JP2015183846A - electromagnetic clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a share of a magnetic field which is generated at an electromagnetic coil, and to suppress the sedimentation of ferromagnetic particles in a magnetic viscous fluid in a paused state.SOLUTION: An MR fluid clutch 5 comprises a first disc 51 connected to an input shaft 6, a second disc 52 connected to an output shaft 8, an MR fluid layer 53, a permanent magnet 59, an electromagnetic coil 54, and a clutch control circuit 60. The MR fluid layer 53 is formed between disc-opposing faces of the first disc 51 and the second disc 52, and filled with an MR fluid 4 in which ferromagnetic particles are dispersed in oil. The permanent magnet 59 generates a fixed magnetic field which generates transmission torque by a change of viscosity with respect to the MR fluid layer 53. The electromagnetic coil 54 generates a variable magnetic field which generates transmission torque by a change of viscosity corresponding to electricity-carrying to the MR fluid layer 53. The clutch control circuit 60 is connected to the electromagnetic coil 54, and controls a flow direction of a coil current and a magnitude of the coil current.

Description

  The present invention relates to an electromagnetic clutch using a magnetorheological fluid (= MR fluid) whose viscosity changes according to a magnetic field.

  Conventionally, an electromagnetic clutch using an MR fluid whose viscosity changes according to a magnetic field generated by energization of an electromagnetic coil is known (see, for example, Patent Document 1).

JP 61-112124 A

  However, in the conventional electromagnetic clutch, the magnetic field generated to generate the transmission torque is all provided by an electromagnet configured by energizing the electromagnetic coil. For this reason, a large current is required as an energization current to the electromagnetic coil, and the electromagnetic coil becomes large. In addition, in the resting state in which the energization to the electromagnetic coil is stopped, the magnetic field is not generated, so that the ferromagnetic particles in the MR fluid in which the ferromagnetic particles are dispersed in the oil are precipitated. there were.

  The present invention has been made by paying attention to the above-described problem. An electromagnetic clutch that can reduce the sharing of the magnetic field generated by the electromagnetic coil and can suppress the precipitation of ferromagnetic particles in the magnetorheological fluid in a resting state. The purpose is to provide.

In order to achieve the above object, an electromagnetic clutch of the present invention includes a first disk, a second disk, a magnetorheological fluid layer, a permanent magnet, an electromagnetic coil, and a clutch control circuit.
The first disk is connected to an input shaft.
The second disk is connected to an output shaft.
The magnetorheological fluid layer is formed between the disk-facing surfaces of the first disk and the second disk, and is filled with a magnetorheological fluid in which ferromagnetic particles are dispersed in oil.
The permanent magnet generates a fixed magnetic field that generates a transmission torque by a viscosity change with respect to the magneto-rheological fluid layer.
The electromagnetic coil generates a variable magnetic field that generates a transmission torque by a change in viscosity according to energization of the magnetorheological fluid layer.
The clutch control circuit is connected to the electromagnetic coil and controls the flow direction of the coil current and the magnitude of the coil current.

Therefore, when energization to the electromagnetic coil is made zero, a fixed magnetic field is generated by the permanent magnet, and a predetermined torque transmission amount is generated due to the viscosity of the magneto-rheological fluid layer according to the generated magnetic field. When the energization of the electromagnetic coil is gradually increased from zero in the direction of forming a magnetic force line in the same direction as the magnetic force line direction by the permanent magnet, the magnetic force line by the electromagnetic coil works to supplement the magnetic force line by the permanent magnet. On the other hand, when the energization of the electromagnetic coil is gradually increased from zero to the direction of forming a magnetic force line opposite to the direction of the magnetic force line by the permanent magnet, the magnetic force line by the electromagnetic coil works to cancel the magnetic force line by the permanent magnet.
In this way, even if the energization of the electromagnetic coil is zero, a fixed magnetic field is generated by the permanent magnet, thereby reducing the magnetic field sharing generated by the electromagnetic coil. In addition, since the ferromagnetic particles dispersed in the oil are held by a fixed magnetic field by a permanent magnet even in a resting state in which the electromagnetic coil is not energized, precipitation of the ferromagnetic particles is suppressed.
As a result, the magnetic field generated by the electromagnetic coil can be reduced, and the precipitation of the ferromagnetic particles in the magnetorheological fluid can be suppressed in a resting state.

