JP6475644B2 - Single cylinder shock absorber damper - Google Patents

Description

  The present invention relates to a damper for a shock absorber that constitutes a suspension of an automobile or the like, and more particularly to a damper for a single tube type (monotube) shock absorber.

  This type of shock absorber is configured by combining a spring and a damper. As a conventional damper for a single-cylinder shock absorber, for example, Patent Document 1 is available. FIG. 8 is a schematic cross-sectional view showing the basic configuration of the damper 100 of the single cylinder type shock absorber. A free piston 30 that partitions the oil chamber 50 and the gas chamber 60 is provided in the damper cylinder 40. The free piston 30 is slidable with respect to the damper cylinder 40. Further, the piston portion 20 has a piston rod 21 that penetrates one end of the oil chamber 50 and a piston valve 22 provided at the tip thereof. The piston valve 22 moves the oil chamber 50 into the first compartment 51 and the second compartment 52. Partition. The piston valve 22 includes, for example, an oil passage 23 that always communicates the first compartment 51 and the second compartment 52 and an oil passage 24 with a check valve (one-way valve). As the piston rod 21 reciprocates, a damping force is generated by resistance when oil moves between the first compartment 51 and the second compartment 52 through the oil passage 23 of the piston valve 23. The oil passage 24 with a check valve is closed when the piston rod 21 is contracted (forward), and is opened only when the piston rod 21 is extended (return), thereby changing the flow rate of the oil, thereby returning the piston rod 21 when the piston rod is extended. Promote and adjust the damping force when shrinking and stretching.

  In the above basic configuration, the damper 100 is normally functioned to generate a damping force, and the gas chamber 60 is filled with high-pressure gas in order to prevent aeration (bubbles) from occurring in the oil chamber 50. Conventionally, a pressure of 1.0 MPa or more is required. Due to the high pressure in the gas chamber 60, the free piston 30 can slide smoothly and operate normally, and aeration is not generated. When aeration occurs, the damping action of the damper is impaired.

  However, in the above basic configuration, the higher the pressure in the gas chamber 60, the more harmful the repulsive force when the piston rod 21 moves backward becomes too large. In addition, the stronger the repulsive force, the greater the load on the piston rod 21 and the possibility of bending. If the pressure in the gas chamber 60 is lowered in order to reduce the repulsive force against the piston rod, the damper does not function normally, aeration occurs, and the damper life is reduced and abnormal noise is generated. In addition, even when the pressure is necessary for preventing aeration, aeration may occur when the piston rod 21 moves backward faster.

  In order to reduce the pressure in the gas chamber and allow the damper to function normally, there is a method in which a reserve tank is provided outside the damper cylinder as in Patent Documents 2 and 3. In the reserve tank system, the pressure can be reduced by setting the gas chamber to a large capacity and the free piston to have a large diameter. However, a reserve tank connected with a damper and an oil passage is required, which increases the installation space. is there.

  As another method, as in Patent Documents 4 and 5, a configuration in which a damping force adjusting mechanism of a damper is provided between a piston valve and a free piston is also known. Since the damping force adjusting mechanism is fixedly installed as a partition wall dividing the second compartment into two, a third compartment is further formed in the oil chamber. The damping force adjusting mechanism includes a check valve (reference numeral 19 of Patent Document 4 and reference numeral 11b of Patent Document 5) that is closed when the piston rod is contracted and is opened only when the piston rod is extended, thereby returning the piston rod when the piston rod is extended. And adjust the damping force when shrinking and stretching.

JP 2003-90380 A JP 2001-295877 A JP 2004-332792 A Japanese Utility Model Publication No. 48-9515 JP 2006-194328 A

  The damping force adjusting mechanisms of Patent Documents 4 and 5 are mainly configured to adjust the damping force that makes the damping force different between when the piston rod is contracted and when it is extended. It is not intended to be configured as a decompression device that ensures the above.

  An object of the present invention is to provide a damper for a single-cylinder shock absorber that can reduce the pressure of a gas chamber and ensure a normal damper operation by a pressure reducing device provided between a piston valve and a free piston. .

