JP2009074562A - Damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a damper capable of exhibiting damping force with excellent responsiveness even in a contraction stroke. <P>SOLUTION: For solving the problem, this damper has a cylinder 1, a piston 2 slidingly inserted into the cylinder 1 and partitioned into a rod chamber R1 and a piston chamber R2 in the cylinder 1, a rod 3 movably inserted into the cylinder 1 and having one end connected to the piston 2, a reservoir R, an extension side damping flow passage 4 allowing a flow turning to the piston chamber R2 from the rod chamber R1 and applying resistance to a flow of a passing liquid, a pressure side damping flow passage 5 allowing a flow turning to the reservoir R from the piston chamber R2 and applying resistance to the flow of the passing liquid, a piston chamber side suction flow passage 6 allowing only a flow turning to the piston chamber R2 from the reservoir R, and a rod chamber side suction flow passage 7 allowing only a flow turning to the rod chamber R1 from the reservoir R. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a shock absorber.

  In a conventional shock absorber, for example, a piston that is slidably inserted into a cylinder and partitioned into a piston chamber and a rod chamber in the cylinder, and is movably inserted into the cylinder and one end connected to the piston Rod, a reservoir formed between the cylinder and the outer cylinder, a piston valve that allows flow from the rod chamber to the piston chamber and provides resistance to the flow of liquid passing through, and a flow from the piston chamber to the reservoir And a check valve that only allows the flow from the reservoir to the piston chamber, and a piston-side check valve that only allows the flow from the piston chamber to the rod chamber And is configured as a so-called single rod double cylinder type shock absorber (see, for example, Patent Document 1) .

  According to this shock absorber, in the expansion / contraction stroke of the shock absorber in which the piston moves in the axial direction with respect to the cylinder, the volume in which the rod enters the cylinder or the rod moves out of the cylinder becomes excessive or insufficient in the cylinder. The reservoir is compensated for by supplying or absorbing the excess or insufficient volume of hydraulic oil.

  In particular, during the contraction stroke, the volume of the rod chamber increases and the volume of the piston chamber decreases, so that the hydraulic oil flows into the flow from the piston chamber to the rod chamber and the flow from the piston chamber to the reservoir. Two flows occur.

  At this time, the hydraulic oil corresponding to the expansion of the rod chamber volume moves from the piston chamber to the rod chamber, and the hydraulic oil corresponding to the rod entry volume that is excessive in the cylinder is discharged from the piston chamber to the reservoir.

In the case of this shock absorber, in order to exert the compression side damping force during the contraction stroke, resistance is mainly given to the flow of hydraulic oil flowing out of the cylinder to increase the pressure in the rod chamber and the piston chamber, A damping force is generated by the pressure receiving area difference from the rod chamber, and the base valve is responsible for this pressure rise, giving resistance to the flow of hydraulic oil from the piston chamber to the reservoir, To increase the pressure.
Japanese Patent Laid-Open No. 11-182610 (FIG. 1)

  In such a double cylinder type shock absorber, the cylinder diameter cannot be increased because a reservoir is formed on the outer periphery, and the pressure in the piston chamber and the rod chamber is increased by increasing the pressure in the cylinder during the contraction stroke. Since the damping force is generated by the area difference, not only the piston chamber but also the rod chamber is compressed, and the amount of liquid to be compressed is larger than that during the expansion stroke, and the damping force is exhibited with good response during the contraction stroke. It is difficult.

  This is because the hydraulic oil has compressibility because it contains gas, and in order to generate a damping force with good responsiveness during the contraction stroke with a large amount of compressed liquid, the hydraulic oil is increased by increasing the pressure in the cylinder. It is conceivable to increase the apparent rigidity of the base valve and increase the resistance of the base valve, but if this is done, the cylinder internal pressure will become too high and the oil seal that seals the outer circumference of the rod will become stronger with the cylinder internal pressure. There is a risk of causing a new problem that the rod is pressed to the side and the smooth movement of the rod with respect to the cylinder is hindered.

  As another method, instead of the piston-side check valve, a valve that provides resistance to the flow from the piston chamber to the rod chamber during the contraction stroke is provided to depressurize the rod chamber. A method of generating a differential pressure between the two can be considered, but when this happens, the rod chamber is excessively decompressed, resulting in aeration in which the gas mixed in the compressed state in the hydraulic oil in the rod chamber appears as bubbles, There is a risk that not only the response of the damping force generation of the shock absorber will be deteriorated, but also a new problem that causes an undesirable phenomenon such as cavitation and erosion may occur.

  Therefore, the present invention was devised to improve the above-described problems, and an object of the present invention is to provide a shock absorber that can exhibit a damping force with good responsiveness even during a contraction stroke.