It is sectional drawing which shows the torque converter with a lockup clutch which applied the MR fluid clutch (electromagnetic clutch) of Example 1 as a lockup clutch. It is action explanatory drawing which shows the magnetic force line in the MR fluid clutch of the comparative example which produces | generates a magnetic field only with an electromagnetic coil. It is a figure which shows the magnetic circuit in the MR fluid clutch of the comparative example which produces | generates a magnetic field only with an electromagnetic coil. It is a current-torque characteristic diagram showing the relationship between torque and current in an MR fluid clutch of a comparative example that generates a magnetic field only with an electromagnetic coil. It is operation | movement explanatory drawing which shows the magnetic force line in the MR fluid clutch of Example 1 which produces | generates a magnetic field with a permanent magnet and an electromagnetic coil. It is a figure which shows the magnetic circuit in the MR fluid clutch of Example 1 which produces | generates a magnetic field with a permanent magnet and an electromagnetic coil. It is an electric current-torque characteristic view showing the relation of torque to electric current in the MR fluid clutch of Example 1 which generates a magnetic field with a permanent magnet and an electromagnetic coil.

  Hereinafter, the best mode for realizing the electromagnetic clutch of the present invention will be described based on Example 1 shown in the drawings.

First, the configuration will be described.
The configuration of the MR fluid clutch (an example of an electromagnetic clutch) in the first embodiment will be described by dividing it into [the overall configuration of the torque converter with a lockup clutch] and [the detailed configuration of the MR fluid clutch].

[Overall configuration of torque converter with lock-up clutch]
FIG. 1 shows a torque converter A with a lockup clutch in which the MR fluid clutch 5 of the first embodiment is applied as a lockup clutch. Hereinafter, based on FIG. 1, the whole structure of the torque converter A with a lockup clutch is demonstrated.

  As shown in FIG. 1, the torque converter A with a lock-up clutch includes a pump impeller 1, a turbine runner 2, a stator 3, a magnetorheological fluid 4 (hereinafter referred to as “MR fluid 4”), and an MR fluid. And a clutch 5.

  The pump impeller 1 is connected to an input shaft 6 via a converter cover 7. The pump impeller 1 is manufactured from an aluminum alloy or the like, and includes a pump outer shell 1a, a plurality of pump blades 1b protruding from the inner surface of the pump outer shell 1a toward the turbine runner 2, and a plurality of pump blades 1b. A pump inner shell 1c connecting the inner ends.

  A rotary shaft 9 is connected to the pump impeller 1 at a position including the output shaft 8, and a slip ring 10 for applying a current to the electromagnetic coil 54 of the MR fluid clutch 5 is provided on the outer peripheral surface of the rotary shaft 9. 10 is provided. The ring contacts 12 and 12 of the coil current application terminal 11 are brought into contact with the slip rings 10 and 10 by spring bias. Here, the slip rings 10, 10 and the electromagnetic coil 54 are connected by a lead wire (not shown) via the pump outer shell 1 a and the converter cover 7. A rotation sensor gear 13 for detecting the rotational speed of the input shaft is fixed to the end surface position of the pump impeller 1 on the drive source side by a bolt (not shown).

  The turbine runner 2 is disposed opposite to the pump impeller 1 and is connected to the output shaft 8 via the output hub 14. The turbine runner 2 is manufactured from an aluminum alloy or the like, and includes a turbine outer shell 2a, a plurality of turbine blades 2b protruding from the inner surface of the turbine outer shell 2a toward the pump impeller 1, and the turbine blade 2b. A turbine inner shell 2c connecting the inner end portions.

