JP2024056525A - Hydraulic shock absorber - Google Patents

Abstract

[Problem] To provide a hydraulic shock absorber that can quickly reach a peak damping force by an oil lock mechanism and maintain that damping force. [Solution] An oil lock mechanism 26 includes a first member 30 having an inner circumferential surface 33 with a constant inner diameter, and a second member 40 that can be inserted into the first member 30. An outer circumferential surface 60 of a tubular portion 45 of the second member 40 and the inner circumferential surface 33 of the first member 30 can define a steady flow path 51 with a constant flow path area regardless of the position in the axis AX direction. The steady flow path 51 includes a first flow path 52 and a second flow path 53 that 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. [Selected Figure] Figure 7

Description

The present invention relates to a hydraulic shock absorber equipped with an oil lock mechanism.

Saddle-type vehicles, such as motorcycles and three-wheeled vehicles, are equipped 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.

The hydraulic shock absorber disclosed in Patent Document 1 is a rear suspension installed on a motorcycle. This rear suspension includes a cylindrical cylinder, a piston that divides the inside 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 blocking member that blocks the lower end of the cylinder and supports the rod.

When an impact is applied to the rear suspension rod from the wheel, the piston moves and oil (hydraulic oil) flows 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, and the rear suspension absorbs the impact.

JP 2019-44786 A

Inside the second oil chamber of the cylinder, there is an oil lock mechanism that uses oil pressure to prevent the piston from moving toward the vehicle body, thus preventing bottoming out. The oil lock mechanism is equipped with a cup-shaped first member (oil lock cup) that opens downward, and a second member (oil lock piece) that is attached to the upper end of the rod and can be inserted inside the first member.

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 surrounded by the first and second members flows through the flow path into the second oil chamber, generating a damping force.

The second member further 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, the oil in the oil chamber surrounded by the first member and the second member flows into the second oil chamber through the flow path, generating a damping force.

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,
Through this gap, oil flows from the second oil chamber into the oil chamber surrounded by the first member and the second member, and it is possible to prevent the oil chamber surrounded by the first member and the second member from becoming negative pressure.

In a hydraulic shock absorber configured in this way, the damping force increases as the amount of insertion of the second member into the first member increases, so it takes time for the damping force to reach its peak.

The objective of the present invention is to provide a hydraulic shock absorber that can quickly reach a peak damping force using an oil lock mechanism and maintain that damping force.

After extensive research, the inventors have found that it is possible to provide a hydraulic shock absorber in which the outer circumferential surface of the tubular portion of the second member of the oil lock mechanism and the inner circumferential 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, which 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, and which allows the damping force of the oil lock mechanism to reach its peak early and maintain that damping force. The present invention was completed based on these findings.

According to the present disclosure, a cylindrical cylinder is provided with a piston that divides the inside 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 the lower end of the cylinder, a blocking member that blocks the axle side of the cylinder and supports the rod, and an oil lock mechanism that hydraulically suppresses movement of the piston toward the second oil chamber, 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 blocking member that extends from the outer circumferential edge of the bottom portion toward the vehicle body side, and a cylindrical portion through which the second member is inserted, the bottom of the second member has a communication hole that can communicate the inside of the second member with the second oil chamber, the communication hole has a valve that can be opened and closed according to the oil pressure generated when the second member is inserted into the first member, the second member can move along the axis of the rod to contact or separate from the valve, 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 area regardless of the axial position, 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.

This disclosure makes it possible to provide a hydraulic shock absorber that allows the damping force of the oil lock mechanism to reach its peak quickly and maintain that damping force.

1 is a cross-sectional view of a hydraulic shock absorber provided with a second member according to a first embodiment. FIG. 2 is a cross-sectional view of an oil lock mechanism of the hydraulic shock absorber shown in FIG. 1 . 1 is a cross-sectional view of the oil lock mechanism in a state in which the hydraulic shock absorber is compressed and the second member is inserted into the first member. FIG. 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. 13 is a cross-sectional view of the oil lock mechanism in a state in which the second member is separated from the valve due to the hydraulic shock absorber being extended. FIG. FIG. 13 is a perspective view of a second member and a valve that can be nested on the bottom of the second member. 7A is a cross-sectional view of a flow path defined by an inner circumferential surface of a first member and an outer circumferential surface of a second member, and FIG 7B is a view taken along line 7B in FIG 6. 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 an outer circumferential surface of the second member and an inner circumferential surface of the first member in Fig. 8A.

