JP2009270720A - Strut slide bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a strut slide bearing capable of reducing weight and costs of a suspension of an automobile by excluding an upper part spring seat member made of sheet metal. <P>SOLUTION: The strut slide bearing 1 includes an upper case 3 having an annular undersurface 2 and made of polyacetal resin, a lower case 5 rotatably overlapped on the upper case 3 in the direction R around an axis O of the upper case 3, having an annular top face 4 facing the annular undersurface 2 of the upper case 3, and made of reinforced synthetic resin containing reinforcement fiber such as glass fiber contained in the polyacetal resin in addition to the polyacetal resin, an annular strut slide bearing piece 6 made of polyacetal resin interposed between the annular undersurface 2 and the annular top face 4, and a cylindrical radial slide bearing piece 7 made of polyacetal resin. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a strut slide bearing, and more particularly to a strut slide bearing that is preferably incorporated as a slide bearing of a strut suspension (McPherson type) in a four-wheeled vehicle.

  In general, a strut suspension is mainly used for a front wheel of a four-wheeled vehicle, and is a combination of a suspension coil spring and a strut assembly in which a hydraulic shock absorber is incorporated in an outer cylinder integrated with a main shaft. Such a suspension has a structure in which the axis of the suspension coil spring is positively offset with respect to the axis of the strut to smoothly slide the piston rod of the shock absorber built in the strut, and the axis of the strut In contrast, there is a structure in which the axis of the suspension coil spring is arranged so as to coincide with each other. In any structure, when the strut assembly rotates together with the suspension coil spring by the steering operation, a thrust bearing is arranged between the attachment member to the vehicle body and the upper spring seat member of the suspension coil spring so that the rotation is performed smoothly. Has been.

Japanese Patent Laid-Open No. 11-303873 JP 2002-257146 A Japanese Utility Model Publication No. 6-45693

  As this thrust bearing, a rolling bearing using a ball or a needle or a synthetic resin sliding bearing is used. Rolling bearings are extremely preferable because they can reduce the friction torque and perform steering operation lightly. However, when they are expensive and require low prices, sliding bearings can be used as thrust bearings instead of rolling bearings. Used.

  By the way, as described above, any of the thrust bearings is interposed between the attachment member to the vehicle body and the upper spring seat member of the suspension coil spring. However, since the upper spring seat member is usually made of sheet metal, As a result of heavy and sheet metal upper spring seats requiring anti-corrosion coating, sliding bearings are used instead of expensive rolling bearings to reduce the weight and cost of automobile suspensions. However, there is a limit to such weight reduction and price reduction due to the weight of the upper spring seat member, manufacturing costs, assembly costs, and the like.

  The present invention has been made in view of the above-mentioned points, and an object of the present invention is to eliminate the upper spring seat member made of sheet metal, thereby reducing the weight and cost of the undercarriage of the automobile. It is an object of the present invention to provide a strut slide bearing capable of achieving the above.

  The strut slide bearing according to the first aspect of the present invention includes an upper case made of synthetic resin having an annular lower surface, and an upper case and an upper case that are superposed on the upper case so as to be rotatable around the axis of the upper case. A lower case made of synthetic resin having an annular upper surface facing the annular lower surface of the case, and an annular thrust sliding bearing piece made of synthetic resin interposed between the annular lower surface and the annular upper surface; Has a spring seat surface for the suspension coil spring on the lower surface.

  According to the strut slide bearing of the first aspect, since the upper case, the lower case, and the thrust slide bearing piece are made of synthetic resin, the weight can be reduced sufficiently and the price can be reduced. Since it has a spring seat surface for the suspension coil spring on its lower surface, one end of the suspension coil spring can be received by the lower case, and the upper spring seat member made of sheet metal can be omitted. The weight increase caused by the upper spring seat member made of sheet metal and the price increase caused by the manufacture, painting and assembly of the upper spring seat member made of sheet metal can be eliminated. It is possible to further reduce the weight and the price.

  The strut slide bearing of the present invention should essentially function as a thrust bearing. However, like the strut slide bearing of the second aspect of the present invention, it further includes a cylindrical radial slide bearing piece. In this case, the upper case has an upper annular portion in which an annular lower surface is formed, and a cylindrical side surface that extends integrally downward from an inner peripheral edge or an outer peripheral edge in the radial direction of the upper annular portion. The lower case has a cylindrical side surface facing the cylindrical side surface, and the radial sliding bearing piece is formed by the cylindrical side surface of the upper case cylindrical portion and the cylindrical side surface of the lower case. Is intervening.