  In order to achieve the above object, a shock absorber in the problem solving means of the present invention includes a cylinder, a piston that is slidably inserted into the cylinder and partitioned into a rod chamber and a piston chamber, and a cylinder. A rod inserted movably and connected at one end to the piston, a reservoir, an extension-side damping channel that allows flow from the rod chamber to the piston chamber and resists the flow of liquid passing therethrough, and from the piston chamber A pressure-side damping flow path that allows flow toward the reservoir and provides resistance to the flow of liquid that passes through, a piston chamber-side suction flow path that allows only flow from the reservoir to the piston chamber, and only flow from the reservoir to the rod chamber And a rod chamber side suction flow path that allows

  According to the shock absorber of the present invention, during the contraction stroke, only the piston chamber is compressed and the pressure is increased to generate the compression side damping force, so that the pressure difference between the rod chamber and the piston chamber can be increased. As well as being able to reduce the amount of compressed liquid compared to conventional shock absorbers, it is possible to generate a damping force on the compression side with good responsiveness even for shock absorbers that employ a double cylinder type in which the cylinder diameter cannot be increased. Can do.

  In addition, in order to generate the damping force on the compression side with good responsiveness to the shock absorber, it is not necessary to pressurize the reservoir to increase the pressure in the rod chamber and piston chamber in the cylinder, that is, the pressure in the cylinder. Therefore, there is no problem that the rod is prevented from moving by strongly pressing the rod toward the rod side with the pressure in the cylinder.

  Further, during the contraction stroke, the rod chamber whose volume is expanded sucks the hydraulic oil from the reservoir through the rod chamber side suction flow path, so that the rod chamber is excessively decompressed and aeration occurs, generating damping force of the shock absorber. The responsiveness is not deteriorated, and undesirable phenomena such as cavitation and erosion are not caused.

  That is, in this shock absorber, it is possible to generate the damping force on the compression side with good responsiveness during the contraction stroke while avoiding the problems that occur in the conventional shock absorber, and the practicality and reliability of the shock absorber are improved. .

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a diagram illustrating the shock absorber of the present invention in principle. FIG. 2 is a longitudinal sectional view of a specific configuration example of the shock absorber according to the present invention. FIG. 3 is a partially enlarged longitudinal sectional view of a specific configuration example of the shock absorber according to the present invention.

  As shown in FIG. 1, the shock absorber D of the present invention includes a cylinder 1, a piston 2 that is slidably inserted into the cylinder 1, and is divided into a rod chamber R <b> 1 and a piston chamber R <b> 2. A rod 3 that is movably inserted into 1 and has one end connected to the piston 2, a reservoir R, and an extension side that allows flow from the rod chamber R1 to the piston chamber R2 and provides resistance to the flow of liquid passing therethrough. A damping channel 4, a compression side damping channel 5 that allows a flow from the piston chamber R2 to the reservoir R and provides resistance to the flow of liquid passing therethrough, and a piston chamber that allows only a flow from the reservoir R to the piston chamber R2. A side suction flow path 6 and a rod chamber side suction flow path 7 that allows only a flow from the reservoir R toward the rod chamber R1 are provided.

  More specifically, the cylinder 1 has a cylindrical shape. A piston 2 is slidably inserted into the cylinder 1, and the cylinder 1 is filled with a rod chamber R1 that is filled with liquid working oil. A piston chamber R2 is formed. A rod 3 is movably inserted into the cylinder 1 and one end thereof is connected to the piston 2. In the present embodiment, the liquid is hydraulic oil, but is not limited to this, and other liquids may be used.

  The piston 2 is provided with a port 4a that communicates the rod chamber R1 and the piston chamber R2, and a damping valve that provides resistance to the flow of hydraulic oil passing through the port 4a in the middle of the port 4a. 4b and a check valve 4c that allows only the flow from the rod chamber R1 to the piston chamber R2 are provided. In this embodiment, the port 4a, the damping valve 4b, and the check valve 4c are extended. A damping channel 4 is formed, and the extension side damping channel 4 is provided in the piston 2 in this way.

  The extension side damping flow path 4 allows the hydraulic oil to move from the rod chamber R1 to be compressed to the piston chamber R2 to be expanded during the extension stroke of the shock absorber D, and provides resistance to the passage of the hydraulic oil. It functions as a damping force generating element that generates a predetermined pressure loss to increase the pressure in the rod chamber R1 and generate a damping force on the extension side.

