Spring sheet structure of hydraulic shock absorber

In a spring sheet structure of a hydraulic shock absorber having a sheet rubber seated on a spring sheet and supporting a spring through the sheet rubber, an end coil portion of the spring is stored in the sheet rubber, the spring sheet includes a movement restraint unit for restraining a movement of the sheet rubber, the sheet rubber includes an abutment unit corresponding to the movement restraint unit of the spring sheet, and the abutment unit of the sheet rubber is engaged with the movement restraint unit of the spring sheet while the sheet rubber is seated on a flat sheet surface provided in a circumferential direction of the spring sheet, thereby restraining a movement of the spring relative to the spring sheet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a spring sheet structure of a hydraulic shock absorber.

2. Description of the Related Art

There is known a spring sheet structure of a hydraulic shock absorber, as disclosed in Japanese Patent Application Laid-Open No. 8-200414 (Patent document 1), configured so that a sheet rubber is seated on a spring sheet and supported through this sheet rubber. An end coil portion of a spring is stored in the sheet rubber, a terminal end of the end coil portion of the spring is arranged in a stepped portion provided at a circumferentially predetermined position of the sheet rubber, and the stepped portion of the sheet rubber is seated on a stepped portion provided at a circumferentially predetermined position on a sheet surface of the spring sheet. By this arrangement, rotation of the spring on its own axis is received by the stepped portion on the sheet surface of the spring sheet and thereby restrained.

With the spring sheet structure of the hydraulic shock absorber disclosed in the Patent document 1, the stepped portion is required to be provided at the circumferential predetermined position on the sheet surface of the spring sheet. This makes a shape of the spring sheet complicated, with the result that it disadvantageously takes lots of time to design the spring sheet and that manufacturing steps are disadvantageously complicated.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a spring sheet structure of a hydraulic shock absorber for preventing rotation of a spring, which structure enables simplifying a shape of a spring sheet and improving design efficiency and manufacturing efficiency.

In accordance with embodiments of the present invention, there is provided a spring sheet structure of a hydraulic shock absorber having a sheet rubber seated on a spring sheet and supporting a spring through the sheet rubber. An end coil portion of the spring is stored in the sheet rubber. The spring sheet includes movement restraint means for restraining a movement of the sheet rubber. The sheet rubber includes abutment means corresponding to the movement restraint means of the spring sheet. The abutment means of the sheet rubber is engaged with the movement restraint means of the spring sheet while the sheet rubber is seated on a flat sheet surface provided in a circumferential direction of the spring sheet, thereby restraining a movement of the spring relative to the spring sheet.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment (FIGS.1to9)

A hydraulic shock absorber10is a strut damper type shock absorber. As shown inFIG. 1, the hydraulic shock absorber10is configured so that a piston rod12is inserted into a cylinder (not shown) included in an outer tube (damper tube)11, the outer tube11is equipped with a wheel-side attachment bracket13and connected to a wheel, and so that the piston rod12protruding from the outer tube11is equipped with a vehicle body-side attachment bracket14and attached to a vehicle body. The vehicle body-side attachment bracket14includes a mount rubber assembly18that consists of a stay15, upper and lower mount bases16A and16B, and a mount rubber17. The stay15of this mount rubber assembly18is inserted into an upper end-side small-diameter portion of the piston rod12and fastened thereto by a nut19.

A stabilizer attachment arm20is provided on the outer tube11and an end of a stabilizer (not shown) is connected to the stabilizer attachment arm20, whereby the stabilizer (not shown) can be attached to the hydraulic shock absorber10.

In the hydraulic shock absorber10, the outer tube11and the piston rod12serve as an absorber main body, and a coil spring24is interposed between a lower spring sheet21fixed to an outer circumference of the outer tube11and an upper spring sheet22equipped with a thrust bearing23, provided around the piston rod12, fixed to the vehicle body-side attachment bracket14by low pressure fitting or the like, and having a back surface supported by the vehicle body-side attachment bracket14. Specifically, the coil spring24is supported by the lower spring sheet21as will be described later, and supported by the upper spring sheet22through a sheet rubber22A.