  According to the strut sliding bearing of the second aspect, the radial sliding force applied between the lower case and the upper case can be received by the radial sliding bearing piece, and as a result, even when the radial force is applied, Relative rotation with the upper case can be performed with low frictional resistance, and thus steering operation can be performed lightly.

  The cylindrical portion of the upper case only needs to be integrally extended downward from the inner peripheral edge or the outer peripheral edge in the radial direction of the upper annular portion, but instead, the cylindrical portion is an upper annular portion. These may be integrally extended downward from both the inner and outer peripheral edges in the radial direction.

  The lower case, like the strut slide bearing according to the third aspect of the present invention, has an inner peripheral cylindrical projection that protrudes upward integrally from an annular upper surface on the inner peripheral side in the radial direction, and an outer peripheral side in the radial direction. And an outer peripheral cylindrical protrusion protruding integrally upward from the annular upper surface. In this case, the thrust slide bearing piece is arranged between the inner peripheral cylindrical protrusion and the outer peripheral cylindrical protrusion. In addition, or instead of this, the upper case is an inner peripheral cylinder that hangs down integrally from the annular lower surface on the inner peripheral side in the radial direction, like the strut slide bearing of the fourth aspect of the present invention. And a cylindrical outer portion on the outer peripheral side that hangs down integrally from the annular lower surface on the outer peripheral side in the radial direction. In this case, the thrust sliding bearing piece is also connected to the inner cylindrical portion and the outer peripheral side. It is arranged between the cylindrical hanging parts.

  According to the strut sliding bearing of the third and fourth aspects, the thrust sliding bearing piece can be positioned by the inner circumferential cylindrical projection and the outer circumferential cylindrical projection or the inner circumferential cylindrical hanging portion and the outer circumferential cylindrical hanging portion. The thrust force can be reliably received by the thrust slide bearing piece. In the case where an inner peripheral cylindrical protrusion and an outer peripheral cylindrical protrusion are provided in addition to the inner peripheral cylindrical protrusion and the outer peripheral cylindrical protrusion, a preferable labyrinth (maze) can be formed by these. Intrusion of mud, rainwater, etc. into the space between the lower case and the upper case where the sliding bearing pieces are mounted can be more effectively prevented.

  The lower case is preferably an annular base and an upper cylindrical portion formed integrally with the upper surface of the annular base and having an annular upper surface, as in the strut slide bearing of the fifth aspect of the present invention, A lower cylindrical portion integrally formed on the lower surface of the annular base portion. In this case, the lower surface of the annular base portion on the radially outer side of the lower cylindrical portion is a spring seat surface.

  According to the strut sliding bearing of the fifth aspect, the end portion of the suspension coil spring can be held in the radial direction by the lower cylindrical portion, and as a result, the end portion of the suspension coil spring can be prevented from falling off from the spring seat surface.

  In a preferred example, like the strut slide bearing according to the sixth aspect of the present invention, the upper case is integrally extended downward from the upper annular portion having the annular lower surface and the radial outer periphery of the upper annular portion. The lower case is formed integrally with the annular base portion and the substantially central portion in the radial direction of the upper surface of the annular base portion, and the upper cylinder formed with the annular upper surface. And a lower cylindrical portion integrally formed on the lower surface of the annular base portion, the upper cylindrical portion is surrounded by the cylindrical portion of the upper case, and the annular base portion on the radially outer side of the lower cylindrical portion The lower surface of is a spring seat surface.

  According to the strut slide bearing of the sixth aspect, the upper cylindrical portion is integrally formed at the substantially central portion in the radial direction of the upper surface of the annular base portion and is surrounded by the cylindrical portion of the upper case. As a result of being able to cover the lower gap between the cylindrical portion of the case and the upper cylindrical portion of the lower case with the annular base, the gap between the cylindrical portion of the upper case and the upper cylindrical portion of the lower case via the lower gap Intrusion of mud, rainwater, etc. can be effectively prevented.