  In order to achieve the above object, the present invention provides the following configurations. The numbers in parentheses are reference numerals in the drawings to be described later, and are attached for reference.

An aspect of the present invention includes a free piston (30) that divides the damper cylinder (40) into an oil chamber (50) and a gas chamber (60) and is slidable in the cylinder,
A piston rod (21) penetrating through one end of the damper cylinder (40) and capable of reciprocating in the first compartment (51) of the oil chamber (50) and the oil chamber located at the tip of the piston rod (21) A piston valve (22) that partitions the first compartment (51) and the second compartment (52) of (50);
A pressure reducing device (1) positioned between the piston valve (22) and the free piston (30) and defining a second compartment (52) and a third compartment (53) of the oil chamber (50); Single cylinder shock absorber damper (10),
The pressure reducing device (1) is composed of a bolt member (2) and a valve member (3),
The bolt member (2) includes a first thread (2a1) provided in the axial direction of the damper cylinder (40), the second compartment (52), and the third compartment (53) in constant communication with each other. An oil passage (2c),
The valve member (3) is fixed to the damper cylinder (40), and has a female screw (3a1) screwed with the male screw (2a1) of the bolt member (2), and the second compartment (52). A second oil passage (3c) enabling communication with the third compartment (53) and a position on the second oil passage (3c) and closed when the piston rod (21) is contracted and opened when extended. A check valve (3d) ,
The size of the gap between the bolt member (2) and the valve member (3) varies depending on the degree of screwing between the bolt member (2) and the valve member (3), whereby the second oil passage ( The flow rate of 3c) is adjustable .

  In the above aspect, the check valve (3d) is a ball body and is disposed in a valve chamber (3c1) provided in the valve member (3), and the valve chamber (3c) is the second chamber. It is preferable that the third chamber (53) can communicate with the third chamber (53) through a valve hole (3c2) that opens to the side of the chamber (52) and serves as a valve seat for the ball body.

  In the above aspect, at least one of the bolt member and the valve member is configured such that the second oil passage (3c) and the second compartment (52) are in a state where the bolt member and the valve member are completely screwed together. It is preferable to provide a groove (2e, 3e) or a through-hole for communicating with each other.

  In the damper of the single cylinder type shock absorber, since the pressure reducing device with a check valve is provided between the piston valve and the free piston, the pressure reducing operation is performed while maintaining the damper function normally and preventing the occurrence of aeration. The pressure in the gas chamber can be lowered as compared with the case without the device. Furthermore, the pressure reducing device has a bolt member having a male screw and a valve member having a female screw, and the flow rate of the check valve can be adjusted depending on the degree of screwing. By the adjustment, the pressure of the gas chamber can be set to an optimum value, and the damping force can be adjusted.

  According to the present invention, while ensuring the normal function of the damper of the single cylinder type shock absorber, the pressure of the gas chamber can be made lower than before, reducing the load when the piston rod is extended, and extending the life of the damper. Can do. In addition, the user can be made aware of an appropriate maintenance time, and overuse can be prevented.

FIG. 1 is a schematic cross-sectional view of a damper of a single cylinder type shock absorber according to the present invention, wherein (a) shows when the piston rod is contracted and (b) shows when it is extended. 2A and 2B are diagrams illustrating a configuration example of the first embodiment of the decompression device according to the present invention illustrated in FIG. 1, in which FIG. 2A is a top view and FIG. (C) is a bottom view. 3 is a perspective view of the decompression device shown in FIG. 1, wherein (a) is a perspective view seen from the top surface side, and (b) is a perspective view seen from the bottom surface side. 4 is an exploded view of the decompression device shown in FIG. FIG. 5 is a diagram for explaining the operation of the decompression device shown in FIGS. 2 to 4, and (a) is a cross-sectional view schematically showing the vicinity of the decompression device when the piston rod is contracted. b) is the same when stretched. 6A and 6B are diagrams illustrating a configuration example of a second embodiment of the decompression device according to the present invention, in which FIG. 6A is a top view of the valve member, FIG. c) is a longitudinal sectional view of a state in which a bolt member and a valve member are screwed together. FIG. 7 is a view showing a configuration example of a third embodiment of the decompression device according to the present invention, where (a) is a bottom view of the bolt member, (b) is a cross-sectional view taken along the line CC of (a), c) is a longitudinal sectional view of a state in which a bolt member and a valve member are screwed together. FIG. 8 is a schematic cross-sectional view showing a configuration of a general damper of a single cylinder type shock absorber.

