JP6376779B2 - shock absorber - Google Patents

Description

  The present invention relates to a technique for improving braking accuracy without increasing the manufacturing cost of a shock absorber.

  Conventionally, a piston and an orifice are accommodated together with a viscous fluid in a cylindrical cylinder with a bottom, and when the piston moves in the axial direction in the cylinder, a braking force is generated by a flow resistance of the viscous fluid passing through the orifice. Shock absorbers are known. For example, it is as described in Patent Document 1 and Patent Document 2.

JP 2001-132790 A JP 2005-188893 A

  In a shock absorber configured as in the prior art, a technique is known in which a spring is inserted between a piston and an orifice, and the magnitude of the flow resistance is changed between when the piston rod is pushed into the cylinder and when the piston rod returns. . However, since the free length of the spring when the piston rod returns is not constant, there has been a problem that the rising of the braking force in the shock absorber varies. On the other hand, if the accuracy of the free length of the spring is increased in order to improve the accuracy of rising of the braking force, there is a problem that the cost increases due to an increase in the number of parts.

The present invention has been made in view of the above situation.
That is, the problem to be solved by the present invention is to provide a shock absorber with a simple and inexpensive configuration that can suppress variations in rising of the braking force.

  Hereinafter, means for solving the above problems will be described.

That is, in claim 1, the cylinder is formed in a bottomed cylindrical shape having an opening on one end side and a bottom on the other end side, and a cylinder in which viscous fluid is sealed, and the opening is closed, A cap having an insertion hole in a portion thereof, a piston that slidably slides on the inner peripheral surface of the cylinder in the axial direction, and a space between the bottom of the cylinder and the piston. A first spring that is inserted and urges the piston toward the opening, and is inserted into the insertion hole of the cap, with one end extending outside the cylinder and the other end inserted into the cylinder. A piston rod that is fixed to the other end of the piston rod, and is connected to the piston and has an orifice in which an viscous passage for allowing viscous fluid to flow is formed. A shock absorber that generates a braking force by a flow resistance of a viscous fluid passing through the orifice when the piston moves axially in the cylinder together with the ton rod, and the piston and the orifice are more than a predetermined distance apart from each other. A second spring is interposed between the piston and the orifice to bias the piston and the orifice in a direction away from each other within a small range . When the end face on the direction side close to the piston side is in contact with the end face on the direction side close to the orifice side of the piston, the orifice blocks the flow path other than the orifice flow path, thereby causing flow resistance. together increases, the direction close to the piston side of the orifice When the surface is spaced apart from the end face of the direction close to the orifice side of the piston, in which the flow resistance of the viscous fluid is reduced by the orifice to open the flow path other than the orifice passage .

  According to a second aspect of the present invention, the piston and the orifice are formed with an engaging projection on one side and an engaging groove having a predetermined axial width on the other, and the engaging projection is engaged with the engagement. By being engaged with the groove portion, they are configured to be close to and away from each other within a range smaller than a predetermined interval.

  According to a third aspect of the present invention, the orifice is formed by inserting a columnar member into a cylindrical member having a channel hole opened at the bottom, and a plurality of flow channels are provided between the cylindrical member and the columnar member. A plurality of plate-like members having passage holes are inserted, and the orifice flow path includes the flow-path hole of the tubular member, the flow-path hole of the plate-shaped member, and the tubular member. It is formed by a gap between the peripheral surface and the outer peripheral surface of the columnar member.

  According to a fourth aspect of the present invention, the orifice has a flow path hole opened at the bottom and a diameter of the female screw member having a diameter reduced toward the tip reduced toward the tip. A male screw part is formed by screwing a male screw member formed on an outer peripheral surface thereof, and the orifice flow path includes the flow path hole of the female screw member, the female screw part of the female screw member, and the male screw part of the male screw member. It is formed by the gap between.

  The present invention has an effect of providing a shock absorber that can suppress variation in rising of braking force with a simple and inexpensive configuration.

