JP6434735B2 - Shock absorber manufacturing method - Google Patents

Description

The present invention relates to an improvement in slow衝器manufacturing method.

  This type of piston is, for example, slidably inserted into the cylinder of the shock absorber and divides the inside of the cylinder into two pressure chambers. And a pressure side port through which hydraulic oil passes when the container contracts. In addition, leaf valves are stacked on the top and bottom of the piston, and the outlet ends of the extension side port and the pressure side port are opened and closed by these leaf valves, and pass through the extension side port and the pressure side port when the shock absorber expands and contracts. A resistance is applied to the flow of the hydraulic oil by the leaf valve to cause a difference between the pressures in the two pressure chambers, thereby generating a damping force.

  Furthermore, a piston ring made of synthetic resin that is in sliding contact with the inner periphery of the cylinder is attached to the outer periphery of the piston, and the extension side chamber and the pressure side chamber formed in the cylinder are not communicated with each other via the piston outer periphery. The piston can move smoothly in the cylinder.

  The piston ring is attached to a mounting portion having a plurality of protrusions arranged in the axial direction on the outer periphery of the piston, and is integrated with the piston. The piston ring has a disk shape before being attached to the piston, and is provided with a hole having a smaller diameter than the outer diameter of the piston at the center. Then, the piston ring is laminated on the annular die together with the piston in a state where it is easily deformed by heating, and in that state, the piston is pushed into the annular die so that it is handled by the die and deformed into a cylindrical shape. And fixed to the mounting portion on the outer periphery of the piston (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2004-21757

  By the way, in recent years, in a shock absorber interposed between a vehicle body and wheels of a vehicle and incorporated in a suspension device, the piston speed is particularly high with respect to the damping force characteristic on the extension side from the viewpoint of improving the riding comfort in the vehicle. Saturation characteristics have been favored in which the damping force rises quickly when in the low speed range, and the rate of increase of the damping force with respect to the piston speed decreases when the piston speed reaches the high speed range.

  By realizing such a damping force characteristic, the shock absorber can firmly suppress the vibration of the vehicle body when the piston speed is in the low speed range, and excessive damping force when the piston speed is in the high speed range. Thus, the ride comfort in the vehicle can be improved.

  In a vehicle shock absorber, as described above, an annular leaf valve whose inner periphery is fixed to a piston is stacked, and the expansion side port is opened and closed by the leaf valve. A damping force is exerted by applying resistance to the flow of hydraulic oil passing therethrough. Here, in order to realize the above-described damping force characteristic, it is required to increase the pressure receiving area of the leaf valve as much as possible and to increase the diameter of the valve seat on which the leaf valve is seated.

  By increasing the pressure receiving area of the leaf valve, a large force can be applied to the leaf valve with a small pressure, and by increasing the valve seat diameter, the length from the inner peripheral support part of the leaf valve to the valve seat can be increased. It becomes long and the bending rigidity of a leaf valve can be made small. By doing so, the leaf valve becomes easy to bend and the gap formed between the valve seat and the leaf valve increases when the leaf valve is separated from the valve seat, and the leaf valve operates when the piston speed is in the high speed range. The resistance given to the oil flow can be reduced, and the aforementioned saturation characteristics can be realized.

  Recently, a saturation characteristic type piston has been proposed in order to realize the aforementioned saturation characteristic. The piston 100 has an annular shape as shown in FIG. 5, and includes a disk portion 101 provided with a mounting portion 102 provided on the outer periphery and to which the piston ring 110 is mounted, and a small diameter portion rising from one end side in the axial direction of the disk portion 101. 103, a large-diameter seat portion 104 provided on the side opposite to the disk portion of the small-diameter portion 103 and having a valve seat 105 at the end, a port 106 opened from one end and leading into the valve seat 105 of the seat portion 104, A port 108 that communicates with the other end of the disk part 101 from an annular groove 107 formed between the disk part 101 and the sheet part 104 is provided. The outer diameter of the seat portion 104 is set as large as possible without closing the annular groove 107 when the piston 100 is inserted into a cylinder (not shown), and the diameter of the annular valve seat 105 protruding from the seat portion 104 is set. Is set as large as possible.

