Hydraulic shock absorber

Abstract

To provide a hydraulic buffer capable of quickly reaching a peak in damping force due to an oil lock mechanism and maintaining a damping force.SOLUTION: An oil lock mechanism 26 comprises a first member 30 having an inner peripheral surface 33 with a constant inner diameter, and a second member 40 that can be inserted into the first member 30. An outer peripheral surface 60 of a cylindrical part 45 of the second member 40 and an inner peripheral surface 33 of the first member 30 can define a steady flow path 51 with a constant flow path area regardless of a position in an axial line AX direction. The steady flow path 51 has a first flow path 52 and a second flow path 53, which have different flow path areas. A flow pass area S2 of the second flow path 53 is larger than a flow pass area S1 of the first flow path 52.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a hydraulic shock absorber equipped with an oil lock mechanism. [Background technology]

[0002] Saddle-type vehicles such as motorcycles and three-wheeled vehicles are provided with hydraulic shock absorbers that connect the axles to the vehicle body and absorb vibrations from the road surface. Prior art related to such hydraulic shock absorbers is disclosed in Patent Document 1.

[0003] The hydraulic shock absorber disclosed in Patent Document 1 is a rear suspension provided on a motorcycle. This rear suspension includes a cylindrical cylinder, a piston that divides the interior of the cylinder into a first oil chamber on the axle side (lower side) and a second oil chamber on the vehicle body side (upper side), a rod to which the piston is fixed and part of which protrudes from the lower end of the cylinder, and a closing member that closes the lower end of the cylinder and supports the rod.

[0004] When an impact is applied from the wheel to the rear suspension rod, the piston moves and oil (hydraulic oil) flows back and forth between the first and second oil chambers through a communication hole formed in the piston, generating a damping force due to the resistance of the oil flow path, allowing the rear suspension to absorb the impact. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-44786 Summary of the Invention [Problem to be solved by the invention]

[0006] An oil lock mechanism is provided inside the second oil chamber of the cylinder to prevent the piston from bottoming out by using oil pressure to restrict movement of the piston toward the vehicle body. The oil lock mechanism includes a cup-shaped first member (oil lock cup) that opens downward, and a second member (oil lock piece) that is provided at the upper end of the rod and can be inserted into the first member.

[0007] When the second member is inserted into the first member, the outer peripheral surface of the second member and the inner peripheral surface of the first member form an annular flow path through which oil flows. The oil in the oil chamber enclosed by the first and second members flows through the flow path into the second oil chamber, generating a damping force.

[0008] Furthermore, the second member has a communication hole that allows communication between the oil chamber surrounded by the first member and the second member and the second oil chamber. This communication hole can be opened and closed by a valve. When the valve is opened, oil in the oil chamber surrounded by the first member and the second member flows into the second oil chamber through a flow path, generating a damping force.

[0009] Furthermore, the second member is provided so as to be movable along the axis, and can come into contact with or separate from the valve 47. When the hydraulic shock absorber extends, a gap is generated between the second member and the valve, Oil flows from the second oil chamber into the oil chamber surrounded by the first and second members through this gap, preventing the oil chamber surrounded by the first and second members from becoming negative pressure.

[0010] In a hydraulic shock absorber having such a configuration, the damping force increases as the insertion amount of the second member relative to the first member increases, so it takes time for the damping force to reach its peak.

[0011] An object of the present invention is to provide a hydraulic shock absorber that can quickly reach a peak damping force by an oil lock mechanism and maintain that damping force. [Means for solving the problem]

[0012] As a result of extensive research, the inventors have found that it is possible to provide a hydraulic shock absorber in which the outer peripheral surface of the tubular portion of the second member of the oil lock mechanism and the inner peripheral surface of the first member can define a steady flow path with a constant flow path area regardless of axial position, the steady flow path having a first flow path on the first member side and a second flow path on the second member side with different flow path areas, the flow path area of ​​the second flow path being larger than the flow path area of ​​the first flow path, and which allows the damping force of the oil lock mechanism to reach its peak earlier and maintain that damping force. The present invention was completed based on these findings.

