JP2009191867A - Return spring holding structure for disc brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a return spring holding structure having simplified manufacturing processes while forming a stator thinner than a stator on which a pin is mounted for holding a return spring. <P>SOLUTION: Grooves 37, 38 are formed at inner peripheries of first and second housings 16, 17, and the grooves 37, 38 store a plurality of protruded portions 34a-36a formed on outer peripheral faces of first and second stators 34, 36 and an intermediate stator 35. A first return spring 39 is mounted between the first stator 34 and the intermediate stator 35. A second return spring 42 is mounted between the intermediate stator 35 and the second stator 36. In the first and second return springs 39, 42, annular first and second collars 40, 43 are provided for encircling outer peripheries of the first and second rotors 31, 33 while holding the first and second return springs 39, 42 in a state of abutting on the stators 34-36. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a return spring holding structure in a disc brake.

  As the disc brake, for example, a rotor configured to be rotatable integrally with the rotating shaft of the motor and movable in the axial direction, and disposed so as to sandwich the rotor therebetween, is not rotatable, and is axially And a plurality of movable stators. Such a disc brake, for example, generates friction between the stator and the rotor by pressing the stator with a piston as an operating body and bringing it into contact with the rotor, and brakes the rotating shaft via the rotor. A return spring that biases the two stators away from the rotor is interposed between the two adjacent stators. When not braked, the two springs sandwich the rotor and rotor between the two stators. Clearance between is ensured. And as a return spring holding structure for holding this return spring, a fitting hole is formed in at least one stator, a spring pin is fitted into the fitting hole, and the spring pin is inserted inside the return spring. There is a structure to hold the return spring.

  In addition, a wet disc brake is proposed in which a piston return spring is interposed between a stator that abuts on a piston fitted to the cylinder body and a stator that abuts on a caliper that constitutes a part of the brake body. (For example, refer to Patent Document 1). In the wet-type disc brake described in Patent Document 1, the caliper is provided with an insertion hole having a C-shaped cross section in the radial direction of the drive shaft, and a piston return spring is inserted into the insertion hole, so It is held in contact.

In addition, a brake disk that faces the piston that operates the disk brake is provided, a tongue piece is formed on the outer periphery of the brake disk, and a biasing force is applied to the tongue piece to return the piston to its original position. A disk brake device provided has been proposed (see, for example, Patent Document 2). In the disc brake device described in Patent Document 2, the return spring is held by the rear housing via a spring receiver supported in a hole formed in the end surface of the rear housing.
JP-A-55-107131 JP 2000-304078 A

  However, the conventional return spring holding structure is a structure in which the spring pin is fixed to the stator by providing the stator with a fitting hole into which the spring pin can be fitted. Therefore, the stator for fixing the spring pin is thick. Things were used.

  Further, in the wet disc brake described in Patent Document 1, the spring receiving portion is configured differently from the torque receiving portion formed in the stator, and the insertion hole is provided in the caliper and is fitted to the torque receiving portion and the spline. It is a different configuration from the possible grooves. Therefore, in the wet disc brake, a spring receiving portion must be formed in the stator separately from the torque receiving portion, and an insertion hole must be provided in the caliper separately from the groove, and an extra manufacturing process must be performed accordingly. There was an inconvenience of not becoming. Further, in the disc brake device described in Patent Document 2, in order to form the hole for supporting the spring receiver, it is necessary to cut the rear housing in the axial direction. For this reason, the disc brake device also has a disadvantage that an extra manufacturing process has to be performed in order to obtain a structure for holding the return spring, similarly to the wet disc brake of Patent Document 1.

  The present invention has been made in view of the above problems, and its object is to reduce the thickness of the stator as compared with a stator to which a pin for holding a return spring is attached. Provided is a return spring holding structure in a disc brake that can be simplified.

  In order to achieve the above-mentioned object, the invention according to claim 1 is housed in a housing, and is configured to be housed in the housing, and a rotor configured to be integrally rotatable with the rotating shaft and movable in the axial direction. A plurality of stators provided so as to be movable in the axial direction and non-rotatable with respect to the housing and sandwiching the rotor therebetween, and an operating body capable of pressing the stator toward the rotor. In a return spring holding structure for a disc brake, a return spring provided between two stators sandwiching the rotor and energizing the two stators in a direction to separate them from the rotor, and surrounding the outer periphery of the rotor And provided inward of the return spring and in contact with the stator. An annular holding member for holding the return spring, further comprising a a gist.

