JP2017106599A - shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber capable of regulating radial regulation of a piston, and obtaining a stable characteristic.SOLUTION: A shock absorber includes a cylinder 3 configured to store working fluid and form a pressure chamber 13, a piston 5 disposed in the cylinder 3 so as to be reciprocatable to the pressure chamber 13, and a piston rod 7 whose one end is connected to the piston 5 and the other end projects outside the cylinder 3. On an inner periphery of the pressure chamber 13, provided are six ribs 17a projecting toward an inner diameter direction in a clearance between the pressure chamber 13 and the piston 5 and configured to locate the piston 5 at a center part of the pressure chamber 13.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a shock absorber that absorbs energy of a heavy object in operations of a printing machine, an automobile conveyance line, an assembly robot, and the like.

  Conventionally, a dash pot (annular orifice) type shock absorber has a large variation in operation time, and its characteristics tend to be unstable.

  The cause is that the flow rate of the hydraulic oil is different between the case where the axes of the piston and the cylinder are aligned and the case where the piston is biased in contact with the inside of the cylinder. For this reason, there has been a problem that the characteristics become unstable, for example, the repeated operation time changes due to the change in the radial bias when the operation is repeated.

  Further, as a hydraulic shock absorber, a shock absorber that controls the shock absorbing capacity at the time of collision or the peak value of impact acceleration is made as small as possible has already been disclosed in, for example, Patent Document 1 and Patent Document 2. ing. The shock absorber disclosed in Patent Document 1 has a tapered shape in which the inner peripheral surface of a pressure chamber of a cylinder filled with hydraulic fluid becomes thinner in a linear or quadratic curve in the direction in which the piston operates. Formed. The shock absorber disclosed in Patent Document 2 has a tapered shape in which the inner peripheral surface of the pressure chamber is linearly narrowed in the direction in which the piston operates, and the taper ratio is in the range of 1/50 to 1/130. Is formed.

  In the shock absorber of Patent Document 1, since the orifice formed in the gap between the cylinder and the piston becomes smaller as the piston moves, the shock absorbing capacity is small at the start of buffering, the rod moves, and the orifice becomes smaller. Then, it is explained that the amount of energy absorption increases and the speed of the moving object to be buffered stops changes to a low speed.

  In the shock absorber of Patent Document 2, when an experiment was performed under a specific condition using a specific experimental device, the experimental result that the peak value of the impact acceleration was low in the range of 1/50 to 1/130 was obtained. From the obtained results, the range is said to be effective for impact relaxation.

  On the other hand, the shock absorber of Patent Document 3 is based on the shock absorbers of Patent Documents 1 and 2, and the stage in which the moving object collides with the rod end of the piston and the piston starts moving, and the subsequent main deceleration stage. And the change in diameter reduction of the inner peripheral surface of the pressure chamber at the end of the buffer stop afterwards is set appropriately, and the performance meets the user's request as much as possible while considering the ease of processing to some extent It is said that.

  On the other hand, in general, when trying to obtain a waveform having a characteristic indicating the optimum absorption efficiency of the impact energy shown in FIG. 3, the inner peripheral surface 103 of the cylinder 101 has a non-linear taper shape with respect to the piston 105 as shown in FIG. become.

  In this manner, various characteristics can be obtained by customizing the shape of the inner peripheral surface of the cylinder, and it is possible to appropriately satisfy the user's requirements.

  However, when the pressure chamber has a structure in which the diameter changes in the moving direction of the piston, such as a taper shape in which the inner peripheral surface of the pressure chamber becomes linear or quadratic, or other shapes, the piston is If it is located on the side where the inner diameter is larger, the clearance between the outer peripheral surface of the piston and the inner peripheral surface of the pressure chamber will increase, and stable operation will not be possible due to the radial deviation of the piston relative to the cylinder, making the characteristics unstable. There was a problem.

Japanese Utility Model Publication No. 62-140241 JP 2006-250309 A 2012-215272 gazette

  The problem to be solved is that the operation becomes unstable due to the radial deviation of the piston relative to the cylinder, and the characteristics become unstable.

  The present invention regulates the radial deviation of the piston and makes it possible to obtain stable characteristics. Therefore, a cylinder that contains a working liquid and forms a pressure chamber, and the pressure chamber in the cylinder A piston disposed so as to be capable of reciprocating, and a piston rod having one end coupled to the piston and the other end projecting out of the cylindrical body, and the pressure chamber and the piston are disposed on an inner periphery of the pressure chamber. A protrusion is provided so as to protrude in the inner diameter direction within the clearance between the pistons and restricts the position of the piston at the center of the pressure chamber.