  Hereinafter, a damper of a single cylinder type shock absorber according to the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same or similar component in each drawing.

  FIG. 1 is a schematic cross-sectional view of a damper of a single cylinder type shock absorber according to the present invention, wherein (a) shows when the piston rod is contracted and (b) shows when it is extended. For convenience, the vertical direction in FIG. 1 will be described as the vertical direction of the damper of the present invention. However, when actually mounted on a vehicle or the like, the vertical direction, horizontal direction, and diagonal direction may be used.

  Reference is made to FIG. The damper 10 is provided with a free piston 30 that partitions an oil chamber 50 and a gas chamber 60 in a damper cylinder 40. The free piston 30 is slidable with respect to the inner surface of the damper cylinder 40. The oil chamber 50 is filled with oil, and the gas chamber 60 is filled with air of a predetermined pressure. The piston portion 20 includes a piston rod 21 that penetrates one end of the oil chamber 50 and a piston valve 22 provided at the tip of the piston rod 21. In the illustrated example, the piston rod 21 and the piston valve 22 are fixed by nuts. The piston rod 21 is connected to one end of a shock absorber spring (not shown), and the damper cylinder 40 is connected to the other end of the spring.

  The piston valve 22 partitions the first compartment 51 and the second compartment 52 in the oil chamber 50. As an example, the piston valve 22 includes an oil passage 23 that constantly communicates the first compartment 51 and the second compartment 52 and an oil passage 24 with a check valve, as in the damper 100 shown in FIG. 8. As the piston rod 21 reciprocates, a damping force is generated by resistance when oil moves between the first compartment 51 and the second compartment 52 through the oil passage 23 of the piston valve 23. The oil passage 24 with a check valve is closed when the piston rod 21 is contracted (forward movement), and is opened only when the piston rod 21 is expanded (reverse movement), and the piston rod 21 quickly returns by increasing the oil flow rate. The configuration of the piston valve 22 is not limited to this, and may be configured only by the oil passage 24 with a check valve when it is configured by only the oil passage 23 that is always in communication. There are also various check valve configurations.

  The decompression device 1 according to the present invention is located between the piston valve 22 and the free piston 30 and partitions the second compartment 52 and the third compartment 53 of the oil chamber 50. The decompression device 1 is fixed to the damper cylinder 40. Although the detailed structure of the decompression device 1 will be described later, it includes a plurality of oil passages that allow the second compartment 52 and the third compartment 53 to communicate with each other.

  When the piston rod 21 is retracted, that is, when the piston rod 21 moves forward, the second compartment 52 is pushed by the piston valve 22 to become a high pressure, and the pressure in the third compartment 53 communicating with the second compartment 52 also increases. The free piston 30 moves so as to compress the gas chamber 60. The amount of movement of the free piston 30 corresponds to the volume of the piston rod 21 that has entered. At this time, the oil moves from the second compartment 52 to the first compartment 51 and also moves from the second compartment 52 to the third compartment 53, thereby generating a damping force due to its resistance. When the piston rod 21 is moved backward in FIG. 1B, that is, when pulled by the piston valve 22, the second compartment 52 becomes low pressure, and the pressure of the third compartment 53 communicating with the second compartment 52 also becomes low. The free piston 30 moves so as to expand the gas chamber 60. At this time, the oil moves from the first compartment 51 to the second compartment 52 and also moves from the third compartment 53 to the second compartment 52, thereby generating a damping force due to its resistance.