  The “annular holding member” includes not only a closed annular holding member but also an annular holding member partially opened. The term “return spring provided between two stators sandwiching a rotor” is not limited to a return spring provided between two adjacent stators with one rotor interposed therebetween, and a plurality of rotors and their It also includes a return spring provided between two stators sandwiching a stator disposed between the rotors.

  In the present invention, the return spring is held by the holding member in contact with the stator, and the return spring is restricted from moving inward than the holding member. Therefore, the return spring can be prevented from coming into contact with the rotor without using a pin, and it is not necessary to provide a hole or hole for attaching the pin to the stator, so that the thickness of the stator can be reduced.

  Also, since the return spring can be held by providing a holding member, it is not necessary to cut the housing to form a hole or groove for holding the return spring, and the disc brake can be manufactured in a simple manufacturing process. Can be manufactured.

  When the operating body moves to the braking position, the stator is pressed toward the rotor and pressed against the rotor. Then, the rotor and the two stators sandwiching the rotor come into contact with each other, friction is generated between the rotor and the two stators, and the rotating shaft is braked through the rotor. When the operating body moves to the non-braking position, the two stators are moved away from the rotor by the return spring, and the two stators are separated from the rotor. The two stators sandwiching the rotor return to a position where a predetermined clearance exists with respect to the rotor.

  According to a second aspect of the present invention, in the first aspect of the present invention, the housing is disposed in the housing such that the ends of the two rotation shafts protrude in a coaxial state, and the rotor is One is provided on each rotating shaft, and three stators are provided alternately with the rotor with the rotor interposed therebetween, and the return spring is interposed between the opposing surfaces of the two stators. It is a summary.

  In the present invention, even when a disc brake is provided between the end portions of two rotating shafts arranged on the same axis, each rotating shaft can be braked via the rotor by three stators. During non-braking, the return spring can hold the stator at a position where a predetermined clearance exists between the three stators and the rotors.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, oil is stored in the housing, and a protrusion is provided on the outer peripheral surface of the stator. The gist is provided with a groove portion that guides the axial movement of the protrusion, and the holding member is a collar formed of a material that prevents the oil from passing therethrough.

  In the present invention, even when the oil flows due to the rotation of the rotor, the oil is prevented from reaching the recess by the collar. Accordingly, since the oil flow is prevented from being disturbed by the oil hitting the recess, the resistance received from the oil flow when the rotor is rotating can be reduced, and the rotor can be smoothly rotated.

  According to the present invention, the thickness of the stator can be reduced as compared with a stator to which a pin for holding a return spring is attached, and the manufacturing process can be simplified.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, a drive unit 11 as a drive device for a battery-type forklift is provided with a first motor 12 that drives a right wheel and a second motor 13 that drives a left wheel. The first motor 12 and the second motor 13 are arranged so that the first rotating shaft 14 of the first motor 12 and the second rotating shaft 15 of the second motor 13 are coaxial. In the drive unit 11, the first housing 16 and the second housing 17 are joined by bolts 18. The first housing 16 and the second housing 17 are each provided with a first partition wall 19 and a second partition wall 20 extending so as to protrude inward from the inner periphery thereof. By providing the first and second partition walls 19 and 20, a brake chamber 21 that can store oil is defined between the first motor 12 and the second motor 13.

  The first end 22 of the first rotating shaft 14 and the first end 23 of the second rotating shaft 15 protrude into the brake chamber 21 in a state of facing each other. The first end 22 of the first rotating shaft 14 is rotatably supported by a first bearing 24 mounted on the first partition wall 19. The first end 23 of the second rotating shaft 15 is rotatably supported by a second bearing 25 attached to the second partition wall 20. A second end (not shown) on the opposite side of the first rotating shaft 14 from the first end 22 and a second end (not shown) on the second rotating shaft 15 opposite to the first end 23 are also shown. It is supported rotatably by non-bearing. Moreover, the 2nd end part of the 1st rotating shaft 14 and the 2nd rotating shaft 15 is connected so that it may link with the gear mechanism not shown which has a helical gear. The gear mechanism is configured to transmit the rotational force to the left and right wheels of the forklift when the first rotating shaft 14 and the second rotating shaft 15 rotate. A lid member 27 is fastened to the wall surface of the first partition wall 19 opposite to the side wall surface of the brake chamber 21 by a bolt 26, and the first bearing 24 is clamped and fixed by the first partition wall 19 and the lid member 27. Has been. A lid member 29 is fastened to the wall surface of the second partition wall 20 opposite to the side wall surface of the brake chamber 21 by bolts 28, and the second bearing 25 is sandwiched and fixed by the second partition wall 20 and the lid member 29. ing.