[0013] According to the present disclosure, there is provided an oil lock mechanism comprising: a cylindrical cylinder; a piston that divides the interior of the cylinder into a first oil chamber on the axle side and a second oil chamber on the vehicle body side; a rod to which the piston is fixed and a portion of which protrudes from a lower end of the cylinder; a closing member that closes the axle side of the cylinder and supports the rod; and an oil lock mechanism that hydraulically suppresses movement of the piston towards the second oil chamber side, the oil lock mechanism comprising: a first member that is provided in the second oil chamber of the cylinder and has an inner circumferential surface with a constant inner diameter; and a second member that is provided at the vehicle body side end of the rod and can be inserted into the first member, the second member having a bottom portion with a through hole through which the rod passes, and a second member that extends from the outer circumferential edge of the bottom portion towards the vehicle body side. the bottom of the second member has a communication hole that can communicate the interior of the second member with the second oil chamber, the communication hole has a valve that can open and close in response to oil pressure generated when the second member is inserted into the first member, the second member can come into contact with or move away from the valve by moving along the axis of the rod, the outer peripheral surface of the cylindrical portion of the second member and the inner peripheral surface of the first member can define a steady flow path with a constant flow path area regardless of position in the axial direction, the steady flow path has a first flow path on the first member side and a second flow path on the second member side that have different flow path areas, and the flow path area of ​​the second flow path is larger than the flow path area of ​​the first flow path. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a hydraulic shock absorber that can quickly reach a peak damping force due to an oil lock mechanism and maintain that damping force. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view of a hydraulic shock absorber provided with a second member according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of an oil lock mechanism of the hydraulic shock absorber shown in FIG. [Figure 3] FIG. 10 is a cross-sectional view of the oil lock mechanism in a state where the hydraulic shock absorber is compressed and the second member is inserted into the first member. [Figure 4] FIG. 4 is a cross-sectional view of the oil lock mechanism in a state where the oil is further compressed from the state shown in FIG. 3 and the valve is open. [Figure 5] FIG. 10 is a cross-sectional view of the oil lock mechanism in a state where the second member is separated from the valve due to the extension of the hydraulic shock absorber. [Figure 6] FIG. 10 is a perspective view of a second member and a valve that can be nested on the bottom of the second member. [Figure 7] 7A is a cross-sectional view of a flow path defined by the inner circumferential surface of the first member and the outer circumferential surface of the second member, and FIG. 7B is a view taken along line 7B in FIG. [Figure 8] Fig. 8A is a perspective view of a second member according to Example 2. Fig. 8B is a cross-sectional view of a flow path defined by the outer circumferential surface of the second member and the inner circumferential surface of the first member in Fig. 8A. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will be described below with reference to the accompanying drawings, in which Up indicates the top (body side) and Dn indicates the bottom (axle side).

[0017] Example 1 1 shows a rear suspension that is a hydraulic shock absorber 10 that can be mounted on a motorcycle. This hydraulic shock absorber 10 includes a cylindrical cylinder 11, a piston 16 that divides the interior of the cylinder 11 into a first oil chamber 13 on the axle side (lower side) and a second oil chamber 14 on the vehicle body side (upper side), a rod 17 to which the piston 16 is fixed and part of which protrudes from the vehicle body side of the cylinder 11, a closing member 15 that closes the vehicle body side end of the cylinder 11 and supports the rod 17, and a cap 21 that covers the closing member 15.

[0018] Furthermore, the hydraulic shock absorber 10 includes an outer tube 22 that surrounds the rod 17 protruding from the cylinder 11 and is slidable against the outer surface of the cylinder 11, a suspension spring 23 that is a compression coil spring that surrounds the cylinder 11 and the outer tube 22, an axle-side mounting member 24 that is fixed to the lower end of the rod 17, and a vehicle-side mounting member 25 that is fixed to the upper end of the cylinder 11.

