shock absorber

Abstract

To provide a shock absorber including a valve capable of suppressing generation of abnormal sounds and developing a check valve function.SOLUTION: A valve 93 according to this invention includes a leaf valve element 931, an opposite face 932 opposed to the leaf valve element 931 for prohibiting passage of working liquid through a liquid path 91 where the leaf valve element 931 is arranged, and a seated surface 933 for, when the leaf valve element 931 is elastically deformed by a predetermined amount, abutting on the leaf valve element 931 for prohibiting the passage of the working liquid through the liquid path 91 where the leaf valve element 931 is arranged. The leaf valve element 931 is elastically deformed in a direction of separating from the seated surface 933 so that the working liquid can pass in a permission stroke for permitting the passage of the working liquid. The predetermined amount is set so that the leaf valve element 931 abuts on the seated surface 933 when a speed of a piston 3 exceeds an upper limit value in a predetermined normal range in a limit stroke.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a shock absorber. [Background technology]

[0002] Generally, a shock absorber includes a cylinder, a piston that divides the interior of the cylinder into a first chamber and a second chamber, a main communication passage provided in the piston that connects the first chamber to the second chamber, and a main valve that opens and closes the main communication passage. As described in, for example, Japanese Patent Laid-Open Publication No. 8-223994, some shock absorbers include an auxiliary communication passage that connects the first chamber to the second chamber in addition to the above communication passage, a rotary valve that changes the flow cross-sectional area of the auxiliary communication passage, and an auxiliary valve that opens and closes the auxiliary communication passage. The rotary valve is rotated by the driving force of an electric motor. In this configuration, the flow cross-sectional area of the auxiliary communication passage is adjusted in accordance with the rotation of the rotary valve, thereby enabling adjustment of the damping force characteristics of the shock absorber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-223994 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-173140 Summary of the Invention [Problem to be solved by the invention]

[0004] The auxiliary valve is composed of an annular leaf spring member that elastically deforms due to the pressure difference to open and close the auxiliary communication passage. The auxiliary valve is composed of an extension stroke valve that opens during the extension stroke when the shock absorber extends, and a compression stroke valve that opens during the compression stroke when the shock absorber compresses. The leaf valve element of the extension stroke valve is configured to seat on a seating surface in the initial state and during the compression stroke, and to move away from the seating surface during the extension stroke. The leaf valve element of the compression stroke valve is configured to seat on a seating surface in the initial state and during the extension stroke, and to move away from the seating surface during the compression stroke.

[0005] The leaf valve element of each valve elastically deforms in response to the movement of the shock absorber, and comes into contact with and separates from the seating surface. Therefore, every time the shock absorber moves, the leaf valve element comes into contact with and separates from the seating surface. When the leaf valve element comes into contact with the seating surface, abnormal noise occurs.

[0006] On the other hand, for example, Japanese Patent Application Laid-Open No. 2016-173140 describes a valve consisting of a leaf valve element and a facing surface that faces the leaf valve element. With this configuration, there is no seating surface for the leaf valve element, and noise caused by the two elements coming into contact with each other is not generated. However, this valve does not function as a check valve. For example, in a shock absorber in which the extension stroke fluid path and the compression stroke fluid path are formed independently, a valve with check valve function is essential. An object of the present invention is to provide a shock absorber that can suppress the generation of abnormal noise and is equipped with a valve that can function as a check valve. [Means for solving the problem]

[0007] The shock absorber of the present invention comprises a cylinder, a piston slidably disposed within the cylinder and dividing the interior of the cylinder into a first chamber and a second chamber, a fluid passage provided within the cylinder for communicating the first chamber with the second chamber, and a valve provided for the fluid passage, wherein the valve comprises a leaf valve element having a fixed end and a free end, an opposing surface facing the free end of the leaf valve element and, together with the leaf valve element, forbidding the passage of hydraulic fluid through the fluid passage in which the leaf valve element is disposed at least when the leaf valve element is not elastically deformed, and a valve for preventing the passage of hydraulic fluid. and a seating surface that abuts against the leaf valve element when the leaf valve element elastically deforms by a predetermined amount during a limiting stroke to restrict the hydraulic fluid, and together with the leaf valve element, prohibits the passage of the hydraulic fluid through the hydraulic path in which the leaf valve element is arranged, wherein during an allowing stroke to allow the passage of the hydraulic fluid, the leaf valve element elastically deforms in a direction away from the seating surface so that the hydraulic fluid can pass through via a clearance between the free end and the opposing surface, and the predetermined amount is set so that the leaf valve element abuts against the seating surface during the limiting stroke when the speed of the piston exceeds an upper limit value of a predetermined normal range. [Effects of the Invention]

[0008] According to the present invention, a valve is configured with a leaf valve element, an opposing surface, and a seating surface. When the piston speed is equal to or less than the upper limit of the normal operating range, the leaf valve element does not contact the seating surface, thereby suppressing the generation of abnormal noise. On the other hand, when the piston speed exceeds the upper limit of the normal operating range, the leaf valve element contacts the seating surface and functions as a highly accurate check valve. As a result, the valve restricts the passage of hydraulic fluid while suppressing the generation of abnormal noise within the normal operating range of piston speed, and functions as a highly accurate check valve by seating outside the normal operating range. Outside the normal operating range, i.e., in the range where the piston speed is high, the damping force increases and the elastic deformation speed of the leaf valve element slows. Therefore, with this configuration, the intensity of abnormal noise caused by seating is suppressed. According to the present invention, a valve that can suppress the generation of abnormal noise and function as a check valve can be realized. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a conceptual diagram of a shock absorber according to the present embodiment. [Figure 2] FIG. 2 is a cross-sectional conceptual view showing the detailed configuration (excluding the cylinder) of the shock absorber of the present embodiment. [Figure 3] FIG. 2 is a conceptual diagram of an inner pipe according to the present embodiment. [Figure 4] 2 is a conceptual cross-sectional view showing a cross section perpendicular to the axial direction of the hollow rod, the rotary valve, and the inner pipe of the embodiment. FIG. [Figure 5] 1 is a conceptual cross-sectional view showing a cross section perpendicular to the axial direction of a hollow rod and a rotary valve in a conventional configuration without an inner pipe. [Figure 6] FIG. 6 is a partial enlarged view of the rod hole and valve hole at the bottom of FIG. 5. [Figure 7] FIG. 2 is a conceptual diagram of an extension stroke valve according to the present embodiment. [Figure 8] FIG. 2 is a conceptual diagram of an extension stroke valve according to the present embodiment. [Figure 9] FIG. 2 is a conceptual diagram of an extension stroke valve according to the present embodiment. [Figure 10] FIG. 2 is a conceptual diagram of an extension stroke valve according to the present embodiment. [Figure 11] FIG. 2 is a conceptual diagram of an extension stroke valve according to the present embodiment. [Figure 12] FIG. 10 is a diagram showing the relationship between travel time ratio and piston speed in the present embodiment. [Figure 13] FIG. 10 is a diagram showing the relationship between the damping force and the valve opening / closing speed relative to the piston speed. [Figure 14] FIG. 2 is a conceptual diagram of a compression stroke valve according to the present embodiment. [Figure 15] FIG. 10 is a conceptual diagram showing a modified embodiment of the extension stroke valve of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a shock absorber 1 according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition to the embodiment described below, the present invention can be embodied in various forms that include various modifications and improvements based on the knowledge of those skilled in the art.