  An outer spline 30 is formed at the first end 22 of the first rotating shaft 14, and an annular first rotor 31 is fitted with the spline. The first rotor 31 is configured to be able to rotate integrally with the first rotating shaft 14 and to be slidable in the axial direction of the first rotating shaft 14.

  On the other hand, an outer spline 32 is formed at the first end 23 of the second rotating shaft 15 and an annular second rotor 33 is spline-fitted. The second rotor 33 is configured to be able to rotate integrally with the second rotating shaft 15 and to be slidable in the axial direction of the second rotating shaft 15.

  An annular first stator 34 and intermediate stator 35 are provided in the brake chamber 21 so as to be adjacent to each other with the first rotor 31 interposed therebetween, and adjacent to the intermediate stator 35 with the second rotor 33 interposed therebetween. Thus, an annular second stator 36 is provided. A friction material (not shown) is attached to the first stator 34 on the surface facing the first rotor 31. A friction material (not shown) is attached to the surface of the intermediate stator 35 facing the first rotor 31 and the second rotor 33, and a friction material (not shown) is attached to the surface of the second stator 36 facing the second rotor 33. It is pasted. The intermediate stator 35 is not formed with a fitting hole, a fitting hole, or the like, and the thickness thereof is substantially the same as the thickness of the second stator 36.

  As shown in FIG. 2A, the first stator 34 has a plurality of tongue-like protrusions 34a formed on the outer peripheral surface thereof at equal intervals in the circumferential direction. The protrusions 34 a are fitted in U-shaped grooves 37 formed in the same number as the protrusions 34 a in the portions corresponding to the protrusions 34 a in the inner peripheral portion of the first housing 16. Is not rotatable and is slidable in the axial direction. As shown in FIG. 1, also in the intermediate stator 35 and the second stator 36, protrusions 35a and 36a having the same configuration as the protrusion 34a of the first stator 34 are formed on the respective outer peripheral surfaces. The projecting portions 35 a and 36 a are fitted into a groove portion 37 formed in the first housing 16 and a groove portion 38 formed in the second housing 17, respectively.

  As shown in FIG. 3, the first end 39 a is in contact with the protrusion 34 a of the first stator 34 and the second end 39 b is in contact with the protrusion 35 a of the intermediate stator 35. A first return spring 39 is interposed between the opposing surfaces of the stator 34 and the intermediate stator 35. The first return spring 39 separates the first stator 34 and the intermediate stator 35 from the first rotor 31 so that a clearance can be secured between the first stator 34 and the intermediate stator 35 and the first rotor 31 during non-braking. Energized in the direction. As shown in FIG. 2A, the first return springs 39 are arranged every other in the groove portion 37. A first collar 40 as a holding member made of metal and formed in a closed annular shape is provided on the inner side of all the first return springs 39.

  The first collar 40 surrounds the outer periphery of the first rotor 31, and the first and second end portions 39a and 39b (see FIG. 3) of the first return spring 39 are in contact with the projections 34a and 35a, respectively. Holding. The first collar 40 is formed so that its inner diameter S1 is larger than the outer diameter of the first rotor 31 and larger than the minimum inner diameter P of the first housing 16 in the portion that houses the first rotor 31. . The first collar 40 is formed of a material that prevents the passage of oil, so that the first rotor 31 side and the groove portion 37 side are out of communication. As shown in FIGS. 2A and 2B, the first collar 40 is fitted into a stepped portion 41 having a shape that follows the outer shape of the first collar 40. The step portion 41 is formed on the inner wall portion of the first housing 16 so as to extend in the circumferential direction between the groove portions 37.