[0019] [Oil lock mechanism] See Figure 2. An oil lock mechanism 26 is provided inside the second oil chamber, which uses oil pressure to prevent piston 16 (see Figure 1) from moving toward the vehicle body. Oil lock mechanism 26 includes a first member 30 provided in the second oil chamber, and a second member 40 provided at the upper end 18 (the end on the vehicle body side) of rod 17 and insertable into first member 30.

[0020] [First member] The first member 30 is cup-shaped overall, with an insertion opening that opens toward the second member 40. In detail, the first member 30 is configured by integrating a cylindrical tube portion 31 and a top plate portion 37 that closes the upper end of the tube portion 31.

[0021] An outer peripheral surface 32 of the first member 30 is fixed to an inner peripheral surface 12 of the cylinder 11. That is, the first member 30 defines a second oil chamber 14 and a third oil chamber 29 that is located closer to the vehicle body than the second oil chamber 14. The oil in the third oil chamber 29 is pressurized by a free piston 28 (see FIG. 1 ) provided in the cylinder 11. The third oil chamber 29 and the interior of the cylindrical portion 31 of the first member 30 communicate with each other via a hole 38 in a top plate portion 37. The hole 38 may be omitted. The third oil chamber 29 and the second oil chamber 14 communicate with each other via at least one hole 36 in the cylindrical portion 31.

[0022] [Inner surface of first component] The inner circumferential surface 33 of the tubular portion 31 of the first member 30 has an inner circumferential surface constant portion 34 whose diameter is constant regardless of the position in the direction of the axis AX of the rod 17, and an inner circumferential surface expanded diameter portion 35 that is located on the axle side of the inner circumferential surface constant portion 34 and whose diameter increases toward the axle side. The inner circumferential surface expanded diameter portion 35 can also be said to be an insertion port for the first member 30.

[0023] [Second member] The second member 40 is integrally formed of a disk-shaped bottom portion 41 having a through hole 42 at its center through which the rod 17 passes, and a tubular portion 45 extending from the outer peripheral edge of the bottom portion 41 toward the vehicle body.

[0024] The bottom portion 41 has a plurality of communication holes 46 that extend in the direction of the axis AX and allow communication between the interior of the second member 40 and the second oil chamber 14. Each communication hole 46 can be opened and closed by a valve 47 that is superimposed on the lower end surface 43 (the end surface on the axle side) of the bottom portion 41. The valve 47 is formed by superimposing at least one disc. Each disc is made of spring steel and is elastically deformable.

[0025] [Second member movement mechanism] The second member 40 is provided so as to be movable along the axis AX. The position of the second member 40 relative to the valve 47 can be changed so that the second member 40 can come into contact with or separate from the valve 47.

[0026] A cylindrical spacer 48 is disposed between the outer peripheral surface 19 of the upper end 18 of the rod 17 and the inner peripheral surface of the through-hole 42 of the bottom portion 41. The upper end of the spacer 48 has an expanded diameter to form a spring retainer 48a. A valve spring 47a is disposed between the spring retainer 48a and the upper end surface 44 of the bottom portion 41, and generates a force that presses the bottom portion 41 of the second member 40 against the valve 47.

[0027] A fixing member 49 (for example, a nut) for fixing a spacer 48 is provided on the upper end portion 18 of the rod 17. The fixing member 49 sandwiches the spacer 48 together with the valve 47.

[0028] [Oil lock mechanism operation] 3 shows the oil lock mechanism 26 in a state where the hydraulic shock absorber 10 is compressed and the second member 40 is inserted into the first member 30. The oil chamber surrounded by the first member 30 and the second member 40 is referred to as the oil lock oil chamber 27. The oil pressure in the oil lock oil chamber 27 increases as the hydraulic shock absorber 10 is compressed.