[0011] 1, 2, and 3, the shock absorber 1 includes a cylinder 2, a piston 3, a hollow rod 4, a rotary valve 5, an electric motor 6, an inner pipe 7 as a cylindrical member, a main valve mechanism 8, and an auxiliary valve mechanism 9.

[0012] The cylinder 2 is a cylindrical member with a bottom, and is filled with hydraulic fluid. In the following description, the direction parallel to the central axis of the cylinder 2 is referred to as the axial direction, with one axial direction being referred to as the upper side and the other axial direction being referred to as the lower side. The upper end of the cylinder 2 is closed by an end cap (not shown), and a gas chamber 20 is formed at the lower end. The gas chamber 20 is defined by the lower end including the bottom surface of the cylinder 2 and the free piston 2a. As the shock absorber 1 expands and contracts, the volume of the rod portion 11 present in the cylinder 2 changes, and the gas chamber 20 absorbs this volume change.

[0013] The rod portion 11 extends through an end cap at the upper end of the cylinder 2 to the outside of the cylinder 2. Although not shown, the upper end of the rod portion 11 is connected to the vehicle body, and the lower end of the cylinder 2 is connected to an unsprung member of the vehicle. A spring (not shown) is arranged on the outer periphery of the rod portion 11.

[0014] The piston 3 is a cylindrical member slidably disposed within the cylinder 2 and divides the interior of the cylinder 2 into an upper chamber 21 as a first chamber and a lower chamber 22 as a second chamber. The piston 3 is disposed so that its central axis coincides with the central axis of the cylinder 2 and is slidable in the axial direction. The piston 3 is connected to a rod portion 11 via a hollow rod 4. In other words, the piston 3, hollow rod 4, and rod portion 11 move integrally.

[0015] The upper chamber 21 and the lower chamber 22 are each defined by the cylinder 2 and the piston 3. When the shock absorber 1 is installed on a vehicle, the upper chamber 21 is located above the piston 3, and the lower chamber 22 is located below the piston 3. The outer peripheral surface (sliding surface) of the piston 3 is made of resin.

[0016] The piston 3 is formed with a first main communication passage 31 and a second main communication passage 32, which are independent of each other and communicate between the upper chamber 21 and the lower chamber 22. The first main communication passage 31 (corresponding to the "communication passage") is a fluid passage whose upper end opens to the upper chamber 21 and whose lower end opens to the lower chamber 22, and the lower end opening is closed by a first main valve 81. During the extension stroke in which the shock absorber 1 extends, the upper chamber 21 becomes pressurized higher than the lower chamber 22, causing the first main valve (corresponding to the "valve mechanism") 81 to open, thereby communicating between the upper chamber 21 and the lower chamber 22 via the first main communication passage 31. The first main valve 81 is made of an annular leaf spring member fixed to the hollow rod 4. The outer periphery of the first main valve 81 moves downward due to elastic deformation, causing the lower end of the first main communication passage 31 to open to the lower chamber 22.

[0017] The second main communication passage 32 (corresponding to the "communication passage") is a fluid passage whose upper end opens to the upper chamber 21 and whose lower end opens to the lower chamber 22, and the upper end opening is closed by a second main valve (corresponding to the "valve mechanism") 82. During the compression stroke in which the shock absorber 1 compresses, the lower chamber 22 becomes pressurized higher than the upper chamber 21, the second main valve 82 opens, and the upper chamber 21 and the lower chamber 22 communicate with each other via the second main communication passage 32. The second main valve 82 is made up of an annular leaf spring member fixed to the hollow rod 4. The outer periphery of the second main valve 82 moves upward due to elastic deformation, and the upper end of the second main communication passage 32 opens to the upper chamber 21. In this way, the main valve mechanism 8 is made up of the first main valve 81, the second main valve 82, the first main communication passage 31, and the second main communication passage 32.

[0018] The hollow rod 4 is a cylindrical member disposed to penetrate the piston 3, and has a rod hole 41 opening to the upper chamber 21 and an internal fluid passage 42 connecting the rod hole 41 and the lower chamber 22. The upper end of the hollow rod 4 is closed by a rod portion 11 fixed to the upper end. The lower end of the hollow rod 4 opens to the lower chamber 22. A plurality of rod holes 41 are formed in a portion of the side surface of the hollow rod 4 that is located in the upper chamber 21. In this embodiment, two rows of rod holes 41, each consisting of four rod holes 41 spaced apart in the axial direction, are formed in the hollow rod 4, spaced apart in the circumferential direction (eight in total). The internal fluid passage 42 is formed inside the hollow rod 4; in other words, it is a fluid passage extending in the axial direction located inside the hollow rod 4. The internal fluid passage 42 can be said to be a portion through which working fluid flows inside the hollow rod 4.

[0019] The rotary valve 5 is rotatably disposed inside the hollow rod 4 and is a hollow member (cylindrical member) having a valve hole 51 that, together with the rod hole 41, connects the upper chamber 21 and the internal fluid passage 42. There is almost no clearance between the outer peripheral surface of the rotary valve 5 and the inner peripheral surface of the hollow rod 4, and the hydraulic fluid does not flow through the clearance. It can be said that the clearance exists to the extent that hydraulic fluid does not flow through it. The upper end of the rotary valve 5 is fixed to the output shaft 61 of the electric motor 6. The rotary valve 5 rotates by the driving force of the electric motor 6. A plurality of valve holes 51 are formed corresponding to the rod holes 41. That is, in this embodiment, two rows of valve holes 51, each consisting of four valve holes 51 spaced apart in the axial direction, are formed in the rotary valve 5, spaced apart in the circumferential direction (eight in total). The lower end of the rotary valve 5 is located above the lower end of the hollow rod 4. The "axial direction" can also be defined as follows. That is, the direction in which the rotation axis of the rotary valve 5 extends is defined as the axial direction, the direction from the piston 3 toward the upper chamber 21 is defined as one axial direction (upward), and the direction from the piston 3 toward the lower chamber 22 is defined as the other axial direction (downward). The extension line of the rotation axis of the rotary valve 5 and the extension line of the central axis of the cylinder 2 coincide with each other.

[0020] The electric motor 6 is configured to rotate the rotary valve 5 to adjust the cross-sectional area (which can also be referred to as the flow path cross-sectional area or the opening area) of the fluid path formed by the rod hole 41 and the valve hole 51. The flow path cross-sectional area of the fluid path connecting the upper chamber 21 and the internal fluid path 42 changes depending on the phase of the valve hole 51. The electric motor 6 is an example of an actuator, and a rotary solenoid, for example, may be used instead of the electric motor 6. The flow path cross-sectional area can be referred to as the area of a cross section obtained by cutting the object along a plane perpendicular to the flow direction of the working fluid (the penetration direction of the hole). In addition, in FIG. 2, due to space limitations, only one of the holes 41, 51, and 71, which are arranged symmetrically, is labeled (i.e., the labels for four of the eight holes are omitted).