  The stator 3 is disposed between the pump impeller 1 and the turbine runner 2 and is disposed in an inner region of the opposed regions of the two and 1, and is provided via a one-way clutch 16 to a case 15 that is a stationary fixing member. It is done. The stator 3 includes a stator inner ring 3a, a plurality of stator blades 3b protruding from the outer surface of the stator inner ring 3a in the outer diameter direction, and a stator outer ring 3c that connects the outer ends of the stator blades 3b. Configured.

  The MR fluid 4 is covered with the pump impeller 1 and the converter cover 7 and is enclosed in a converter space sealed by a first MR fluid seal 17, a second MR fluid seal 18, and a third MR fluid seal 19. Here, the MR fluid 4 is a functional fluid in which ferromagnetic particles such as iron nanoparticles are dispersed in oil, and the viscosity changes according to an external magnetic field. The MR fluid 4 forms a circulating flow in the torus portion where the pump impeller 1, the turbine runner 2, and the stator 3 gather when the torque converter is operated, and is filled in the magnetorheological fluid layer 53 of the MR fluid clutch 5.

  The MR fluid clutch 5 is a lock-up clutch using the MR fluid 4, and is interposed between the converter cover 7 and the turbine runner 2, and performs lock-up fastening, slip lock-up fastening, and lock-up release. At the time of lock-up fastening, the input shaft 6 and the output shaft 8 are directly connected. At the time of slip lockup fastening, the input shaft 6 and the output shaft 8 are fastened while allowing a predetermined differential rotation. When the lockup is released, the input shaft 6 and the output shaft 8 are connected via a torque converter using the MR fluid 4.

[Detailed configuration of MR fluid clutch]
The detailed configuration of the MR fluid clutch 5 will be described below with reference to FIG.
As shown in FIG. 1, the MR fluid clutch 5 includes a first disk 51, a second disk 52, a magnetorheological fluid layer 53 (hereinafter referred to as "MR fluid layer 53"), an electromagnetic coil 54, A yoke portion 55, a permanent magnet 59, and a clutch control circuit 60 are provided.

  The first disk 51 has a multi-layered disk structure having a donut shape, and is connected to the pump impeller 1 via the converter cover 7. The first disk 51 has an inner peripheral end portion embedded in an outer peripheral surface of a first flange portion 57 extending in the axial direction from the converter cover 7 toward the turbine runner 2. As the first disk 51, three spaces of equal intervals are formed by a total of four disks, two of which are embedded in the outer peripheral surface of the first flange portion 57 and two of which are also used as the yoke portions 55 provided on both sides thereof. It has a multi-layer disc structure. Note that the thickness of the two discs on both sides that also serve as the yoke portion 55 is thicker than the thickness of the two discs arranged inside. The first disk 51 and the yoke portion 55 are made of a ferromagnetic material such as iron, and the first flange portion 57 is made of an aluminum alloy or the like.

  The second disk 52 has a multi-layer disk structure with a donut shape, and is connected to the turbine runner 2. The second disk 52 has an outer peripheral end portion embedded in an inner peripheral surface of a second flange portion 58 extending in the axial direction from the outer peripheral end portion of the turbine runner 2 toward the converter cover 7. The second disk 52 has a three-layered disk structure embedded in the inner peripheral surface of the second flange portion 58 and is arranged at an intermediate position between three equally spaced spaces formed by the first disk 51. The thickness of the three disks is set to the same thickness as the thickness of the two first disks 51 embedded in the outer peripheral surface of the first flange portion 57. The second disk 52 is made of a ferromagnetic material such as iron, and the second flange portion 58 is made of an aluminum alloy or the like.

  The MR fluid layer 53 is formed in a plurality of layers so as to extend along the plane perpendicular to the converter rotation axis CL between the disk-facing surfaces of the first disk 51 and the second disk 52. In the first embodiment, as shown in FIG. 1, six MR fluid layers 53 filled with the MR fluid 4 are formed at equal intervals. The radial direction range in which the MR fluid layer 53 is set is from the position of the core region where the MR fluid 4 stays when the circulating flow is formed in the torus portion in order to suppress an increase in the radial size. The range up to the position of the outer diameter end region is set.