[0029] [Flow path] See Figure 4. When the second member 40 is inserted into the first member 30, the outer peripheral surface 60 of the tubular portion 45 of the second member 40 and the inner peripheral surface 33 of the first member 30 form an annular flow path 50 through which oil flows. The oil in the oil lock oil chamber 27 flows into the second oil chamber 14 through the flow path 50, generating a damping force. The detailed configuration of the flow path 50 will be described later.

[0030] When the hydraulic shock absorber 10 is compressed and the oil pressure in the oil lock oil chamber 27 reaches a predetermined pressure, the valve 47 opens due to the oil pressure. The oil in the oil lock oil chamber 27 flows into the second oil chamber 14 via the communication hole 46, generating a damping force.

[0031] Figure 5 shows the oil lock mechanism 26 in a state where the hydraulic shock absorber 10 is extended and the piston 16 (see Figure 1) is moving toward the axle. When the piston 16 moves toward the axle, the oil lock oil chamber 27 temporarily drops, and the second member 40 moves toward the bottom 41 of the first member 30 (toward the vehicle body) against the elastic force of the valve spring 47a. The bottom 41 of the second member 40 moves away from the valve 47, creating a gap. Oil in the second oil chamber 14 passes through the gap between the second member 40 and the valve 47 and flows into the oil lock oil chamber 27. This prevents the oil lock oil chamber 27 from becoming negative pressure.

[0032] [Shape of the outer surface of the second component] Referring to Figure 6, the outer peripheral surface 60 of the tubular portion 45 of the second member 40 has a vehicle body-side reduced diameter portion 61 whose diameter decreases toward the vehicle body side (upper side), an axle-side reduced diameter portion 62 whose diameter decreases toward the axle side, and an outer peripheral surface constant portion 63 located between these portions 61, 62 and having a constant diameter (not reduced or expanded) regardless of position in the direction of the axis AX. The outer peripheral surface constant portion 63 has a large diameter portion 64 and a small diameter portion 65 whose diameters differ from each other. The small diameter portion 65 is located on the axle side of the large diameter portion 64.

[0033] [Steady flow path] 7A, the flow path 50 includes a constant flow path 51 whose flow area is constant regardless of the position in the direction of the axis AX.

[0034] [First flow path, second flow path] The steady flow path 51 is composed of a first flow path 52 on the first member 30 side (vehicle body side, upper side) and a second flow path 53 on the second member 40 side (axle side, lower side), which have different flow path areas. The flow path area S2 of the second flow path 53 is larger than the flow path area S1 of the first flow path 52.

[0035] Specifically, the first flow path 52 is defined by the large diameter portion 64 of the tubular portion 45 of the second member 40 and the constant inner circumferential surface portion 34 of the first member 30. The second flow path 53 is defined by the small diameter portion 65 of the tubular portion 45 of the second member 40 and the constant inner circumferential surface portion 34 of the first member 30.

[0036] [groove] Referring to Figure 6, the lower end surface 43 (the end surface on the axle side) of the bottom portion 41 of the second member 40 has an annular groove 70 that connects the multiple communication holes 46 to each other and surrounds the through-hole 42. When the valve 47 closes the communication hole 46, the groove 70 is blocked by the valve 47.

[0037] Groove Width Referring to FIG. 7B, the width W of the groove 70 is smaller than the diameter R of the communicating hole 46 (W <R)。

[0038] [Effects of Example 1] 6 and 7A, when the hydraulic shock absorber 10 is compressed and the second member 40 is inserted into the first member 30, oil flows through the flow path 50 between the inner circumferential surface 33 of the first member 30 and the outer circumferential surface 60 of the second member 40, generating a damping force.