  Further, in this shock absorber D, the pressure in the piston chamber R2 is increased and the pressure in the rod chamber R1 is reduced during the contraction stroke, so in principle, the piston chamber R2 and the rod chamber R1 are reduced during the contraction stroke. However, in this embodiment, the port 8a that connects the piston chamber R2 and the rod chamber R1 and the damping valve that provides resistance to the flow of hydraulic oil that passes through the port 8a are not required. The pressure side damping flow path 8 provided with 8b and the non-return valve 8c which accept | permits only the flow which goes to the rod chamber R1 from piston chamber R2. The second pressure side damping flow path 8 allows only the flow of hydraulic oil from the piston chamber R2 toward the rod chamber R1, and gives resistance to the flow.

  Here, in the shock absorber D, it is not necessary to move the hydraulic oil directly from the piston chamber R2 to the rod chamber R1 during the contraction stroke, and therefore it is not necessary to install the second pressure side damping flow path 8. By installing the second pressure side attenuation channel 8, the degree of pressure increase in the piston chamber R2 with respect to the piston speed during the contraction stroke can be adjusted by the resistance provided by the second pressure side attenuation channel 8.

  Therefore, in this case, during the contraction stroke of the shock absorber D, the hydraulic oil is allowed to move from the piston chamber R2 compressed through the port 8a to the rod chamber R1, and the damping valve 8b is allowed to pass through the hydraulic oil. Thus, resistance is applied to reduce the pressure in the rod chamber R1, and a differential pressure can be generated between the pressure in the piston chamber R2 and the pressure in the rod chamber R1.

  Moreover, although the ports 4a and 8a are provided in the piston 2 in the present embodiment, the rod chamber R1 and the piston chamber R2 may be communicated with each other by bypassing the piston 2.

  Furthermore, although the damping valves 4b and 8b are fixed orifices in the drawing, they may be leaf valves that also function as the check valves 4c and 8c, or a variable throttle that makes the flow path area variable. And so on.

  An outer cylinder 9 that covers the cylinder 1 is provided outside the cylinder 1, and a reservoir R is formed by an annular gap between the outer cylinder 9 and the cylinder 1. 1 is closed by a head member 10 that slidably supports the rod 3, and the upper ends of the cylinder 1 and the outer cylinder 9 are sealed. That is, in this shock absorber D, the reservoir R is configured as a double-tube shock absorber formed on the outer peripheral side of the cylinder 1.

  Further, the lower ends of the outer cylinder 9 and the cylinder 1 are closed by the bottom member 11, and the lower ends of the cylinder 1 and the outer cylinder 9 are sealed.

  The reservoir R is filled with hydraulic oil, and gas G is filled in the upper part in FIG. 1 with the oil surface of the hydraulic oil as a boundary. The volume of hydraulic oil that moves forward and backward into the cylinder 1 of the rod 3 that becomes excessive or insufficient is supplied to the cylinder 1 or absorbed from the cylinder 1.

  A passage 7a that extends from the lower side of the hydraulic oil surface of the reservoir R and passes through the head member 10 and communicates with the rod chamber R1 is provided. In the middle of the passage 7a, there is a passage from the reservoir R to the piston chamber. A check valve 7b that allows only the flow toward R2 is provided, and the rod chamber side suction flow path 7 is formed by the passage 7a and the check valve 7b. In this case, the check valve 7b is provided in the head member 10, but may be provided anywhere in the passage 7a. Further, the passage 7a may be installed in the reservoir R using a pipe material or the like.

  The head member 10 is annular so that the rod 3 can be pivotally supported. The head member 10 includes a seal member 12 that slides on the outer periphery of the rod 3 and seals the outer periphery of the rod 3 on the inner peripheral side. Prevents hydraulic fluid leakage.

  On the other hand, the bottom member 11 is provided with ports 5a and 6a for communicating the piston chamber R2 and the reservoir R. In the middle of the port 5a, resistance given to the flow of hydraulic oil passing through the port 5a is provided. A damping valve 5b is provided, and a check valve 5c that allows only a flow from the piston chamber R2 to the reservoir R is provided. In the middle of the other port 6a, the flow of the hydraulic oil that passes through the port 6a is resisted. And a check valve 6c that allows only the flow from the reservoir chamber R to the piston chamber R2. In this embodiment, the pressure side damping flow path 5 is formed by the port 5a, the damping valve 5b and the check valve 5c, and the piston chamber side suction is formed by the port 6a, the damping valve 6b and the check valve 6c. The flow path 6 is formed, and the pressure side attenuation flow path 5 and the piston chamber side suction flow path 6 are thus provided in the bottom member 11.