  Since this invention is the said structure, a piston can be located in the center part of a pressure chamber with a protrusion. For this reason, the bias of the piston is restricted, and the characteristics can be stabilized by a stable operation.

It is sectional drawing of a shock absorber. (Example 1) (A) is the IIA-IIA arrow expanded sectional view of FIG. 1, (B) is the expanded sectional view of the comparative example corresponding to the IIA-IIA arrow of FIG. (Example 1) It is a wave form diagram of the characteristic which shows the optimal absorption efficiency of impact energy. (Conventional example) It is a schematic sectional drawing of a shock absorber. (Conventional example)

  The purpose of restricting the deviation of the piston in the radial direction and making it possible to obtain a stable characteristic is to protrude in the inner diameter direction within the clearance between the pressure chamber and the piston, on the inner periphery of the pressure chamber. This is realized by providing a protrusion for regulating the position of the piston at the center of the pressure chamber.

  The pressure chamber may have a different diameter part whose inner diameter changes in the moving direction of the piston, and the protrusion may be provided on the inner circumference of the different diameter part.

  The protrusion may be at least three ribs at predetermined intervals in the circumferential direction along the moving direction of the piston.

[shock absorber]
1 is a cross-sectional view of a shock absorber according to the present embodiment, FIG. 2 is an enlarged cross-sectional view taken along line IIA-IIA in FIG. 1, and FIG. 2B is a cross-sectional view taken along line IIA-IIA in FIG. It is an expanded sectional view of the comparative example corresponding to vision. The cylinder axis means the center axis of the cylinder.

  As shown in FIG. 1, the shock absorber 1 includes a cylinder 3, a piston 5, and a piston rod 7.

  The cylinder 3 is made of metal or resin, one end is opened, the other end is closed, and the main body is formed in a substantially cylindrical shape to constitute the cylinder of this embodiment.

  In the cylinder 3, first and second circular holes 11a and 11b having a circular cross section are provided. The inner peripheral diameter of the second circular hole portion 11b on one end side is formed larger than the inner peripheral diameter of the first circular hole portion 11a on the other end side.

  The first circular hole portion 11a is formed such that the inner peripheral diameter changes in the moving direction of the piston 5, that is, the cylinder axis direction of the cylinder 3, and the different diameter portion 15 is formed in the pressure chamber 13 formed by the first circular hole portion 11a. have. However, the present invention can also be applied to a cylinder that does not have the different diameter portion 15 and in which the inner diameter of the pressure chamber 13 does not change in the cylinder axis direction.

  The different diameter portion 15 is formed in a tapered shape in the present embodiment, and is set so that the diameter is maximum at one end 11aa of the first circular hole portion 11a and is minimum at the other end 11ab. However, the setting range and setting shape of the different-diameter portion 15 can be changed according to the characteristics to be obtained.

  About the setting range of the different diameter part 15, it can also form only in a part in the cylinder axis direction of the pressure chamber 13. FIG. For the formation of only a part, a taper shape is formed by dividing the pressure chamber 13 only at one end side in the cylinder axis direction, only at the intermediate portion, or at one end side and the other end side by a reverse taper or a forward taper. There are various settings.

  The shape of the different diameter portion 15 is not limited to a linear shape, and may be set to a tapered shape that narrows to a quadratic curve, a tapered shape with a taper ratio in the range of 1/50 to 1/130, or the like. Furthermore, the diameter change of the inner peripheral surface of the pressure chamber at the stage where the moving object collides with the rod tip of the piston and the piston starts moving, the subsequent main deceleration stage, and the end stage where the buffering is stopped thereafter. There is also a setting of a shape in which each is appropriately set.

  The different diameter portion 15 can include, in the concept, parallel portions that are present on one end side, the other end side, and the intermediate portion in the cylinder axis direction of the pressure chamber 13 in the characteristic setting. It can be a part to be provided.

  As shown in FIGS. 1 and 2A, in the embodiment of the present invention, a protrusion 17 is provided on the inner periphery of the different diameter portion 15 in particular. The protrusion 17 is provided so as to protrude in the inner diameter direction within the clearance between the pressure chamber 13 and the piston 5, and restricts the position of the piston 5 at the center of the pressure chamber 13. By this position restriction, the piston 5 is positioned in the radial direction with respect to the cylinder 3 so that the axial center of the piston 5 coincides with the central portion of the pressure chamber 13, that is, the cylinder shaft.

