JP2009115303A - Pressing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressing device optimizing a relative position to a pressing body. <P>SOLUTION: In this pressing device, the pressing body abutting on a predetermined object to press the object is retained movably backward and forward by a holder 3 coupled to an actuator operated linearly backward and forward. The pressing device includes: an integration mechanism regulating relative backward movement of the pressing body to the holder when the holder is advanced to relatively push back the pressing body by the object; and a thrust mechanism pressing the pressing body relatively in an advancing direction to the holder when the holder is further moved backward. The pressing device includes a regulating means regulating the movement of the pressing body in the advancing direction by the thrust mechanism when the holder with pressing body relatively moved backward by abutting the pressing body on the object retreats in a direction separating from the object. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pressing device that presses a predetermined object such as a friction plate in a clutch, and more particularly, to a pressing device that includes a mechanism that adjusts the tip position of a pressing body that actually presses the object by operating an actuator. Is.

  2. Description of the Related Art Conventionally, there is known an apparatus configured to contact a friction plate by attracting an armature using an electromagnet. An example of this is described in Patent Document 1. The electromagnetic friction clutch described in Patent Document 1 is intended to automatically adjust the air gap of an electromagnet. The electromagnet resists the return spring by the electromagnet. A rotating piece that allows the electromagnet to move in a direction that widens the air gap of the electromagnet and prevents movement in the opposite direction. Is provided.

  Conventionally, a magnetic fluid for generating a fastening force of an electromagnetic clutch has been provided, and an example thereof is described in Patent Document 2. In the electromagnetic clutch, an input joint member and an output joint member are arranged to face each other, and a magnetic reaction medium is filled between the joint members, and a magnetic field is applied to the magnetic reaction medium to increase a viscous shear force. Thus, the torque is transmitted between the input joint member and the output joint member.

JP 2004-232835 A JP 2002-36898 A

  When pressing an object such as a friction plate, the distance (interval) between the actuator made of an electromagnet and an armature, or an actuator made of a fluid pressure cylinder or a ball screw, and the object is set to a predetermined value in design. However, it may differ from the design value due to assembly errors and wear. The apparatus described in Patent Document 1 described above is configured to automatically adjust the error in such a manner so that the air gap falls within the target value. However, since the device described in Patent Document 1 has a single adjustment direction, it is appropriate when the distance is initially adjusted to reduce the stroke due to the short distance and then the distance increases. Adjustment may not be possible.

  An example of this will be explained by taking a friction plate as an example. The unused friction plate does not undergo any compression deformation and wear, so the overall thickness is less than the standard thickness determined by design. In some cases, the distance between the member that presses the friction plate and the friction plate is short, and the stroke of the pressing member is adjusted to be short. On the other hand, when the friction plate is worn or thinned by receiving a compressive load, the thickness is reduced as a whole, so that the required stroke of the pressing member is increased. Therefore, the stroke of the pressing member needs to be adjusted in both the long and short directions. However, in the invention of Patent Document 1, since the air gap is automatically adjusted in the increasing direction, wear of the friction plate proceeds. In such a case, adjustment cannot be performed.

  The present invention has been made paying attention to the above technical problem, and can adjust the stroke of the member that directly contacts and presses the object in both the long and short directions, and maintains the adjusted stroke. It is an object of the present invention to provide a pressing device that can do this.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a holding body connected to an actuator that linearly moves back and forth, and a pressing body that abuts against a predetermined object and presses the object. An integrated mechanism that is held movably and restricts the backward movement of the pressing body relative to the holding body when the holding body moves forward and the pressing body is pushed back relatively by the object. And a pressing device provided with a propulsion mechanism that presses the pressing body in a forward direction relative to the holding body when the holding body moves backward, and the pressing body is used as the object. When the holding body that has been brought into contact and relatively moved backward moves backward in a direction away from the object, the holding body is provided with a regulating unit that regulates movement of the pressing body in the forward direction by the propulsion mechanism. Specially It is an.