  The compression-side damping flow path 5 allows the hydraulic oil to move from the compressed piston chamber R2 to the reservoir R during the contraction stroke of the shock absorber D, and provides resistance to the passage of the hydraulic oil to give a predetermined pressure loss. And the pressure in the piston chamber R2 is increased to function as a damping force generating element that generates a damping force on the compression side.

  Further, in the piston chamber side suction flow path 6, during the expansion stroke of the shock absorber D, the hydraulic oil is allowed to move from the reservoir R to the piston chamber R2, and the damping valve 6b is allowed to pass through the hydraulic oil. Therefore, a large difference can be generated by the pressure in the rod chamber R1 and the pressure in the piston chamber R2. Note that the damping valve 6b may be omitted and the pressure in the piston chamber R2 may be the same as the pressure in the reservoir R during the extension stroke.

  Moreover, although the ports 5a and 6a are provided in the bottom member 11 in the present embodiment, the reservoir R and the piston chamber R2 may be communicated with each other by bypassing the bottom member 11.

  Further, the damping valves 5b and 6b are fixed orifices in the drawing, but, like the damping valves 4a and 8a, the damping valves 5b and 6b may be leaf valves that also function as check valves 5c and 6c. A variable throttle or the like that can change the flow path area may be used. The pressure-side damping flow path 5 allows the hydraulic oil to move from the piston chamber R2 that is compressed during the contraction stroke of the shock absorber D to the reservoir R, and gives resistance to the passage of the hydraulic oil to give a predetermined pressure loss. And the pressure inside the piston chamber R2 is increased to function as a damping force generating element that generates a damping force on the compression side, so that the check valve 5c can be omitted.

  In the shock absorber D configured as described above, the rod chamber R1 is compressed and the piston chamber R2 is expanded during the extension stroke in which the rod 3 is displaced upward in FIG. The oil moves from the rod chamber R1 to the piston chamber R2 via the expansion side attenuation flow path 4, and the hydraulic oil corresponding to the volume of the rod 3 retreating from the cylinder 1 passes from the reservoir R via the piston chamber side suction flow path 6. To the piston chamber R2.

  At this time, since the expansion side damping flow path 4 gives resistance to the flow of the hydraulic oil passing therethrough, a predetermined pressure loss occurs, the pressure in the rod chamber R1 is increased, and a large pressure is generated between the rod chamber R1 and the piston chamber R2. A differential pressure is generated and a damping force on the extension side is generated. In addition, since the damping valve 6b is also provided in the middle of the piston chamber side suction flow path 6, the damping force at the time of the extension stroke can be increased as compared with the one without the damping valve 6b.

  On the other hand, in the contraction stroke in which the rod 3 is displaced downward in FIG. 1 with respect to the cylinder 1, the piston chamber R2 is compressed and the rod chamber R1 is enlarged. Here, in this shock absorber D, the hydraulic oil corresponding to the volume that is reduced by the rod 3 being displaced downward from the piston chamber R2 to be compressed moves to the reservoir R via the compression side damping flow path 5. Then, it moves to the rod chamber R1 via the second pressure side attenuation flow path 8 described above. Further, the shock absorber D includes the rod chamber side suction flow path 7 that allows only the flow from the reservoir R to the rod chamber R1, so that the rod 3 is displaced downwardly in the cylinder 1. Insufficient volume of hydraulic oil is supplied from the reservoir R to the rod chamber R1 via the rod chamber side suction flow path 7.

  Since the pressure side damping flow path 5 and the second pressure side damping flow path 8 give resistance to the flow of hydraulic fluid passing therethrough, pressure loss occurs, and further, hydraulic fluid is supplied from the reservoir R to the rod chamber R1. In the shock absorber D, during the contraction stroke, unlike the conventional shock absorber in which both the rod chamber and the piston chamber are compressed, the pressure in the piston chamber R2 is increased, and a damping force on the compression side is generated. .

  Therefore, the shock absorber D compresses and increases only the piston chamber R2 during the contraction stroke to generate a compression-side damping force, thereby increasing the pressure difference between the rod chamber R1 and the piston chamber R2. In addition, since the amount of compressed liquid is smaller than conventional shock absorbers, even a shock absorber adopting a double cylinder type that cannot increase the cylinder diameter generates a damping force on the compression side with good responsiveness. Can be made.

  Further, in order to generate the damping force on the compression side in the shock absorber D with high responsiveness, it is necessary to pressurize the reservoir R to increase the pressure in the rod chamber R1 and the piston chamber R2 in the cylinder 1, that is, the pressure in the cylinder. Therefore, there is no problem that the seal member 12 is strongly pressed to the rod 3 side by the pressure in the cylinder to prevent the rod 3 from moving.