[0021] A main body 60 of the electric motor 6 is fixed inside the rod portion 11. The electric motor 6 is, for example, a stepping motor. An output shaft 61 of the electric motor 6 extends downward (in the other axial direction) from the main body 60 and is made up of multiple members. The driving force of the electric motor 6 is transmitted to the rotary valve 5 by the output shaft 61. The driving of the electric motor 6 is controlled by a controller 12. The controller 12 is an electronic control unit (ECU) equipped with a CPU, memory, etc.

[0022] The inner pipe 7 is a cylindrical member that is arranged inside the rotary valve 5 and is immovable relative to the hollow rod 4 so as to cover at least a portion of the inner circumferential surface of the rotary valve 5. The inner pipe 7 is fixed to the hollow rod 4. The inner circumferential surface of the inner pipe 7 forms at least a portion of the internal liquid passage 42. In this embodiment, the inner pipe 7 extends from the upper end of the rotary valve 5 to the lower end of the hollow rod 4, and therefore the entire internal liquid passage 42 is formed by the inner circumferential surface of the inner pipe 7.

[0023] The inner pipe 7 has a communication hole 71 at a position facing the rod hole 41. In other words, a plurality of communication holes 71 are formed in the side surface of the inner pipe 7 in correspondence with the rod holes 41. In this embodiment, two rows of communication holes 71, each consisting of four communication holes 71 spaced apart in the axial direction, are formed in the inner pipe 7 in two rows spaced apart in the circumferential direction (eight in total).

[0024] 4, in this embodiment, the opening area (flow path cross-sectional area) of the communicating hole 71 is larger than the opening area (flow path cross-sectional area) of the rod hole 41 so that the rod hole 41 can be easily disposed within the communicating hole 71 when viewed in the radial direction, in other words, so that the entire rod hole 41 can easily overlap with the communicating hole 71 in the radial direction. The rod hole 41 and the communicating hole 71 are formed in the same phase. In this way, the upper chamber 21 and the internal liquid path 42 are communicated by the rod hole 41, the valve hole 51, and the communicating hole 71. The opening area of the rod hole 41 and the opening area of the valve hole 51 are equal to each other.

[0025] More specifically, the inner pipe 7 includes a small diameter portion 72 that forms the upper portion (one axial direction) and a large diameter portion 73 that forms the lower portion (the other axial direction). The small diameter portion 72 and the large diameter portion 73 are integrally formed. The outer diameter of the small diameter portion 72 is smaller than the outer diameter of the large diameter portion 73. The inner diameters of the small diameter portion 72 and the large diameter portion 73 are equal. The difference between the outer diameters of the small diameter portion 72 and the large diameter portion 73 corresponds to the plate thickness (radial width) of the rotary valve 5.

[0026] The rotary valve 5 is disposed between the outer circumferential surface of the small diameter portion 72 and the outer circumferential surface of the hollow rod 4. In other words, the lower end of the small diameter portion 72 is located lower than the lower end of the rotary valve 5. The upper end of the small diameter portion 72 is located at a position corresponding to the upper end of the rotary valve 5. There is almost no clearance between the outer circumferential surface of the small diameter portion 72 and the inner circumferential surface of the rotary valve 5, and the working fluid does not flow through this clearance. It can also be said that this clearance exists to the extent that the working fluid does not flow through it. All of the communicating holes 71 are formed in the small diameter portion 72.

[0027] The large-diameter portion 73 is positioned to face the outer peripheral surface of the hollow rod 4. The large-diameter portion 73 extends from a position below the lower end of the rotary valve 5 to the lower end of the hollow rod 4. There is almost no clearance between the outer peripheral surface of the large-diameter portion 73 and the inner peripheral surface of the hollow rod 4, and hydraulic fluid does not flow through this clearance. It can be said that this clearance exists to the extent that hydraulic fluid does not flow through it. A flange portion 74 is formed at the lower end of the large-diameter portion 73 and abuts against the lower end surface of the hollow rod 4. The lower end of the inner pipe 7 and the lower end of the hollow rod 4 are fixed, for example, by crimping. Fixing the inner pipe 7 to the lower end of the hollow rod 4 allows the fixing work to be performed after each component is placed inside the hollow rod 4, for example, facilitating the manufacturing and assembly of the shock absorber 1. Note that fixing the inner pipe 7 to the hollow rod 4 can be done by any known method, not just crimping.

[0028] The sub-valve mechanism 9 is a valve mechanism that includes a rotary valve 5 and is provided in the cylinder 2 separately from the main valve mechanism 8. The sub-valve mechanism 9 is equipped with an extension stroke fluid passage 91, a compression stroke fluid passage 92, an extension stroke valve 93, and a compression stroke valve 94. The extension stroke fluid passage 91 and the compression stroke fluid passage 92 are provided separately from the main communication passages 31, 32 and are fluid passages that independently connect the upper chamber 21 and the lower chamber 22. A portion of the extension stroke fluid passage 91 is formed by a first fluid passage forming portion 95, and a portion of the compression stroke fluid passage 92 is formed by a second fluid passage forming portion 96.

[0029] The first liquid path forming portion 95 comprises a cylindrical member 951 fixed to the outer peripheral surface of the hollow rod 4, a bottomed cylindrical member 952 fixed to the outer peripheral surface of the hollow rod 4 so as to encase the cylindrical member 951, and a cover member 953 fixed to the outer peripheral surface of the hollow rod 4 so as to close the upper opening of the bottomed cylindrical member 952.

[0030] The cylindrical member 951 is cylindrical and disposed so as to face the upper four of the eight rod holes 41. Two radially extending liquid paths 951a are formed at positions on the side surface of the cylindrical member 951 corresponding to the rod holes 41, spaced apart in the circumferential direction. Furthermore, an annular liquid path 951b connecting the two liquid paths 951a is formed in the inner peripheral portion of the cylindrical member 951. All four rod holes 41 located inside the cylindrical member 951 open to the liquid path 951b. The liquid path 951b is defined and formed by the inner peripheral surface of the cylindrical member 951, the outer peripheral surface of the hollow rod 4, and the bottomed cylindrical member 952.

[0031] The bottomed tubular member 952 is formed in the shape of a bottomed cylinder with a larger diameter than the tubular member 951. A clearance through which hydraulic fluid can flow is formed between the outer circumferential surface of the bottomed tubular member 952 and the inner circumferential surface of the cylinder 2. This clearance can be said to be an annular fluid path. The bottom surface that forms the lower end of the bottomed tubular member 952 abuts against the lower end surface of the tubular member 951. Inside the bottomed tubular member 952, an annular fluid chamber 95a is formed by the inner circumferential surface of the bottomed tubular member 952, the outer circumferential surface of the tubular member 951, and the cover member 953.