  The clearance between the pressure chamber 13 and the piston 5 is set according to the required performance.

  In addition, the accuracy of position regulation of the piston 5 varies depending on the required characteristics, and the shaft center of the piston 5 and the cylinder shaft of the pressure chamber 13 may be allowed to be slightly shifted due to a gap between them. Even in this case, the axial center of the piston 5 and the cylinder axis of the pressure chamber 13 tend to coincide with each other as compared with the case where the protrusion 17 does not exist in the pressure chamber 13.

  The protrusion 17 is formed integrally with the inner peripheral surface of the different-diameter portion 15 and is formed along the moving direction of the piston. At least three ribs at predetermined intervals in the circumferential direction, in this embodiment, six ribs 17a. Are evenly arranged at intervals of 60 degrees in the circumferential direction.

  When there are three ribs 17a, each rib is arranged at the apex of a triangle surrounding the cylinder axis in the radial cross section. With this arrangement, the position of the piston 5 can be stably regulated toward the cylinder axis. In addition, the number of ribs 17a is not limited as long as a clearance is formed between the piston 5 and the different diameter portion 15 such as four, five, seven, etc. and the required characteristics are satisfied.

  In this embodiment, the inner peripheral surface of the different-diameter portion 15 is formed integrally with the first circular hole portion 11a. For example, a separate lining is provided on the first circular hole portion 11a, and the inner periphery of this lining is provided. The surface may be the inner peripheral surface of the different-diameter portion 15, and the protrusion 17 may be provided integrally with the lining.

  In this case, the inner peripheral surface of the first circular hole portion 11a can be formed into a cylindrical shape having a uniform diameter, and the diameter of the inner peripheral surface of the lining can be changed in the cylinder axis direction. Moreover, it can also be set as the shape which changed the diameter of both the internal peripheral surface of the 1st circular hole part 11a, and the internal peripheral surface of lining to the cylinder axial direction.

  When the lining is used, the cylinder 3 can be made of resin or metal, and the lining can be made of metal or resin. As the lining material, it is possible to select a material having extremely low frictional resistance as compared with the cylinder 3.

  For example, the rib 17a has a semicircular cross section, and the semicircular top facing the piston 5 extends in the cylinder axis direction, and the semicircular top is parallel between the opposing ribs 17a. ing. The rib 17a is formed continuously from one end side to the other end side of the different-diameter portion 15 in the cylindrical axis direction. It is set to disappear on the end side, that is, on the other end 11ab side of the first circular hole portion 11a.

  However, the rib 17a may be configured to disappear at an intermediate portion of the different diameter portion 15 in the cylinder axis direction. In addition, the formation range of the ribs 17a can be variously set according to the form of the different diameter portion 15.

  The rib 17a guides the piston 5 with respect to the different-diameter portion 15 while extremely reducing the resistance caused by the contact of the piston 5 with the rib 17a.

  In addition, the rib 17a is not limited to a form that is continuous in the cylinder axis direction, but may be a form that is divided in the middle. The protrusions 17 are not limited to the ribs 17a, and local protrusions can be continuously arranged in the cylinder axis direction. In this case, it is desirable that the protrusions are hemispherical formed on the inner peripheral surface of the first circular hole portion 11a, and the distance between the protrusions continuous in the cylinder axis direction is smaller than the length of the piston 5.

  In the case where the protrusion is hemispherical, the disappearance of the protrusion on the other end 11ab side can be performed by gradually reducing the diameter of the hemisphere or by gradually reducing the curvature of the hemisphere to make it flat.

  Further, in the case of a cylinder that does not have the different-diameter portion 15 and the inner diameter of the pressure chamber 13 does not change in the cylinder axis direction, the protrusion can be in a constant protruding state in the cylinder axis direction.

  The first circular hole portion 11 a is closed by a closing member 19 attached to the other end of the cylinder 3. The closing member 19 is fixed to the other end of the cylinder 3 by press fitting, bonding, welding, or the like.

  The first circular hole portion 11a accommodates a working liquid such as an automatic transmission fluid (ATF), a working oil such as mineral oil, a silicone oil, and the like, and constitutes the pressure chamber 13. The operating characteristics can be finely adjusted by changing the viscosity of the oil.