  The electromagnetic coil 54 generates a magnetic field by energizing the MR fluid layer 53, and is arranged at a position on the axial center side of the six MR fluid layers 53 that generate a transmission torque in accordance with a viscosity change caused by the magnetic field. The electromagnetic coil 54 is disposed at an inner peripheral side position of the first flange portion 57, and an outer peripheral portion excluding the first flange portion 57 is disposed in a cross-sectional right triangle region surrounded by the V-shaped yoke portion 55. . Here, the reason why the electromagnetic coil 54 has a right-angled triangular cross section is that the torque converter T / C with a lock-up clutch using the hydraulic clutch indicated by the phantom line in FIG. This is because the torque converter A with a lock-up clutch using the fluid clutch 5 is applied.

  The yoke portion 55 constitutes a magnetic circuit based on the lines of magnetic force when the electromagnetic coil 54 is energized, and is set in a region of the converter cover 7 where the magnetorheological fluid layer 53 is formed. That is, a part of the converter cover 7 connected to the pump impeller 1 is provided integrally with the converter cover 7 while also serving as the first disk 51.

  The permanent magnet 59 generates a fixed magnetic field with respect to the MR fluid layer 53 by a magnetic force line in a direction determined by the relationship between the N pole and the S pole. As shown in FIG. Placed in position. That is, the permanent magnet 59 is disposed at the axial center side position of the MR fluid layer 53 and between the first flange portion 57 and the electromagnetic coil 54. The strength of the maximum magnetic field generated by energizing the electromagnetic coil 54 is set to be equal to or higher than the strength of the magnetic field generated by the permanent magnet 59.

  The clutch control circuit 60 is connected to the electromagnetic coil 54 and controls the flow direction of the coil current and the magnitude of the coil current with respect to the electromagnetic coil 54 based on input information. Here, the direction in which the coil current flows is defined as (+) on the side where the magnetic lines of force in the same direction as the direction of the magnetic lines of force by the permanent magnet 59 is formed, And

Next, the operation will be described.
The operation of the MR fluid clutch 5 according to the first embodiment will be described separately for [comparative operation of torque transmission capacity control by clutch control circuit] and [other characteristic operation].

[Comparison of torque transmission capacity control by clutch control circuit]
First, an MR fluid clutch 5 ′ that generates a magnetic field only by the electromagnetic coil 54 ′ is used as a comparative example (FIG. 2). In the case of this comparative example, the magnetic circuit in the MR fluid clutch 5 ′ is a circuit in which the magnetic field by the electromagnetic coil 54 ′ and the MR fluid layer (consumption) are connected in series as shown in FIG. Then, the magnetic field lines B ′ when the electromagnetic coil 54 ′ is energized are generated only in one direction as shown by the arrows in FIG.

  Therefore, in the current control performed by the clutch control circuit of the comparative example, as shown in FIG. 4, when the MR fluid clutch 5 'is unlocked, the current applied to the electromagnetic coil 54' is zero. At the time of lock-up engagement of the MR fluid clutch 5 ', a maximum current for obtaining a target transmission torque that does not allow slipping with respect to the input torque is applied to the electromagnetic coil 54'. Further, at the time of slip lock-up engagement of the MR fluid clutch 5 ', a current (0 to maximum current) determined so as to obtain a target slip amount is applied to the electromagnetic coil 54'.