When the piston ring 110 is attached to such a piston 100, a disc-shaped synthetic resin base material 111 is laminated on the seat portion 104 of the piston 100 as shown by a broken line in the figure, and the synthetic resin base material 111 is attached. When handled with a die as described above, it is deformed into a cylindrical shape and is mounted as a piston ring 110 on the outer periphery of the mounting portion 102 of the disk portion 101. Compared with the piston without the seat portion 104, the piston 100 of the saturation characteristic type takes a long distance over the seat portion 104 whose diameter is increased to the limit before the piston ring 110 is mounted on the outer periphery of the mounting portion 102. Will be moved. When the synthetic resin base material 111 serving as a piston ring moves while being handled by a die, the inner periphery thereof is pressed against the corner portion 112 of the outer periphery of the seat portion 104, so that shavings of the piston ring are generated and the seat May be deposited between the corner 112 of the outer periphery of the part and the valve seat 105.

  If the piston is assembled in the cylinder with the piston ring shavings accumulated in this way, the shavings may bite into the valve and cause poor performance. It is only necessary to remove the shavings, but the removal work is complicated and causes a new problem that increases the manufacturing cost.

The present invention, which was invented in order to improve the problem described above, it is an object with a piston which can suppress the generation of shavings during mounting of the piston rings It is providing the manufacturing method of a buffer.

In order to solve the above-mentioned object, the problem-solving means in the present invention includes a cylinder and a piston that is slidably inserted into the cylinder and divides the cylinder into an extension side chamber and a pressure side chamber, The piston includes a disc-shaped piston main body and a cylindrical piston ring made of synthetic resin and mounted on the outer periphery of the piston main body, and the piston main body includes a mounting portion on which the piston ring is mounted on the outer periphery. A small diameter part having a smaller diameter than the disk part rising on one end side in the axial direction of the disk part, and a larger diameter than the small diameter part provided on the side opposite to the disk part of the small diameter part. A seat portion having an annular valve seat at the end, and a first port that opens from the end of the disk portion on the side of the anti-small diameter portion and that is on the side of the anti-small diameter portion of the seat portion and communicates with the inner peripheral side of the valve seat; , The end of the disk part opposite the small diameter part A second port that opens and communicates between the sheet part and the disk part, and the sheet part is a method of manufacturing a shock absorber having a chamfered part on the outer peripheral edge of the side opposite to the small diameter part, With the process of laminating a ring-shaped synthetic resin base material to be a piston ring on the seat part of the piston body, and with the synthetic resin base material laminated on the sheet part, the piston body is pushed into the cylindrical die from the seat part side. A step of mounting a piston ring on the outer periphery of the piston main body and a step of inserting the piston into the cylinder from the seat portion side are provided. According to this configuration, since the chamfered portion is provided on the outer peripheral edge of the anti-small-diameter side end of the seat portion provided in the piston body, the inner periphery is seated while the synthetic resin base material forming the piston ring is dragged by the die. The inner periphery of the synthetic resin base material is not scraped even when pressed against. Therefore, according to the loose衝器production method of the present invention, since the inner periphery during processing of mounting the piston ring on the piston body is not cut, it is possible to suppress the generation of swarf.

Further, since no shavings are generated, it is not necessary to perform a removing operation for removing the shavings, the number of processing steps can be reduced , the manufacturing time of the shock absorber can be shortened, and the manufacturing cost can be reduced.

  In addition, since no shavings are generated, there is no fear that the shavings enter the shock absorber and cause a performance failure, and the shock absorber can stably exhibit the damping force as intended.

According to slow衝器production method of the present invention, it is possible to suppress the generation of shavings during mounting of the piston ring.

It is a longitudinal cross-sectional view of the shock absorber in one embodiment. It is an expansion longitudinal cross-sectional view of the piston in the shock absorber of one embodiment. It is a figure explaining the process sequence which equips the piston main body in the buffer of one Embodiment with a piston ring. It is a figure explaining the deformation | transformation state of a piston ring in the process which mounts a piston ring to the piston main body of the buffer of one Embodiment. It is a longitudinal cross-sectional view of the piston in the conventional shock absorber.