  According to a second aspect of the present invention, a magnetic fluid whose viscosity is increased in a magnetic field is filled between the holding body and the pressing body so as to flow in and out, and the restricting means applies a magnetic field to the magnetic fluid to flow the magnetic fluid. The pressing device includes means for preventing the magnetic fluid from flowing in and out as the pressing body moves forward relative to the holding body.

  According to a third aspect of the present invention, the actuator includes an electromagnetic coil and an armature that is magnetically attracted to the electromagnetic coil and integrated with the holding body. It is a pressing device further comprising gap estimating means for estimating a distance between the electromagnetic coil and the armature based on a flow rate.

  According to the first aspect of the present invention, when the holding body is advanced by the actuator, the pressing body held by the holding body advances in the same manner. And when a press body contacts a target object, since the advance is stopped, a press body retreats relatively with respect to a holding body. In this way, when the holding body moves forward by a predetermined amount, that is, when the operation amount of the actuator reaches a predetermined amount, the pressing mechanism is integrated with the holding body by operating the integration mechanism, so that the thrust by the actuator is held. Acting on the pressing body through the body, the object is pressed. Further, when the holding body is moved backward by a predetermined means such as a return spring or an actuator, the pressing body moves backward together with the holding body, and the pressing of the object is released. By releasing the integration of the holding body and the pressing body by the integration mechanism during the retreating process, the pressing body is advanced relative to the holding body by the propulsion mechanism. That is, the pressing body relatively pushed back by the object is pushed in a direction of moving forward relative to the holding body so as to restore the pushing back. At that time, the restricting means acts to restrict the relative forward movement of the pressing body. That is, the stroke adjustment amount by maintaining the pressing body in contact with the object and relatively moving backward is maintained. Therefore, since the stroke amount by the subsequent actuator is maintained without going through the adjustment step, the substantial stroke amount of the actuator can be reduced, and accordingly, the pressing response of the object is good. It becomes.

  Further, according to the invention of claim 2, since the regulating means includes means for preventing the magnetic fluid from flowing in and out by applying a magnetic field to the magnetic fluid and regulating the flow thereof, the controllability is improved and the whole The configuration as can be simplified.

  Furthermore, according to the invention of claim 3, the pressure body further includes gap estimating means for estimating the distance between the electromagnetic coil and the armature based on the pressure of the magnetic fluid and the amount of current flowing to the electromagnetic coil. The response to the object is improved and the amount of current flowing to the electromagnetic coil can be reduced, so that it is possible to save power. And since an air gap can be performed by the gap estimation means from the pressure of a magnetic fluid and the command value of an electromagnetic coil, it becomes possible to suppress cost and to perform control with high precision.

  The best mode for carrying out the invention will be described below. FIG. 1 shows a first embodiment in which the present invention is applied to an electromagnetic clutch mechanism. The electromagnetic clutch mechanism 1 in the first embodiment shown here is configured to generate thrust by an electromagnet 2 and a magnetic body (hereinafter, referred to as an armature) 3 that is a holding body attracted to the electromagnet 2. The electromagnet 2 has an annular shape as a whole and a yoke 4 having a U-shaped cross section in the axial direction and an electromagnetic coil that generates a magnetic field when energized (hereinafter referred to as a main coil). ) 5. The main coil 5 is fitted inside the yoke 4.

  The armature 3 includes a ring-shaped flat plate portion 6 that faces the yoke 4 and a cylinder portion 7 that is integrated with an outer peripheral end of the flat plate portion 6. The cylinder part 7 includes an inner cylinder part 7a and an outer cylinder part 7b having a diameter larger than that, and has an annular shape as a whole, and a peripheral part has a hollow shape.

  The cylinder portion 7 is disposed so as to cover at least a part of the outer periphery side of the yoke 4, and a thin plate-like retainer 8 is attached to the tip portion thereof. Another retainer 9 facing this retainer 8 is fixed to a predetermined fixing portion 10 holding the electromagnet 2. A return spring 11 is disposed between the retainers 8 and 9. The return spring 11 is compressed when the armature 3 is attracted by the electromagnet 2 and moves forward, and has an elastic force that pushes the armature 3 back to the original initial position when the attraction force (thrust of the armature 3) by the electromagnet 2 is lost. Is configured to occur.