  On the other hand, as shown in FIG. 1, the second end 42a is in contact with the protrusion 35a of the intermediate stator 35 and the second end 42b is in contact with the protrusion 36a of the second stator 36. A second return spring 42 is interposed between the opposing surfaces of the stator 36 and the intermediate stator 35. The second return spring 42 separates the intermediate stator 35 and the second stator 36 from the second rotor 33 so that a clearance can be secured between the intermediate stator 35 and the second stator 36 and the second rotor 33 during non-braking. Energized in the direction. The second return springs 42 have the same configuration as the first return springs 39, and are arranged every other groove portion 38 so as to correspond to the first return springs 39.

  A second collar 43 as a holding member having the same configuration as that of the first collar 40 is provided inside all the second return springs 42. The second collar 43 is fitted into a step portion (not shown) formed in the second housing 17. The step portion has the same configuration as the step portion 41 formed in the first housing 16. The first and second collars 40 and 43 are formed by extrusion molding.

  A piston portion 45 is provided between the first stator 34 and the first partition wall 19 as an operating body capable of pressing the first stator 34 toward the first rotor 31. The piston portion 45 is sandwiched between the fixed ring 46 fixed to the first partition wall 19, a rotatable cam ring 47 that is movable in the axial direction, and the fixed ring 46 and the cam ring 47 so as to allow rolling. It consists of a steel ball 48. The structures of the fixing ring 46, the cam ring 47, and the steel ball 48 are the same as those of the fixing ring, the cam ring, and the steel ball disclosed in Japanese Patent Application Laid-Open No. 2000-289588, respectively. The fixing ring 46 and the cam ring 47 have a plurality of protrusions 46 a and 47 a formed at predetermined intervals on the outer peripheral surface, and the protrusions 46 a and 47 a are disposed in a state of engaging with the inner peripheral surface of the first housing 16. When an operation mechanism (not shown) is operated so that the distance between the cam ring 47 and the fixed ring 46 is increased, the cam ring 47 rotates and moves toward the first stator 34, and the cam ring 47 moves the first stator 34 to the first stator 34. A pressure is applied to the rotor 31.

Next, the operation of the drive unit 11 configured as described above will be described.
The drive unit 11 rotates the first rotating shaft 14 of the first motor 12 and the second rotating shaft 15 of the second motor 13, and transmits the rotational force to the left and right wheels of a battery-type forklift (not shown) via a gear mechanism. A forklift is driven. At this time, the first rotor 31 and the second rotor 33 rotate integrally with the first rotating shaft 14 and the second rotating shaft 15, respectively, and the oil stored in the brake chamber 21 is the first rotor 31 and the second rotor 33. Agitated by the rotor 33, a flow is generated in the oil. However, at this time, the first and second collars 40 and 43 are not in communication with the first and second rotors 31 and 33 and the grooves 37 and 38, so that the oil hits the grooves 37 and 38. There is no. Therefore, the oil flow is rectified. Further, when the drive unit 11 is driven, the first return spring 39 and the second return spring 42 are held in the grooves 37 and 38 by the first collar 40 and the second collar 43, respectively. Movement to the inside of the collar 43 is restricted. Therefore, the first return spring 39 and the second return spring 42 are prevented from contacting the first rotor 31 and the second rotor 33.

  Further, when an operation mechanism (not shown) of the drive unit 11 is operated so that the interval between the cam ring 47 and the fixed ring 46 is increased, the cam ring 47 presses the first stator 34. Then, the first stator 34 presses the first rotor 31 to move toward the intermediate stator 35 and presses it against the intermediate stator 35. Then, the intermediate stator 35 moves toward the second rotor 33 and presses the second rotor 33, and the second rotor 33 moves toward the second stator 36 and presses the second stator 36. Accordingly, the first rotor 31 is sandwiched between the first stator 34 and the intermediate stator 35, and the second rotor 33 is sandwiched between the intermediate stator 35 and the second stator 36. Then, friction is generated between the first rotor 31 and the first stator 34 and the intermediate stator 35, and between the second rotor 33 and the intermediate stator 35 and the second stator 36, and the first and second rotors 31, The first and second rotary shafts 14 and 15 are braked through 33, and the forklift stops.