With reference to FIG.1 (b), one of the effects of the decompression device 1 in this invention is demonstrated.
An oil seal 42 is built in the upper lid 41 of the damper 10. At the time of elongation, a small amount of oil adheres to the piston rod 21 and slides with respect to the oil seal 42 to perform a lubrication and sealing function. By this operation at the time of extension, a small amount of oil adhering to the piston rod 21 is sent to the outside, so that the amount of oil in the oil chamber 50 gradually decreases. When the amount of oil in the oil chamber 50 decreases, the position of the free piston 30 gradually rises and the pressure in the gas chamber 60 changes. As a result of the pressure in the gas chamber 60 changing, the damper performance is degraded. Since the amount of oil delivered to the outside is small, the reduction in the amount of oil proceeds gradually, making it difficult for the user to notice. In the case of the conventional damper shown in FIG. 8, since the user does not notice when the time for maintenance has come, it is often overused. As a result, eventually, the free piston 30 that has risen due to the decrease in oil comes into contact with the piston valve 22 and breaks, so that fatal oil leakage may occur.

  In the present invention, the presence of the pressure reducing device 1 limits the moving distance of the free piston 30 that rises according to the gradually decreasing amount of oil in the oil chamber 50. That is, since the position of the decompression device 1 is the upper limit position of the free piston 30, the free piston 30 cannot be brought into direct contact with the piston valve 22. Thereby, the damage by contact with the free piston 30 and the piston valve 22 can be prevented. Further, when the free piston 30 rises and comes into contact with the pressure reducing device 1 due to the oil decrease, the pressurizing function of the free piston 30 suddenly becomes zero at that moment, and thus a large aeration occurs. At this time, since a significant decrease in damping force and abnormal noise are generated, the user can immediately recognize the abnormality. As a result, the number of backward movements of the piston rod 21 becomes excessive and the user can be made aware of the need for maintenance before being overused. Alternatively, repairs can be urged at the time of inspection by the automobile inspection registration system. As a result, accidents due to fatal damage or damage due to overuse can be prevented, and safer use becomes possible.

  2A and 2B are diagrams illustrating a configuration example of the first embodiment of the decompression device according to the present invention illustrated in FIG. 1, in which FIG. 2A is a top view and FIG. (C) is a bottom view. 3 is a perspective view of the decompression device shown in FIG. 1, wherein (a) is a perspective view seen from the top surface side, and (b) is a perspective view seen from the bottom surface side. 4 is an exploded view of the decompression device shown in FIG.

  As shown in FIGS. 2 to 4, the decompression device 1 is composed of two parts, a bolt member 2 and a valve member 3.

  The bolt member 2 has an outer shape similar to that of a hexagonal bolt, and includes a screw portion 2a having a male screw 2a1 formed around it and a bolt head 2b. A concave portion is formed on the upper surface side of the hexagonal bolt head 2b for weight reduction. When the piston valve 22 approaches the pressure reducing device 1, the concave portion also serves as a clearance for the fixing nut on the lower surface of the piston valve 22 (see FIG. 1). Furthermore, the 1st oil path 2c which is a hole penetrated to an axial direction from the recessed part center of the volt | bolt head 2b to the lower end center of the screw part 2a is drilled. The flow rate of the oil passing through the first oil passage 2c can be adjusted by the diameter of the first oil passage 2c.

  The valve member 3 includes a substantially cylindrical valve main body 3a and a reinforcing cylindrical wall portion 3b extending upward from the peripheral edge of the upper surface of the valve main body 3a. A female screw 3a1 that can be screwed with the male screw 2a1 of the bolt member 2 is formed in the central through hole of the valve body 3a. 2 and 3 show a state in which the bolt member 2 and the valve member 3 are screwed most deeply. Therefore, as shown in FIG. 2B, the bottom surface of the bolt head 2b and the top surface of the valve body 3a are in contact. When the bolt member 2 is rotated in the loosening direction, a gap is formed between the bottom surface of the bolt head 2b and the top surface of the valve body 3a. The size of the gap varies depending on the relative degree of rotation of the bolt member 2 and the valve member 3 (that is, depending on the degree of screwing).

  The outer surfaces of the valve main body 3a and the cylindrical portion 3b of the valve member 3 are fixed so as to be in close contact with the inner surface of the damper cylinder 40, for example, by means such as press fitting. Thereby, the screw part 2 a of the bolt member 2 is arranged along the axial direction of the damper cylinder 40.