  The cap 21 is fixed to the opening of the second circular hole portion 11b, that is, one end of the cylinder 3, and the second circular hole portion 11b is closed. The cap 21 is hollow and serves as a rod guide and also functions as a spring seat.

  In the second circular hole portion 11b, a packing receiving seat 23 is inserted and disposed at an intermediate portion in the cylinder axis direction. The packing receiving seat 23 is hollow, and its outer diameter is set to be slightly smaller than the inner diameter of the second circular hole portion 11b, so that it can move in the cylinder axis direction with respect to the second circular hole portion 11b. Yes.

  A coil spring 25 is interposed between the cap 21 and the packing receiving seat 23.

  A U packing 27 made of an elastic material such as nitrile rubber (NBR) or silicone rubber is disposed on the packing receiving seat 23. The U-packing 27 is formed in a hollow shape, and has a protrusion on the outer periphery in a circular shape, and the outer periphery is in close contact with the inner peripheral surface of the second circular hole portion 11b. One end of the U packing 27 is received by the packing receiving seat 23, and the peripheral edge of the other end abuts on the piston 5.

  A liquid storage chamber 29 is formed between the U packing 27 and the piston 5 and communicates with the pressure chamber 13. When the piston 5 and the piston rod 7 enter the pressure chamber 13, the liquid storage chamber 29 receives the hydraulic oil from the first circular hole 11 a side via the clearance between the piston 5 and the different diameter portion 15. . At this time, the U packing 27 and the packing receiving seat 23 move against the urging force of the coil spring 25, and the liquid storage chamber 29 expands.

  On the contrary, when the piston 5 and the piston rod 7 are retracted from the pressure chamber 13, the hydraulic oil that has moved at the time of impact absorption is returned to the first circular hole 11a side via the clearance.

  A shaft portion 3a projects from the tip of the piston 5, and a valve seat 31 is fixed to the shaft portion 3a. A protrusion for receiving a valve is formed on the surface of the valve seat 31 on the piston 5 side. A gap is formed between the valve seat 31 and the piston 5, and the valve 33 is disposed in the gap and is fitted to the shaft portion 3a.

  Accordingly, when the piston 5 moves into the pressure chamber 13, the valve 33 is positioned on the piston 5 side as shown in FIG. 1, and when the piston 5 moves away from the pressure chamber 13, the valve 33 moves along the shaft portion 3a. It is received by the valve seat 31.

  When the valve 33 is received by the valve seat 31, the hydraulic oil that flows back to the pressure chamber 13 through the clearance between the piston 5 and the different diameter portion 15 passes through the surface of the valve 33 on the piston 5 side. It can be distributed between the ribs 17a.

  The piston 5 is fitted and disposed at one end portion 7 a of the piston rod 7, and the piston rod 7 passes through the U packing 27, the packing receiving seat 23, and the cap 21, and the other end portion 7 b side protrudes outside the cylinder 3. . The other end portion 7b of the piston rod 7 protruding out of the cylinder 3 is coupled to a coupling portion (not shown) provided on the controlled object.

[Shock absorber operation]
When the piston rod 7 receives an impact force from the controlled object and is pushed into the cylinder 3, the piston 5 enters the pressure chamber 13 of the cylinder 3 in conjunction with the piston rod 7. At this time, the hydraulic oil in the pressure chamber 13 passes through the clearance between the piston 5 and the different diameter portion 15 and generates fluid resistance.

  The clearance between the piston 5 and the different diameter portion 15 corresponds to the movement of the piston 5 entering the pressure chamber 13 toward the other end 11ab side of the first circular hole portion 11a by setting the tapered shape of the different diameter portion 15. And the fluid resistance increases as the clearance decreases.

  The shock absorber 1 can buffer the external force by the shock absorption waveform caused by such fluid resistance.

  When the piston 5 enters the cylinder 3, the hydraulic oil moves from the first circular hole 11 a side to the liquid storage chamber 29 side via the clearance between the piston 5 and the different diameter portion 15. At this time, the U packing 27 and the packing receiving seat 23 move against the urging force of the coil spring 25, and the liquid storage chamber 29 expands.

  When the external force acting on the piston rod 7 disappears, the piston 5 and the piston rod 7 move away from the pressure chamber 13.

  When the retraction movement is performed, the flow resistance of the clearance is reduced according to the retraction movement of the piston 5 by setting the different diameter portion 15, and the piston 5 can be returned with good response.