  Thereafter, when the piston portion 45 moves to the non-braking position, the intermediate stator 35 and the first stator 34 are separated from the second rotor 33 and the first rotor 31 by the urging force of the first return spring 39 and the second return spring 42, respectively. To move. The intermediate stator 35 is returned to a position where a predetermined clearance exists between the first rotor 31 and the second rotor 33. Further, the first stator 34 is returned to a position where a predetermined clearance exists between the first rotors 31.

In this embodiment, the following effects can be obtained.
(1) An annular first collar 40 is provided inside the first return spring 39 so as to surround the outer periphery of the first rotor 31. An annular second collar 43 is provided inside the second return spring 42 so as to surround the outer periphery of the second rotor 33. The first and second collars 40 and 43 restrict the first and second return springs 39 and 42 from moving inward relative to the first and second collars 40 and 43, and the first and second returns. The springs 39 and 42 are held. Therefore, since it is not necessary to use a pin to hold the first and second return springs 39 and 42, each of the stators 34 and 35 is compared with a stator configured to be attached with a pin that holds the return spring. , 36 can be made thinner.

  (2) Since the first and second return springs 39 and 42 can be held by the first and second collars 40 and 43 without forming a hole or groove for holding the return spring in the housing, it is manufactured. At this time, it is not necessary to cut the housing in the axial direction at a plurality of locations, and the housing can be manufactured by a simple manufacturing process.

  (3) A first rotor 31 and a second rotor 33 are provided on the first rotating shaft 14 and the second rotating shaft 15, respectively, and a first stator 34 and an intermediate stator are provided between the first and second rotors 31 and 33. 35, a second stator 36 is provided. In addition, first and second return springs 39 and 42 are provided between the stators 34 to 36. Therefore, even when the disc brake structure is provided between the first motor 12 and the second motor 13 arranged so that the first rotating shaft 14 and the second rotating shaft 15 are coaxial, The first and second rotating shafts 14 and 15 can be braked by the three stators 34 to 36.

  (4) The first and second collars 40 and 43 are made of a material that prevents passage of oil. Therefore, the first and second rotors 31 and 33 side and the groove portions 37 and 38 side are in a non-communication state, and the disturbance of the oil flow is suppressed, and the first rotor 31 and the second rotor 33 are smoothly made. Can be rotated.

  (5) The first housing 16 is provided with a step portion 41 along the outer shape of the first collar 40, and the first collar 40 is fitted to the step portion 41. The second housing 17 is similarly provided with a step portion (not shown), and the second collar 43 is fitted to the step portion. Therefore, the first and second collars 40 and 43 can be positioned reliably, and there is a situation where the first and second collars 40 and 43 rattle and come into contact with the first and second rotors 31 and 33. It can be avoided. It is also possible to avoid a situation in which the first and second collars 40 and 43 are loose in the axial direction and come into contact with the first and second stators 34 and 36, respectively. Further, since the first housing 16 and the second housing 17 can be assembled with the first collar 40 fitted to the first housing 16 and the second collar 43 fitted to the second housing 17, the assembly is simple. is there.

  (6) The first and second collars 40 and 43 are formed in a closed ring shape. Therefore, since the first and second collars 40 and 43 are not cut in the circumferential direction, all the first and second return springs 39 and 42 can be held.

The embodiment is not limited to the above, and may be embodied as follows, for example.
○ The material forming the holding member may be changed. For example, if a resin that can withstand the temperature rise during braking is used, the first and second collars 40 and 43 may be formed of resin. In this case, the first and second collars 40 and 43 can be reduced in weight compared to the case where the first and second collars 40 and 43 are formed of metal.

  ○ The attachment state of the holding member to the housing may be changed. For example, the step portion 41 formed in the first housing 16 is omitted, and the outer diameter is smaller than the minimum inner diameter P of the first housing 16 in the portion accommodating the first rotor 31 as shown in FIG. The first collar 49 is formed so as to be slightly smaller. In addition, the first collar 49 may be attached so that the entire outer peripheral surface of the first collar 49 is in contact with the inner peripheral surface of the first housing 16. Further, if the first return spring 39 can be held and does not reliably contact the first rotor 31, the outer diameter of the first collar is further reduced by reducing the outer diameter of the first collar. The first collar may be attached in a state where it does not contact the inner peripheral surface. Note that the second color may be changed to the same configuration as the first color described above.