Sectional drawing which shows the normal state of the shock absorber which concerns on 1st embodiment. Sectional drawing which similarly shows the shock absorber at the time of the pushing start of a piston rod. Sectional drawing which similarly shows the shock absorber in the middle of pushing in of a piston rod. Sectional drawing which shows the shock absorber in the state where the piston rod was similarly pushed in. Sectional drawing which similarly shows the shock absorber at the time of the return start of a piston rod. Sectional drawing which similarly shows the shock absorber in the middle of return of a piston rod. Similarly the expanded sectional view which shows the flow path of the viscous fluid in the middle of pushing in of a piston rod. The expanded sectional view which similarly shows the flow path of the viscous fluid in the middle of return of a piston rod. The expanded sectional view which shows the orifice flow path in the shock absorber which concerns on 2nd embodiment.

  First, the shock absorber 10 which concerns on 1st embodiment of this invention is demonstrated using FIGS. 1-8. In the following description, the upper side in each figure is described as being above the shock absorber 10.

  As shown in FIG. 1, the shock absorber 10 includes a cylinder 11, a cap 12, an oil seal 13, a volume absorber 14, an oil sealing screw 15, an O-ring 16, a piston rod 17, a rod cover 18, and the like. , Piston 21, first spring 22, second spring 23, and orifice 20 (tubular member 24, plate-like members 25, 25..., Columnar member 26). Hereinafter, each member will be specifically described.

  The cylinder 11 is formed in a bottomed cylindrical shape having an opening portion 11a on one end side (upper side in FIG. 1) and a bottom portion 11b on the other end side. A sealing hole 11c penetrating the bottom 11b is opened in the bottom 11b. An oil sealing screw 15 is inserted into the sealing hole 11 c in a state where oil as a viscous fluid is filled in the cylinder 11, and an O-ring 16 is interposed between the lower surface of the cylinder 11 and the oil sealing screw 15. Is inserted. Thereby, oil is enclosed in the cylinder 11.

  The cap 12 is a columnar member that closes the opening 11 a of the cylinder 11. An insertion hole 12 a that passes through both planes of the cap 12 is opened at the center of the cap 12. As shown in FIG. 1, the piston rod 17 is inserted into the insertion hole 12a.

  The oil seal 13 is a columnar member that is fitted into the cylinder 11 adjacent to the lower side of the cap 12. The oil seal 13 seals the opening 11 a of the cylinder 11, thereby preventing leakage of the oil enclosed in the cylinder 11. Note that the cap 12 may have a sealing function.

  A volume absorber 14 is fitted into the cylinder 11 adjacent to the lower side of the oil seal 13. The volume absorber 14 is a cylindrical member configured by combining closed cell rubber and sponge. Then, as will be described later, when the piston rod 17 is pushed into the cylinder, the air bubbles are compressed to absorb the volume increase of the inserted piston rod 17.

  As described above, the piston rod 17 is a rod-like member that is inserted into the insertion hole 12 a that is opened in the cap 12. One end side (the upper side in FIG. 1) of the piston rod 17 extends to the outside of the cylinder 11, and the other end side is inserted into the cylinder 11. That is, the piston rod 17 passes through the cap 12, the oil seal 13, and the volume absorber 14, and is disposed so as to be slidable in the vertical direction. A rod cover 18 is disposed at the upper end of the piston rod 17.

  The piston 21 is a substantially cylindrical member housed in the cylinder 11, and the outer peripheral surface 21 c slides on the inner peripheral surface of the cylinder 11, thereby dividing the internal space of the cylinder 11 into two in the axial direction. A communication hole 21a is opened on the bottom surface of the piston 21, and oil flows up and down through the inside of the piston 21 through the communication hole 21a. A storage chamber 21b is formed inside the piston 21, and a second spring 23 is stored in the storage chamber 21b as will be described later. A cylindrical portion 21d protrudes from the upper portion of the piston 21, and an engaging groove portion 21e having a predetermined width D in the axial direction (vertical direction) (see FIGS. 7 and 8) is provided in the circumferential direction on the cylindrical portion 21d. Is formed. A first spring 22 that urges the piston 21 toward the opening 11 a (upper side) is interposed between the upper surface of the bottom of the cylinder 11 and the piston 21.