The hydraulic shock absorber10includes a rubber bumper26inserted and attached into a rubber bumper attachment body25welded to a lower surface of the vehicle body-side attachment bracket14so as to firmly embrace a lower portion of the piston rod12than the vehicle body-side attachment bracket14. During maximum compression, the hydraulic shock absorber10restricts a maximum compression stroke by striking this rubber bumper26against a bumper stopper cap27provided on an upper end surface of the outer tube11. In this embodiment, a dust cover28is formed integrally on a lower end of the sheet rubber22A provided on the upper spring sheet22. A lower end of the dust cover28is stopped by a cover reception portion29provided on the outer tube11, and the outer tuber11and the piston rod12are covered with the dust cover28.

Namely, the hydraulic shock absorber10is stretched so that an elastic force of the coil spring24can absorb a shock force which a vehicle receives from a road surface. During vertical movement of a piston (not shown) following the stretching of the hydraulic shock absorber10, a stretching vibration is promptly suppressed by a damping force generated by a piston valve device provided on the piston, a base valve device provided on the cylinder, or the like.

The hydraulic shock absorber10is configured as follows (FIGS. 2 to 9) so as to seat a sheet rubber50on a sheet surface30of the lower spring sheet21, and to support the coil spring24through this sheet rubber50. It is noted that the coil spring24has an effective end coil portion24A that has a three-quarter turn and has a coil central axis bent into a C shape.

(1) The coil spring24is arranged offset and inclined with respect to the outer tube11and the piston rod12. Namely, in the front view of the hydraulic shock absorber10(FIG. 1), a central axis C1of the coil spring24is arranged to be inclined (or may be arranged to be bent) from a central axis A of the outer tube11and the piston rod12. In the plan view of the hydraulic shock absorber10(FIG. 3), the lower spring sheet21and the upper spring sheet22are arranged so that the central axis C1of the coil spring24is offset with respect to the central axis A of the lower spring sheet21coaxial with the outer tube11(by as much as an offset amount “e”), and so that the central axis C1of the coil spring24substantially coincides with the central axis A of the upper spring sheet22coaxial with the piston rod12.

As shown inFIG. 3, therefore, the lower spring sheet21is in the form of a bowl surrounded by an outer circumferential rib21A rising on an outer circumference of the lower spring sheet21. The sheet surface30corresponding to the effective end coil portion24A of the coil spring24is formed flat to spread over an entire circumference of the lower spring sheet21. A spring starting end support portion30A, a quarter turn support portion30B, a half turn support portion30C, and a three-quarter turn support portion30D are provided on this sheet surface30. The lower spring sheet21is configured as follows. The quarter turn support portion30B is arranged inside of a vehicle body and the three-quarter turn support portion30D is arranged outside of the vehicle body. The sheet surface30is an inclined flat surface having a falling gradient from the quarter turn support portion30B to the three-quarter turn support portion30D. In addition, a center B of the sheet surface30coincident with the central axis C1of the coil spring24is offset with respect to the central axis A of the lower spring sheet21(which is also the central axis of the outer tube11) (by as much as the offset amount “e”).

The lower spring sheet21has a spring falling prevention flange31formed on an outside diameter-side entire circumference of the sheet surface30, and has the outer circumferential rib21A formed on an outer circumference of the spring falling prevention flange31.

(2) The effective end coil portion24A of the coil spring24is stored in the sheet rubber50. As shown inFIGS. 6A to 6DandFIG. 7, the sheet rubber50consists of a rubber tube51seated on the flat sheet surface30provided on the circumference (entire circumference in this embodiment) of the spring sheet21and formed into a generally three-quarter circular arc on a single plane (a cross section of which tube orthogonal to a tube axis is circular). The sheet rubber50has a closed end51A on one end of the circular arc of the rubber tube51and an opening portion51B on the other end thereof. The sheet rubber50also includes a slit51C ranging from the closed end51A to be continuous to the opening portion51B along an inner circumference of the circular arc of the rubber tube51, and a bore51D including the slit51C and formed near the closed end51A on the inner circumference of the circular arc of the rubber tube51. A wire of the effective end coil portion24A of the coil spring24is inserted and attached into the rubber tube51by elastically enlarging the slit51C of the sheet rubber50. A terminal24B of the effective end coil portion24A is abutted on the closed end51A and the effective end coil portion (rising portion) of the coil spring24extends outward from the opening portion51B. The bore51D prevents the sheet rubber50from being torn off following enlargement of the slit51C.