  ○ The holding member may be formed of a plate material. In this case, for example, a closed annular holding member may be formed by preparing a flexible plate material and rounding the plate material so as to partially overlap. Moreover, you may form the cyclic | annular holding member closed by abutting and joining the both ends of a board | plate material.

  ○ The holding member is not limited to a closed annular holding member. For example, as shown in FIG. 4B, an annular holding member 51 having a part opened may be formed by rounding and forming a flexible plate member 50 in a state where the part is not connected.

○ The holding member may be formed of a material that allows passage of oil. For example, the holding member may be formed in a net shape so that oil can pass through the holding member.
○ The holding member does not have to be annular. If the first and second return springs 39 and 42 can be held so as not to contact the first and second rotors 31 and 33, for example, the first collar 40 and the second collar 43 may be formed in an elliptical ring shape. It may be formed in a polygonal ring shape.

  The second return spring 42 may be omitted, and the first return spring 39 alone may be used to return the stator from the braking position to the non-braking position. In this case, for example, the first return spring 39 may be provided so as to straddle between the first stator 34 and the second stator 36.

The present invention may be applied to a brake of a drive unit in which only one motor is mounted.
The rotating shaft that the disc brake in the present invention brakes is not limited to the rotating shaft of the motor. For example, a rotating shaft driven by an engine or a rotating shaft driven by a motor may be used.

  -You may change the structure of the action body which can press a stator toward a rotor. For example, a piston that is operated by hydraulic pressure and presses the stator may be used as the operating body. Moreover, you may use the type of piston which operate | moves with air instead of oil as an operation body.

  The present invention may be mounted on a device other than a battery-type forklift drive unit as long as it has a rotating shaft. The present invention may be used for, for example, a brake of a drive device that drives an axle of an industrial vehicle other than a forklift, or may be used for a brake of a drive device that drives an axle of a train.

  The present invention may be used for dry brakes.

The partial fracture | rupture schematic cross section of the return spring holding structure of this embodiment. (A) is the schematic diagram which looked at the state where the 1st rotor, the 1st stator, the 1st return spring, and the 1st collar were assembled in the 1st housing from the direction of an axis, and (b) is the model in the AA line Sectional drawing. The partial expansion schematic cross section of FIG. (A) is a schematic diagram which shows the return spring holding structure in another embodiment, (b) is a schematic perspective view which shows the holding member in another embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 14 ... 1st rotating shaft, 15 ... 2nd rotating shaft, 16 ... 1st housing, 17 ... 2nd housing, 31 ... 1st rotor, 33 ... 2nd rotor, 34 ... 1st stator, 35 ... Intermediate stator, 36 2nd stator, 39 ... 1st return spring, 40, 49 ... 1st collar as holding member, 42 ... 2nd return spring, 43 ... 2nd collar as holding member, 45 ... Piston part as operating body, 51. Holding member.

Claims (3)

A rotor housed in the housing and configured to be rotatable integrally with the rotation shaft and movable in the axial direction; and a rotor housed in the housing and movable in the axial direction and non-rotatable with respect to the housing; In a return spring holding structure in a disc brake comprising a plurality of stators provided so as to sandwich the rotor therebetween, and an operating body capable of pressing the stator toward the rotor,
A return spring provided between two stators sandwiching the rotor, and urging the two stators away from the rotor;
In the disc brake comprising: an annular holding member that is provided inside the return spring so as to surround the outer periphery of the rotor and that holds the return spring in a state of contacting the stator. Return spring holding structure. In the housing, the ends of the two rotating shafts are arranged so as to protrude in a coaxially facing state,
One rotor is provided for each rotating shaft,
Three stators are provided alternately with the rotor with the rotor in between,
The return spring holding structure for a disc brake according to claim 1, wherein the return spring is interposed between the opposing surfaces of the two stators. Oil is stored in the housing,
A protrusion is provided on the outer peripheral surface of the stator,
A groove for guiding movement of the protrusion in the axial direction is provided on the inner peripheral portion of the housing,
The return spring holding structure in the disc brake according to claim 1 or 2, wherein the holding member is a collar formed of a material that prevents the oil from passing therethrough.

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