  On the other end side (the lower side in FIG. 1) of the piston rod 17, an orifice 20 is fixed, in which an orifice channel for allowing the viscous fluid to flow is formed. The lower portion of the orifice 20 is connected to the piston 21. The orifice 20 includes a cylindrical member 24, plate-like members 25, 25, and a columnar member 26. The orifice 20 is formed by fitting the columnar member 26 into the cylindrical member 24 in a state where the three plate-shaped members 25, 25. That is, in the orifice 20, plate-like members 25, 25... Are inserted between the tubular member 24 and the columnar member 26. In the present embodiment, three plate-like members 25 are provided, but the number is not limited. It is also possible to adopt a configuration in which the plate-like member 25 is not provided.

  The cylindrical member 24 is formed in a cylindrical shape having a channel hole 24a opened at the bottom. On the outer peripheral surface at the bottom of the cylindrical member 24, an engaging protrusion 24b that protrudes outward is formed. A plurality of channel holes 25a (see FIGS. 7 and 8) are opened in the thickness direction of the plate-like members 25, 25. A gap is formed between the inner peripheral surface of the cylindrical member 24 and the outer peripheral surface of the columnar member 26 to such an extent that oil can circulate. In the orifice 20, the flow path hole 24 a of the cylindrical member 24, the flow path holes 25 a of the plate-shaped members 25, 25, and the inner peripheral surface of the cylindrical member 24 and the outer peripheral surface of the columnar member 26. A gap is formed as an orifice channel.

  As shown in FIG. 1, the engagement protrusion 24 b of the cylindrical member 24 engages with the engagement groove 21 e of the piston 21. Accordingly, the orifice 20 and the piston 21 are configured to be close to and away from each other within a range smaller than a predetermined interval (a predetermined width D of the engagement groove portion 21e). Further, a second spring 23 is interposed between the piston 21 and the orifice 20 to urge the piston 21 and the orifice in a direction away from each other. Specifically, as shown in FIG. 1, the second spring 23 is accommodated in the accommodation chamber 21 b of the piston 21, and the second spring 23 contacts the bottom surface of the cylindrical member 24 in the orifice 20, whereby the second spring 23 is The piston 21 and the orifice are urged away from each other. In the present embodiment, the engagement protrusion 24b is formed on the orifice 20 and the engagement groove 21e is formed on the piston 21, but the engagement groove is formed on the orifice 20 and the piston 21 is engaged. It is also possible to adopt a configuration in which a mating protrusion is formed.

  The shock absorber 10 according to the present embodiment is configured as described above, so that when the piston 21 together with the piston rod 17 moves in the cylinder 11 in the axial direction, a braking force is generated by the flow resistance of the oil passing through the orifice 20. It is configured to generate.

  Specifically, as shown in FIG. 2, when the piston rod 17 starts to be pushed, the piston 21 is not displaced by the elastic force of the first spring 22 and the frictional resistance on the outer peripheral surface 21c, and only the orifice 20 is lowered. As a result, the second spring 23 is compressed, and the lower surface of the orifice 20 comes into contact with the upper surface of the piston 21. At this time, the storage chamber 21 b is in a state of communicating only with the flow path hole 24 a of the cylindrical member 24. That is, when the orifice 20 is in contact with the piston 21, the orifice 20 closes a flow path other than the orifice flow path.