  The strut sliding bearing of the sixth aspect may further include a cylindrical radial sliding bearing piece as in the strut sliding bearing of the seventh aspect of the present invention. In this case, the upper cylindrical portion of the lower case Has a cylindrical side facing the cylindrical side of the cylindrical part of the upper case, and the radial sliding bearing piece is interposed between the cylindrical side of the cylindrical part of the upper case and the cylindrical side of the upper cylindrical part of the lower case. ing.

  The synthetic resin constituting the thrust sliding bearing piece and the radial sliding bearing piece preferably has a self-lubricating property. In the strut sliding bearing of the second or seventh aspect, the radial sliding bearing piece is preferably of the present invention. Like the strut slide bearing of the eighth aspect, it is made of a synthetic resin containing at least one of a polyacetal resin, a polyamide resin, a thermoplastic polyester resin, a polyolefin resin, and a fluororesin.

  The upper case is preferably elastically fitted to the lower case like the strut slide bearing of the ninth aspect of the present invention.

  The synthetic resin that constitutes the upper case and the lower case has excellent sliding characteristics such as wear resistance, impact resistance and creep resistance, and mechanical characteristics such as rigidity, and is particularly used for thrust sliding bearing pieces. It is preferable to use a synthetic resin having a good friction characteristic and a synthetic resin. Specifically, as in the sliding bearing of the tenth aspect of the present invention, the upper case is made of a polyacetal resin, a polyamide resin. The thrust sliding bearing piece may be made of a synthetic resin including at least one of thermoplastic polyester resin, polyolefin resin, polycarbonate resin, and fluororesin, and the thrust sliding bearing piece is similar to the sliding bearing of the eleventh aspect of the present invention. And a synthetic resin containing at least one of polyacetal resin, polyamide resin, thermoplastic polyester resin, polyolefin resin and fluororesin. The lower case may be made of a synthetic resin similar to the synthetic resin constituting the upper case. However, like the sliding bearing of the twelfth aspect of the present invention, the polyacetal resin, the polyamide resin, and the polypropylene resin may be used. It consists of the reinforced synthetic resin containing the synthetic resin containing at least 1 of these, and the reinforced fiber contained in this synthetic resin. Examples of reinforcing fibers include glass fibers and ceramic fibers, but other reinforcing fibers may be used.

  The strut slide bearing of the present invention is for use in a strut suspension in a four-wheeled vehicle, and is preferably interposed between a mounting member for a vehicle body and a suspension coil spring.

  ADVANTAGE OF THE INVENTION According to this invention, the strut slide bearing which can omit the upper spring seat member made from sheet metal, and can achieve weight reduction and price reduction of the undercarriage of a motor vehicle by this can be provided.

FIG. 1 is a cross-sectional view of a preferred example of an embodiment of the present invention. FIG. 2 is an enlarged sectional view of a part of the example shown in FIG. FIG. 3 is a cross-sectional view of the upper case shown in FIG. FIG. 4 is a cross-sectional view of the lower case shown in FIG. FIG. 5 is a perspective view of the thrust slide bearing piece of the example shown in FIG. FIG. 6 is a perspective view of the radial sliding bearing piece of the example shown in FIG.

  Next, the present invention and its embodiments will be described with reference to preferred examples shown in the drawings. The present invention is not limited to these examples.

  1 to 6, a strut slide bearing 1 for use in a strut suspension in a four-wheeled vehicle of this example has an annular lower surface 2 and is made of a synthetic resin, for example, a polyacetal resin upper case 3 and an upper case 3. In addition to a synthetic resin made of, for example, polyacetal resin, which is overlapped so as to be rotatable in the R direction around the axis O of the upper case 3 and has an annular upper surface 4 facing the annular lower surface 2 of the upper case 3. A lower case 5 made of a reinforced synthetic resin containing reinforcing fibers such as glass fibers contained in the polyacetal resin, and an annular thrust made of a synthetic resin, for example, a polyacetal resin, interposed between the annular lower surface 2 and the annular upper surface 4 A sliding bearing piece 6 and a cylindrical radial sliding bearing piece 7 made of synthetic resin, for example, polyacetal resin are provided.