  An electromagnet 12 is fixed at a substantially central portion in the axial direction inside the cylinder portion 7. The electromagnet 12 includes a base ring 12a fixed to the outer peripheral surface of the inner cylindrical portion 7a, an electromagnetic coil (hereinafter referred to as a subcoil) 12b fitted to the outer peripheral side, and a frame member that covers the subcoil 12b. 12c. A slight gap is formed between the base ring 12a, the subcoil 12b, and the frame member 12c, and this gap forms a flow path for a magnetic fluid or a magnetorheological fluid described later.

  A first piston 13 corresponding to a pressing body is fitted in one side (right side in FIG. 1) sandwiching the electromagnet 12 inside the cylinder part 7 so as to move back and forth while maintaining a liquid-tight state. . Accordingly, a first piston chamber 14 is formed between the electromagnet 12 and the first piston 13. Further, the second piston 15 is fitted to the other side (left side in FIG. 1) sandwiching the electromagnet 12 inside the cylinder part 7 so as to move back and forth while maintaining a liquid-tight state. Accordingly, a second piston chamber 16 is formed between the electromagnet 12 and the second piston 15.

  The first piston 13 includes a portion that extends in the axial direction from a portion that fits inside the cylinder portion 7, and the so-called extended portion is a friction that is a predetermined object constituting the clutch mechanism 17. It is close to the plate 18 and faces it. The friction plate 18 includes a brake plate that is spline-fitted to the inner peripheral surface of the casing 19, and a brake disk that is spline-fitted to the outer peripheral surface of the brake drum 20 and arranged alternately with respect to the brake plate. By being pressed in the thickness direction (axial direction) by the first piston 13, they are configured to frictionally contact each other and transmit torque. In the example shown in FIG. 1, the brake drum 20 is integrated with the sun gear 22 of the planetary gear mechanism 21, and the sun gear 22 is selectively braked.

  The second piston 15 includes a portion that extends in the axial direction (left direction in FIG. 1) from a portion that fits inside the cylinder portion 7, and the so-called extending portion is attached to the casing 19. It is comprised so that it may contact | abut to the stopper 23 which is. The stopper 23 corresponds to the propulsion mechanism in the present invention, and is for pushing the second piston 15 back into the cylinder portion 7. Therefore, instead of forming the extending portion on the second piston 15, A portion protruding toward the piston 15 may be provided on the stopper 23.

  In each of the piston chambers 14 and 16, a magnetic fluid or a magnetorheological fluid (hereinafter referred to as a magnetic fluid) 24 that constitutes an integrated mechanism in the present invention together with the subcoil 12b is enclosed. . The magnetic fluid 24 is conventionally known, and is a fluid whose fluidity is lowered or solidified by applying magnetism or in a magnetic field.

  An electronic control unit ECU for controlling energization of the coils 5 and 12b is provided. This electronic control unit ECU is composed mainly of a microcomputer, performs calculations based on input data, stored data and programs, and controls currents to the coils 5 and 12b according to the calculation results. The instruction signal is output. The electronic control unit ECU includes a sensor that detects a detection signal, a current value of each of the coils 5 and 12b, and a pressure of each of the piston chambers 14 and 16 from a sensor (not shown) that detects the stroke amount of the armature 3. A detection signal from (not shown) is input.

  Next, the operation of the above-described apparatus will be described. The state shown in FIG. 1 is a state in which the main coil 5 is in an off state and no pressing action is performed, and the armature 3 is pushed back to the initial position on the reverse side together with the pistons 13 and 15 by the return spring 11. . In this state, the subcoil 12b is also turned off, and therefore the magnetic fluid 24 maintains fluidity because no magnetism is applied. Further, the second piston 15 abuts against the stopper 23 and is relatively pushed into the second piston chamber 16. Therefore, since the volume of the second piston chamber 16 is small, most of the magnetic fluid 24 has moved to the inside of the first piston chamber 14. Accordingly, the first piston chamber 14 has a large volume or a large amount of the magnetic fluid 24 in the first piston chamber 14, so that the first piston 13 protrudes relatively large from the armature 3.