[0032] The cover member 953 is a cylindrical member and has one or more through-holes 953a (three in this example) that communicate with the upper chamber 21 and the liquid chamber 95a. The three through-holes 953a each extend axially and are spaced apart circumferentially. The lower end of each through-hole 953a forms a liquid chamber 953a1 that expands circumferentially. In other words, the lower end opening of the through-hole 953a expands circumferentially to form the liquid chamber 953a1 with a relatively large flow path cross-sectional area. Therefore, as shown in the right portion of the cover member 953 in FIG. 2, the liquid chamber 953a1, which is the space between the extension stroke valve 93 and the cover member 953, is part of the through-hole 953a (not shown). In this way, the extension stroke fluid passage 91 is made up of the through hole 953a, the fluid chamber 95a, the fluid passage 951a, the fluid passage 951b, the rod hole 41, the valve hole 51, the communication hole 71, and the internal fluid passage .

[0033] The extension stroke valve 93 is disposed within the fluid chamber 95a so as to close the lower end opening of the through-hole 953a. The extension stroke valve 93 is disposed inside the bottomed cylindrical member 952, between the cylindrical member 951 and the cover member 953, and is fixed to the outer peripheral surface of the hollow rod 4. The extension stroke valve 93 is configured to permit the passage of hydraulic fluid from the upper chamber 21 to the lower chamber 22 via the extension stroke fluid path 91 during the extension stroke, and to restrict the passage of hydraulic fluid from the lower chamber 22 to the upper chamber 21 via the extension stroke fluid path 91 during the compression stroke. In the following description, the stroke that permits the passage of hydraulic fluid will be referred to as the permit stroke, and the stroke that restricts the passage of hydraulic fluid will be referred to as the restrict stroke.

[0034] During the extension stroke, the piston 3 slides upward, the upper chamber 21 becomes pressurized higher than the lower chamber 22, and the extension stroke valve 93 elastically deforms downward to open, causing the lower end of the through-hole 953a to open to the fluid chamber 95a, and hydraulic fluid flows from the upper chamber 21 to the lower chamber 22 via the extension stroke fluid path 91. The detailed configuration of the extension stroke valve 93 will be described later.

[0035] The second liquid path forming portion 96 is a cylindrical member and is disposed between the first liquid path forming portion 95 and the piston 3. A ring-shaped liquid path (clearance) through which hydraulic fluid can pass is formed between the second liquid path forming portion 96 and the cylinder 2. The second liquid path forming portion 96 is fixed to the outer peripheral surface of the hollow rod 4 so as to face the lower four of the eight rod holes 41. Liquid paths 96a and 96b that communicate between the upper chamber 21 and the rod hole 41 are formed in the second liquid path forming portion 96.

[0036] One or more liquid passages 96a (here, three liquid passages 96a spaced apart in the circumferential direction) are formed in the second liquid passage forming portion 96, and extend at an angle with respect to the axial direction so as to extend radially outward as they extend downward. The lower ends of the liquid passages 96a open to the upper chamber 21, and the upper ends open to the liquid passages 96b. The liquid passages 96b are annular liquid passages formed in the inner peripheral portion of the second liquid passage forming portion 96 so that all of the liquid passages 96a are connected to each other. All four rod holes 41 located in the second liquid passage forming portion 96 open to the liquid passages 96b. The lower ends of the liquid passages 96a form a liquid chamber 96a1 extending in the circumferential direction.

[0037] In this way, the compression stroke fluid path 92 is made up of the fluid path 96a, the fluid path 96b, the rod hole 41, the valve hole 51, the communication hole 71, and the internal fluid path 42. The internal fluid path 42 is a fluid path that serves both the fluid paths 91, 92.

[0038] The compression stroke valve 94 is disposed below the second fluid path forming portion 96 so as to close the lower end opening of the fluid path 96a (fluid chamber 96a1). The compression stroke valve 94 is configured to permit the passage of hydraulic fluid from the lower chamber 22 to the upper chamber 21 via the compression stroke fluid path 92 during the compression stroke, and to restrict the passage of hydraulic fluid from the upper chamber 21 to the lower chamber 22 via the compression stroke fluid path 92 during the extension stroke. During the compression stroke, the piston 3 slides downward, the lower chamber 22 becomes higher in pressure than the upper chamber 21, and the compression stroke valve 94 elastically deforms downward to open, whereupon the lower end of the fluid path 96a opens to the upper chamber 21, and hydraulic fluid flows from the lower chamber 22 to the upper chamber 21 via the compression stroke fluid path 92. The detailed configuration of the compression stroke valve 94 will be described later.

[0039] The above-described components of the shock absorber 1 (cylinder 2, piston 3, hollow rod 4, rotary valve 5, output shaft 61, inner pipe 7, valves 81, 82, 93, 94, fluid path forming portions 95, 96, etc.) are arranged so that the lines including their own central axes coincide with each other. In other words, the components are arranged coaxially.

[0040] (torque for rotary valve) As the cross-sectional area of the fluid path formed by the rod hole 41 and the valve hole 51 decreases due to rotation of the rotary valve 5, it becomes more difficult for hydraulic fluid to flow through the extension stroke fluid path 91 or the compression stroke fluid path 92 when the shock absorber 1 expands or contracts, resulting in a harder driving feel. On the other hand, as the cross-sectional area of the fluid path increases, it becomes easier for hydraulic fluid to flow through the extension stroke fluid path 91 or the compression stroke fluid path 92, resulting in a softer driving feel.

[0041] In a conventional configuration without an inner pipe 7 (hereinafter also referred to as the "conventional configuration"), the rotary valve 5 receives torque due to fluid force generated when hydraulic fluid flows. Here, a case in which hydraulic fluid flows from the upper chamber 21 into the rotary valve 5 (corresponding to the internal fluid passage 42) through the rod hole 41 and the valve hole 51 during the extension stroke in the conventional configuration will be described with reference to FIGS. 5 and 6. Note that FIG. 6 is a partially enlarged view (conceptual diagram) of the rod hole 41 and the valve hole 51 at the bottom of FIG. 5. In the description, the rightward direction in FIG. 6 is defined as positive.

[0042] When the hydraulic fluid flows into the rotary valve 5, it is subjected to a force in the left direction in FIG. 6 and is decelerated. On the other hand, the rotary valve 5 is subjected to a force (reaction force) in the right direction in FIG. 6 due to the inflow of the hydraulic fluid. In other words, the rotary valve 5 is subjected to a counterclockwise torque. The flow velocity of the hydraulic fluid when it flows from the rod hole 41 into the valve hole 51 is defined as V. in The inflow angle of the hydraulic fluid at this time is α, and the flow velocity of the hydraulic fluid when it flows into the rotary valve 5 from the valve hole 51 is V. out where β is the inflow angle of the working fluid, r is the inner diameter of the rotary valve 5, ρ is the density of the working fluid, and Q is the flow rate of the working fluid, then the fluid force F and torque T1 that the rotary valve 5 receives are expressed by the following equations. F=-ρQ(v out cosβ-v in cosα) T1=2rF