  Hereinafter, the shock absorber D of the present invention will be described with reference to the drawings. As shown in FIG. 1, a shock absorber D in one embodiment includes a cylinder 1 and a piston 2 that is slidably inserted into the cylinder 1 and divides the cylinder 1 into an extension side chamber R1 and a pressure side chamber R2. And a piston rod 3 having one end connected to the piston 2 and the other end protruding out of the cylinder 1.

  In the shock absorber D of this embodiment, a sliding partition wall 7 is provided in the lower part of the cylinder 1 in the drawing to slidably contact the inner periphery of the cylinder 1 and partition the pressure side chamber R2 and the gas chamber G. The expansion side chamber R1 and the compression side chamber R2 are filled with a liquid such as hydraulic oil. In addition to the hydraulic oil, for example, a liquid such as water or an aqueous solution can be used as the liquid filled in the extension side chamber R1 and the pressure side chamber R2. The gas chamber G is filled with an inert gas such as nitrogen, but can be filled with a gas other than the inert gas.

  The cylinder 1 is closed at the lower end in FIG. 1 by a bottom cap 4, and an annular rod guide 5 that slidably supports the piston rod 3 is attached to the upper end in FIG. 1. Further, a seal member 6 is mounted on the upper end of the cylinder 1 in FIG. 1 and above the rod guide 5 in FIG. The seal member 6 seals the outer periphery of the piston rod 3 to prevent the liquid in the cylinder 1 from leaking.

  As shown in FIG. 1, the piston 2 includes a disc-shaped piston main body 10 and a cylindrical piston ring 11 made of synthetic resin and attached to the outer periphery of the piston main body 10.

As shown in FIGS. 1 and 2, the piston main body 10 includes a disk part 12 having a mounting part 13 to which a piston ring 11 is attached on the outer periphery, and a lower part in FIG. 1 that is one end side in the axial direction of the disk part 12. a small diameter small diameter portion 14 from the disk portion 12 which rises on the side, the counter-diameter portion side end a larger diameter than the small diameter portion 14 provided in Figure 1 the lower side serving as a counter-disc side of the small-diameter portion 14 1 A seat portion 15 having an annular valve seat 15a at the middle and lower ends, and a lower end in FIG. 1 that opens from the upper end in FIG. 1 is formed between the seat portion 15 and the disc portion 12 so as to open from the upper end in FIG. 1, which is the first end 16 that communicates with the inner peripheral side of the valve seat 15 a and the end on the side opposite to the small diameter portion of the disc portion 12. A second port 18 communicating with the annular groove 17, the disk portion 12, the small diameter portion 14, and the seat portion 5 around the through axially the piston rod 3 is constituted by a through hole 19 to be inserted.

  In the case of the present embodiment, the piston main body 10 is formed by sintering molding, and the disk portion 12, the small diameter portion 14, and the seat portion 15 are integrated. The disk portion 12 includes a mounting portion 13 having a plurality of annular ridges along the circumferential direction on the outer periphery. The piston ring 11 is pressed and attached to the attachment portion 13 in a heated state, whereby the inner periphery is deformed into a shape that matches the attachment portion 13 and is integrated with the disk portion 12.

  The sheet portion 15 is connected to a disk-shaped small diameter portion 14 protruding from the lower end of the disk portion 12 in FIG. 1, and has an outer diameter smaller than the disk portion 12 and larger than the small diameter portion 14. Then, by providing the small diameter portion 14 between the sheet portion 15 and the disk portion 12, an annular groove 17 is formed between the sheet portion 15 and the disk portion 12 on the outer periphery of the small diameter portion 14.

  The seat portion 15 has a disk shape and includes an annular valve seat 15a provided at the lower end in FIG. 1 and protruding downward in the drawing. The outer diameter of the valve seat 15a is set to be smaller than the outer diameter of the seat portion 15, and an annular shape is formed on the outer peripheral side of the valve seat 15a at the lower end in FIG. An outer peripheral portion 15b is provided. Further, the outer peripheral edge of the outer peripheral portion 15b is chamfered to form a chamfered portion 15c. The chamfered portion 15c may be formed by performing C chamfering in a tapered shape, or may be formed by performing R chamfering in a circular arc shape in cross section.