[0039] The flow path 50 includes a steady flow path 51 whose flow path area is constant regardless of position in the direction of the axis AX. The steady flow path 51 is composed of a first flow path 52 and a second flow path 53 whose flow path areas are different from each other. The flow path area S2 of the second flow path 53 is larger than the flow path area S1 of the first flow path 52. In detail, the first flow path 52 is defined by the large diameter portion 64 of the tubular portion 45 of the second member 40 and the inner circumferential surface steady portion 34 of the first member 30. The second flow path 53 is defined by the small diameter portion 65 of the tubular portion 45 of the second member 40 and the inner circumferential surface steady portion 34 of the first member 30.

[0040] With the above configuration, the damping force reaches its peak before the entire second member 40 is inserted into the first member 30. Compared to a second member with a constant outer diameter from its upper end to its lower end, as in a prior art hydraulic shock absorber, the damping force of the oil lock mechanism 26 reaches its peak earlier.

[0041] In addition, as described above, the small diameter portion 65 of the second member 40 is located on the axle side of the large diameter portion 64, and the first flow path 52 having a large flow path area is provided. Even if the second member 40 is further inserted into the first member 30 after the entire large diameter portion 64 of the second member 40 is inserted into the first member 30, the damping force does not increase and can be maintained at its peak.

[0042] Therefore, the hydraulic shock absorber 10 can make the damping force of the oil lock mechanism 26 reach its peak quickly and can maintain that damping force.

[0043] Note that, instead of the small diameter portion 65, for example, a groove may be formed along the circumferential direction on the outer peripheral surface 60 of the tubular portion 45 of the second member 40. That is, as long as the flow path area S2 of the second flow path 53 is larger than the flow path area S1 of the first flow path 52, the configuration of the outer peripheral surface 60 of the second member 40 does not matter.

[0044] 6 and 7B. In addition, the lower end surface 43 (the end surface on the axle side) of the bottom portion 41 of the second member 40 has an annular groove 70 that connects the communication holes 46 to each other and surrounds the through-hole 42. When the valve 47 closes the communication hole 46, the groove 70 is closed by the valve 47. The width W of the groove 70 is smaller than the diameter R of the communication hole 46 (W <R)。

[0045] That is, when the second member 40 is inserted into the first member 30 and oil flows from the oil lock chamber 27 into the communication hole 46, the pressure-receiving area of ​​the valve 47 that receives the oil pressure is set small. Compared to when the width W of the groove 70 is set larger than the diameter of the communication hole 46 (W>R), the valve 47 is less likely to open, so the oil pressure in the oil lock chamber 27 increases, and this can compensate for the damping force that occurs when oil flows through the flow path 50. Furthermore, as long as the valve 47 functions as a lid, the relationship between the W of the groove 70 and the diameter R of the communication hole 46 is not limited to this (W>R may also be true).

[0046] <Example 2> 8A and 8B show a second member 40A provided in the hydraulic shock absorber according to Example 2. The same reference numerals as in Example 1 are used for the configurations and effects common to the second member 40 of Example 1, and descriptions thereof will be omitted.

[0047] The outer peripheral surface 60A of the cylindrical portion 45 of the second member 40 in the second embodiment has an outer peripheral surface constant portion 63A whose diameter is constant regardless of the position in the direction of the axis AX. An annular member 80 is fitted into a groove 66 formed in the outer peripheral surface constant portion 63A. Within the outer peripheral surface constant portion 63A, the annular member 80 is positioned biased toward the vehicle body. The diameter of the outer peripheral surface 64A of the annular member 80 is larger than the diameter of the outer peripheral surface constant portion 63A of the second member 40.

[0048] That is, the outer peripheral surface 64A of the annular member 80 corresponds to the large diameter portion 64 of the first embodiment. The outer peripheral surface constant portion 63A of the second member 40 corresponds to the small diameter portion 65 of the first embodiment.

[0049] 8B. The flow path 51A includes a steady flow path 51A whose flow path area is constant regardless of the position in the direction of the axis AX. The steady flow path 51A is composed of a first flow path 52A and a second flow path 53A whose flow path areas are different from each other. The flow path area T2 of the second flow path 53A is larger than the flow path area T1 of the first flow path 52A.