[0043] Furthermore, the rotary valve 5 receives a counterclockwise torque according to the axial length L. The hydraulic fluid that has flowed into the rotary valve 5 flows while swirling as it passes through the fluid path (inside the rotary valve 5) of length L. As a result, the hydraulic fluid is slowed down by the resistance of the inner peripheral surface of the rotary valve 5, and a fluid force acts on the rotary valve 5. The rotational speed of the counterclockwise flow of hydraulic fluid that occurs near the valve hole 51 (inlet) of the rotary valve 5 is defined as ω in and the counterclockwise rotational speed ω of the hydraulic fluid generated near the lower end (outlet) of the rotary valve 5 is out Then, the torque T2 that the rotary valve 5 receives due to the swirling of the hydraulic fluid inside the rotary valve 5 in the conventional configuration is expressed by the following equation. T2=-rρQ(ω out -ω in )

[0044] (Effect of inner pipe) According to this embodiment, the inner pipe 7 is disposed inside the rotary valve 5 to form the internal fluid passage 42. Therefore, the inner pipe 7 receives at least a portion of the fluid force (torque T2) generated inside the rotary valve 5, thereby reducing the torque received by the rotary valve 5. As described above, according to this embodiment, the inner pipe 7 receives the torque T2 caused by the swirling of the hydraulic fluid that has flowed into the rotary valve 5, thereby reducing the torque received by the rotary valve 5 and reducing the load on the electric motor 6. Furthermore, the torque T1 generated when the hydraulic fluid flows in and out can be reduced by reducing the plate thickness of the rotary valve 5. The presence of the inner pipe 7 is thought to improve the structural durability of the rotary valve 5 and also enable a reduction in plate thickness.

[0045] The inner pipe 7 of this embodiment is arranged so as to cover the entire axial length of the portion of the inner circumferential surface of the rotary valve 5 that corresponds to the internal liquid passage 42. In other words, the upper end (one axial end) of the inner pipe 7 is located above the uppermost valve hole 51, and the lower end (the other axial end) of the inner pipe 7 is located below the lower end of the rotary valve 5. With this configuration, the length L of the portion of the rotary valve 5 that receives fluid force can be made virtually zero or approaching zero, and the generation of torque due to the wall resistance (resistance of the inner circumferential surface) of the rotary valve 5 can be made nearly zero (T2 ≒ 0).

[0046] Furthermore, since the inner pipe 7 has the small diameter portion 72, it is possible to easily assemble the inner pipe 7 to an existing configuration having the hollow rod 4 and the rotary valve 5 without making any design changes. The number and arrangement positions of the series of holes 41, 51, 71 can be set as desired.

[0047] (Details of the extension stroke valve) As shown in Figures 2 and 7, the extension stroke valve 93 is configured to include a leaf valve element 931 (corresponding to the "extension stroke leaf valve element"), an opposing surface 932 (corresponding to the "extension stroke opposing surface"), and a seating surface 933 (corresponding to the "extension stroke seating surface"). The leaf valve element 931 has a fixed end 931a and a free end 931b. The inner periphery of the leaf valve element 931 is the fixed end 931a that is fixed to the hollow rod 4, and the outer periphery is the free end 931b. The leaf valve element 931 is configured from one or more annular leaf spring members.

[0048] The leaf valve element 931 is disposed below the cover member 953 so as to close the lower end opening of the through-hole 953a (liquid chamber 953a1). The leaf valve element 931 is configured with multiple annular leaf spring members stacked in the axial direction, and the damping characteristics can be adjusted by changing the number and thickness of the leaf spring members. The leaf valve element 931 of this embodiment is configured with three leaf spring members stacked in the axial direction, and the outer diameter decreases from top to bottom. The leaf valve element 931 is elastically deformed by the pressure difference between the top and bottom, and the free end 931b is displaced.

[0049] The opposing surface 932 faces the free end 931b of the leaf valve element 931 and, together with the leaf valve element 931, prohibits the passage of hydraulic fluid through the fluid path in which the leaf valve element 931 is disposed (i.e., the extension stroke fluid path 91) at least when the leaf valve element 931 is not elastically deformed. The clearance between the leaf valve element 931 and the opposing surface 932 is set so that hydraulic fluid cannot pass through. The opposing surface 932 is formed in an annular shape so as to surround the outer circumferential surface of the leaf spring member 931d, which has the largest outer diameter of the leaf valve element 931. The radial overlap between the leaf spring member 931d and the opposing surface 932 (corresponding to the plate thickness of the leaf spring member 931d) affects the ease with which the extension stroke valve 93 changes state from closed to open. In the axial direction, the lower end position of the leaf spring member 931d of the leaf valve element 931 and the lower end position of the opposing surface 932 coincide.

[0050] The facing surface 932 is formed by the lower end of the cover member 953. An annular portion 953c that protrudes in an annular shape is formed on the outer periphery of the lower end of the cover member 953. The facing surface 932 is the inner circumferential surface of the annular portion 953c. The outer circumferential surface of the leaf valve element 931 faces the inner circumferential surface (facing surface 932) of the annular portion 953c over the entire periphery.

[0051] When the leaf valve element 931 elastically deforms by a predetermined amount during the restriction stroke in which the passage of hydraulic fluid is restricted, the seating surface 933 comes into contact with the leaf valve element 931 and, together with the leaf valve element 931, prohibits the passage of hydraulic fluid through the fluid path in which the leaf valve element 931 is arranged (i.e., the extension stroke fluid path 91). The seating surface 933 is arranged above the free end 931b of the leaf valve element 931 and spaced apart from the leaf valve element 931. The seating surface 933 is flat and extends annularly so as to face the free end 931b of the leaf valve element 931 over the entire circumference. The seating surface 933 is formed by a portion of the lower end surface of the cover member 953 that is radially inward of the facing surface 932.

[0052] During an enabling stroke in which the hydraulic fluid is permitted to pass, the leaf valve element 931 elastically deforms in a direction away from the seating surface 933 so that the hydraulic fluid can pass through a clearance between the free end 931b and the opposing surface 932. In the extension stroke valve 93, the enabling stroke is the extension stroke, and the restricting stroke in which the hydraulic fluid is restricted to pass is the compression stroke. On the other hand, in the compression stroke valve 94, the enabling stroke is the compression stroke, and the restricting stroke is the extension stroke.

[0053] During the extension stroke in which the shock absorber 1 extends (the stroke in which the piston 3 slides upward), the fluid pressure in the fluid chamber 953a1 located above the leaf valve element 931 becomes higher than the fluid pressure in the fluid chamber 95a located below the leaf valve element 931. This pressure difference causes the leaf valve element 931 to elastically deform, moving the free end 931b downward, as shown in Figure 8, and as shown in Figure 9, the clearance between the free end 931b of the leaf valve element 931 and the opposing surface 932 becomes large enough to allow hydraulic fluid to pass through, causing the extension stroke valve 93 to open.

[0054] When the extension stroke valve 93 opens, hydraulic fluid flows from the upper chamber 21 to the lower chamber 22 via the extension stroke fluid path 91. When the pressure difference decreases due to the flow of hydraulic fluid, the leaf valve element 931 transitions from the state shown in FIG. 9 to the state shown in FIG. 8 due to its own restoring force, and returns to the state shown in FIG. 7 (initial state). In the state shown in FIG. 8, the passage of hydraulic fluid is prohibited. At least when the outer peripheral surface of the leaf spring member 931d is positioned opposite the opposing surface 932, the passage of hydraulic fluid is restricted or prohibited.