As described above, in the comparative example, the magnetic field generated to generate the transmission torque is all provided by the electromagnet configured by energizing the electromagnetic coil 54 ′. For this reason, it has the subject described below.
(a ′) A large maximum current (energy) capable of obtaining the target transmission torque is required as the energization current to the electromagnetic coil. Alternatively, in order to obtain the target transmission torque while suppressing the maximum current, it is necessary to increase the number of turns of the electromagnetic coil, and in this case, the electromagnetic coil (cross-sectional area) becomes large.
(b ′) In the resting state in which the energization of the electromagnetic coil is stopped, no magnetic field is generated, and therefore, the ferromagnetic particles in the MR fluid in which the ferromagnetic particles are dispersed in oil are precipitated. When the ferromagnetic particles in the MR fluid are precipitated, the current-torque characteristics change so that the desired transmission torque is not generated with respect to the coil current when energization to the electromagnetic coil is started next. End up.

  On the other hand, in the first embodiment, a configuration is adopted in which the MR fluid clutch 5 generates a total magnetic field by adding a fixed magnetic field by the permanent magnet 59 and a variable magnetic field by the electromagnetic coil 54 (FIG. 5). In the case of the first embodiment, as shown in FIG. 6, the magnetic circuit in the MR fluid clutch is a circuit in which the magnetic field by the permanent magnet 59, the magnetic field by the electromagnetic coil 54, and the MR fluid layer (consumption) are connected in series. It becomes. And the magnetic force line by the permanent magnet 59 is formed as shown by the arrow B in FIG. In addition, the lines of magnetic force when the electromagnetic coil 54 is energized to the (+) side are formed as shown by the arrow C in FIG. 5, and the lines of magnetic force when the electromagnetic coil 54 is energized to the (−) side are 5 is formed as shown by an arrow D in FIG. 5 (FIG. 5 is a diagram for explaining how the magnetic lines of force generated by the electromagnetic coil 54 and the permanent magnet 59 act on the MR fluid clutch 5, respectively. The arrangement of the permanent magnet 59 and the MR fluid layer 53 is different from that of the first embodiment). For this reason, the torque transmission capacity control action in the MR fluid clutch 5 by the clutch control circuit 60 is as follows.

  First, when energization to the electromagnetic coil 54 is made zero, a fixed magnetic field is generated by a magnetic field line in a direction determined by the relationship between the N pole and the S pole of the permanent magnet 59, and according to the fixed magnetic field generated by the permanent magnet 59. Torque is transmitted through the MR fluid clutch 5 due to the viscosity of the MR fluid layer 53 (normally closed, position a in FIG. 7).

  Then, when the energization of the electromagnetic coil 54 is gradually increased from zero energization to the (+) side energization, the magnetic lines of force by the electromagnetic coil 54 are added to the magnetic lines of force of the permanent magnet 59, and MR according to the magnetic field generated by the added magnetic lines of force. As the viscosity of the fluid layer 53 increases, the total torque transmitted via the MR fluid clutch 5 also increases. That is, the magnetic lines of force by the electromagnetic coil 54 work so as to supplement the magnetic lines of force of the permanent magnet 59 (torque addition section in FIG. 7, area b).

  Further, when the energization of the electromagnetic coil 54 is gradually increased from the zero energization to the (−) side energization, the magnetic field lines generated by the electromagnetic coil 54 are generated in the opposite direction to the magnetic field lines generated by the permanent magnet 59 and generated by the subtracted magnetic field lines. The total torque transmitted via the MR fluid clutch 5 also decreases as the viscosity of the MR fluid layer 53 decreases in accordance with the magnetic field. That is, the magnetic field lines due to the electromagnetic coil 54 work so as to cancel the magnetic field lines due to the permanent magnet 59 (torque reduction section in FIG. 7, area c).

  When the (−) side energization is performed so that the absolute value of the magnetic field lines generated by the electromagnetic coil 54 coincides with the magnetic field lines generated by the permanent magnet 59, the two magnetic field lines cancel each other, and the MR fluid clutch 5 enters the lockup release state (FIG. 7 L / U open, d position).

  As a result, in the first embodiment, the magnetic field generated by the electromagnetic coil 54 can be reduced, and the precipitation of the ferromagnetic particles in the MR fluid 4 can be suppressed in the resting state. In the following, the reduction of magnetic field sharing and the suppression of particle precipitation will be described in detail.