(3) As shown inFIGS. 2 to 5, the spring sheet21includes movement restraint means40for restraining movement of the sheet rubber50on the sheet surface30.

The movement restraint means40has two protrusions41protruding in an inside diameter direction of the spring sheet21at two positions (between which the quarter turn support portion30B is sandwiched) along the circumferential direction of the outer circumferential rib21A provided on the spring falling prevention flange31on the outer circumference of the sheet surface30of the spring sheet21on which the end coil portion24A of the coil spring24is seated, respectively. Inner wall surfaces41A opposite each other of the both protrusions41will be referred to as “rotation restraint portions” that restrain rotation of the coil spring24(rotation on its own axis (coil axis) following compression of the coil spring24). Protrusion apexes41B of the both protrusions41will be referred to as “outside diameter restraint portions” that restrain the outside diameter of the coil spring24.

The movement restraint portion40has an inner circumferential rib42extending in a range of a circular arc angle along the circumferential direction of the inner circumference of the sheet surface30of the spring sheet21on which surface the end coil portion24A of the coil spring24is seated, which range corresponds to a range from the spring starting end support portion30A to the half turn support portion30C. This inner circumferential rib42will be referred to as “an inside diameter restraint portion” that restrains an inside diameter of the coil spring24.

(4) Abutment means60corresponding to the movement restraint means40of the spring sheet21is provided on the sheet rubber50.

The abutment means60has a projecting portion61which is generally rectangular in a plan view, which protrudes in an outside diameter direction of the sheet rubber50, and which is provided on an outer circumference of the circular arc of the rubber tube51of the sheet rubber50(at a position corresponding to a range from the closed end51A to a quarter turn portion of the coil spring24). While the rubber tube51of the sheet rubber50is seated on the sheet surface30of the spring sheet21, the projecting portion61of the rubber tube51is sandwiched and fitted between the both protrusions41of the spring sheet21and, therefore, held therebetween. Namely, a rotation force of the coil spring24generated when the coil spring24rotates on its own axis to follow compression of the coil spring24is transmitted from the terminal24B of the coil spring24to the projecting portion61via the closed end51A and the rubber tube51of the sheet rubber50. Outer wall surfaces61A on both sides of the projecting portion61along the circular arc of the rubber tube51will be referred to as “rotation direction abutment portions” engaged with the inner wall surfaces41A (rotation restraint portions) of the both protrusions41of the spring sheet21in the rotation direction of the coil spring24, respectively. In addition, both outer circumferential surfaces61B that are a bottom of the projecting portion61will be referred to as “outside diameter direction abutment portions” engaged with the protrusion apexes41B (outside diameter restraint portions) of the both protrusions41of the spring sheet21in a diameter direction of the coil spring24, respectively.

Further, an inner circumferential surface62of the sheet rubber50which is an inner circumferential surface of the rubber tube51in a range from the closed end51A, which range forms a half circular arc, will be referred to as “an inside diameter direction abutment portion” engaged with the inner circumference rib42of the spring sheet21in the diameter direction of the coil spring24.

The projecting portion61of the sheet rubber50may be provided at an arbitrary position on the outer circumference of the circular arc of the rubber tube51. However, if the coil spring24having the coil axis bent into C shape is used, then the end coil portion24A forms an angle with respect to the sheet surface30when the sheet rubber50is seated on the sheet surface30, and only a part of the end coil portion24A can be strongly mounted on the sheet surface30. In this case, the projecting portion61is preferably provided near a position at which the end coil portion24A of the coil spring24is strongly mounted on the sheet surface30of the spring sheet21through the rubber tube51.