  Further, four second oil passages 3c are formed in the valve body 3a of the valve member 3 so as to penetrate from the upper surface to the lower surface of the valve body 3a. Each of the second oil passages 3c includes a large-diameter valve chamber 3c1 that opens to the upper surface and a small-diameter valve hole 3c2 that opens to the lower surface. A ball body which is a check valve 3d is arranged in the valve chamber 3c1. A boundary portion between the valve chamber 3c1 and the valve hole 3c2 serves as a valve seat of the ball body. Accordingly, the second oil passage 3c is closed or opened by the operation of the check valve 3d.

  In the illustrated example, four sets of the second oil passage 3c and the check valve 3d are arranged at equiangular intervals around the axis. The second oil passage 3c and the check valve 3d are not limited to four sets, and at least one set may be provided, but it is preferable to arrange a plurality of sets evenly around the axis. Further, the diameter and number of the valve chamber 3c1 and the valve hole 3c2 can be appropriately designed so that the flow rate of the second oil passage 3c is a predetermined value.

  When the bolt member 2 is loosened, the second oil passage 3c communicates with the gap between the bolt head 2b and the valve body 3a from the upper surface opening of the valve chamber 3c1. This gap is also regarded as an extension of the second oil passage 3c. This gap further communicates with the space between the bolt head 2b and the cylindrical wall 3b. Since the size of the gap between the bolt member 2 and the valve member 3 changes depending on the degree of screwing of the male screw 2a1 of the bolt member 2 and the female screw 3a1 of the valve member 3, by changing the degree of screwing, The flow rate of the oil passing through the second oil passage 3c can be adjusted. Further, the flow rate of the oil passing through the second oil passage 3c can also be adjusted by the diameter and number of the valve chamber 3c1 and the valve hole 3c2.

  The operation of the decompression device shown in FIGS. 2 to 4 will be described with reference to FIG. FIG. 5A is a cross-sectional view schematically showing the vicinity of the decompression device when the piston rod is contracted, and FIG. In FIG. 5, a predetermined gap t is formed between the bolt member 2 and the valve member 3.

  At the time of contraction in FIG. 5A, the second compartment 52 on the upper surface side of the decompression device 1 has a relatively high pressure and the third compartment 53 on the lower surface side has a relatively low pressure (this is referred to as a “positive pressure” state). Called). At this time, oil flows from the second compartment 52 to the third compartment 53 in the first oil passage 2c that is always in communication. On the other hand, since the check valve 3d is pressed against the valve seat of the valve hole 3c2, the second oil passage 3c is closed and no oil flows. The oil that has moved to the third compartment 53 through the narrow first oil passage 2c of the decompression device 1 pushes and moves the free piston 30 in FIG.

  5B, the second compartment 52 has a relatively low pressure, and the third compartment 53 has a relatively high pressure (this is referred to as a “negative pressure” state). At this time, oil flows from the third compartment 53 to the second compartment 52 in the first oil passage 2c that is always in communication. Further, since the check valve 3d is separated from the valve seat of the valve hole 3c2, the second oil passage 3c is opened, and a large amount of oil flows from the third compartment 53 to the second compartment 52. The oil flowing out from the third compartment 53 through the thin oil passage of the decompression device 1 pulls and moves the free piston 30 in FIG. 1 to expand the gas chamber 60.

  The pressure reducing device 1 acts so as to reduce the pressing force received from the second compartment 52 side when the piston rod is contracted, and the tensile force received from the second compartment 52 side when the piston rod is extended. It acts to increase on the third compartment 53 side. Therefore, in the present invention, since the pressure reducing device 1 acts to assist the operation of the free piston 30, compared to the case where the free piston 30 is moved almost depending on the pressure of the gas chamber 60 as in the prior art. The pressure in the gas chamber 60 can be reduced.

  Since the free piston can move normally even when the gas chamber 60 is set to a low pressure, it can operate normally as a damper, and aeration can be prevented. Moreover, since the pressure of the gas chamber 60 can be made lower than before, the load on the piston rod 21 can be reduced.