  As shown in particular detail in FIG. 3, the annular upper case 3 having the through-hole 11 is integrally lowered from the upper annular portion 12 in which the annular lower surface 2 is formed and the outer peripheral edge in the radial direction of the upper annular portion 12. A cylindrical portion 14 having a cylindrical side surface 13 on the inner side in the radial direction, an inner cylindrical hanging portion 15 that hangs downward integrally from the inner circumferential edge of the upper annular portion 12, and An engagement hook portion 16 formed on the cylindrical side surface 13 on the radially inner side of the cylindrical portion 14 is provided, and is integrally formed.

  The annular lower case 5 having the through hole 21 concentric with the through hole 11 is integrated with the annular base portion 22 and the substantially central portion in the radial direction of the upper surface 23 of the annular base portion 22 as shown in detail in FIG. The upper cylindrical portion 24 having a cylindrical side surface 29 facing the cylindrical side surface 13 of the cylindrical portion 14 of the upper case 3, and the annular base portion 22. A lower cylindrical portion 26 integrally formed at a substantially central portion in the radial direction of the lower surface 25, an inner peripheral cylindrical projection portion 27 protruding upward from the annular upper surface 4 on the inner peripheral side in the radial direction, and a diameter The outer peripheral cylindrical projection 28 integrally projecting upward from the annular upper surface 4 on the outer peripheral side in the direction and the engaged hook portion 30 formed on the cylindrical side surface 29 are integrally formed. The cylindrical side surface 13 is disposed on the radially inner side of the cylindrical portion 14, and the cylindrical side surface 29 facing the cylindrical side surface 13 is disposed on the radially outer side of the upper cylindrical portion 24.

  The lower surface of the lower case 5, that is, the lower surface 25 of the annular base 22 on the radially outer side of the lower cylindrical portion 26 is a spring seat surface 36 for the suspension coil spring 61, and the upper cylindrical portion 24 is a cylinder of the upper case 3. The annular base portion 22, the upper cylindrical portion 24, and the lower cylindrical portion 26 are provided with a plurality of meat removal cavities 37 in order to reduce weight and the like.

  As shown in particular detail in FIG. 5, the thrust slide bearing piece 6 is slidably in contact with the annular lower surface 2 at the annular upper surface 41 and the annular upper surface 4 at the annular lower surface 42, respectively. Between the inner circumferential side cylindrical projection portion 27 and the outer circumferential side cylindrical projection portion 28.

  As shown in particular detail in FIG. 6, the radial plain bearing piece 7 is slidably in contact with the cylindrical side surface 13 with the cylindrical radial outer surface 45 and the cylindrical side surface 29 with the cylindrical radial inner surface 46. Then, it is interposed between the cylindrical portion 14 of the upper case 3 and the upper cylindrical portion 24 of the lower case 5.

  The upper case 3 is elastically engaged with the engaged hook portion 30 of the lower case 5 at the engaging hook portion 16 in a snap-fit manner, and is elastically fitted to the lower case 5.

  The upper annular portion 12 and the cylindrical portion are provided at at least one of the outer peripheral edge portion and the inner peripheral edge portion in the radial direction of the upper annular portion 12 and the upper cylindrical portion 24 of the upper case 3 and the lower case 5. The labyrinth (maze) 51 is formed by the upper cylindrical portion 24 and the outer cylindrical projection 28, and the labyrinth 52 is formed by the upper annular portion 12, the inner cylindrical hanging portion 15 and the inner cylindrical projection 27, respectively. Dust from outside to the annular space in which the thrust slide bearing piece 6 between the upper annular portion 12 and the upper cylindrical portion 24 is mounted by the labyrinth 51 at the outer peripheral edge and the labyrinth 52 at the inner peripheral edge. Intrusion of muddy water is prevented.

  The strut sliding bearing 1 described above is mounted to attach one end 62 of a suspension coil spring 61 in a strut type suspension assembly 60 and the strut type suspension assembly 60 to a vehicle body of a four-wheel vehicle as shown in detail in FIGS. 1 and 2. It is used by being interposed between the members 63.

  A mounting member 63 on the vehicle body on which one end portion 65 of the piston rod 64 of the hydraulic damper in the strut suspension assembly 60 is supported includes a mounting plate 67 that is mounted to the vehicle body of the four-wheeled vehicle via a screw 66, the upper case 3, The substantially identical receiving member 68, a cylindrical member 69 in which one end portion 65 of the piston rod 64 is disposed, a seat plate 70 through which the one end portion 65 of the piston rod 64 passes, and one end portion of the mounting plate 67 are embedded. In addition, the receiving member 68 and the cylindrical member 69 are vulcanized and bonded to each other, and the mounting plate 67, the elastic member 73 that integrates the receiving member 68 and the cylindrical member 69, and one end portion 62 of the suspension coil spring 61 are provided. It is seated on the spring seat surface 36.