The abutment means60is formed integrally with the rubber tube51when the sheet rubber50is formed, and dimensions of the abutment means60can be freely set. An outside surface groove61C provided in an outside surface of a central portion of the projecting portion61along the circumferential direction of the rubber tube51coincides with a protrusion position confirmation mark given on a fitting bottom41C of the spring sheet21on which the projecting portion61is sandwiched and fitted between the both protrusions41of the spring sheet21.

(5) By thus configuring as stated in paragraphs (1) to (4) above, while the sheet rubber50into which the end coil portion24A of the coil spring24is inserted and attached is seated on the flat sheet surface30provided on the spring sheet21in the circumferential direction thereof, the abutment means60(the rotation direction abutment portions61A, the outside diameter direction abutment portions61B, and the inside diameter direction abutment portion62) of the sheet rubber50are engaged with the movement restraint means40(the rotation restraint portions41A, the outside diameter restraint portions41B, and the inside diameter restraint portion42) of the spring sheet21, respectively. This can thereby restrain free movement of the coil spring24relative to the spring sheet21.

The number and positions of the protrusions41that constitute the movement restraint means40of the spring sheet21and those of the projecting portions61that constitute the abutment means60of the sheet rubber50can be arbitrarily set. If the coil spring24and the sheet rubber50cannot be surely and easily positioned by a single projecting portion61, a plurality of projecting portions61can be employed.

By making the movement restraint means40provided on the spring sheet21and the abutment means60provided on the sheet rubber50different according to specifications of the hydraulic shock absorber10and the coil spring24, it is possible to prevent erroneous combination of the coil spring24and the like.

One or more embodiments of a hydraulic shock absorber according to the first embodiment exhibit one or more of the following functions and advantages.

While the sheet rubber50is seated on the flat sheet surface30provided on the spring sheet21in the circumferential direction thereof, the abutment means60of the sheet rubber50is engaged with the movement restraint means40of the spring sheet21. It is thereby possible to restrain the movement of the spring24relative to the spring sheet21. Namely, the rotation of the spring24on its own axis following the compression of the spring24is transmitted to and received by the movement restraint means40of the spring sheet21through the abutment means60of the sheet rubber50. The sheet surface30of the spring sheet21on which surface the sheet rubber50is seated can be, therefore, formed into a simple flat surface without any stepped portion.

Since the shape of the spring sheet21can be simplified, it is possible to simplify the designing and manufacturing of the hydraulic shock absorber such as abilities to promptly design the hydraulic shock absorber and to eliminate a pressing step in a manufacturing phase.

The movement restraint means40provided on the spring sheet21correspond to the protrusions41protruding in the diameter direction of the spring sheet21. In addition, the abutment means60provided on the sheet rubber50correspond to the rotation direction abutment portions61A and the diameter direction abutment portions61B and62. It is thereby possible to easily restrain the rotation and diameter direction movement of the spring24and to position the spring24.

By making the movement restraint means40provided on the spring sheet21and the abutment means60provided on the sheet rubber50different according to the specifications of the coil spring24(and those of the hydraulic shock absorber10), the spring sheet21and the sheet rubber50equal in specification can be combined. It is, therefore, possible to prevent erroneous combination of the spring sheet21and the sheet rubber50.

The movement restraint means40provided on the spring sheet21and the abutment means60provided on the sheet rubber50are provided at a plurality of positions according to the specifications of the coil spring24(and those of the hydraulic shock absorber10). It is thereby possible to use the spring sheet21and sheet rubber50common to a plurality of specifications and combine the spring sheet21and the sheet rubber50according to each specification. In addition, by using a plurality of movement restraint means40and the sheet rubber50in combination (simultaneously), it is possible to ensure that the movement of the spring24is restrained.