  In this state, when the determination to start the engagement of the clutch mechanism 17 is established and an engagement instruction is output, first, as shown in the flowchart of FIG. 2, the current of the main coil 5 is controlled (step S1). As a result, the armature 3 is attracted by the magnetic force generated by the main coil 5, and axial thrust is generated. Then, the current of the subcoil 12b is decreased in order to reduce the application to the magnetic fluid 24 and cause the fluid to flow (step S2). The flat plate portion 6 and the cylinder portion 7 are moved together with a first piston (hereinafter simply referred to as a piston) 13 that is a pressing body. At this time, since the solidification of the magnetic fluid 24 is reduced and fluidized, the piston 13 is easily moved. The piston 13 comes into contact with the friction plate 18 (step S3). By this contact, the piston 13 stops and the magnetic fluid 24 flows from the first piston chamber 14 to the second piston chamber 16.

  Here, it is determined in advance by the stroke sensor or the like that the air gap has become a predetermined value (step S4). When the air gap reaches the target predetermined value, the sub-coil 12b is energized to increase the current and solidify the magnetic fluid 24 (step S5). As a result, the piston 13 and the armature 3 are integrated (step S6). After integrating the piston 13 and the armature 3, the current of the main coil 5 is controlled (step S7). Then, the friction plate pressing pressure is determined (step S8).

  Next, as shown in the flowchart of FIG. 3, when the release determination of the clutch mechanism 17 is established and a clutch release instruction is output (step S <b> 9), first, current control of the main coil 5 is started ( Step S10). Specifically, the current of the main coil 5 is reduced and the energization of the current of the subcoil 12b is maintained (step S11). As a result, when the elastic force of the return spring 11 is greater than the attractive force of the main coil 5, the piston 13 moves backward while being integrated with the armature 3 (step S12).

  When the armature 3 moves backward, the second piston 15 held at a so-called rear end portion of the cylinder portion 7 integrated with the armature 3 comes into contact with a stopper 23 which is a propulsion mechanism. At that time, since the energization amount of the subcoil 12b is maintained at a predetermined value, the flow of the magnetic fluid 24 is prevented, so that the second piston 15 and the cylinder portion 7 are integrated, and the second piston When 15 is in contact with the stopper 23, the cylinder part 7 and the armature 3 integrated with the cylinder part 7 are prevented from moving backward, and the whole is stopped (step S13). Therefore, the current value of the sub-coil 12b that is maintained is a current value that solidifies the magnetic fluid 24 to such an extent that the magnetic fluid 24 does not flow due to the elastic force of the return spring 11, and is predetermined in design or experimentally. Current value. Thereby, since the stroke amount at the time of clutch engagement can be reduced while maintaining the clutch pack clearance, the responsiveness can be improved. Further, since the moving amount of the piston 13 can be reduced, the moving flow rate of the magnetic fluid 24 after the contact between the piston 13 and the friction plate 18 is also reduced, so that it can be solidified with less power, thereby saving power. Can be realized.

  Thus, even if the armature 3 moves backward in the direction away from the main coil 5, the amount of protrusion of the first piston 13 is adjusted as described above, and accordingly, the second piston 15 protrudes to the rear end side. The amount of retraction of the armature 3 is reduced by the increase in the protruding amount. Therefore, when the main coil 5 is energized again and the armature 3 is rapidly advanced, the air gap is shorter than the initial dimension. Therefore, even if the current amount of the main coil 5 is smaller than the initial current amount, the same as before. The suction force can be generated. As a result, the Joule loss in the main coil 5 is reduced, energy efficiency is improved, and the temperature change of the magnetic fluid 24 due to heat generation is reduced, so that the thermal expansion of the magnetic fluid in the first piston chamber 14 is suppressed. Can do.