  A petal-type valve seat 12a is provided at the end of the disk portion 12 on the side opposite to the small diameter portion, which is the upper end in FIG. 1, and opens from the independent opening window 12b surrounded by the valve seat 12a into the annular groove 17. A plurality of second ports 18 serving as pressure-side ports that communicate with each other are provided.

  Moreover, it is an anti-small-diameter part side end which is an anti-small-diameter part side end which is the upper end of the disk part 12 in FIG. A plurality of first ports 16 are provided as extension ports that communicate with the inside of the valve seat 15a.

  The piston body 10 is provided with an insertion hole 19 penetrating the centers of the disk portion 12, the small diameter portion 14 and the seat portion 15 in the axial direction, and the piston rod 3 is inserted into the insertion hole 19. .

  Further, an annular pressure side leaf valve V1 seated on the valve seat 12a is laminated at the upper end in FIG. 1 facing the expansion side chamber R1 of the piston 2, and at the lower end in FIG. 1 facing the pressure side chamber R2 of the piston 2. Is formed by laminating an annular extended leaf valve V2 seated on the valve seat 15a.

  In a state where the pressure side leaf valve V1 and the extension side leaf valve V2 are stacked on the piston 2, these are assembled to the outer periphery of the small diameter piston mounting portion 3a provided at the tip of the piston rod 3, and then the screw at the tip of the piston mounting portion 3a. The piston 2, the compression side leaf valve V1, and the extension side leaf valve V2 are fixed to the piston rod 3 by attaching and tightening the piston nut 8 to the portion 3b.

  When the piston 2, the pressure side leaf valve V1, and the extension side leaf valve V2 are fixed to the piston rod 3 in this way, the pressure side leaf valve V1 and the extension side leaf valve V2 are allowed to bend on the outer periphery, while the inner periphery is a piston. Fixed to the rod 3.

When the pressure side leaf valve V1 is seated on the valve seat 12a, the second port 18 is closed, and when the outer peripheral side is bent, the second port 18 is opened, and the second port 18 can be opened and closed. it can. The extension side leaf valve V2 closes the first port 16 when seated on the valve seat 15a, and opens the first port 16 when the outer peripheral side is bent, and opens and closes the first port 16. Can do.

  When the piston 2 moves downward in FIG. 1 and the shock absorber D contracts in the cylinder 1, the expansion side leaf valve V2 is pressed to the piston 2 side by the pressure of the compression side chamber R2 which is compressed and rises in pressure. While the port 16 is closed, the pressure-side leaf valve V1 receiving the pressure of the pressure-side chamber R2 through the second port 18 is bent and separated from the valve seat 12a to open the second port 18. Since the pressure side leaf valve V1 provides resistance to the flow of the liquid that passes through the second port 18 and moves from the pressure side chamber R2 to the extension side chamber R1, the shock absorber D exhibits a pressure side damping force that prevents the contraction.

  On the contrary, when the piston 2 moves upward in FIG. 1 and the shock absorber D extends in the cylinder 1, the pressure side leaf valve V1 is pressed to the piston 2 side by the pressure of the expansion side chamber R1 which is compressed and rises in pressure. While the second port 18 is closed, the extension side leaf valve V2 receiving the pressure of the extension side chamber R1 via the first port 16 is bent and separated from the valve seat 15a to open the first port 16. The extension side leaf valve V2 provides resistance to the flow of liquid that passes through the first port 16 and moves from the extension side chamber R1 to the compression side chamber R2, and therefore the shock absorber D exhibits an extension side damping force that prevents the extension. .

  In this embodiment, the second port 18 serving as the pressure side port communicates with the annular groove 17. If a gap is provided between the cylinder 1 and the seat portion 15, the annular groove 17 extends through the gap to the extension side chamber. The fluid is communicated with R1, and the liquid can be moved from the compression side chamber R2 to the expansion side chamber R1 through the second port 18 in the contraction stroke of the shock absorber D. Therefore, only the opening of the first port 16 can be provided in the seat portion 15, and the outer diameter of the seat portion 15 can be increased, so that the inner diameter of the valve seat 15a can also be increased.