  Further, during the contraction stroke, the rod chamber R1 to be depressurized sucks the hydraulic oil from the reservoir R through the rod chamber side suction flow path 7, so that the rod chamber R1 is excessively depressurized to generate aeration and the shock absorber. The response of the generation of damping force is not deteriorated, and undesirable phenomena such as cavitation and erosion are not caused.

  That is, in this shock absorber D, it is possible to generate a compression-side damping force with good responsiveness during the contraction stroke while avoiding the problems that occur in conventional shock absorbers, and the practicality and reliability of the shock absorber D are improved. become.

  If the second pressure side damping flow path 8 is not installed, all of the hydraulic oil commensurate with the volume reduction is discharged from the piston chamber R2 to the reservoir R via the pressure side damping flow path 5, and the piston chamber R2 increases. Since the hydraulic fluid corresponding to the expansion of the volume is supplied from the reservoir R to the rod chamber R1, the rod chamber R1 is decompressed and the piston chamber R2 is increased in the same manner as described above. A damping force on the compression side is generated.

  Although the shock absorber D has been conceptually described above, a specific example of the shock absorber D 'will be described below.

  As shown in FIGS. 2 and 3, the shock absorber D ′ having a specific configuration is basically slidably inserted into the cylinder 1 in the same manner as the conceptual shock absorber described above. The piston 2 partitioned into the rod chamber R1 and the piston chamber R2 in the cylinder 1, the rod 3 that is movably inserted into the cylinder 1 and connected to the piston 2 at one end, the reservoir R, and the rod chamber R1 The extension side damping flow path 4 that allows the flow from the piston chamber R2 to the piston chamber R2 and provides resistance to the flow of the liquid that passes through, and the flow from the piston chamber R2 toward the reservoir R and allows the flow of the liquid that passes through the resistance. Pressure side damping flow path 5, piston chamber side suction flow path 6 allowing only flow from reservoir R to piston chamber R2, and rod chamber allowing only flow from reservoir R to rod chamber R1 It is constituted by a suction passage 7. In addition, about the member similar to the above-mentioned fundamental shock absorber D, the same code | symbol is attached | subjected and demonstrated also in description of specific shock absorber D '.

  In this specific shock absorber D ′, the piston 2 is provided with ports 4a and 8a that connect the rod chamber R1 and the piston chamber R2, and the lower end of the piston 2 in FIG. A leaf valve 13 that gives resistance to the flow of hydraulic oil passing through the end opening and closing and permits only the flow from the rod chamber R1 to the piston chamber R2 is laminated and fixed to the rod 3, and 2 is laminated with a leaf valve 14 that opens and closes the outlet end of the port 8a to give resistance to the flow of hydraulic oil and allows only the flow from the piston R2 to the rod chamber R1, and is fixed to the rod 3 Has been.

  Therefore, in the case of this specific shock absorber D ′, the expansion side attenuation flow path 4 is configured to include the port 4 a and the leaf valve 13, and, like the basic shock absorber D, In the two-pressure-side damping flow path 8, resistance is given by the leaf valve 14 when the hydraulic oil passes through the port 8 a.

  Further, in this shock absorber D ′, a pipe 15 is provided which forms an annular gap 71 which is disposed outside the cylinder 1 and forms a part of the rod chamber side suction flow path 7 with the cylinder 1. The lower end in FIG. 2 of the gap 71 is connected to the reservoir R. The outer cylinder 9 is disposed on the outer peripheral side of the pipe 15, and the reservoir R is formed by an annular gap between the pipe 15 and the outer cylinder 9.

  Then, when the rod chamber R1 whose volume is expanded in the contraction stroke of the shock absorber D ′ sucks the hydraulic oil from the reservoir R, if the flow velocity of the hydraulic oil passing through the rod chamber side suction flow path 7 becomes too low, the hydraulic oil is reduced. Since the suction becomes difficult, the cross-sectional area of the annular gap 71 is adjusted so that the flow rate of the hydraulic oil passing through the annular gap 71 at the time of suction is more than a certain level.

  A cylindrical plug 16 is fitted to the upper end in FIG. 2 that is the rod side end of the cylinder 1 and the upper end in FIG. 2 that is the rod side end of the pipe 15.

  The plug 16 has a cylindrical shape, a small-diameter portion 16a fitted to the inner periphery of the upper end of the cylinder 1, and a larger diameter than the small-diameter portion 16a connected to the small-diameter portion 16a. A boundary between the intermediate portion 16b fitted to the intermediate portion 16b, the large diameter portion 16c connected to the intermediate portion 16b and having a larger diameter than the intermediate portion 16b, and the large inner diameter portion 16d on the inner periphery and the small inner diameter portion 16e on the lower side And a passage 16g that opens from the boundary between the small-diameter portion 16a and the intermediate portion 16b and communicates with the step portion 16f. The rod 3 is inserted on the inner peripheral side. It is like that.