[0055] On the other hand, during the compression stroke in which the shock absorber 1 is compressed (the stroke in which the piston 3 slides downward), the fluid pressure in the fluid chamber 95a located below the leaf valve element 931 becomes higher than the fluid pressure in the fluid chamber 953a1 located above the leaf valve element 931. This pressure difference causes the leaf valve element 931 to elastically deform, and the free end 931b moves upward, transitioning from the state shown in Fig. 7 to the state shown in Fig. 10. When the leaf valve element 931 elastically deforms by a predetermined amount, the free end 931b seats (comes into contact with) the seating surface 933, as shown in Fig. 11.

[0056] In the state shown in FIG. 10, the clearance between the free end 931b and the opposing surface 932 is kept small, and hydraulic fluid can hardly or not pass through the clearance at all. The extension stroke valve 93 is configured to allow a small (negligible) amount of hydraulic fluid to leak upward in the state shown in FIG. 10. In the state shown in FIG. 11, the leaf valve element 931 abuts against the seating surface 933, and the passage of hydraulic fluid is prohibited (a state in which passage is impossible). In this way, the extension stroke valve 93 limits or prohibits the passage of hydraulic fluid during the compression stroke, thereby functioning as a check valve.

[0057] In the state shown in FIG. 11, the leaf valve element 931 is elastically deformed by a predetermined amount from the state shown in FIG. 7. This predetermined amount is set so that the leaf valve element 931 comes into contact with the seating surface 933 when the speed of the piston 3 exceeds the upper limit of a predetermined normal range during the limiting stroke (here, the compression stroke). In other words, the leaf valve element 931 does not come into contact with the seating surface 933 when the speed of the piston 3 is equal to or lower than the upper limit of the normal range during the limiting stroke. The speed of the piston 3 can also be referred to as the stroke speed, and can be measured by, for example, a rod-shaped displacement meter or an acceleration sensor. The speed of the piston 3 can also be predicted by simulation.

[0058] As shown in Figure 12, the relationship between the speed of the piston 3 and its frequency when traveling on a good road (equivalent to an ordinary national highway) reveals that the speed of the piston 3 is 0.1 m / s or less for most of the traveling time. Furthermore, the speed of the piston 3 is 0.02 m / s or less for approximately 70% of the total traveling time, and 0.01 m / s or less for approximately 50% of the total traveling time. The upper limit of the normal range of the piston speed can be set based on the above experimental values. For example, the range of piston speeds that accounts for 50% of the total traveling time may be set as the normal range.

[0059] The upper limit of the normal operating range is preferably a value between 0.01 m / s and 0.1 m / s, for example. This ensures that, in calculations, the leaf valve element 931 and the seating surface 933 do not come into contact with each other for approximately 50% or more of the total travel time, and that they come into contact (seat) during extension and retraction at high piston speeds. Furthermore, the upper limit of the normal operating range is preferably a value between 0.02 m / s and 0.1 m / s, for example. This ensures that, in calculations, the leaf valve element 931 and the seating surface 933 do not come into contact with each other for 70% or more of the total travel time. The lower the frequency of contact between the leaf valve element 931 and the seating surface 933, the lower the frequency of abnormal noise.

[0060] The normal range of piston speed may be set depending on the vehicle type. The lower limit of the normal range is 0. In FIG. 12, the horizontal axis represents the speed (m / s) of the piston 3, and the vertical axis represents the ratio of running time to the total running time (the bar graph represents the running time ratio, and the line graph represents the cumulative ratio). In this experiment, a typical passenger car was used, and the total running time was approximately 18 minutes.

[0061] It is known that the damping force Fd of the extension stroke valve 93 is proportional to the two-thirds power of the velocity v of the piston 3 (Fd=Kv 2 / 3 ) (K is a proportionality constant). The lift amount (deformation amount) x of the leaf valve element 931 is proportional to the damping force F d (x=kF d ) (k is a proportionality constant). Therefore, as shown in FIG. 13, the opening and closing speed of the extension stroke valve 93 is inversely proportional to the one-third power of the speed of the piston 3 (dx / dv=2 / 3 kKv -1 / 3 ) In other words, the higher the speed of piston 3, the greater the damping force F d becomes larger, and the opening / closing speed (valve opening / closing speed) of the extension stroke valve 93 becomes slower. The slower the opening / closing speed of the extension stroke valve 93, the quieter the sound generated when the leaf valve element 931 seats on the seating surface 933.

[0062] For example, if the upper limit of the normal range is set to 0.1 m / s, during the compression stroke, when the speed of the piston 3 is 0.1 m / s or less, the leaf valve element 931 restricts the passage of hydraulic fluid in the state shown in Fig. 10. When a compression operation occurs in which the speed of the piston 3 exceeds 0.1 m / s, the amount of elastic deformation (lift amount) of the leaf valve element 931 increases, and the amount of hydraulic fluid leaking upward increases, but the leaf valve element 931 seats on the seating surface 933, reliably prohibiting the passage of hydraulic fluid.

[0063] (Details of the compression stroke valve) The compression stroke valve 94 has a similar configuration to the extension stroke valve 93, and as shown in Figures 2 and 14, is configured to include a leaf valve element 941 (corresponding to the "compression stroke leaf valve element"), an opposing surface 942 (corresponding to the "compression stroke opposing surface"), and a seating surface 943 (corresponding to the "compression stroke seating surface"). The leaf valve element 941 has an inner circumferential portion which is a fixed end 941a fixed to the hollow rod 4, and an outer circumferential portion which is a free end 941b. The leaf valve element 941 is configured from one or more annular leaf spring members.

[0064] The leaf valve element 941 is disposed below the second fluid path forming portion 96 so as to close the lower end opening of the fluid path 96a (fluid chamber 96a1). The leaf valve element 941 is configured with multiple annular leaf spring members stacked in the axial direction, and the damping characteristics can be adjusted by changing the number and thickness of the leaf spring members. The leaf valve element 941 of this embodiment is configured with three leaf spring members stacked in the axial direction, and the outer diameter decreases from top to bottom. The differential pressure between the top and bottom causes elastic deformation of the outer periphery of the leaf valve element 941.

[0065] The opposing surface 942 faces the free end 941b of the leaf valve element 941 and, together with the leaf valve element 941, prohibits the passage of hydraulic fluid through the fluid path in which the leaf valve element 941 is disposed (i.e., the compression stroke fluid path 92) at least when the leaf valve element 941 is not elastically deformed. The clearance between the leaf valve element 941 and the opposing surface 942 is set so that hydraulic fluid cannot pass through. The opposing surface 942 is formed in an annular shape so as to surround the outer circumferential surface of the leaf spring member 941d, which has the largest outer diameter of the leaf valve element 941. The radial overlap between the leaf spring member 941d and the opposing surface 942 (corresponding to the plate thickness of the leaf spring member 941d) affects the ease with which the compression stroke valve 94 changes from a closed state to an open state. In the axial direction, the lower end position of the leaf spring member 941d of the leaf valve element 941 coincides with the lower end position of the opposing surface 942.

