JP6626336B2 - shock absorber - Google Patents

Description

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

  Conventionally, a dashpot (annular orifice) type shock absorber has a tendency that operation time varies widely and characteristics are not stable.

  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 with each other 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, when the operation is repeated, the repetition operation time is changed due to a change in the radial deviation.

  Further, as a hydraulic shock absorber, one that controls a buffering capacity at the time of a collision or minimizes a peak value of an impact acceleration has been already disclosed in, for example, Patent Documents 1 and 2 and the like. ing. The shock absorber disclosed in Patent Literature 1 has an inner peripheral surface of a pressure chamber of a cylinder filled with a working fluid formed in a tapered shape such that the inner circumferential surface becomes thinner in a linear or quadratic curve shape in a direction in which the piston operates. It was formed. The shock absorber disclosed in Patent Literature 2 is such that the inner peripheral surface of the pressure chamber is linearly thinner in the direction in which the piston operates, and has a taper ratio in a range of 1/50 to 1/130. It is formed in.

  In the shock absorber of Patent Literature 1, the orifice formed in the gap between the cylinder and the piston becomes smaller as the piston moves, so that the shock absorbing capacity is small at the start of buffering, and the rod moves to make the orifice smaller. It is described that when this happens, the amount of energy absorption increases, and the speed of the moving object to be buffer-stopped changes to a low speed.

  In the shock absorber of Patent Document 2, when an experiment was performed under specific conditions using a specific experimental device, an experimental result that the impact acceleration peak value was low in a taper ratio in the range of 1/50 to 1/130 was obtained. Based on the 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, in which a moving object collides with the tip of the rod of the piston and the piston starts moving, and a subsequent main deceleration step. And the diameter change of the inner peripheral surface of the pressure chamber at the end stage of buffer stop after that were set appropriately, and the performance was to satisfy the user's requirements as much as possible while taking into account the ease of processing to some extent. It has been.

  On the other hand, in general, when it is desired 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 tapered shape with respect to the piston 105 as shown in FIG. become.

  As described above, 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, if the inner peripheral surface of the pressure chamber has a structure in which the diameter changes in the direction of movement of the piston, such as a tapered shape or another shape in which the inner peripheral surface becomes thinner in a linear or quadratic curve shape, the piston becomes If the piston is located on the side with the larger inner diameter, the clearance between the outer peripheral surface of the piston and the inner peripheral surface of the pressure chamber becomes large, and stable operation cannot be performed due to radial deviation of the piston with respect to the cylinder, resulting in unstable characteristics. There was a problem.

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

  The problem to be solved is that a stable operation cannot be performed due to the radial deviation of the piston with respect to the cylinder, and the characteristics become unstable.

The present invention regulates the radial deviation of the piston, and in order to be able to obtain stable characteristics, a cylindrical body containing a working liquid to form a pressure chamber having a circular cross section , a piston disposed for reciprocal movement relative to the pressure chamber, and a piston rod the other end one end of which is coupled to the piston projects into the tube outside, an inner periphery of the circular section of the pressure chamber, the cross-section A protrusion is provided so as to protrude in the inner diameter direction within a clearance between the inner periphery of the circular pressure chamber and the piston, and regulates the position of the piston at the center of the pressure chamber. .

  Since the present invention has the above configuration, the piston can be positioned at the center of the pressure chamber by the projection. For this reason, the bias of the piston is regulated, and the characteristics can be stabilized by the stable operation.

It is sectional drawing of a shock absorber. (Example 1) (A) is an enlarged sectional view taken along the line IIA-IIA in FIG. 1, and (B) is an enlarged sectional view taken along the line IIA-IIA in FIG. 1. (Example 1) It is a waveform 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 radial deviation of the piston and enabling to obtain stable characteristics is to project in the inner diameter direction of the pressure chamber, in the clearance between the pressure chamber and the piston, in the radial direction. This was realized by providing a projection for regulating the position of the piston at the center of the pressure chamber.

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

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

[shock absorber]
1 is a cross-sectional view of the shock absorber according to the present embodiment, FIG. 2A is an enlarged cross-sectional view taken along line IIA-IIA of FIG. 1, and FIG. 2B is a cross-sectional view taken along line IIA-IIA of FIG. It is an expanded sectional view of a comparative example corresponding to a view. In addition, a cylinder axis | shaft means the center axis of a 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, has one end opened, the other end closed, and a main body formed in a substantially cylindrical shape to constitute the cylinder of the present embodiment.