  Since the inner diameter of the valve seat 15a can be increased, the pressure receiving area of the extension side leaf valve V2 receiving the pressure of the extension side chamber R1 can be increased, and the portion of the extension seat leaf valve V2 seated on the valve seat 15a can be increased. The diameter can also be increased.

  Thus, since the pressure receiving area of the extension side leaf valve V2 can be increased, the force for bending the extension side leaf valve V2 can be increased even with a small pressure. Moreover, since the diameter of the part seated on the valve seat 15a of the extension side leaf valve V2 can be increased, the bending rigidity of the extension side leaf valve V2 can be reduced. Therefore, the expansion-side leaf valve V2 can be greatly deflected with a small pressure, and when the piston speed reaches the high speed region during the expansion stroke of the shock absorber D, the expansion-side leaf valve V2 is largely bent and the first port 16 is opened. can do. Thus, in the shock absorber D of the present invention, when the piston speed during the extension stroke reaches the high speed range, the extension-side leaf valve V2 can be greatly bent and the first port 16 can be opened. When the piston speed is in the low speed range, the damping force can be quickly raised, and when the piston speed reaches the high speed range, a saturation characteristic in which the rate of increase of the damping force with respect to the piston speed is small can be realized. The volume of the piston rod 3 that enters and exits the cylinder 1 is absorbed by compressing or expanding the gas chamber G as the sliding partition 7 moves within the cylinder 1. Therefore, although this shock absorber D is a single cylinder shock absorber, although not shown, it is configured as a so-called reverse cylinder shock absorber in which a base valve is provided at the lower end of the cylinder 1 and a reservoir is provided outside the cylinder. Also good.

  Next, processing for mounting the piston ring 11 to the mounting portion 13 of the piston body 10 will be described. When the piston ring 11 is attached to the piston main body 10, as shown in FIG. 3, a synthetic resin base material J, which is a perforated disk-shaped piston ring, is laminated on the seat portion 15 of the piston main body 10 to form a synthetic resin base material. The piston body 10 is pushed into the cylindrical die 20 together with the synthetic resin base material J from the seat portion 15 side with J being laminated. The inner diameter of the die 20 is larger than the outer diameter of the disk portion 12 of the piston body 10, but the gap between the die 20 and the disk portion 12 is narrower than the thickness of the synthetic resin base material J. .

  And since the synthetic resin base material J is heated and softened, as shown in FIG. 4, as the amount of penetration of the piston main body 10 into the die 20 increases, The sheet is dragged to move over the outer periphery of the sheet portion 15 to the mounting portion 13 while being deformed into a cylindrical shape, and is pressed against the mounting portion 13 by the die 20 from the outer periphery. Then, as shown in FIG. 2, the synthetic resin base material J is deformed so that the inner periphery follows the outer peripheral shape of the mounting portion 13 and enters between the protrusions, and is firmly fixed to the piston body 10.

  Thus, even if the process of attaching the piston ring 11 to the piston body 10 is performed, the chamfered portion 15c is provided on the outer peripheral edge of the anti-small-diameter side end that is the lower end in FIG. Even if the synthetic resin base material J that forms the sheet is dragged by the die 20, the synthetic resin base material J is pressed by the die 20 from the outer peripheral side and the inner periphery is pressed against the sheet portion 15. The circumference is not cut. Therefore, according to the shock absorber D and the piston 2 of the present invention, since the inner periphery is not cut during the process of mounting the piston ring 11 on the piston body 10, the generation of shavings can be suppressed. Since generation | occurrence | production of shavings can be suppressed, it becomes unnecessary to perform the removal operation | work which removes shavings, a processing man-hour can be reduced, the manufacturing time of the buffer D and piston 2 can be shortened, and manufacturing cost can be reduced. .

  Moreover, since generation | occurrence | production of shavings is suppressed, there is no worry that shavings enter into the shock absorber D and cause a poor performance, and the shock absorber D can stably exhibit the desired damping force.

  Here, when the shock absorber D is used in a suspension application in which the vibration of the vehicle is attenuated by being interposed between the vehicle body and the wheel of the vehicle, it is necessary to increase the damping force during the expansion stroke than during the contraction stroke. In particular, it is possible to effectively improve the riding comfort of the vehicle by reducing the excessive damping force during the extension stroke.