  Further, when the plug 16 is fitted to the cylinder 1 and the pipe 15, the upper end of the annular gap 71 communicates with the rod chamber R1 through the passage 16g, and the rod chamber side suction flow is formed between the annular gap 71 and the passage 16g. A passage 7 a in the passage 7 is formed. Then, the seal ring 17 interposed between the outer periphery of the small diameter portion 16a and the cylinder 1 prevents the upper end of the annular gap 71 from directly communicating with the rod chamber R1 without passing through the passage 16g. The upper end of the annular gap 71 is prevented from communicating with the reservoir R by the seal ring 18 interposed between the intermediate portion 16 b and the pipe 15.

  Further, a rod guide 19 that fits the upper end in FIG. 2 that is the rod side end of the outer cylinder 9 and supports the rod 3 is fitted to the inner periphery of the upper end of the plug 16. The rod guide 19 is formed in an annular shape, and includes a socket portion 19a that fits to the inner periphery of the upper end of the plug 16, and holds a cylindrical bearing 29 that is in sliding contact with the outer periphery of the rod 3 on the inner periphery side. It is fixed to the outer cylinder 9 together with the seal member 20 laminated on the upper end. In the case of this embodiment, a cylindrical screw member 21 having a screw portion on the outer periphery is coupled to the upper end of the outer cylinder 9, and a cap 22 that is screwed into the screw member 21 is screwed into a rod. The guide 19 and the seal member 20 are fixed to the outer cylinder 9, and the rod guide 19 is directly fitted to the screw member 21, but the rod guide 19 is thus attached to the outer cylinder. 9 is a concept including indirect fitting via a member coupled to the outer cylinder 9 such as the screw member 21. Incidentally, when the rod guide 19 is fixed to the outer cylinder 9 by tightening the cap 22 into the screw member 21 in this way, the shock absorber D ′ can be disassembled, so that maintenance and the bending of the leaf valves 13 and 14 are possible. Although there is an advantage that adjustment of rigidity change or the like is possible, the screw member 21 and the cap 22 are omitted, the rod guide 19 is directly fitted to the outer cylinder 9 and the seal member 20 is laminated, and the opening of the outer cylinder 9 Of course, these may be fixed to the outer cylinder 9 by crimping the ends to the inner peripheral side.

  The seal member 20 includes an annular plate 20a, an inner peripheral seal 20b provided on the inner periphery of the annular plate 20a and in sliding contact with the outer periphery of the rod 3, and an inner periphery of the screw member 21 provided on the outer periphery of the annular plate 20a. 2 and an annular check seal 20d provided at the lower end in FIG. 2 of the annular plate 20a and in contact with the upper end of the rod guide 19, and the check seal 20d is composed of the rod chamber R1. 2, the hydraulic oil accumulated in the space above the rod guide 19 in FIG. 2 is opened and released to the reservoir R to prevent pressure accumulation in the space. The gas G is prevented from flowing back to the rod chamber R1.

  Returning, the vertical length in FIG. 2 which is the axial length of the socket portion 19 a fitted to the inner periphery of the plug 16 at the lower end of the rod guide 19 is the axial length of the large inner diameter portion 16 d of the inner periphery of the plug 16. 2 is set to be shorter than the vertical length in FIG. 2, and a gap is formed between the lower end of the socket portion 19 a in FIG. 2 and the step portion 16 f of the plug 16. A seal ring 30 is interposed between the outer periphery of the socket portion 19a and the large inner diameter portion 16d of the plug 16 so that the rod chamber R1 and the reservoir R are interposed between the rod guide 19 and the plug 16. Communication is blocked.

  A plate-like annular valve element 23a is laminated on the step part 16f, and a spring 23b is interposed between the annular valve element 23a and the lower end of the socket part 19a in FIG. 2, and these annular valve elements 23a. The check valve 23 is formed at the outlet end of the passage 16f by the spring 23b.

  In the check valve 23, when the pressure in the rod chamber R1 becomes lower than the pressure in the reservoir R due to volume expansion during the contraction stroke of the shock absorber D ′, the annular valve body 23a is separated from the step portion 16f and the passage By opening 16g, hydraulic oil is supplied from the reservoir R to the rod chamber R1, and conversely, when the shock absorber D ′ is in the extension stroke, the pressure in the rod chamber R1 is high, so that the annular valve body 23a is stepped. The passage 16g is closed while being seated on the portion 16f, and the hydraulic oil is prevented from moving from the rod chamber R1 to the reservoir R via the rod chamber side suction flow path 7.