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

  The first circular hole portion 11a is formed so that the inner peripheral diameter changes in the moving direction of the piston 5, that is, in the cylinder axis direction of the cylinder 3, and the pressure chamber 13 formed by the first circular hole portion 11a has a different diameter portion 15a. have. However, the present invention can also be applied to 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 different diameter portion 15 is formed in a tapered shape in this 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 the setting shape of the different diameter portion 15 can be changed according to the desired characteristics.

  The setting range of the different diameter portion 15 can be formed only in a part of the pressure chamber 13 in the cylinder axis direction. In order to form only a part of the pressure chamber 13, only one end in the cylinder axis direction of the pressure chamber 13, only the middle part, or one end and the other end of the pressure chamber 13 are formed with a reverse taper or a forward taper to form a tapered shape. There are various settings.

  For example, the shape of the different diameter portion 15 is not limited to a linear shape, but may be a tapered shape that becomes thinner in a quadratic curve shape, a taper shape having a taper ratio in a range of 1/50 to 1/130, and the like. Furthermore, the diameter reduction of the inner peripheral surface of the pressure chamber during the stage where the moving object collides with the tip of the rod of the piston and the piston starts to move, the subsequent main deceleration stage, and then the end stage of buffer stop Is appropriately set.

  The different diameter portion 15 may include, in concept, a parallel portion that is present at one end, the other end, and an intermediate portion of the pressure chamber 13 in the cylinder axis direction in terms of characteristics. It can be provided.

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

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

  In addition, the accuracy of the position regulation of the piston 5 differs depending on required characteristics, and in some cases, the axial center of the piston 5 and the cylinder axis of the pressure chamber 13 may be allowed to slightly shift due to a gap therebetween. Also 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 projection 17 does not exist in the pressure chamber 13.

  The projecting portion 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, and has at least three ribs at predetermined intervals in the circumferential direction, in this embodiment, six ribs 17a. Are equally arranged at intervals of 60 degrees in the circumferential direction.

  When the number of the ribs 17a is three, the ribs are arranged at the vertices 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, there is no limitation on the number of ribs 17a, such as four, five, and seven ribs, as long as a clearance is formed between the piston 5 and the different diameter portion 15 and required characteristics are satisfied.

  The inner peripheral surface of the different diameter portion 15 is formed integrally with the first circular hole portion 11a in the present embodiment. For example, a separate lining is provided in the first circular hole portion 11a, and the inner peripheral surface of this lining is provided. The surface may be the inner peripheral surface of the different diameter portion 15, and the projection 17 may be provided integrally with this 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 inner peripheral surface of the lining can be formed in a shape in which the diameter changes in the cylinder axis direction. The diameter of both the inner peripheral surface of the first circular hole portion 11a and the inner peripheral surface of the lining may be changed in the cylinder axis 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. It is also possible to select a material having extremely low frictional resistance as compared with the cylinder 3 as the material of the lining.

  The rib 17a is formed, for example, to have a semicircular cross section, a semicircular top facing the piston 5 extends in the cylinder axis direction, and the semicircular top is parallel between the facing ribs 17a. ing. The rib 17a is formed continuously from one end to the other end of the different diameter portion 15 in the cylinder axis direction. It is set so as to disappear on the end side, that is, on the other end 11ab side of the first circular hole 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 rib 17a can be variously set according to the form of the different diameter portion 15.

  The rib 17a guides the piston 5 to the different diameter portion 15 while extremely reducing the resistance of the piston 5 against the rib 17a.

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

  When 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 gradually reducing the curvature of the hemisphere and making 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 projection can be set to a constant projection state in the cylinder axis direction.

  The first circular hole 11a 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, adhesion, welding, or the like.

  The first chamber 11a contains a working liquid, for example, an automatic transmission fluid (ATF), a working oil such as a mineral oil, a silicone oil, and the like, and forms the pressure chamber 13. By changing the viscosity of the oil, fine adjustment of the operating characteristics is possible.

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

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

  A coil spring 25 is interposed between the cap 21 and the packing 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 is provided with a ridge 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 11b. One end of the U packing 27 is received by the packing receiving seat 23, and the other end of the U packing 27 is in contact with 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 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.

  Conversely, when the piston 5 and the piston rod 7 are retracted from the pressure chamber 13, they serve to return the hydraulic oil, which has moved at the time of absorbing the shock, to the first circular hole 11a via the clearance.