  (a) Even if the energization to the electromagnetic coil 54 is made zero, a fixed magnetic field is generated by the permanent magnet 59, so that the magnetic field sharing generated by the electromagnetic coil 54 is reduced. For example, in the normal state (zero current), when the permanent magnet 59 generates about 50% of the target transmission torque, the magnetic field generated by the electromagnetic coil 54 is about 50% of the target transmission torque. It becomes a share to generate. For this reason, the maximum current (energy) required to obtain the target transmission torque as the energization current to the electromagnetic coil 54 can be reduced to about half that of the comparative example. Alternatively, when the target transmission torque is obtained while suppressing the maximum current, the number of turns of the electromagnetic coil 54 can be reduced as compared with the comparative example, and the electromagnetic coil (cross-sectional area) can be suppressed small. In addition, the magnitude | size of the magnetic force line which forms a magnetic field is represented by the integrated value of the number of coil turns, and an electric current.

  (b) Since the ferromagnetic particles dispersed in the oil are held by the fixed magnetic field by the permanent magnet 59 even in a resting state in which the electromagnetic coil 54 is not energized, precipitation of the ferromagnetic particles is suppressed. The Therefore, for example, even when energization to the electromagnetic coil 54 is started after parking for a long time, the ferromagnetic particles are dispersed in the oil of the MR fluid 4, and a desired transmission torque with respect to the coil current. Can be generated stably.

  Furthermore, the following actions can also be obtained. Since the magnetic field applied to the MR fluid 4 can be generated by the permanent magnet 59, the MR fluid clutch 5 can be brought into the engaged state without supplying current to the electromagnetic coil 54. In addition, since the magnetic field generated by the electromagnetic coil 54 can weaken the magnetic field of the permanent magnet 59, the torque transmission capacity of the MR fluid clutch 5 can be reduced. Thus, since torque can be transmitted without supplying current to the electromagnetic coil 54, consumption of electric power during traveling can be suppressed.

  Further, since the direction of the current flowing through the electromagnetic coil 54 can be switched to the opposite direction, the magnetic coil 54 can generate a magnetic field having the same direction as the magnetic field generated by the permanent magnet 59. Compared with the case where a magnetic field is generated, the torque transmission capacity of the MR fluid clutch 5 can be increased. For this reason, even if a large torque transmission capacity of the MR fluid clutch 5 is required temporarily during traveling, it can be dealt with by simply passing a current through the electromagnetic coil 54. Therefore, the required torque of the MR fluid clutch 5 is required. It is not necessary to cover the entire capacity with the permanent magnet 59, and the permanent magnet 59 can be downsized.

[Other features]
In the first embodiment, a configuration is adopted in which the strength of the maximum magnetic field generated by energization of the electromagnetic coil 54 is set to be greater than or equal to the strength of the magnetic field generated by the permanent magnet 59.
That is, in order to meet the demand for opening the MR fluid clutch 5, it is necessary to generate a magnetic field in the reverse direction with a magnitude that cancels at least the magnetic field generated by the permanent magnet 59 by energizing the electromagnetic coil 54.
On the other hand, since the magnetic field generated by the permanent magnet 59 can be canceled out by the magnetic field generated by the electromagnetic coil 54 capable of generating more than the strength of the magnetic field generated by the permanent magnet 59, the MR fluid clutch 5 is disconnected. It can be in a state (open state).