  That is, in this specific shock absorber D ′, the head member 10 in the basic shock absorber D is constituted by the plug 16, the rod guide 19, and the seal member 20.

  In turn, a valve disc 24 is fitted to the lower end of the cylinder 1 in FIG. 2 and the lower end of the pipe 15, and this valve disc 24 has a cylindrical shape, and the lower end of the cylinder 1 in FIG. A small-diameter portion 24a to be fitted, an intermediate portion 24b which is continuous with the small-diameter portion 24a and has a larger diameter than the small-diameter portion 24a and is fitted to the lower end in FIG. 2 of the pipe 15, and is continuous with the intermediate portion 24b and larger than the intermediate portion 24b. A large-diameter portion 24c having a diameter, a notch 24d provided from the large-diameter portion 24c to the intermediate portion 24b and communicating between the inside and the outside, and ports 5a and 6a communicating the piston chamber R2 and the reservoir R are configured. The plug 16, the rod guide 19, and the seal member 20 are placed on the lower end of the outer cylinder 9 formed in a bottomed cylindrical shape, and are screwed into the screw member 21 of the cap 22 through the cylinder 1. It is fixed to the monitor outer cylinder 9. The cylinder 1 is sandwiched between the plug 16 and the valve disk 24 so as to receive an axial load. However, the plug 16 and the pipe 15 are connected with the plug 16 fitted to the rod side end of the cylinder 1. An axial gap is formed between the rod side end, and even if the cylinder 1 is sandwiched between the plug 16 and the valve disk 24, the pipe 15 is free from an axial load due to play due to the gap.

  Therefore, even if there is a dimensional error between the pipe 15 and the cylinder 1, when the cylinder 1 and the pipe 15 are assembled to the outer cylinder 9, an axial load is applied to the cylinder 1. There will be no play and play, and there is no fear that the function of the shock absorber D 'will be impaired. Further, by providing the pipe 15 with axial play in this way, high dimensional accuracy is not required for the cylinder 1 and the pipe 15, the plug 16 and the valve disk 24 sandwiching them, and therefore the shock absorber D The manufacturing cost of 'will also be reduced.

  When the valve disc 24 is fitted to the lower ends of the cylinder 1 and the pipe 15 in this way, the lower end of the annular gap 71 is secured to the reservoir R via the notch 24d. The piston chamber R2 communicates with the notch 24d and the ports 5a and 6a.

  2 is provided with a leaf valve 25 that gives resistance to the flow of hydraulic oil passing through the outlet end of the port 5a at the lower end in FIG. A leaf that is fixed in a stacked manner and gives resistance to the flow of hydraulic fluid that passes through the outlet end of the port 6a by opening and closing the outlet end of the port disk 24 and permits only the flow from the reservoir R to the piston R2. The valve 26 is laminated and fixed. In this embodiment, in order to increase the damping force during the expansion stroke of the shock absorber D ′, the leaf valve 26 functioning as a damping valve is provided to open and close the port 6a. A check valve may be used.

  Therefore, in the case of this specific shock absorber D ′, the compression side damping flow path 5 is configured to include the port 5 a and the leaf valve 25, and the hydraulic oil passes through the piston chamber side suction flow path 6. When doing so, resistance is provided by the leaf valve 26.

  Thus, in the shock absorber D ′, it is possible to install the rod chamber side suction flow path 7 on the outer peripheral side of the cylinder 1 of the double-tube shock absorber only by providing the pipe 15 and the plug 16. There is an advantage that the structure can be realized without making a great design change to the structure of the shock absorber.

  Furthermore, since the rod chamber side suction flow path 7 can be installed in the outer cylinder 9 and on the outer peripheral side of the cylinder 1 by providing the pipe 15, the outer diameter of the shock absorber D 'is smaller than that of the conventional shock absorber. In other words, the diameter of the shock absorber D ′ is not impaired.

  Further, the check valve 23 to be provided in the rod chamber side suction flow path 7 includes a step portion 16f of the plug 16, an annular valve body 23a that is attached to and detached from the step portion 16f, an annular valve body 23a, and a rod guide 19. Since it is composed of springs 23b interposed therebetween, these can be easily installed without taking up space by adding parts to the existing double-tube shock absorber. Since no significant design change is added to the structure, there is also an advantage that the configuration of the shock absorber D ′ can be realized in this respect.