Second Embodiment (FIGS.10to17)

A second embodiment differs from the first embodiment in movement restraint means70of a lower spring sheet21, a sheet rubber80, and abutment means90of the sheet rubber80.

Namely, a hydraulic shock absorber10according to the second embodiment is configured as follows (FIGS. 10 to 15) so as to seat the sheet rubber80on a sheet surface30of the lower spring sheet21, and to support a coil spring24through this sheet rubber80. It is noted that the coil spring24has an effective end coil portion24A that has a three-quarter turn and has a straight coil central axis.

(1) The coil spring24is arranged offset and inclined with respect to the outer tube11and the piston rod12. Namely, in the front view of the hydraulic shock absorber10(FIG. 10), a central axis C1of the coil spring24is arranged to be inclined (or may be arranged to be bent) from a central axis A of the outer tube11and the piston rod12. In the plan view of the hydraulic shock absorber10(FIG. 12), the lower spring sheet21and the upper spring sheet22are arranged so that the central axis C1of the coil spring24is offset with respect to the central axis A of the lower spring sheet21coaxial with the outer tube11(by as much as an offset amount “e”), and so that the central axis C1of the coil spring24substantially coincides with the central axis A of the upper spring sheet22coaxial with the piston rod12.

As shown inFIG. 12, therefore, the lower spring sheet21is in the form of a bowl surrounded by an outer circumferential rib21A rising on an outer circumference of the lower spring sheet21. The sheet surface30corresponding to the effective end coil portion24A of the coil spring24is formed flat to spread over an entire circumference of the lower spring sheet21. A spring starting end support portion30A, a quarter turn support portion30B, a half turn support portion30C, and a three-quarter turn support portion30D are provided on this sheet surface30. The lower spring sheet21is configured as follows. The quarter turn support portion30B is arranged inside of a vehicle body and the three-quarter turn support portion30D is arranged outside of the vehicle body. The sheet surface30is an inclined flat surface having a falling gradient from the quarter turn support portion30B to the three-quarter turn support portion30D. In addition, a center B of the sheet surface30coincident with the central axis C1of the coil spring24is offset with respect to the central axis A of the lower spring sheet21(which is also the central axis of the outer tube11) (by as much as the offset amount “e”).

(2) The effective end coil portion24A of the coil spring24is stored in the sheet rubber80. As shown inFIGS. 14A to 14DandFIG. 15, the sheet rubber80consists of a rubber tube81seated on the flat sheet surface30provided on the circumference (entire circumference in this embodiment) of the spring sheet21and formed into a generally three-quarter circular arc on a single plane (a cross section of which tube orthogonal to a tube axis is circular). The sheet rubber80has a closed end81A on one end of the circular arc of the rubber tube81and an opening portion81B on the other end thereof. The sheet rubber80also includes a slit81C ranging from the closed end81to be continuous to the opening portion81B along an inner circumference of the circular arc of the rubber tube81. A wire of the effective end coil portion24A of the coil spring24is inserted and attached into the rubber tube81by elastically enlarging the slit81C of the sheet rubber80. A terminal24B of the effective end coil portion24A is abutted on the closed end81A and the effective end coil portion (rising portion)24A of the coil spring24extends outward from the opening portion81B.

(3) As shown inFIGS. 11 to 13, the spring sheet21includes movement restraint means70for restraining movement of the sheet rubber80on the sheet surface30.

The movement restraint means70has one bore71(or a plurality of bores) in the sheet surface30(the quarter turn support portion30B) of spring sheet21on which the end coil portion24A of the coil spring24is seated. This bore71will be referred to as “a restraint portion” that restrains rotation of the coil spring24on its own axis (rotation on the coil axis) and inside and outside diameter directions thereof following compression of the coil spring24.