  A shaft 3a is protruded from the tip of the piston 5, and a valve seat 31 is fixed to the shaft 3a. A valve receiving projection 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 fitted to the shaft 3a.

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

  When the valve 33 is received by the valve seat 31, the hydraulic oil flowing 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 arranged at one end 7a of the piston rod 7, and the piston rod 7 penetrates the U packing 27, the packing receiving seat 23, and the cap 21, and the other end 7b side projects outside the cylinder 3. . The other end 7b of the piston rod 7 protruding out of the cylinder 3 is connected to a connecting portion (not shown) provided on the control target.

[Operation of shock absorber]
When the piston rod 7 receives the impact force from the control target and is pushed into the cylinder 3, the piston 5 moves into the pressure chamber 13 of the cylinder 3 in conjunction therewith. 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 depends on the movement of the piston 5 entering the pressure chamber 13 toward the other end 11ab of the first circular hole portion 11a by setting the tapered shape of the different diameter portion 15. And the fluid resistance increases with decreasing clearance.

  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 to the liquid storage chamber 29 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 there is no external force acting on the piston rod 7, the piston 5 and the piston rod 7 retreat from the pressure chamber 13.

  In the evacuation movement, the flow resistance of the clearance is reduced according to the evacuation movement of the piston 5 by the setting of the different diameter portion 15, thereby enabling the piston 5 to return with a good response.

  As shown in FIG. 2A, when the piston 5 moves from one end of the different diameter portion 15 in the cylinder axis direction to the other end, the six ribs 17a move the outer peripheral surface of the piston 5 along the cylinder axis direction. Since the guide is performed, 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 located 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, the six ribs 17a face the outer peripheral surface of the piston 5, so that 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 stabilized, and stable operation characteristics can be obtained.

  Further, by restricting the position 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, if there is no protrusion on the inner peripheral surface of the pressure chamber 13 as in the comparative example of FIG. 2B, the piston 5 moves from the axis C of the cylinder shaft in the pressure chamber 13 as shown by a chain line in the drawing. And a uniform clearance cannot be provided around the piston 5. For this reason, since the flow rate of the hydraulic oil is different between the case where the piston 5 is biased and the case where the piston 5 is not biased, the operation time of the repetition in which the radial position of the piston is different each time changes, and the characteristics become unstable. .

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

[Effects of Embodiment]
The pressure chambers 13 of the embodiment of the present invention are provided so as to protrude in the radial direction within the clearance between the pressure chambers 13 and the pistons 5, and are used to regulate the position of the pistons 5 at the center of the pressure chambers 13. A rib 17a is 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.

  Further, in the present embodiment, the clearance between the pressure chamber 13 and the piston 5 is reduced in accordance with the approach of the piston 5 by setting the different diameter portion 15 to a tapered shape, and the shock absorption characteristic according to this is reduced. While being obtained, the position of the piston 5 can be regulated at 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 the position regulation by the six ribs 17a of the piston 5, the piston 5 can be stably moved on the cylinder axis of the cylinder 3, and the operating characteristics can be stabilized.

  Further, 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 size of the clearance between the different diameter portion 15 and the piston 5, and the shock absorber 1 is stabilized. 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, and the piston 5 is kept 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 regulated at the center of the thirteenth position.

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

1 Shock absorber 3 Cylinder (cylindrical body)
5 Piston 7 Piston rod 13 Pressure chamber 15 Different diameter part 17 Projecting part 17a Rib

Claims (3)

A cylinder containing a working liquid to form a pressure chamber having a circular cross section ;
A piston disposed reciprocally with respect to the pressure chamber in the cylinder;
A piston rod having one end coupled to the piston and the other end protruding outside the cylindrical body,
The inner periphery of the circular section of the pressure chamber, the position of the piston is provided so as to protrude radially inward to the central portion of the pressure chamber in a clearance between the circular cross section of the inner peripheral and the piston of the pressure chamber With protrusions to regulate,
A shock absorber characterized in that: The shock absorber according to claim 1,
The pressure chamber has a different diameter portion whose inner peripheral diameter changes in the moving direction of the piston,
On the inner periphery of the different diameter portion, provided with the protrusion,
A shock absorber characterized in that: The shock absorber according to claim 1 or 2,
The protrusion is at least three ribs at predetermined intervals in a circumferential direction along a movement direction of the piston.
A shock absorber characterized in that:

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