  4 (a) to 4 (d) are schematic cross-sectional views showing respective states when the clutch is engaged (a), when the clutch is released (b), when the subcoil is not controlled (c), and when the clutch is engaged (d). is there. In FIG. 5A, when the clutch is engaged, the subcoil 12b is energized, and a thrust is applied to the clutch. That is, the piston 13 presses the friction plate 18. In FIG. 5B, when the clutch is released, the current of the subcoil 12b is in a set value state, and the piston 13 is moved rightward in the drawing, but the air gap 25 at this time is reduced. . In FIG. 5C, the subcoil 12b is in a non-control state, so that the air gap 25 is larger than when the clutch is released. In FIG. 6D, when the clutch is engaged, the subcoil 12b is energized, so that the piston 13 moves to the left in the drawing and presses the friction plate 18.

  Next, a second embodiment will be described with reference to FIG. As shown in FIG. 5, in the second embodiment, a portion corresponding to the main coil 5 shown in the first embodiment is constituted by an electric motor 26 and a ball screw 27 which are rotation driving portions. For this reason, the portions other than the electric motor 26 and the ball screw 27 are the same as those in the first embodiment, and thus the description thereof is omitted. First, the electric motor 26 including the stator 28 and the rotor 29 is configured such that the rotor 29 rotates around the rotation axis. The rotational motion of the rotor 29 is converted into a linear motion by a ball screw (deceleration unit) 27. The linear movement by the ball screw 27 makes it possible to press the piston 30 against the friction plate 31, and when the piston 30 is pressed against the friction plate 31, the pressure is adjusted by adjusting the current to the subcoil 32. Yes. The electric motor 26 used here is relatively small in size and may consume less power.

  In this state, when the determination to start engagement of the clutch mechanism is made and an engagement command is output, first, as shown in the flowchart of FIG. 6, the electric motor 26 rotates (step S14). A propulsive force is applied to the ball screw 27 by the rotation of the electric motor 26 (step S15). The piston 30 moves in the axial direction by the driving force of the ball screw 27 (step S16). Then, it is determined whether the piston 30 and the friction plate 31 are in contact (step S17). At this time, detecting means for detecting that the piston 30 and the friction plate 31 are in contact with each other is provided. This detection means determines that the piston 30 and the friction plate 31 are in contact with each other, for example, by increasing the hydraulic pressure of the magnetic fluid in the piston chamber 33. This can be judged because the pressure resistance of the piston chamber 33 increases. Further, it can be determined from the current value of the electric motor 26. This can be determined because the current value increases because the motor torque of the electric motor 26 increases.

  FIG. 7 shows that the piston 30 and the friction plate 31 are brought into contact with each other in this way and the piston 30 is stopped, and then the sub-coil 32 is energized to control the piston 30 to press the friction plate 31. FIG. 7 is a time chart showing the relationship between the hydraulic pressure of the magnetic fluid in the piston chamber 33 and the movement of the piston 30. It is determined whether or not the piston 30 and the friction plate 31 are in contact with each other. If the determination result is negative, the process returns to step S14 for controlling the rotation of the electric motor 26. A certain electric motor 26 is stopped (step S18). And after the electric motor 26 stops, it supplies with electricity to the subcoil 32 (step S19). By energizing the subcoil 32, the magnetic fluid in the piston chamber 33 is solidified to move the ball screw 27 and the piston 30 together (step S20). Thereafter, torque control of the electric motor 26 is performed (step S21). Then, the friction plate pressing pressure is determined (step S22).