  Now, even in this specific shock absorber D ′ configured as described above, the same operation as that of the basic shock absorber D is exhibited, so that only the piston chamber R2 is provided during the contraction stroke. Compression and pressure increase will generate a compression-side damping force, and the pressure difference between the rod chamber R1 and the piston chamber R2 can be increased, and the amount of compressed liquid is reduced compared to the conventional shock absorber. Even if the shock absorber adopts a double cylinder type in which the cylinder diameter cannot be increased, the compression side damping force can be generated with good responsiveness.

  Further, in order to generate a compression-side damping force in the shock absorber D ′ with high responsiveness, the reservoir R is pressurized to increase the pressure in the rod chamber R1 and the piston chamber R2 in the cylinder 1, that is, the pressure in the cylinder. Since there is no necessity, the inner peripheral seal 20b in the seal member 20 is strongly pressed against the rod 3 side by the pressure in the cylinder, and there is no problem of preventing the rod 3 from moving.

  Furthermore, during the contraction stroke, the rod chamber R1 whose volume is expanded sucks the hydraulic oil from the reservoir R through the rod chamber side suction flow path 7, so that the rod chamber R1 is excessively depressurized and aeration is generated, resulting in a shock absorber. The response of the generation of the damping force is not deteriorated, and undesirable phenomena such as cavitation and erosion are not caused.

  That is, in this shock absorber D ′, it is possible to generate a compression-side damping force with good responsiveness during the contraction stroke while avoiding problems that occur in the conventional shock absorber, and the practicality and reliability of the shock absorber D are improved. It will be.

  Furthermore, in the above description, the shock absorbers D and D ′ have been described as double-tube shock absorbers, but the present invention can be embodied in a monotube shock absorber, which impairs the operational effects. There is nothing.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

It is the figure which showed the shock absorber of this invention in principle. It is a longitudinal cross-sectional view in one specific structural example of the buffer of this invention. It is a partially expanded longitudinal cross-sectional view in one specific structural example of the shock absorber of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 3 Rod 4 Extension side damping flow path 4a, 5a, 6a, 8a Port 4b, 5b, 6b, 8b Damping valve 4c, 5c, 6c, 7b, 8c, 23 Check valve 5 Pressure side damping flow path 6 Piston Chamber side suction flow path 7 Rod chamber side suction flow path 7a, 16g Passage 8 Second pressure side damping flow path 9 Outer cylinder 10 Head member 11 Bottom member 12, 20 Seal member 13, 14, 25, 26 Leaf valve 15 Pipe 16 Plug 16a, 24a Small diameter portions 16b, 24b Intermediate portions 16c, 24c Large diameter portion 16d Large inner diameter portion 16e Small inner diameter portion 16f Step portions 17, 18, 30 Seal ring 19 Rod guide 19a Socket portion 20a Annular plate 20b Inner circumference seal 20c Outer circumference seal 20d Check seal 21 Screw member 22 Cap 23a Annular valve body 23b Spring 24d Notch 29 Bearing 1 annular passage D, D 'buffer G gaseous R reservoir R1 rod chamber R2 piston chamber

Claims (5)

A cylinder, a piston that is slidably inserted into the cylinder and partitioned into a rod chamber and a piston chamber, a rod that is movably inserted into the cylinder and has one end connected to the piston, and a reservoir. An expansion-side damping flow path that allows flow from the rod chamber to the piston chamber and provides resistance to the flow of liquid passing through the shock absorber, and allows flow to flow from the piston chamber to the reservoir and flows through the buffer. A pressure-side damping flow path that provides resistance, a piston chamber-side suction flow path that allows only the flow from the reservoir to the piston chamber, and a rod chamber-side suction flow path that allows only the flow from the reservoir to the rod chamber. A shock absorber characterized by that. A pipe that is disposed on the outer peripheral side of the cylinder and forms a rod chamber side suction flow path with the cylinder; and an outer cylinder that is disposed on the outer peripheral side of the pipe and forms a reservoir with the pipe. The shock absorber according to claim 1. A cylindrical plug having a passage that is fitted to the rod side end of the cylinder and the rod side end of the pipe and communicates the annular gap between the cylinder and the pipe to the rod chamber, and the rod side end of the plug and the outer cylinder And a rod guide that pivotally supports the rod, and an axial gap is formed between the plug and the rod side end of the pipe with the plug fitted to the rod side end of the cylinder. The shock absorber according to claim 2. A check valve is provided at the outlet end of the passage in the plug and allows only the flow from the reservoir toward the rod chamber, and the check valve is provided on the inner peripheral side of the plug to form the outlet end of the passage. And a spring interposed between the annular valve body and the rod guide. The shock absorber described. The shock absorber according to any one of claims 1 to 4, further comprising a second pressure-side damping channel that allows a flow from the piston chamber to the rod chamber and provides resistance to the flow of the liquid passing therethrough.

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