The embodiment of the present invention will be described below with reference to the attached drawings. In the drawings, Up indicates the top (body side) and Dn indicates the bottom (axle side).

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 inside 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.

The hydraulic shock absorber 10 further includes an outer tube 22 that surrounds the rod 17 protruding from the cylinder 11 and is slidable against the outer circumferential 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-body-side mounting member 25 that is fixed to the upper end of the cylinder 11.

[Oil lock mechanism]
Please refer to Fig. 2. An oil lock mechanism 26 that uses oil pressure to prevent the piston 16 (see Fig. 1) from moving toward the vehicle body is provided inside the second oil chamber. The oil lock mechanism 26 includes a first member 30 provided in the second oil chamber, and a second member 40 that is provided at the upper end 18 (the end on the vehicle body side) of the rod 17 and can be inserted into the first member 30.

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

The outer peripheral surface 32 of the first member 30 is fixed to the inner peripheral surface 12 of the cylinder 11. That is, the first member 30 divides the second oil chamber 14 and the third oil chamber 29, which 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 inside of the cylindrical portion 31 of the first member 30 are in communication with each other via a hole 38 in the top plate portion 37. The hole 38 does not have to be provided. The third oil chamber 29 and the second oil chamber 14 are in communication with each other via at least one hole 36 in the cylindrical portion 31.

[Inner circumferential surface of first member]
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 which 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.

[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 periphery of the bottom portion 41 toward the vehicle body.

The bottom 41 has a number 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 41. The valve 47 is composed of at least one superimposed disk. Each disk is made of spring steel and is elastically deformable.

[Moving mechanism for second member]
The second member 40 is provided so as to be movable along the axis line AX. The position of the second member 40 with respect to the valve 47 is changed, so that the second member 40 can come into contact with or be separated from the valve 47.

A cylindrical spacer 48 is disposed between the outer circumferential surface 19 of the upper end 18 of the rod 17 and the inner circumferential surface of the through hole 42 of the bottom 41. The upper end of the spacer 48 is expanded in diameter to form a spring bearing 48a. A valve spring 47a is disposed between the spring bearing 48a and the upper end surface 44 of the bottom 41, which generates a force pressing the bottom 41 of the second member 40 against the valve 47.

A fixing member 49 (e.g., a nut) for fixing the spacer 48 is provided at the upper end 18 of the rod 17. The fixing member 49 sandwiches the spacer 48 together with the valve 47.

[Operation of oil lock mechanism]
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 an oil lock oil chamber 27. The oil pressure in the oil lock oil chamber 27 increases as the hydraulic shock absorber 10 is compressed.

[Flow path]
Refer to Fig. 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 passage 50 through which oil flows. The oil in the oil lock oil chamber 27 flows into the second oil chamber 14 through the flow passage 50, generating a damping force. The detailed configuration of the flow passage 50 will be described later.

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

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.

[Shape of outer circumferential surface of second member]
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 is reduced toward the vehicle body side (upper side), an axle side reduced diameter portion 62 whose diameter is reduced toward the axle side, and an outer peripheral surface constant portion 63 located between these portions 61, 62 and whose diameter is constant (not reduced or expanded) regardless of the position in the axis AX direction. The outer peripheral surface constant portion 63 has a large diameter portion 64 and a small diameter portion 65 whose diameters are different from each other. The small diameter portion 65 is located on the axle side of the large diameter portion 64.

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

[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.

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 constant inner 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 surface portion 34 of the first member 30.

[groove]
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.

[Groove width]
7B, the width W of the groove 70 is smaller than the diameter R of the communication hole 46 (W<R).

[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 a flow passage 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.

