JP4726071B2 - Piston structure - Google Patents

Description

  The present invention relates to an improvement of a piston structure.

Conventionally, this type of piston structure has been embodied, for example, in a piston portion of a shock absorber that generates a high damping force, and an annular groove is formed over the entire outer periphery of the piston. An annular seal member such as an O-ring is fitted inside, and the seal member seals a minute gap between the cylinder and the piston. (For example, refer to Patent Document 1).

With such a piston structure, the two pressure chambers partitioned in the cylinder by the piston can be kept oil tight, and hydraulic oil can exchange the pressure chambers through the minute gaps in the piston sliding portion. In particular, even if a high-frequency vibration is input to the shock absorber, the shock absorber can generate a sufficient damping force.
Japanese Unexamined Patent Publication No. 2000-46088 (FIG. 4)

  However, the piston structure as described above may be pointed out to have the following problems.

  That is, in particular, in a shock absorber that is required to generate a high damping force, the valve provided in the piston, as seen in Patent Document 1, the annular valve seat provided in the middle of the passage formed in the piston, Since it is configured with a valve body that sits on the annular valve seat, a spring that biases the valve body, and a spring seat that supports one end of the spring, the piston itself is larger than a shock absorber for a passenger car. Therefore, when trying to provide a seal member on the outer periphery of the piston, it is necessary to form an annular groove into which the seal member fits on the outer periphery of the piston avoiding the passage in the diameter direction. The outer diameter of the piston is further increased by providing this seal member.

  And, naturally, when the piston becomes larger, the cylinder diameter also becomes larger, and the entire hydraulic equipment such as a shock absorber becomes larger, so that the hydraulic equipment can be mounted on an application site such as a vehicle or a building. There is a risk that will worsen.

  Therefore, the present invention has been developed to improve the above-described problems, and an object of the present invention is to provide a piston structure that does not cause an increase in size of hydraulic equipment.

In order to solve the above-described object, the problem-solving means in the present invention is connected to a rod that is movably inserted into a cylinder and is slidably inserted into the cylinder so that two pressure chambers are provided in the cylinder. A first passage having a valve that provides a resistance to the flow of hydraulic fluid that is separated and allows only the flow of hydraulic fluid from one pressure chamber to the other pressure chamber and that passes through, and one pressure from the other pressure chamber In the piston structure of a hydraulic device having a second passage having a valve that allows only the flow of hydraulic oil to the chamber and allows resistance to the flow of the hydraulic oil that passes therethrough, two small-diameter ports are provided from one end of the piston. open, respectively from the other side of the piston to open the two large-diameter port that communicates with the small diameter port, forming a first passage and the second passage of these small ports and the large-diameter port as sets, a first passage The provided valve is accommodated in the large-diameter port and includes a valve body seated on a step formed by the small-diameter port and the large-diameter port, and the valve provided in the second passage is in the large-diameter port. And a valve body seated at the end of a cylindrical valve seat member fixed to the large-diameter port, and a seal member is mounted on the outer periphery of the piston and within the length range of the small-diameter port It is characterized by becoming.

According to the seal structure of the present invention, it is not necessary to secure a space for providing a seal member on the outer periphery of a portion surrounding the large-diameter port of the piston. It is possible to reduce the size and improve the mountability of the hydraulic equipment to the application site.

  Furthermore, since the cylinder inner diameter can be reduced, the sliding resistance between the seal member and the cylinder can be reduced, so that smooth expansion and contraction of hydraulic equipment can be realized, and the rise in hydraulic oil temperature due to sliding friction is suppressed. Therefore, it is possible to suppress a decrease in the viscosity of the hydraulic oil due to a rise in the temperature of the hydraulic oil, and it is possible to cause the hydraulic device to exhibit a stable damping function without causing a decrease in the damping force even when used for a long time.

  In addition, the degree of freedom in designing the seal is increased, and it is possible to employ an optimum seal configuration for the hydraulic device while avoiding an increase in the size of the hydraulic device.

  In addition, since it is possible to adopt an optimal seal configuration for hydraulic equipment while avoiding an increase in the size of the hydraulic equipment, the communication between the pressure chamber and the pressure chamber via a minute gap between the cylinder and the piston is sealed. Since it can be reliably blocked by a highly reliable seal member, it is possible to generate a high damping force in the shock absorber when high frequency vibration is input, especially when the hydraulic equipment is a shock absorber. It becomes.

Then, it is provided with a larger valve to the piston, since a periphery of the piston valve seal member is mounted in a position to avoid the large ports to be inserted, without increasing the size of the outer diameter of the piston The design freedom of the valve is improved.

  Hereinafter, the piston structure of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a piston portion of a hydraulic device in which a piston structure according to an embodiment is embodied. FIG. 2 is a longitudinal sectional view of a disk in which a piston structure according to a modification of the embodiment is embodied. FIG. 3 is a longitudinal sectional view of a disk in which a piston structure according to another modification of the embodiment is embodied.