[0050] Specifically, the first flow path 52A is defined by the outer peripheral surface 64A of the annular member 80 and the inner peripheral surface constant portion 34 of the first member 30. The second flow path 53A is defined by the outer peripheral surface 63A of the second member 40A and the inner peripheral surface constant portion 34 of the first member 30.

[0051] As long as the functions and effects of the present invention are achieved, the present invention is not limited to Example 1 and Example 2. In Example 1 and Example 2, the first member side is the upper side of the vehicle body side and the second member side is the lower side of the axle side, but the second member side may be the upper side of the vehicle body side and the first member side may be the lower side of the axle side. In other words, the hydraulic shock absorbers of the examples may be of either an upright type or an inverted type. [Industrial Applicability]

[0052] The load generating member of the present invention is suitable for use in a hydraulic shock absorber for a motorcycle. [Explanation of symbols]

[0053] 10...Hydraulic shock absorber 11...Cylinder 13...No. 1 oil room 14…Second oil chamber 15...Blocking member 16...Piston 17...Rod 26...Oil lock mechanism 27...Oil lock oil chamber 30...First member 31...Cylinder part 33...Inner surface of the cylindrical portion 40...Second member 41...bottom 43...Bottom end surface (end surface) 45...Cylinder part 46...communicating hole, R...diameter of communicating hole 47...Valve 50...flow path 51…Steady flow path 52...First flow path, S1, T1...Flow path area of ​​the first flow path 53...Second flow path, S2, T2...Flow path area of ​​second flow path 60...Outer circumferential surface of second member 64...Large diameter section 65…Small diameter part 70...groove, W...groove width 80...Annular member

Claims

1. the oil lock mechanism includes a cylindrical cylinder, a piston that divides the interior of the cylinder into an upper first oil chamber and a lower second oil chamber, a rod to which the piston is fixed and a portion of which protrudes from a lower end of the cylinder, a closing member that closes the lower side of the cylinder and supports the rod, and an oil lock mechanism that hydraulically restricts movement of the piston toward the second oil chamber, the oil lock mechanism includes a first member provided in the second oil chamber of the cylinder and having an inner circumferential surface with a constant inner diameter, and a second member provided on the rod and insertable into the first member, the second member has a bottom portion having a through hole through which the rod passes, and a tubular portion extending upward from an outer circumferential edge of the bottom portion, the bottom portion of the second member has a communication hole that allows communication between the interior of the second member and the second oil chamber, the communication hole has a valve that can be opened and closed in response to oil pressure generated when the second member is inserted into the first member, the second member is movable along the axis of the rod to come into contact with or move away from the valve; an outer peripheral surface of the cylindrical portion of the second member and an inner peripheral surface of the first member can define a steady flow path having a constant flow path area regardless of a position in the axial direction, the steady flow path has a first flow path on the first member side and a second flow path on the second member side, the flow paths having different flow path areas; A hydraulic shock absorber, wherein a flow path area of ​​the second flow path is larger than a flow path area of ​​the first flow path.

2. the outer circumferential surface of the cylindrical portion of the second member has a large diameter portion and a small diameter portion having different diameters, The hydraulic shock absorber according to claim 1 , wherein the large diameter portion defines the first flow passage, and the small diameter portion defines the second flow passage.

3. the cylindrical portion of the second member has an annular member, an outer diameter of the annular member is larger than a diameter of the outer circumferential surface of the second member; The hydraulic shock absorber according to claim 1 , wherein the annular member defines the first flow passage, and the outer peripheral surface of the second member is capable of defining the second flow passage.

4. an end surface of the bottom of the second member has a groove that communicates with the communication hole and surrounds the through hole; When the valve closes the communication hole, the groove is closed by the valve, 4. The hydraulic shock absorber according to claim 1, wherein a width of the groove is smaller than a diameter of the communication hole.

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