  Since the damping characteristic in the extension stroke is determined by the extension side leaf valve V2 stacked on the pressure side chamber R2 side of the piston 2, when trying to obtain the saturation characteristic in the extension stroke, the piston 2 is connected to the tip of the piston rod 3. It is necessary to insert the piston 2 into the cylinder 1 with the seat portion 15 side facing the front end side and the seat portion 15 side facing the compression side chamber R2. In the lower part of the cylinder 1 in FIG. 1, a sliding partition 7 is provided in the case of a single cylinder type shock absorber, and a base valve is provided in the case of a reverse cylinder type shock absorber. I have to insert it inside.

  Incidentally, since the piston ring 11 is mounted on the outer periphery of the piston body 10 by handling the synthetic resin base material J with the die 20 from the seat portion 15 side, the piston ring 11 on the side opposite to the seat portion, which becomes the upper end in FIG. It is fixed to the outer periphery of the piston body 10 with the end portion opened in a trumpet shape on the outer peripheral side. Since the piston ring 11 is fixed to the piston body 10 with the opposite end of the piston ring 11 opened to the outer peripheral side, the piston 2 is inserted into the cylinder 1 from the seat portion side. The part-side end can be easily inserted without being caught by the opening end of the cylinder 1. On the contrary, when the piston 2 is inserted into the cylinder 1 from the non-seat portion side, the anti-sheet portion side end of the piston ring 11 is caught by the opening end of the cylinder 1, so that the piston 2 is moved from the anti-sheet portion side into the cylinder 1. It is difficult to insert.

  From the above, by disposing the seat portion 15 toward the compression side chamber R2, it is possible to insert the piston 2 into the cylinder 1 when the damping characteristic during the expansion stroke of the shock absorber D is desired to be a saturation characteristic. However, it is necessary to perform the process of mounting the piston ring 11 from the seat portion 15 side. However, conventionally, the production process becomes complicated due to generation of shavings, and the cost is increased. However, according to the present invention, since the generation of shavings of the piston ring 11 can be suppressed during the mounting process, the seat portion 15 can be disposed toward the compression side chamber R2, and the shock absorber D can be provided at low cost. It is possible to realize saturation characteristics during the extension stroke.

  In addition, when the cross-sectional shape of the chamfered portion 15c is an arc shape by rounding the outer peripheral edge of the seat portion 15, there is no edge compared to the tapered chamfered portion 15c, so that it is further increased. The generation | occurrence | production of the shavings of the piston ring 11 can be suppressed.

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

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 10 Piston main body 11 Piston ring 12 Disc part 13 Mounting part 14 Small diameter part 15 Seat part 15a Valve seat 15c Chamfering part 16 1st port 17 2nd port D Buffer R1 Extension side chamber R2 Pressure side chamber

Claims (1)

A cylinder,
A piston that is slidably inserted into the cylinder and divides the cylinder into an extension side chamber and a pressure side chamber;
The piston includes a disc-shaped piston body, and a cylindrical piston ring made of synthetic resin and attached to the outer periphery of the piston body.
The piston body includes a disk part having a mounting part on which the piston ring is mounted on the outer periphery, a small diameter part smaller than the disk part rising on one end side in the axial direction of the disk part, and an anti-disk part side of the small diameter part A seat portion having an annular valve seat on the side opposite to the small diameter portion and an end on the side opposite to the small diameter portion of the disk portion. And has a first port that communicates with the inner peripheral side of the valve seat, and a second port that opens from an end on the side opposite to the small diameter portion of the disc portion and communicates between the seat portion and the disc portion,
The sheet portion is a shock absorber manufacturing method having a chamfered portion on the outer peripheral edge of the side opposite to the small diameter portion,
Laminating an annular synthetic resin base material to be the piston ring on the seat portion of the piston body;
In a state where the synthetic resin base material is laminated on the seat part, the piston body is pushed into a cylindrical die from the seat part side, and the piston ring is attached to the outer periphery of the piston body;
Inserting the piston into the cylinder from the seat portion side.
A method for manufacturing a shock absorber.

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