  As shown in FIGS. 1 and 2, in the strut type suspension assembly 60 mounted via the strut slide bearing 1, the relative rotation around the axis O of the lower case 5 via the suspension coil spring 61 during the steering operation is performed. The rotation in the R direction is the relative sliding in the same direction between the upper surface 41 of the thrust slide bearing piece 6 and the annular lower surface 2 of the upper case 3 or the lower surface 42 of the thrust slide bearing piece 6 and the annular upper surface of the lower case 5. Relative sliding in the same direction with respect to 4 and relative sliding in the same direction between the inner surface 46 of the radial sliding bearing piece 7 and the cylindrical side surface 29 of the lower case 5 or the outer surface of the radial sliding bearing piece 7. It is smoothly performed by the relative sliding in the same direction between 45 and the cylindrical side surface 13 of the upper case 3.

  According to the strut sliding bearing 1, since the lower case 5 is also made of a synthetic resin in addition to the upper case 3, the thrust sliding bearing piece 6 and the radial sliding bearing piece 7, the weight and the cost can be reduced. In addition, since the lower case 5 has a spring seat surface 36 for the suspension coil spring 61 on the lower surface 25, the lower case 5 can receive one end 62 of the suspension coil spring 61 and is made of sheet metal. The upper spring seat member can be omitted, thus eliminating the weight increase due to the sheet metal upper spring seat member and the price increase due to the manufacture, painting and assembly of the sheet metal upper spring seat member. Combined with the above, it is possible to further reduce the weight and cost of the undercarriage of the automobile.

  In addition, according to the strut slide bearing 1, the radial force applied between the lower case 5 and the upper case 3 can be received by the radial slide bearing piece 7. As a result, even when a radial force is applied, Relative rotation with the case 3 can be performed with low frictional resistance, and thus the steering operation can be easily performed. Further, the thrust slide bearing piece 6 is connected to the inner cylindrical protrusion 27 and the outer cylindrical protrusion. Since it can be positioned by the portion 28, the thrust sliding bearing piece 6 can reliably receive the thrust force, and in addition, the upper cylindrical portion 24 is integrally formed at a substantially central portion in the radial direction of the upper surface 23 of the annular base portion 22. And the lower gap 71 between the cylindrical portion 14 and the upper cylindrical portion 24 of the upper case 3 can be covered with the annular base 22 as a result of being surrounded by the cylindrical portion 14 of the upper case 3. Intrusion of mud, rainwater, etc. into the gap 72 between the cylindrical portion 14 and the upper cylindrical portion 24 of the upper case 3 via 71 can be effectively prevented, and one end portion of the suspension coil spring 61 is formed by the lower cylindrical portion 26. As a result of holding 62 in the radial direction, it is possible to prevent the end portion 62 of the suspension coil spring 61 from falling off the spring seat surface 36.

  In the strut slide bearing 1, the lower case 5 is configured by including the inner circumferential cylindrical projection 27 and the outer circumferential cylindrical projection 28, but instead of or together with this, the same as the inner circumferential cylindrical projection 27. In addition, it is the same as the inner peripheral cylindrical hanging portion that hangs down downward from the radially inner peripheral annular lower surface 2 and the outer peripheral cylindrical projection 28, and is the radially outer peripheral annular lower surface 2. The upper case 3 is configured to include an outer peripheral cylindrical hanging portion that is integrally suspended downward from the inner side, and a thrust slide bearing piece 6 is disposed between the inner circumferential cylindrical hanging portion and the outer circumferential cylindrical hanging portion. The strut sliding bearing 1 may be configured.