  Further, since the concave portion of the bolt head 2b functions as an oil reservoir, the switching from the positive pressure to the negative pressure when changing from the contraction time to the extension time is performed smoothly.

  6A and 6B are diagrams illustrating a configuration example of a second embodiment of the decompression device according to the present invention, in which FIG. 6A is a top view of the valve member, FIG. c) is a longitudinal sectional view of a decompression device in which a bolt member and a valve member are screwed together.

  In the second embodiment, the shape of the valve member 3A is different from that of the valve member 3 of the first embodiment. As shown in FIGS. 6A and 6B, the valve member 3A has a groove 3e formed on the upper surface of the valve body 3a. The upper surface of the valve body 3A is a surface that faces the bottom surface of the bolt head when screwed with the bolt member, and is a surface that abuts each other when completely screwed. In the illustrated example, one groove 3e extends from the upper end opening of the valve chamber 3c1 of one second oil passage 3c to the radially outer side of the valve member 3A with a predetermined depth and width.

  The decompression device 1A shown in FIG. 6C is a combination of the valve member 3A and the bolt member 2 of the first embodiment. The decompression device 1A of the second embodiment is basically used by completely screwing the bolt member 2 and the valve member 3A. FIG. 6C shows a state when the check valve 3d is opened and extended. At this time, the groove 3e functions as an oil passage that allows the second oil passage 3c and the second compartment 52 to communicate with each other. That is, the groove 3e functions as a part of the second oil passage 3c. The amount of oil passing through the second oil passage 3c can be adjusted by the size of the cross section of the groove 3e. The shape and number of the grooves 3e are not limited to the illustrated example, and various configurations are possible.

  FIG. 7 is a view showing a configuration example of a third embodiment of the decompression device according to the present invention, where (a) is a bottom view of the bolt member, (b) is a cross-sectional view taken along the line CC of (a), c) is a longitudinal sectional view of a state in which a bolt member and a valve member are screwed together.

  The third embodiment differs from the bolt member 2 of the first embodiment in the shape of the bolt member 2A. As shown in FIGS. 7A and 7B, the bolt member 2A has a groove 2e formed on the bottom surface of the bolt head 2b. The bottom surface of the bolt head 2b is a surface that faces the top surface of the valve body when screwed with the valve member, and is a surface that abuts each other when completely screwed. In the illustrated example, one groove 2e extends at a predetermined depth and width outward in the radial direction of the bolt member 2A from a position corresponding to the upper end opening of one second oil passage of the valve member. The outer end of the groove 2e reaches the periphery of the bolt head 2b.

  The decompression device 1B shown in FIG. 7C is a combination of the bolt member 2A and the valve member 3 of the first embodiment. The decompression device 1B of the third embodiment is basically used by completely screwing the bolt member 2A and the valve member 3 together. FIG. 7C shows a state when the check valve 3d is opened and extended. At this time, the groove 2e functions as an oil passage that allows the second oil passage 3c and the second compartment 52 to communicate with each other. That is, the groove 2e functions as a part of the second oil passage 3c. The amount of oil passing through the second oil passage 3c can be adjusted by the size of the cross section of the groove 2e. The shape and number of the grooves 2e are not limited to the illustrated example, and various configurations are possible.

  In the decompression device of the second and third embodiments shown in FIGS. 6 and 7, the bolt member and the valve member are completely screwed onto at least one of the mutually opposing surfaces of the bolt member and the valve member. In the state, a groove for communicating the second oil passage 3c and the second compartment 52 is provided. Since the bolt member and the valve member are completely screwed together, a stable fixing state of these members can be ensured.

  As another form, the form which combined valve member 3A of a 2nd embodiment and bolt member 2A of a 3rd embodiment is also possible.

  Although not shown, as a modification of the second and third embodiments, instead of the grooves 3e and 2e, a through hole is formed in the vicinity of at least one surface of the bolt member and the valve member facing each other. May be. This through-hole functions as an oil passage for communicating the second oil passage 3c and the second compartment 52 in a state where the bolt member and the valve member are completely screwed together.