  Next, as shown in the flowchart of FIG. 8, when the clutch release determination is established and a clutch release instruction is output (step S23), first, the torque of the electric motor 26 is controlled (step S24). Thereafter, the current of the subcoil 32 is reduced (step S25). Then, the electric motor 26 rotates (step S26). As the electric motor 26 rotates, a propulsive force is generated by the ball screw 27, and specifically, a thrust force in the direction of retracting the piston is generated (step S27). The piston 30 is moved by the propulsion of the ball screw 27 (step S28). It is determined whether or not the stopper 34 has come into contact with the piston 30 by the movement of the piston 30 (step S29). If a negative determination is made in step S29, the process returns to step S26 instructing the rotation control of the electric motor 26, and if affirmative, the process proceeds to the next step, an instruction to stop the electric motor 26 (step S30). . And when it moves to the electric motor 26 stop instruction | indication, the ball screw 27 and the piston 30 move relatively (step S31). The electric motor 26, the ball screw 27, and the piston 30 are stopped by the relative movement of the ball screw 27 and the piston 30 (step S32).

  Next, a third embodiment will be described with reference to FIG. Since the third embodiment has substantially the same configuration as the first embodiment, the description of the configuration is omitted and the same reference numerals are used. And it demonstrates using the flowchart of FIG. As shown in the flowchart of FIG. 10, when the clutch engagement start determination is established and the engagement command is output, first, the current of the subcoil 12b is increased (step S33). Here, by increasing the current of the subcoil 12b, the magnetic field to the magnetic fluid 24 is increased and solidified. Next, the current of the main coil 5 is controlled (step S34). As a result, the armature 3 is attracted by the magnetic force generated by the main coil 5, and axial thrust is generated. With this thrust, the piston 13 and the friction plate 18 come into contact (step S35). The hydraulic pressure of the magnetic fluid 24 at the time when the piston 13 and the friction plate 18 contact each other is detected, and the instruction current to the main coil 5 is read (step S36). The pressing force when the piston 13 and the friction plate 18 come into contact can be obtained from the following equation.

PA-kx = {(NI) ² · S · 10 ⁷ · (μ ₀ ) ² } / {8 · π · δ (x) ² }

  In the above formula, P is the hydraulic pressure to the magnetic fluid to be detected, A is the area of the piston 13, k is the spring constant of the spring 11, x is the stroke that is the distance that the piston 13 moves, N is the number of turns of the main coil 5, I is the amount of current flowing through the main coil 5, S is the working area of the armature 3, μ is the permeability of the magnetic fluid, and δ (x) is calculated It is an air gap.

  From this equation, the air gap δ (x), which is the distance between the main coil 5 and the armature 3, can be predicted (estimated) from the current I to the main coil 5 and the hydraulic pressure P to the magnetic fluid (step S37). The air gap δ (x) can be detected from the command value of the hydraulic pressure P to the magnetic fluid and the current I to the main coil without using a stroke sensor or the like as a detecting means, thereby reducing the cost. Became possible. Then, by estimating the air gap from the hydraulic pressure P of the magnetic fluid 24 and the instruction current of the main coil 5, it is possible to draw out the attractive force of the piston 13 and the armature 3 with high accuracy. This eliminates the need for the piston 13 to move relative to the armature 3 or to control the current of the subcoil 12b, so that the response is good and a complicated control system is not required. Then, the current to the main coil 5 can be controlled by estimating the air gap δ (x) (step S38). The pressure applied to the friction plate 18 is determined by controlling the current to the main coil 5 (step S39).

  Then, the engagement of the clutch ends (step S40). After the clutch is engaged, the air gap δ (x) can be adjusted (decreased) by reducing the current to the subcoil 12b (step S41). By adjusting the air gap δ (x), the current of the main coil 5 can be reduced. For this reason, the power consumption can be reduced because less current is supplied to the main coil. Thereby, the piston 13 and the armature 3 move (step S42). Here, the air gap δ (x) can be reduced by lowering the current to the subcoil 12 b and moving the piston 13 and the armature 3. As the piston 13 and the armature 3 move, the current to the subcoil 12b is increased to stop the piston 13 and the armature 3 (step S43). At that time, the air gap δ (x) is maintained at a predetermined value (step S44).

  Next, an example in which a permanent magnet is used as a part of the subcoil will be described with reference to FIGS. 11 (a) to 11 (c) are schematic cross-sectional views each showing a state of engagement of the clutch. FIG. 5A shows a state when the clutch is engaged, and the energization amount of the subcoil 35 in the same magnetic field direction as that of the permanent magnet is reduced. In this state, the energization of the subcoil 35 is increased after the air gap changes from the larger one to the smaller one and reaches a predetermined value. At this time, thrust acts on the clutch. That is, the piston 36 presses the friction plate 37.