[0066] The opposing surface 942 is formed by the lower end of the second liquid path forming portion 96. An annular portion 96c that protrudes in an annular shape is formed on the outer periphery of the lower end of the second liquid path forming portion 96. The opposing surface 942 is the inner circumferential surface of the annular portion 96c. The outer circumferential surface of the leaf valve element 941 faces the inner circumferential surface (opposing surface 942) of the annular portion 96c over the entire circumference.

[0067] When the leaf valve element 941 elastically deforms by a predetermined amount during the restriction stroke in which the passage of hydraulic fluid is restricted, the seating surface 943 comes into contact with the leaf valve element 941 and, together with the leaf valve element 941, prohibits the passage of hydraulic fluid through the hydraulic path in which the leaf valve element 941 is arranged (i.e., the compression stroke hydraulic path 92). The seating surface 943 is arranged above the free end 941b of the leaf valve element 941 and spaced apart from the leaf valve element 941. The seating surface 943 is flat and extends annularly so as to face the free end 941b of the leaf valve element 941 over the entire circumference. The seating surface 943 is formed by a portion of the lower end surface of the second hydraulic path forming portion 96 that is radially inward of the facing surface 942.

[0068] During an enabling stroke in which the hydraulic fluid is permitted to pass, the leaf valve element 941 elastically deforms in a direction away from the seating surface 943 so that the hydraulic fluid can pass through a clearance between the free end 941b and the opposing surface 942. In the compression stroke valve 94, the enabling stroke is the compression stroke, and the restricting stroke is the extension stroke. The state changes of the compression stroke valve 94 are the same as the state changes of the extension stroke valve 93 shown in Figures 7 to 11, and are not shown in the figures.

[0069] During the compression stroke in which the shock absorber 1 compresses (the stroke in which the piston 3 slides downward), the hydraulic pressure in the hydraulic chamber 96a1 located above the leaf valve element 941 becomes higher than the hydraulic pressure in the upper chamber 21 located below the leaf valve element 941. This pressure difference causes the leaf valve element 941 to elastically deform, moving its free end 941b downward. The clearance between the free end 941b of the leaf valve element 941 and the opposing surface 942 becomes large enough to allow hydraulic fluid to pass through, thereby opening the compression stroke valve 94. When the compression stroke valve 94 opens, hydraulic fluid flows from the lower chamber 22 into the upper chamber 21 via the compression stroke fluid path 92. When the pressure difference decreases due to the flow of hydraulic fluid, the leaf valve element 941 returns to its initial state due to its own restoring force. At least when the outer peripheral surface of the leaf spring member 941d is positioned facing the facing surface 942, the passage of the hydraulic fluid is restricted or prohibited.

[0070] On the other hand, during the extension stroke in which the shock absorber 1 extends (the stroke in which the piston 3 slides upward), the hydraulic pressure in the upper chamber 21 located below the leaf valve element 941 becomes higher than the hydraulic pressure in the hydraulic chamber 96a1 located above the leaf valve element 941. This pressure difference causes the leaf valve element 941 to elastically deform, and the free end 941b moves upward. When the leaf valve element 941 elastically deforms by a predetermined amount, the free end 941b seats on (comes into contact with) the seating surface 933.

[0071] When the free end 941b is in an upwardly moved state (not seated state), the clearance between the free end 941b and the opposing surface 942 is maintained small, and hydraulic fluid is unable to pass through the clearance or is unable to pass through the clearance at all. The compression stroke valve 94 is configured to allow a small (negligible) amount of hydraulic fluid to leak upward. When the leaf valve element 941 is in a state where it is elastically deformed a predetermined amount, the leaf valve element 941 abuts against the seating surface 943, and the passage of hydraulic fluid is inhibited (a state where it is impossible to pass through). In this way, the compression stroke valve 94 limits or inhibits the passage of hydraulic fluid during the extension stroke, thereby functioning as a check valve.

[0072] As described above, the leaf valve element 941 is elastically deformed by a predetermined amount from its initial state to seat on the seating surface 943. This predetermined amount is set so that, when the speed of the piston 3 exceeds an upper limit value of a predetermined normal range during the limiting stroke (here, the extension stroke), the leaf valve element 941 comes into contact with the seating surface 943. The upper limit value of the normal range of the piston speed is set to a value of 0.01 m / s or more and 0.1 m / s or less, or a value of 0.02 m / s or more and 0.1 m / s or less, similar to the extension stroke valve 93.

[0073] (Effect of extension stroke valve and compression stroke valve) According to this embodiment, when the speed of the piston 3 is equal to or lower than the upper limit of the normal operating range, the leaf valve elements 931, 941 restrict the passage of hydraulic fluid without contacting the corresponding seating surfaces 933, 943, thereby suppressing the generation of abnormal noise. On the other hand, when the speed of the piston 3 exceeds the upper limit of the normal operating range, the leaf valve elements 931, 941 contact the corresponding seating surfaces 933, 943, reliably prohibiting the passage of hydraulic fluid and functioning as check valves. As a result, during the limiting stroke, the sub-valve mechanism 9 restricts the passage of hydraulic fluid through the fluid paths 91, 92 while suppressing the generation of abnormal noise within the normal operating range of the piston 3 speed, and seats outside the normal operating range, functioning as a highly accurate check valve. Outside the normal operating range, i.e., in the range where the piston 3 speed is high, the damping force increases and the elastic deformation speed of the leaf valve elements slows. Therefore, with this configuration, the intensity of abnormal noise caused by seating is suppressed. As described above, this embodiment realizes the sub-valve mechanism 9 that can suppress the generation of abnormal noise and also function as a check valve. Note that, by configuring at least one of the extension stroke valve 93 and the compression stroke valve 94 as described above, the generation of abnormal noise can be suppressed.

[0074] Furthermore, by setting the upper limit of the normal operating range of piston speed to a value between 0.01 m / s and 0.1 m / s, or between 0.02 m / s and 0.1 m / s, noise can be suppressed for more than 50% of the total running time. In this embodiment, the above-described configuration is employed for both the extension stroke valve 93 and the compression stroke valve 94, so the damping characteristics are substantially the same during the extension stroke and the compression stroke. Examples of fluid paths connecting the upper chamber 21 and the lower chamber 22 within the cylinder 2 include communicating passages 31 and 32 and fluid paths 91 and 92. In this embodiment, the fluid paths 91 and 92 correspond to the "fluid paths" of the present invention, and the valves 93 and 94 correspond to the "valves" of the present invention. When the "fluid paths" of the present invention correspond to the communicating passages 31 and 32, the main valves 81 and 82 correspond to the "valves" of the present invention.

[0075] (others) The present invention is not limited to the above-described embodiment. For example, as shown in FIG. 15, the seating surfaces 933, 943 may be formed radially inward relative to the above-described embodiment. While FIG. 15 shows the extension stroke valve 93 as a representative example, the same applies to the compression stroke valve 94. Even with the configuration shown in FIG. 15, the leaf valve elements 931, 941 abut against the seating surfaces 933, 943 by elastically deforming by a predetermined amount set based on the normal range of piston speed. The configurations of the extension stroke valve 93 and the compression stroke valve 94 are applicable to any valve mechanism requiring a check valve function.