The sheet surface30around the bore71is formed into a flat surface32(FIGS. 12 and 13) for the movement restraint means70spreading outward (or both inward and outward) of the bore71in a diameter direction of the spring sheet21. This flat surface32in the diameter direction extends toward a spring falling prevention flange31on an outer circumference of the sheet surface30. Both wall surfaces32A of the flat surface32opposite each other in the circumferential direction of the spring sheet21will be referred to as “rotation restraint portions” that constitutes the movement restraint means70and that restrain rotation of the coil spring24. In addition, an outer wall surface32B of the flat surface32located outward in the diameter direction of the spring sheet21will be referred to as “an outside diameter restraint portion” that constitutes the movement restraint means70and that restrains an outside diameter of the coil spring24.

An inner circumferential rib72extending in a range of a circular arc angle along the circumferential direction of the inner circumference of the sheet surface30of the spring sheet21on which surface the end coil portion24A of the coil spring24is seated, which range corresponds to a range from the spring starting end support portion30A to the half turn support portion30C. This inner circumferential rib72will be referred to as “an inside diameter restraint portion” that restrains an inside diameter of the coil spring24.

(4) Abutment means90corresponding to the movement restraint means70of the spring sheet21is provided on the sheet rubber80.

The abutment means90has a protrusion91which protrudes along an axial direction of a central axis of the circular arc of the rubber tube81of the sheet rubber80at a central axis of the wire of the end coil portion24A of the coil spring24(a position distant from the center B of the sheet surface by a radius Ra and corresponding to a range from the closed end81A to a quarter turn portion of the coil spring24) on a lower surface of the circular arc, as shown inFIGS. 12,13, and14A. In addition, the abutment means90has a projecting portion92which is generally rectangular in a plan view, which protrudes in a certain range along the circular arc of the rubber tube81in an outside diameter direction of the sheet rubber80, and which is provided on a circularly lower surface of the circular arc of the rubber tube81of the sheet rubber80on which the protrusion91is provided. The projecting portion92has a flat surface and the protrusion91protrudes to a center of the projecting portion92.

While the rubber tube81of the sheet rubber80is seated on the flat sheet surface30of the spring sheet21, the protrusion91of the rubber tube81is engaged and inserted into the bore71of the spring sheet21and, therefore, held therein. The projecting portion92of the rubber tube81is sandwiched and fitted between the both wall surfaces32A of the flat surface32of the spring sheet21and, therefore, held therebetween. Namely, a rotation force of the coil spring24generated when the coil spring24rotates on its own axis to follow compression of the coil spring24is transmitted from the terminal24B of the coil spring24to the protrusion91and the projecting portion92via the closed end81A and the rubber tube81of the sheet rubber80. Therefore, the protrusion91of the rubber tube81will be referred to as “an abutment portion” engaged with the bore71of the spring sheet21in the rotation direction and inside and outside diameter directions of the coil spring24. In addition, the projecting portion92of the rubber tube81will be referred to as “an abutment portion” engaged with the outer wall surface32B of the flat surface32of the spring sheet21in the outside diameter of the coil spring24. As for the sheet rubber80, it is essential to provide the protrusion91but not essential to provide the projecting portion92.

Further, an inner circumferential surface93of the circular arc of the rubber tube81in a range from the closed end81A to form a half circular arc will be referred to as “an inside diameter direction abutment portion” engaged with the inner circumference rib72of the spring sheet21.

The protrusion91and the projecting portion92of the sheet rubber80may be provided at arbitrary positions on the outer circumference of the circular arc of the rubber tube81. However, the end coil portion24A of the coil spring24forms an angle with respect to the sheet surface30when the sheet rubber80is seated on the sheet surface30, and only a part of the end coil portion24A can be strongly mounted on the sheet surface30. In this case, the protrusion91and the projecting portion92are preferably provided near a position at which the end coil portion24A of the coil spring24is strongly mounted on the sheet surface30of the spring sheet21through the rubber tube81.

The abutment means90is formed integrally with the rubber tube81when the sheet rubber80is formed, and dimensions of the abutment means90can be freely set. The protrusion91may be not only a round rod but also a long round rod, a rectangular rod or the like. By providing each of the protrusion91and the projecting portion92on upper and lower surfaces of the circular arc of the rubber tube81, the spring sheet21and the sheet rubber80common to both left and right hydraulic shock absorbers10can be employed in.