<Test method>
A comparative experiment was conducted between the damper of the present invention equipped with a decompression device and the damper without the decompression device. A damper having the same configuration was used except for the presence or absence of a decompressor. The form shown in Drawing 2-Drawing 4 was adopted as the decompression device in the damper of the present invention. The moving speed of the piston rod was 0.2 m / s. This is a relatively fast moving speed.

  In both dampers, the aeration generation status during piston rod movement was confirmed when the pressure in the gas chamber was 3.0 MPa, 2.5 MPa, 2.0 MPa, 1.5 MPa, 1.0 MPa, and 0.5 MPa. .

<Test results>
The test results are shown in Table 1. In a conventional damper without a pressure reducing device, the gas pressure necessary for normal operation of the free piston is 1.0 MPa or more. Even when the required gas pressure is set, aeration may occur when the moving speed of the piston rod is high. The results of the comparative example support this prior art. On the other hand, the damper equipped with the decompression device did not generate aeration even when the gas pressure was reduced to 0.5 MPa. From this result, it was proved that the decompression device assists the normal operation of the free piston. With the decompression device, the required pressure in the gas chamber can be reduced from 2.0 MPa to 0.5 MPa. That is, the gas pressure can be reduced by 75%.

1, 1A, 1B Pressure reducing device 2, 2A Bolt member 2a Screw portion 2a1 Male screw 2b Bolt head 2c First oil passage 2e Groove 3, 3A Valve member 3a Valve body 3a1 Female screw 3b Tube wall portion 3c Second oil passage 3c1 Valve chamber 3c2 Valve hole 3d Check valve 3e Groove 10 Damper 20 Piston part 21 Piston rod 22 Piston valve 23 Oil passage 24 Oil passage with valve 30 Free piston 40 Damper cylinder 41 Top cover 42 Oil seal 50 Oil chamber 51 First compartment 52 First 2nd chamber 53 3rd chamber 60 Gas chamber

Claims (3)

A free piston (30) that divides the damper cylinder (40) into an oil chamber (50) and a gas chamber (60) and is slidable in the cylinder;
A piston rod (21) penetrating through one end of the damper cylinder (40) and capable of reciprocating in the first compartment (51) of the oil chamber (50) and the oil chamber located at the tip of the piston rod (21) A piston valve (22) that partitions the first compartment (51) and the second compartment (52) of (50);
A pressure reducing device (1) positioned between the piston valve (22) and the free piston (30) and defining a second compartment (52) and a third compartment (53) of the oil chamber (50); Single cylinder shock absorber damper (10),
The pressure reducing device (1) is composed of a bolt member (2) and a valve member (3),
The bolt member (2) includes a first thread (2a1) provided in the axial direction of the damper cylinder (40), the second compartment (52), and the third compartment (53) in constant communication with each other. An oil passage (2c),
The valve member (3) is fixed to the damper cylinder (40), and has a female screw (3a1) screwed with the male screw (2a1) of the bolt member (2), and the second compartment (52). A second oil passage (3c) enabling communication with the third compartment (53) and a position on the second oil passage (3c) and closed when the piston rod (21) is contracted and opened when extended. A check valve (3d) ,
The size of the gap between the bolt member (2) and the valve member (3) varies depending on the degree of screwing between the bolt member (2) and the valve member (3), whereby the second oil passage ( A single cylinder shock absorber damper characterized in that the flow rate of 3c) can be adjusted .   The check valve (3d) is a ball body and is disposed in a valve chamber (3c1) provided inside the valve member (3), and the valve chamber (3c1) is the second compartment (52). The damper for a single-cylinder shock absorber according to claim 1, wherein the damper is capable of communicating with the third compartment (53) through a valve hole (3c2) that opens to the side and serves as a valve seat for the ball body. At least one of the bolt member and the valve member is a groove for communicating the second oil passage (3c) and the second compartment (52) in a state where the bolt member and the valve member are completely screwed together. The damper of a single cylinder type shock absorber according to claim 1 or 2 , further comprising (2e, 3e) or a through hole.

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