[0076] The inner pipe 7 may also be fixed to a portion of the hollow rod 4 other than the lower end. The inner pipe 7 may also be arranged so as to cover a portion of the inner circumferential surface of the rotary valve 5 corresponding to the internal fluid passage 42; for example, the lower end of the inner pipe 7 may be located higher than the lower end of the rotary valve 5. In this case, the internal fluid passage 42 is defined by, for example, the inner circumferential surface of the inner pipe 7, the inner circumferential surface of the rotary valve 5, and the inner circumferential surface of the hollow rod 4. By having the inner pipe 7 cover at least a portion of the inner circumferential surface of the rotary valve 5 corresponding to the internal fluid passage 42, the torque that the rotary valve 5 receives due to the fluid force of the hydraulic fluid is reduced. A configuration including an inner pipe 7 is applicable to any valve mechanism including a rotary valve 5.

[0077] The present invention may also be applied to the main valve mechanism 8. That is, at least one of the first main valve 81 and the second main valve 82 may be configured with a leaf valve element, an opposing surface, and a seating surface, as in the embodiment. This also makes it possible to realize a valve mechanism that can suppress the generation of abnormal noise and exhibit check valve function, as in the embodiment. In this way, according to the present invention, at least one of the first main valve 81, the second main valve 82, the extension stroke valve 93, and the compression stroke valve 94 can be formed with a leaf valve element, an opposing surface, and a seating surface. In this way, the valve configuration (leaf valve element, opposing surface, and seating surface) of the present invention can be applied to all valves of a shock absorber, such as a main valve, a sub-valve, and a base valve. [Explanation of symbols]

[0078] 1: shock absorber, 2: cylinder, 21: upper chamber (first chamber), 22: lower chamber (second chamber), 3: piston, 31: first main communicating passage (communicating passage), 32: second main communicating passage (communicating passage), 8: main valve mechanism, 81: first main valve (valve mechanism), 82: second main valve (valve mechanism), 91: extension stroke fluid passage, 92: compression stroke fluid passage, 93: extension stroke valve, 931: leaf valve element (extension stroke leaf valve element), 932: opposing surface (extension stroke opposing surface), 933: seating surface (extension stroke seating surface), 94: compression stroke valve, 941: leaf valve element (compression stroke leaf valve element), 942: opposing surface (compression stroke opposing surface), 943: seating surface (compression stroke seating surface).

Claims

1. A cylinder; a piston slidably disposed within the cylinder and dividing the interior of the cylinder into a first chamber and a second chamber; a fluid passage provided in the cylinder for communicating the first chamber with the second chamber; a valve provided for the liquid path; A shock absorber comprising: The valve is a leaf valve element having a fixed end and a free end; an opposing surface that faces the free end of the leaf valve element and, together with the leaf valve element, prohibits the passage of hydraulic fluid through the fluid path in which the leaf valve element is disposed, at least when the leaf valve element is not elastically deformed; a seating surface that abuts against the leaf valve element and, together with the leaf valve element, prohibits the passage of the hydraulic fluid through the fluid path in which the leaf valve element is arranged when the leaf valve element elastically deforms by a predetermined amount during a restricting stroke in which the passage of the hydraulic fluid is restricted; Equipped with the leaf valve element elastically deforms in a direction away from the seating surface during an enabling stroke that allows the hydraulic fluid to pass through, so that the hydraulic fluid can pass through a clearance between the free end and the opposing surface; The predetermined amount is set so that the leaf valve element abuts on the seating surface when the speed of the piston exceeds an upper limit value of a predetermined normal range during the limit stroke. Shock absorber.

2. a communication passage provided in the piston for communicating the first chamber with the second chamber; a valve mechanism provided for the communication passage; an extension stroke fluid path and a compression stroke fluid path, at least one of which constitutes the fluid path, and which are provided separately from the communication path and independently connect the first chamber and the second chamber; an extension stroke valve configured to allow the hydraulic fluid to pass from the first chamber to the second chamber via the extension stroke fluid path during an extension stroke and to restrict the hydraulic fluid to pass from the second chamber to the first chamber via the extension stroke fluid path during a compression stroke; a compression stroke valve configured to allow the hydraulic fluid to pass from the second chamber to the first chamber via the compression stroke fluid path during the compression stroke and to restrict the hydraulic fluid to pass from the first chamber to the second chamber via the compression stroke fluid path during the extension stroke; Furthermore, At least one of the extension stroke valve and the compression stroke valve corresponding to the fluid path constitutes the valve and includes the leaf valve element, the opposing surface, and the seating surface. The shock absorber according to claim 1 .

3. The extension stroke valve is an extension stroke leaf valve element as the leaf valve element; an extension stroke opposing surface that opposes the free end of the extension stroke leaf valve element and that, together with the extension stroke leaf valve element, prohibits the passage of the hydraulic fluid through the extension stroke hydraulic path at least when the extension stroke leaf valve element is not elastically deformed; an extension stroke seating surface that comes into contact with the extension stroke leaf valve element when the extension stroke leaf valve element elastically deforms by the predetermined amount during the compression stroke, and that, together with the extension stroke leaf valve element, prohibits the passage of the hydraulic fluid through the extension stroke hydraulic path; Equipped with the extension stroke leaf valve element elastically deforms in a direction away from the extension stroke seating surface during the extension stroke so that the hydraulic fluid can pass through a clearance between the free end and the extension stroke opposing surface, The compression stroke valve is a compression stroke leaf valve element as the leaf valve element; a compression stroke opposing surface that opposes the free end of the compression stroke leaf valve element and that, together with the compression stroke leaf valve element, prohibits the passage of the hydraulic fluid through the compression stroke hydraulic path at least when the compression stroke leaf valve element is not elastically deformed; a compression stroke seating surface that comes into contact with the compression stroke leaf valve element and, together with the compression stroke leaf valve element, prohibits the passage of the hydraulic fluid through the compression stroke hydraulic path when the compression stroke leaf valve element elastically deforms by the predetermined amount during the extension stroke; Equipped with the compression stroke leaf valve element elastically deforms in a direction away from the compression stroke seating surface during the compression stroke so that the hydraulic fluid can pass through a clearance between the free end and the compression stroke opposing surface.

3. The shock absorber according to claim 2.

4. the fluid path is at least one of a first communication passage and a second communication passage that are independent of each other and that communicate the first chamber and the second chamber provided in the piston, the valve provided for the fluid path includes the leaf valve element, the opposing surface, and the seating surface; The shock absorber according to claim 1 .

5. The upper limit of the normal range is set to a value of 0.01 m / s or more and 0.1 m / s or less. The shock absorber according to any one of claims 1 to 4.

6. The upper limit of the normal range is set to a value of 0.02 m / s or more and 0.1 m / s or less. The shock absorber according to any one of claims 1 to 4.

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