  As shown in FIG. 2A, when the piston 5 moves from one end side to the other end side in the cylindrical axis direction of the different diameter portion 15, the six ribs 17a move along the outer peripheral surface of the piston 5 along the cylindrical axis direction. Since the guide is used, the movement of the piston 5 along the cylinder axis can be stably performed regardless of the different diameter portion 15.

  When the piston 5 is positioned at one end side of the different-diameter portion 15 in the cylinder axis direction, the clearance between the piston 5 and the different-diameter portion 15 is maximized. Even at this position of the piston 5, since the six ribs 17a face the outer peripheral surface of the piston 5, the position of the piston 5 can be stably regulated on the cylinder axis.

  Therefore, the linear movement of the piston 5 on the cylinder axis is stable, and stable operation characteristics can be obtained.

  Further, due to the position restriction of the piston 5 by the six ribs 17a, stable operation characteristics can be obtained even when the shock absorber 1 is used in an inclined state or a horizontal state.

  On the other hand, as shown in the comparative example of FIG. 2B, if there is no protrusion on the inner peripheral surface of the pressure chamber 13, the piston 5 is shown in the chain line from the axis C of the cylinder shaft in the pressure chamber 13. It is biased in the radial direction and uniform clearance around the piston 5 is not possible. For this reason, since the flow rate of the hydraulic oil is different between when the piston 5 is biased and when it is not, the repeated operation time in which the radial position of the piston is different every time it is repeatedly operated changes, and the characteristics become unstable. .

  Such deviation of the piston 5 can be regulated by the rib 17a.

[Effect of Example]
The pressure chamber 13 according to the embodiment of the present invention is provided so as to protrude in the inner diameter direction within the clearance between the pressure chamber 13 and the piston 5, and six pressure chambers for restricting the position of the piston 5 to the central portion of the pressure chamber 13. Ribs 17a are provided.

  For this reason, since the piston 5 is guided by the rib 17a, the bias of the piston 5 with respect to the pressure chamber 13 is regulated, and the characteristics can be stabilized even in the dashpot structure.

  In the present embodiment, the clearance 15 between the pressure chamber 13 and the piston 5 is reduced in accordance with the ingress of the piston 5 by setting the different-diameter portion 15 in a tapered shape, and the shock absorbing characteristic corresponding to this is reduced. Although it can be obtained, the position of the piston 5 can be restricted to the center of the pressure chamber 13 regardless of the change in the clearance between the different-diameter portion 15 and the piston 5.

  By restricting the position of the piston 5 by the six ribs 17a, the piston 5 can be stably moved on the cylinder axis of the cylinder 3, and the operation characteristics can be stabilized.

  Even when the shock absorber 1 is used in an inclined state or a horizontal state, the position of the piston 5 is regulated by the six ribs 17a regardless of the clearance between the different-diameter portion 15 and the piston 5, and the shock absorber 1 is stable. Operating characteristics can be obtained.

  By setting the different-diameter portion 15 in various ways, the shape of the inner peripheral surface of the cylinder 3 can be customized, but the piston 5 is placed in the pressure chamber regardless of the change in the clearance between the different-diameter portion 15 and the piston 5. The position can be restricted to the center portion of 13.

  The form of the shock absorber 1 is not limited to the embodiment, and various forms can be applied as long as the cylinder has a different diameter portion in the pressure chamber.

1 Shock absorber 3 Cylinder
5 Piston 7 Piston rod 13 Pressure chamber 15 Different diameter part 17 Projection part 17a Rib

Claims (3)

A cylinder that contains a working liquid and forms a pressure chamber;
A piston disposed so as to be capable of reciprocating with respect to the pressure chamber in the cylindrical body;
A piston rod having one end coupled to the piston and the other end protruding out of the cylinder;
Provided on the inner periphery of the pressure chamber is a protrusion for projecting in the inner diameter direction within the clearance between the pressure chamber and the piston and for restricting the position of the piston at the center of the pressure chamber. ,
Shock absorber characterized by that. The shock absorber according to claim 1,
The pressure chamber has a different diameter portion whose inner diameter changes in the moving direction of the piston,
On the inner periphery of the different diameter portion, the protrusion is provided.
Shock absorber characterized by that. The shock absorber according to claim 1 or 2,
The protrusions are at least three ribs at predetermined intervals in the circumferential direction along the moving direction of the piston.
Shock absorber characterized by that.

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