DESCRIPTION OF SYMBOLS 1 Strut slide bearing 2 Annular lower surface 3 Upper case 4 Annular upper surface 5 Lower case 6 Thrust sliding bearing piece

Claims (14)

  A synthetic resin upper case having an annular lower surface, and a synthetic resin having an annular upper surface that is superimposed on the upper case so as to be rotatable around the axis of the upper case and that faces the annular lower surface of the upper case A lower case made of resin and an annular thrust sliding bearing piece made of synthetic resin interposed between the annular lower surface and the annular upper surface are provided. The lower case has a spring seat surface for the suspension coil spring on the lower surface. Strut sliding bearing.   A cylindrical radial sliding bearing piece is further provided, and the upper case is integrally extended downward from the upper annular portion formed with the annular lower surface and the radial inner periphery or outer peripheral edge of the upper annular portion. The lower case has a cylindrical side surface facing the cylindrical side surface, and the radial sliding bearing piece has a cylindrical side surface and a lower side surface of the cylindrical portion of the upper case. The strut plain bearing according to claim 1, which is interposed between a cylindrical side surface of the case.   The lower case includes an inner cylindrical protrusion protruding upward integrally from the annular upper surface on the radially inner side, and an outer cylindrical protrusion protruding integrally upward from the radially outer annular upper surface. The strut sliding bearing according to claim 1, wherein the thrust sliding bearing piece is disposed between the inner circumferential cylindrical projection and the outer circumferential cylindrical projection.   The upper case has an inner cylindrical drooping portion that hangs down integrally from an annular lower surface on the radially inner periphery side, and an outer cylindrical drooping portion that hangs down integrally from an annular lower surface on the outer peripheral side in the radial direction. The strut sliding bearing according to any one of claims 1 to 3, wherein the thrust sliding bearing piece is disposed between the inner circumferential cylindrical hanging portion and the outer circumferential cylindrical hanging portion.   The lower case includes an annular base, an upper cylindrical portion formed integrally with the upper surface of the annular base and an annular upper surface, and a lower cylindrical portion integrally formed on the lower surface of the annular base. The strut plain bearing according to any one of claims 1 to 4, wherein the lower surface of the annular base portion on the radially outer side of the lower cylindrical portion is a spring seat surface.   The upper case includes an upper annular portion in which an annular lower surface is formed, and a cylindrical portion that extends integrally downward from the outer peripheral edge in the radial direction of the upper annular portion. A base, an upper cylindrical part formed integrally with a substantially central portion in the radial direction of the upper surface of the annular base, and formed with an annular upper surface; and a lower cylindrical part integrally formed on the lower surface of the annular base; The strut slip according to claim 1, wherein the upper cylindrical portion is surrounded by the cylindrical portion of the upper case, and the lower surface of the annular base portion on the radially outer side of the lower cylindrical portion is a spring seat surface. bearing.   A cylindrical radial sliding bearing piece is further provided. The upper cylindrical portion of the lower case has a cylindrical side surface facing the cylindrical side surface of the cylindrical portion of the upper case. The radial sliding bearing piece is a cylinder of the upper case. The strut slide bearing according to claim 6, which is interposed between the cylindrical side surface of the upper portion and the cylindrical side surface of the upper cylindrical portion of the lower case.   The strut slide bearing according to claim 2 or 7, wherein the radial slide bearing piece is made of a synthetic resin including at least one of polyacetal resin, polyamide resin, thermoplastic polyester resin, polyolefin resin, and fluororesin.   The strut slide bearing according to any one of claims 1 to 8, wherein the upper case is elastically fitted to the lower case.   The upper case is made of a synthetic resin including at least one of a polyacetal resin, a polyamide resin, a thermoplastic polyester resin, a polyolefin resin, a polycarbonate resin, and a fluororesin. Strut plain bearing.   The strut according to any one of claims 1 to 10, wherein the thrust slide bearing piece is made of a synthetic resin including at least one of polyacetal resin, polyamide resin, thermoplastic polyester resin, polyolefin resin, and fluororesin. Plain bearing.   The lower case is made of a reinforced synthetic resin including a synthetic resin containing at least one of a polyacetal resin, a polyamide resin, and a polypropylene resin, and reinforcing fibers contained in the synthetic resin. The strut plain bearing according to item.   The strut slide bearing according to any one of claims 1 to 12, for use in a strut suspension in a four-wheeled vehicle.   A strut-type suspension structure in a four-wheeled vehicle comprising the strut slide bearing according to any one of claims 1 to 12, and a suspension coil spring seated on a spring seat surface of a lower case at one end.

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