The rubber tube81of the sheet rubber80has an inside diameter equal to a diameter of the wire of the coil spring24. As shown inFIGS. 14A to 14Dand15, the rubber tube81includes drain holes82formed at a plurality of circumferential positions of upper and lower tube walls offset from a tube diameter L, which is orthogonal to a plane including the circular arc of the rubber tube81and on which the protrusion91is provided, toward an opposite side to the slit81C, respectively. On the inner circumference of the rubber tube81, an inside surface thereof facing the slit81C is denoted as a flat surface83A, and an inside surface thereof that connects the drain holes82to the flat surface83A is denoted as a flat surface83B biased with respect to the flat surface83A. As a result, a gap that communicates an interior of the rubber tube81on the opposite side to the slit81C with the drain holes82is formed.

The sheet rubber80includes a bore84provided near the closed end81A provided on one end of the circular arc of the rubber tube81so as to confirm whether the end coil portion24A of the coil spring24is inserted and attached into the rubber tube81. The bore84is formed on the outer wall surface of the circular arc of the rubber tube81. The bore84is set at the same position as an offset range from the closed end81A allowed for a terminal of the end coil portion24A when the end coil portion24A of the coil spring24is inserted and attached into the rubber tube81. Using the bore84, it is confirmed whether the coil spring24is assembled with the sheet rubber80.

(5) By thus configuring as stated in paragraphs (1) to (4) above, while the sheet rubber80into which the end coil portion24A of the coil spring24is inserted and attached is seated on the flat sheet surface30provided on the spring sheet21in the circumferential direction thereof, the abutment means90(the protrusion91and the projecting portion92) of the sheet rubber80are engaged with the movement restraint means70(the bore71, the flat surface32, and the inner circumferential rib72) of the spring sheet21, respectively. This can thereby restrain free movement of the coil spring24relative to the spring sheet21.

The number and positions of the bores71that constitute the movement restraint means70of the spring sheet21and those of the protrusion91and the projecting portion92that constitute the abutment means90of the sheet rubber80can be arbitrarily set. If the coil spring24and the sheet rubber80cannot be surely and easily positioned by a single protrusion91, a plurality of protrusions91can be employed.

By making the movement restraint means70provided on the spring sheet21and the abutment means90provided on the sheet rubber80different according to specifications of the hydraulic shock absorber10and the coil spring24, it is possible to prevent erroneous combination of the coil spring24and the like.

One or more embodiments of a hydraulic shock absorber according to the second embodiment exhibit one or more of the following functions and advantages.

While the sheet rubber80is seated on the flat sheet surface30provided on the spring sheet21in the circumferential direction thereof, the abutment means90of the sheet rubber80is engaged with the movement restraint means70of the spring sheet21. It is thereby possible to restrain the movement of the coil spring24relative to the spring sheet21. Namely, the rotation of the coil spring24on its own axis following the compression of the coil spring24is transmitted to and received by the movement restraint means70of the spring sheet21through the abutment means90of the sheet rubber80. The sheet surface30of the spring sheet21on which surface the sheet rubber80is seated can be, therefore, formed into a simple flat surface without any stepped portion.

Since the shape of the spring sheet21can be simplified, it is possible to simplify the designing and manufacturing of the hydraulic shock absorber such as abilities to promptly design the hydraulic shock absorber and to eliminate a pressing step in a manufacturing phase.

The movement restraint means70provided on the spring sheet21correspond to the bore71. In addition, the abutment means90provided on the sheet rubber80correspond to the protrusion91engaged with and inserted into the bore71. The simple configuration in which only the bore71is formed in the spring sheet21can, therefore, simplify the shape of the spring sheet21, make the spring sheet21small in size and light in weight, and facilitate manufacturing the hydraulic shock absorber.

The protrusion91provided on the sheet rubber80is the protrusion along the axial direction of the sheet rubber80and engaged into and inserted into the bore71of the spring sheet21. It is thereby possible to engage the sheet rubber80with the spring sheet21in the rotation and diameter directions of the coil spring24. In addition, it is possible to easily restrain the rotation and diameter direction movement of the coil spring24and to position the coil spring24.