The flow path 50 includes a steady flow path 51 whose flow area is constant regardless of the 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 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 cylindrical portion 45 of the second member 40 and the inner surface constant portion 34 of the first member 30. The second flow path 53 is defined by the small diameter portion 65 of the cylindrical portion 45 of the second member 40 and the inner surface constant portion 34 of the first member 30.

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 the upper end to the lower end, as in the prior art hydraulic shock absorber, the damping force of the oil lock mechanism 26 reaches its peak earlier.

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 a first flow passage 52 with a large flow passage 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.

Therefore, the hydraulic shock absorber 10 can allow the damping force of the oil lock mechanism 26 to reach its peak quickly and maintain that damping force.

Instead of the small diameter portion 65, for example, a groove may be formed in the circumferential direction on the outer peripheral surface 60 of the tubular portion 45 of the second member 40. In other words, as long as the flow area S2 of the second flow path 53 is larger than the flow area S1 of the first flow path 52, the configuration of the outer peripheral surface 60 of the second member 40 does not matter.

See Figures 6 and 7B. In addition, the lower end surface 43 (the end surface on the axle side) of the bottom 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 blocked by the valve 47. The width W of the groove 70 is smaller than the diameter R of the communication hole 46 (W<R).

That is, when the second member 40 is inserted into the first member 30 and oil flows from the oil lock chamber 27 to 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, compensating for the damping force that occurs when oil flows through the flow path 50. Also, as long as the valve 47 functions as a lid, the W of the groove 70 and the diameter R of the communication hole 46 are not limited to this (W>R may also be acceptable).

Example 2
8A and 8B show a second member 40A included in the hydraulic shock absorber according to the embodiment 2. The same reference numerals as those in the embodiment 1 are used for the configurations and effects common to the second member 40 in the embodiment 1, and the description thereof will be omitted.

The outer peripheral surface 60A of the tubular 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 axis AX direction. 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 63, 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.

That is, the outer peripheral surface 64A of the annular member 80 corresponds to the large diameter portion 64 in Example 1. The outer peripheral surface constant portion 63A of the second member 40 corresponds to the small diameter portion 65 in Example 1.

Refer to FIG. 8B. The flow path 51A includes a steady flow path 51A whose flow 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 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.

In detail, 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.

As long as the action and effect 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 and the second member side is the lower side of the axle, but the second member side may be the upper side of the vehicle body and the first member side may be the lower side of the axle. In other words, the hydraulic shock absorber in the examples may be of either an upright or inverted type.

The load generating member of the present invention is suitable for use in hydraulic shock absorbers for motorcycles.

10... Hydraulic shock absorber 11... Cylinder 13... First oil chamber 14... Second oil chamber 15... Closing member 16... Piston 17... Rod 26... Oil lock mechanism 27... Oil lock oil chamber 30... First member 31... Cylindrical portion 33... Inner peripheral surface of cylindrical portion 40... Second member 41... Bottom portion 43... Lower end surface (end surface) of bottom portion
45...Cylindrical portion 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 first flow path 53...Second flow path, S2, T2...Flow path area of second flow path 60...Outer periphery of second member 64...Large diameter portion 65...Small diameter portion 70...Groove, W...Width of groove 80...Annular member

Claims (4)

the oil lock mechanism includes a cylindrical cylinder, a piston dividing 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 closing the lower side of the cylinder and supporting the rod, and an oil lock mechanism hydraulically restricting movement of the piston towards the second oil chamber,
the oil lock mechanism includes 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 on the rod and can be inserted 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 periphery of the bottom portion,
the bottom portion of the second member has a communication hole that allows communication between an inside 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 an axis of the rod to come into contact with or move away from the valve,
an outer circumferential surface of the cylindrical portion of the second member and an inner circumferential surface of the first member can define a steady flow passage having a constant flow passage area regardless of a position in an axial direction,
The stationary 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. 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 larger diameter portion is capable of defining the first flow passage and the smaller diameter portion is capable of defining the second flow passage. The cylindrical portion of the second member has an annular member,
The outer diameter of the annular member is larger than the diameter of the outer circumferential surface of the second member,
The hydraulic shock absorber of claim 1 , wherein the annular member defines the first flow passage, and the outer circumferential surface of the second member is capable of defining the second flow passage. 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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