  Next, while the piston rod 17 is being pushed in, as shown in FIG. 3, the piston 21 descends with the orifice 20 in contact therewith, and the first spring 22 is gradually compressed. At this time, since the storage chamber 21b is in a state of communicating only with the flow path hole 24a of the cylindrical member 24 (a state in which the flow path other than the orifice flow path is closed), the oil flow resistance increases. Specifically, as shown by arrows a, b, and c in FIG. 7, the oil flows from the storage chamber 21 b to the orifice channel (the channel hole 24 a, the channel hole 25 a, and the inner periphery of the cylindrical member 24. Only between the surface and the outer peripheral surface of the columnar member 26). For this reason, the flow resistance of the oil passing through the orifice 20 is increased and a large braking force is generated. When the piston 21 comes into contact with the oil sealing screw 15 as shown in FIG. 4, the compression of the first spring 22 is finished, and the pushing of the piston rod 17 is completed.

  Next, when the return of the piston rod 17 starts, as shown in FIG. 5, the piston 21 is not displaced by the elastic force of the second spring 23 and the frictional resistance on the outer peripheral surface 21c, and only the orifice 20 rises. Thereby, the second spring 23 extends, and the lower surface of the orifice 20 is separated from the upper surface of the piston 21. At this time, the storage chamber 21b is in a state of communicating with the outer peripheral portion of the cylindrical member 24, which is a portion other than the flow path hole 24a of the cylindrical member 24. That is, when the orifice 20 is separated from the piston 21, the orifice 20 opens a channel other than the orifice channel.

  Next, during the return of the piston rod 17, as shown in FIG. 6, the piston 21 rises with the orifice 20 spaced apart, and the first spring 22 gradually expands. At this time, since the storage chamber 21b is in a state of communicating with a portion other than the flow path hole 24a of the cylindrical member 24 (a state where the flow path other than the orifice flow path is opened), the flow resistance of the oil is reduced. Specifically, as shown by arrows d and e in FIG. 8, oil flows not only from the orifice flow path but also from the outer peripheral portion of the cylindrical member 24 to the accommodation chamber 21b other than the orifice flow path. For this reason, the flow resistance of the oil passing through the orifice 20 is reduced and the piston rod 17 is easily returned. As shown in FIG. 1, when the extension of the first spring 22 is completed, the return of the piston rod 17 is completed. At this time, the orifice 20 maintains the state in which the engaging protrusion 24 b is engaged with the engaging groove 21 e by the elastic force of the second spring 23.

  According to the shock absorber 10 according to the present embodiment, it is possible to suppress variations in the rising of the braking force by configuring as described above. Specifically, as shown in FIGS. 1 and 8, when the piston rod 17 returns, the length of the second spring 23 is kept constant in order to maintain the engagement protrusion 24b engaged with the engagement groove 21e. Can be. That is, since the engaging groove 21e is formed with a predetermined width D in the axial direction, the engaging protrusion 24b can be held at a position of the predetermined width D from the contact surface of the piston 21 with the orifice 20. In other words, since the extended length of the second spring 23 can be made constant, it is possible to improve the rising accuracy of the braking force at the start of the pushing of the piston rod 17 in the shock absorber 10.

  Further, according to the shock absorber 10 according to the present embodiment, the engagement protrusion 24b is formed in the orifice 20, the engagement groove 21e is formed in the piston 21, and the engagement protrusion 24b is engaged with the engagement groove 21e. By doing so, the orifice 20 and the piston 21 are configured to be close to and away from each other within a range smaller than the predetermined width D. Thereby, it becomes possible to make constant the length which the 2nd spring 23 extended with simple composition. That is, it is possible to improve the rising accuracy of the braking force at the start of pushing of the piston rod 17 in the shock absorber 10 with a simple configuration without increasing the number of parts.