In the first embodiment, the configuration in which the electromagnetic coil 54 is disposed at the axial center side position of the MR fluid layer 53 is employed.
Thus, since the electromagnetic coil 54 is disposed at the axial center side position closer to the converter rotation axis CL than the MR fluid layer 53, the occupied volume of the electromagnetic coil 54 can be reduced.
In other words, the magnetic field generated by the electromagnetic coil 54 is determined by the current flowing through the electromagnetic coil 54 and its cross-sectional area, but if the cross-sectional area is the same, the entire circumference of the electromagnetic coil 54 is reduced by placing it on the axial center side. By shortening, the occupied volume of the electromagnetic coil 54 can be reduced. In addition, the material of the electromagnetic coil 54 is often a metal having a high specific gravity such as copper, but even in such a case, it can be controlled by reducing the inertia by disposing it at a position near the converter rotation axis CL. Can be improved.
Further, since the MR fluid layer 53 formed in the gap between the two disks 51 and 52 is arranged on the radially outer side, the torque transmission surface is increased even if the radial width of the MR fluid layer 53 is the same. Further, the torque to be transmitted can be increased even if the shear force of the MR fluid 4 is the same because it is away from the converter rotation axis CL.

In the first embodiment, the first disk 51 is provided on the converter cover 7 connected to the input shaft 6, and the second disk 52 is provided on the turbine runner 2 connected to the output shaft 8. The MR fluid layer 53 is sealed in the sealed space covered with the converter cover 1 and the pump impeller 1 connected to the converter cover 1, and the MR fluid 4 is sealed in the first disk 51 and the second disk. It was configured by filling 52 facing gaps.
That is, by applying the MR fluid clutch 5 to a lock-up clutch of a torque converter using the MR fluid 4, the MR fluid 4 can be shared by the torque converter and the MR fluid clutch 5. For this reason, it is not necessary to prepare another fluid for the lockup clutch, it is not necessary to provide liquid chambers for storing different types of fluids, and the structure can be simplified.

Next, the effect will be described.
In the MR fluid clutch 5 of the first embodiment, the following effects can be obtained.

(1) a first disk 51 coupled to the input shaft 6;
A second disk 52 coupled to the output shaft 8;
A magnetorheological fluid layer (MR fluid) formed between the disc-facing surfaces of the first disc 51 and the second disc 52 and filled with a magnetorheological fluid (MR fluid 4) in which ferromagnetic particles are dispersed in oil. Layer 53);
A permanent magnet 59 for generating a fixed magnetic field that generates a transmission torque by a change in viscosity with respect to the magnetic viscous fluid layer (MR fluid layer 53);
An electromagnetic coil 54 that generates a variable magnetic field that generates a transmission torque by a change in viscosity in response to energization of the magnetorheological fluid layer (MR fluid layer 53);
A clutch control circuit 60 connected to the electromagnetic coil 54 for controlling the flow direction of the coil current and the magnitude of the coil current;
Equipped with.
For this reason, the magnetic field generated by the electromagnetic coil 54 can be reduced, and the precipitation of the ferromagnetic particles in the magnetorheological fluid (MR fluid 4) can be suppressed in a resting state.

(2) The strength of the maximum magnetic field generated by energizing the electromagnetic coil 54 is set to be greater than the strength of the magnetic field generated by the permanent magnet 59.
Therefore, in addition to the effect (1), the MR fluid clutch 5 can be in the disconnected state (opened state) by canceling out the magnetic field generated by the permanent magnet 59 by the magnetic field generated by the electromagnetic coil 54.

(3) The electromagnetic coil 54 is disposed at a position on the axial center side of the magnetorheological fluid layer (MR fluid layer 53).
For this reason, in addition to the effect of (1) or (2), the reduction of the occupied volume of the electromagnetic coil 54, the improvement of the controllability by a small inertia, and the increase of the transmission torque by the expansion of the torque transmission surface are achieved. Can do.

(4) The first disk 51 is provided on the converter cover 7 connected to the input shaft 6;
The second disk 52 is provided on the turbine runner 2 connected to the output shaft 8,
The magnetorheological fluid layer (MR fluid layer 53) is sealed in the sealed space covered with the converter cover 7 and the pump impeller 1 connected to the converter cover 7. 5) is configured by filling the gap between the first disk 51 and the second disk 52 facing each other.
For this reason, in addition to the effects (1) to (3), different types of working fluid for the torque converter and working fluid for the MR fluid clutch 5 are prepared, and liquid chambers for storing the respective fluids are provided. There is no need, and the structure can be simplified.

