 ° C. or higher. That is, it is known that when the viscous coupling is humped, the sound performance deteriorates and NVH (Noise; Vibration; Vibration, Harshness) occurs. However, if it is hung below 160 ° C., the temperature is in the range of normal use, which may give an unpleasant NVH to the driver, and the damper effect is not good. Accordingly, it is necessary to avoid the occurrence of humps when the viscous surface temperature (temperature in the working chamber) is in the range of 80 to 160 ° C., which is the normal use temperature range.

  On the other hand, in the high temperature range, it is possible to bring about a cooling effect that is below this temperature by using the present invention by generating humps actively up to 250 ° C., for example. As will be described later, it is preferable to remove the temperature of 250 ° C. or higher because of the temperature restriction of the material used for the seal portion. That is, this is a high engine rotation speed, and when the snapping is repeated, the differential (operation) speed (ΔN) remains high, and the viscous coupling temperature rises. However, the sealing rings 12 and 13 that are seal portions are damaged when the temperature exceeds the heat resistance temperature, and the silicone oil injected into the inside leaks, and the viscous torque is remarkably reduced. Therefore, in this embodiment, a hump is always generated when the viscous surface temperature is 250 ° C. or lower.

  Under such circumstances, although depending on the value of the viscosity coefficient in any case, as a setting range of the filling rate, the filling rate at normal temperature and normal pressure is 70 to 90% with respect to the space volume in the working chamber 11. The area (area surrounded by a broken line (γ) frame) was found to be preferable. Therefore, when the silicone oil is μ2 from FIG. 5, according to the present invention, based on the above experimental results and the knowledge obtained therefrom, the viscous cup at the heat resistant temperature of the sealing rings 12 and 13 (generally 250 ° C. for fluorine-based materials) or less. In order to hump the ring and avoid the increase in the internal temperature of the working chamber 11, the filling rate of the silicone oil is set within a range of 76 to 85% at normal temperature and normal pressure.

  The present invention is not limited to the embodiment described above, and can be implemented in various forms without departing from the gist of the present invention.

It is sectional drawing which shows the viscous coupling which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the effect | action of the viscous coupling which concerns on the 1st Embodiment. It is sectional drawing which shows the viscous coupling which concerns on 2nd Embodiment of this invention. It is sectional drawing for demonstrating the effect | action of the viscous coupling which concerns on the 2nd Embodiment. It is a graph which shows the correlation with the filling rate of silicone oil and the surface temperature in the viscous coupling of this invention. It is sectional drawing which shows the conventional viscous coupling.

Explanation of symbols

10, 50 Viscous coupling 11, 51 Working chamber 12, 13, 52, 53 Seal ring (O-ring)
21 Hub (front wheel side; inner rotating member)
21A, 33A, 61A, 73A Engaging protrusion 22, 62 Inner plate 31 Housing (rear wheel side; outer rotating member)
32, 72 Outer plate 33, 73 Cylindrical portion 61 Hub (engine side; inner rotating member)
63 driven gear 63A (driven gear) mountain 70 drive shaft 71 housing (alternator; outer rotating member)
C axis

Claims (3)

The outer rotating member connected to one rotating shaft and the inner rotating member connected to the other rotating shaft form a working chamber, the working chamber is filled with a viscous fluid, and the outer plate connected to the outer rotating member and the A viscous coupling that alternately arranges inner plates connected to an inner rotating member and enables power transmission between the two plates via the viscous fluid,
A viscous coupling characterized in that when the viscous fluid in the working chamber rises to a predetermined temperature range, the outer plate and the inner plate are brought into contact with each other and integrally coupled.   The viscous coupling according to claim 1, wherein the outer plate and the inner plate are brought into contact with each other when the surface temperature of the viscous fluid in the working chamber is 250 ° C. or less.   3. The viscous coupling according to claim 1, wherein a filling rate of the viscous fluid with respect to an empty volume in the working chamber is in a range of 70% to 90% at a normal temperature and a normal pressure.

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