Since the sheet rubber80consists of the rubber tube81, the end coil portion24A of the coil spring24can be easily and surely stored in the sheet rubber80.

The drain holes82are formed in the rubber tube81of the sheet rubber80to be offset from the diameter of the rubber tube81toward the opposite side to the slit81C. It is thereby possible to ensure draining water entering the rubber tube81without closing the drain holes82by the wire of the coil spring24.

The bore84is provide in the rubber tube81of the sheet rubber80for confirming whether the end coil portion24A of the coil spring24is inserted and attached into the rubber tube81. It is, therefore, possible to confirm whether or not a state of inserting and attaching the end coil portion24A of the coil spring24into the rubber tube81is good.

The spring falling prevention flange31is provided on the spring sheet21, whereby the movement restraint means70for the sheet rubber80can be provided on this spring falling prevention flange31.

By making the movement restraint means70provided on the spring sheet21and the abutment means90provided on the sheet rubber80different according to the specifications of the coil spring24(and those of the hydraulic shock absorber10), the spring sheet21and the sheet rubber50equal in specification can be combined. It is, therefore, possible to prevent erroneous combination of the spring sheet21and the sheet rubber80.

The movement restraint means70provided on the spring sheet21and the abutment means90provided on the sheet rubber80are provided at a plurality of positions according to the specifications of the coil spring24(and those of the hydraulic shock absorber10). It is thereby possible to use the spring sheet21and sheet rubber80common to a plurality of specifications and combine the spring sheet21and the sheet rubber80according to each specification. In addition, by using a plurality of movement restraint means70and the sheet rubber80in combination (simultaneously), it is possible to ensure that the movement of the coil spring24is restrained.

A sheet rubber100according to a modification of the second embodiment shown inFIGS. 16A to 16DandFIG. 17differs from the sheet rubber80according to the second embodiment shown inFIGS. 14A to 14DandFIG. 15as follows. A protrusion101protruding in the diameter direction of the rubber tube81and abutting on the sheet surface30of the spring sheet21is provided near the closed end81A provided on one end of the circular arc of the rubber spring81. The protrusion101is provided on an inner circumferential wall of the circular arc of the rubber tube81and protrudes in the inside diameter direction of the circular arc of the rubber tube81. A lower surface of the protrusion100(similarly to an upper surface thereof so as to employ the spring sheet21and the sheet rubber80common to both left and right hydraulic shock absorbers10) is seated on the starting end support portion30A of the spring sheet21to follow a curved surface of a range from the sheet surface30to the inner circumferential rib72along the diameter direction.

Accordingly, in the hydraulic shock absorber10using the sheet rubber100, the sheet rubber80protrudes in the diameter direction of the rubber tube81and includes the protrusion101abutting on the sheet surface30of the spring sheet21. It is, therefore, possible to prevent the rubber tube81from being distorted around the tube axis and becoming unstable in response to a torsional deformation of the wire of the coil spring24around the central axis thereof on the sheet surface30of the spring sheet21.

As heretofore explained, embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configurations of the present invention are not limited to the illustrated embodiments but those having a modification of the design within the range of the presently claimed invention are also included in the present invention. For example, the coil spring24is not limited to the coil spring having the coil axis formed into the C shape. A spring having a coil axis bent into an S shape or the like may be used. In that case, if the spring is sandwiched between the upper and lower spring sheets21and22, a lateral force is generated by the spring itself. Further, a straight spring can be used as the coil spring24.

A material for the sheet rubber may be an elastic material such as natural rubber (NR) or resin.

Although the invention has been illustrated and described with respect to several exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made to the present invention without departing from the spirit and scope thereof. Therefore, the present invention should not be understood as limited to the specific embodiment set out above, but should be understood to include all possible embodiments which can be encompassed within a scope of equivalents thereof with respect to the features set out in the appended claims.