  As mentioned above, although the electromagnetic clutch of this invention has been demonstrated based on Example 1, it is not restricted to this Example 1 about a concrete structure, The summary of the invention which concerns on each claim of a claim Unless it deviates, design changes and additions are allowed.

  In the first embodiment, as the MR fluid layer 53, an example in which six layers extend along a plane orthogonal to the converter rotation axis CL is shown. However, the MR fluid layer may be an example that extends other than 6 layers (1-5 layers, 7 layers or more). Further, the MR fluid layer may be a single layer or a multilayer extending along a plane parallel to the converter rotation axis.

  In the first embodiment, the example in which the first disk 51 is provided in the first flange portion 57 and the second disk 52 is provided in the second flange portion 58 has been described. However, the first disc on the input shaft side and the second disc on the output shaft side may be provided on, for example, a clutch hub member and a clutch drum member as long as they form a gap that becomes an MR fluid layer. .

  In the first embodiment, a preferable example in which both the electromagnetic coil 54 and the permanent magnet 59 are arranged at the axial center side position of the MR fluid layer 53 has been shown. However, both the electromagnetic coil and the permanent magnet may be arranged at a position far from the axial center of the MR fluid layer, or the electromagnetic coil and the permanent magnet may be positioned at the axial center side with respect to the MR fluid layer. An example in which one is arranged and the other is arranged at a position far from the axis is also possible. Further, the positions of the electromagnetic coil 54 and the permanent magnet 59 may be exchanged in the radial direction, or may be arranged side by side in the axial direction.

  In Example 1, the example which applies the electromagnetic clutch of this invention as a lockup clutch of a torque converter with a lockup clutch was shown. However, the electromagnetic clutch of the present invention is not limited to a torque converter with a lock-up clutch, and can also be applied as a starting clutch for various vehicles.

A Torque converter with lock-up clutch 1 Pump impeller 2 Turbine runner 3 Stator 4 MR fluid (magnetic viscous fluid)
5 MR fluid clutch (electromagnetic clutch)
51 First disk 52 Second disk 53 MR fluid layer (magnetic viscous fluid layer)
54 Electromagnetic coil 55 Yoke part 57 First flange part 58 Second flange part 59 Permanent magnet 60 Clutch control circuit 6 Input shaft 7 Converter cover 8 Output shaft

Claims (4)

A first disk coupled to the input shaft;
A second disk coupled to the output shaft;
A magnetorheological fluid layer formed between the disc facing surfaces of the first disc and the second disc and filled with a magnetorheological fluid in which ferromagnetic particles are dispersed in oil;
A permanent magnet that generates a fixed magnetic field that generates a transmission torque by a viscosity change with respect to the magneto-rheological fluid layer;
An electromagnetic coil that generates a variable magnetic field that generates a transmission torque by a change in viscosity in response to energization of the magnetorheological fluid layer;
A clutch control circuit connected to the electromagnetic coil for controlling the flow direction of the coil current and the magnitude of the coil current;
An electromagnetic clutch comprising: The electromagnetic clutch according to claim 1,
An electromagnetic clutch characterized in that the strength of the maximum magnetic field generated by energizing the electromagnetic coil is set to be equal to or greater than the strength of the magnetic field generated by the permanent magnet. The electromagnetic clutch according to claim 1 or 2,
The electromagnetic clutch, wherein the electromagnetic coil is arranged at a position on the axial center side of the magneto-rheological fluid layer. In the electromagnetic clutch according to any one of claims 1 to 3,
The first disk is provided on a converter cover connected to the input shaft,
The second disk is provided in a turbine runner connected to the output shaft,
The magnetorheological fluid layer is sealed in the sealed space covered with the converter cover and the pump impeller coupled to the converter cover, and the magnetorheological fluid is sealed between the first disk and the second disk. An electromagnetic clutch characterized in that it is configured by filling the opposing gap.