  FIG. 5B shows a state when the clutch is released, and energization of the subcoil 35 is stopped. At this time, the magnetic fluid sealed around the subcoil 35 is solidified by the magnetic field of only the permanent magnet. For this reason, the piston 36 is moved rightward in the drawing.

  FIG. 6C shows a state when the clutch is engaged, and the sub coil 35 is energized so as to have the same magnetic field direction as the permanent magnet. For this reason, the magnetic fluid is solidified by the magnetic field between the permanent magnet and the subcoil 35. The piston 36 moves to the left in the drawing and presses the friction plate 37. Further, when the clutch is engaged by the magnetic field of the permanent magnet, the clutch can be released by applying a magnetic field opposite to the magnetic field of the permanent magnet by the subcoil 35.

  In addition, the functional means of step S13 or step S30 mentioned above corresponds to the control means of this invention.

It is a figure which shows the 1st Example which applied this invention to the electromagnetic clutch mechanism. It is a flowchart when determination of engagement start of a clutch mechanism is materialized and an engagement instruction | indication is output. It is a flowchart when the judgment of release of a clutch mechanism is materialized. (A)-(d) is a schematic sectional drawing which shows each state at the time of clutch engagement. It is a schematic sectional drawing which shows a 2nd Example. It is a flowchart in case the determination of the engagement start of a clutch mechanism is materialized and an engagement command is output. It is a figure which shows the relationship between the hydraulic pressure of the magnetic fluid in a piston chamber, and the motion of a piston. It is a flowchart when the judgment of release of a clutch mechanism is materialized. It is the schematic sectional drawing which showed the 3rd Example which applied this invention to the electromagnetic clutch mechanism. It is a flowchart in case determination of clutch engagement start is materialized and an engagement command is output. (A)-(c) is a schematic sectional drawing which shows the state at the time of engagement of a clutch, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Clutch mechanism, 2 ... Electromagnet, 3 ... Armature, 4 ... Yoke, 5 ... Main coil, 7 ... Cylinder part, 11 ... Return spring, 12 ... Electromagnet, 12a ... Base ring, 12b ... Subcoil, 13 ... 1st piston , 14 ... 1st piston chamber, 15 ... 2nd piston, 16 ... 2nd piston chamber, 17 ... Clutch mechanism, 18 ... Friction plate, 23 ... Stopper, 24 ... Magnetic fluid, EUC ... Electronic control unit.

Claims (3)

A holding body connected to an actuator that linearly moves back and forth holds a pressing body that abuts against a predetermined object and presses the object so as to be movable back and forth, and the holding body moves forward and moves forward. When the pressing body is pushed back relatively by the object, an integrated mechanism is provided that restricts the backward movement of the pressing body relative to the holding body, and when the holding body moves backward, the pressing body In a pressing device provided with a propulsion mechanism that presses the body in the forward direction relative to the holding body,
When the holding body, which has been relatively moved backward by bringing the pressing body into contact with the object, retreats in a direction away from the object, the pushing mechanism moves the pressing body in the forward direction. A pressing device comprising a regulating means for regulating. A magnetic fluid whose viscosity increases in a magnetic field is filled between the holding body and the pressing body so as to be able to flow in and out,
The restricting means prevents the magnetic fluid from flowing in and out as the pressing body moves forward relative to the holding body by applying a magnetic field to the magnetic fluid to restrict its flow. The pressing device according to claim 1, comprising: The actuator includes an electromagnetic coil and an armature that is magnetically attracted to the electromagnetic coil and integrated with the holding body,
The pressing device according to claim 2, further comprising gap estimating means for estimating an interval between the electromagnetic coil and the armature based on a pressure of the magnetic fluid and an amount of current flowing to the electromagnetic coil. apparatus.

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