  Further, in the shock absorber 10 according to the present embodiment, the orifice 20 is formed by fitting a columnar member 26 into a cylindrical member 24 having a channel hole 24a opened at the bottom, and the cylindrical member 24, the columnar member 26, and the like. A plurality of plate-like members 25 having a plurality of flow passage holes 25a, 25a. Further, the orifice channel includes a channel hole 24 a of the cylindrical member 24, channel holes 25 a, 25 a... Of the plate-shaped member 25, and an inner peripheral surface of the cylindrical member 24 and an outer peripheral surface of the columnar member 26. Formed by the gap. Thereby, the influence on the braking force of the shock absorber 10 in each member is reduced. In other words, a constant braking force can be obtained by compensating for variations in damping force among the components.

  Next, a shock absorber according to a second embodiment of the present invention will be described with reference to FIG. Since the shock absorber according to the present embodiment has substantially the same configuration as the shock absorber 10 according to the first embodiment, the description will focus on portions having different configurations.

  In the present embodiment, the configuration of the orifice is different from that of the first embodiment. Specifically, as shown in FIG. 9, the orifice in this embodiment includes a female screw member 124 and a male screw member 126. The female screw member 124 is formed in a cylindrical shape with a channel hole 124a opened at the bottom, and a tapered female screw portion 124c having a diameter reduced toward the tip is formed on the inner peripheral surface thereof. On the outer peripheral surface of the bottom portion of the female screw member 124, an engaging protrusion 124b that protrudes outward is formed. On the other hand, the male screw member 126 is formed with a tapered male screw portion 126a having a reduced diameter toward the tip on the outer peripheral surface thereof. The female screw member 124 and the male screw member 126 are coupled by the male screw portion 126a being screwed into the female screw portion 124c, thereby forming an orifice in the present embodiment.

  As shown in FIG. 9, a gap is formed between the male screw portion 126a and the female screw portion 124c to such an extent that oil can flow. In the orifice according to the present embodiment, the flow passage hole 124a of the female screw member 124 and the gap between the male screw portion 126a and the female screw portion 124c are spirally formed as the orifice flow channel.

  In the present embodiment, the braking force in the shock absorber can be adjusted by configuring as described above. Specifically, when the male screw part 126a of the male screw member 126 is screwed into the female screw part 124c of the female screw member 124, the width of the orifice channel can be adjusted by adjusting the tightening amount. . That is, when the orifice flow path is narrowed, the flow resistance of oil passing through the orifice increases, so that the braking force generated in the shock absorber can be increased. On the contrary, when the orifice flow path is widened, the flow resistance of the oil passing through the orifice is reduced, so that the braking force generated in the shock absorber can be reduced.

10 Shock absorber 20 Orifice (tubular member 24 / columnar member 26)
21 piston 23 second spring

Claims (1)

A cylinder that is formed in a bottomed cylinder shape having an opening on one end side and a bottom portion on the other end side, and in which a viscous fluid is enclosed;
A cap that closes the opening and has an insertion hole in the center;
A piston that divides the internal space of the cylinder in the axial direction by sliding on the inner peripheral surface of the cylinder;
A first spring interposed between the bottom of the cylinder and the piston and biasing the piston toward the opening;
A piston rod that is inserted into the insertion hole of the cap, has one end extending outside the cylinder, and the other end inserted into the cylinder;
An orifice that is fixed to the other end side of the piston rod and connected to the piston, and in which an orifice channel for allowing a viscous fluid to flow is formed.
A shock absorber that generates a braking force by flow resistance of a viscous fluid passing through the orifice when the piston moves axially in the cylinder together with the piston rod;
The piston and the orifice are configured to be close to and away from each other within a range smaller than a predetermined interval.
A second spring is interposed between the piston and the orifice to bias the piston and the orifice in a direction away from each other.
When the end face of the orifice in the direction close to the piston side is in contact with the end face of the piston in the direction close to the orifice side, the orifice closes a flow path other than the orifice flow path. When the end surface on the direction side close to the piston side of the orifice is separated from the end surface on the direction side close to the orifice side of the piston, the orifice becomes the orifice flow path. A shock absorber characterized in that the flow resistance of a viscous fluid is reduced by opening a flow path other than the above.

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