  As shown in FIG. 1, the piston structure in one embodiment is embodied in a piston portion of a shock absorber as a hydraulic device, and the shock absorber as a hydraulic device in which the piston structure is embodied includes a cylinder 1, A rod 2 movably inserted into the cylinder 1, and a piston 3 connected to the rod 2 and slidably inserted into the cylinder 1 to separate the two pressure chambers R1, R2 into the cylinder 1; , A first passage 6 provided with a valve 4 that provides resistance to the flow of hydraulic fluid that is formed in the piston 3 and passes through the pressure chambers R1 and R2, and hydraulic fluid that passes through the pressure chambers R1 and R2. The second passage 7 is provided with a valve 5 that gives resistance to the flow, and the seal member 23 is mounted on the outer periphery of the piston 3.

  A shock absorber as a hydraulic device in which the seal structure is embodied is well known and will not be described in detail. For example, the cylinder 1 and a head member for sealing the upper end of the cylinder 1 are specifically described. (Not shown), a rod 2 slidably penetrating a head member (not shown), the piston 3 provided at the end of the rod 2, and two pressures partitioned by the piston 3 in the cylinder 1 The chambers R1 and R2 and a sealing member (not shown) for sealing the lower end of the cylinder 1 are provided, and the cylinder 1 is filled with hydraulic oil.

  Hereinafter, each part will be described in detail. The piston 3 has an annular shape, and the piston 3 has a first passage 6 and a first passage 6 formed so as to penetrate through the top and bottom as shown in FIG. The first passage 6 and the second passage 7 communicate with the pressure chambers R1 and R2 described above.

  The first passage 6 has a small-diameter port 6a opened from the lower end in FIG. 1 serving as one end of the piston 3, and a small-diameter port opened from the upper end in FIG. 1 serving as the other end of the piston 3 and communicating with the small-diameter port 6a. 1, a large-diameter port 6 b formed with a larger diameter than 6 a, and even in the other second passage 7, a small-diameter port 7 a opened from the lower end in FIG. The large-diameter port 7b is formed at a larger diameter than the small-diameter port 7a that opens from the upper end in FIG. 1 as the other end and communicates with the small-diameter port 7a.

  A step portion is formed in the middle of the first passage 6 by a small diameter port 6 a and a large diameter port 6 b, and the step portion constitutes an annular valve seat 8. On the other hand, in the middle of the second passage 7, a step portion is formed by the small diameter port 7 a and the large diameter port 7 b, and the spring seat 16 is configured by this step portion.

  Further, a screw portion 6c is formed on the inner periphery of the upper end in FIG. 1 of the large-diameter port 6b of the first passage 6 described above, and the screw portion 6c is formed in a cylindrical shape so as not to block the entire first passage 6. A spring seat 9 is screwed and fixed. A valve body 10 seated on the annular valve seat 8 is accommodated in the large-diameter port 6 b of the first passage 6, and a spring 11 is interposed between the valve body 10 and the spring seat 9. Thus, the valve body 10 is always urged by the spring 11 in the direction of seating on the annular valve seat 8 and closes the first passage 6.

  The valve body 10 includes a shaft 12 whose lower end in FIG. 1 is slidably inserted into the small-diameter port 6a, a frustoconical valve body 13 formed on the outer periphery of the intermediate portion of the shaft 12, and a valve of the shaft 12. 1 is provided with a notch 14 provided on the lower end side of the main body 13. When the valve main body 13 is brought into contact with the upper surface of the annular valve seat 8 in FIG. The notch 14 of the shaft 12 is completely opposed to the inner periphery of the small-diameter port 6a so as to close the first passage 6 and cut off the communication between the pressure chamber R1 and the pressure chamber R2. Yes.

On the other hand, a screw portion 7c is formed on the inner periphery of the upper end in FIG. 1 of the large-diameter port 7b of the second passage 7 described above, and this screw portion 7c is formed in a cylindrical shape so as not to close the entire second passage 7. The valve seat member 15 is screwed and fixed. A valve body 17 seated on the valve seat member 15 is accommodated in the large diameter port 7b of the second passage 7 described above, and a spring formed by the valve body 17, the small diameter port 7a and the large diameter port 7b. A spring 18 is interposed between the seat 16 and the valve element 17 is always urged by the spring 18 in a direction to be seated on the valve seat member 15 to close the second passage 7.

  The valve body 17 includes a shaft 19 whose upper end in FIG. 1 is slidably inserted into the valve seat member 15, a truncated cone-shaped valve body 20 formed on the outer periphery of the intermediate portion of the shaft 19, The valve body 20 includes a notch 21 provided on the upper end side of the valve body 20. When the valve body 20 is brought into contact with the lower surface of the valve seat member 15 in FIG. 1, the upper end of the valve body 20 is in the lower surface of the valve seat member 15. Sitting on the circumference, the notch 21 of the shaft 19 is also completely opposed to the inner circumference of the valve seat member 15 so as to close the second passage 7 and disconnect the communication between the pressure chamber R1 and the pressure chamber R2. It has become.

Therefore, the valve 4 is configured to include the annular valve seat 8, the valve body 10, the spring 11, and the spring seat 9, and the valve body 10 is constantly pressed against the annular valve seat 8 by the spring 11. When the pressure in the pressure chamber R2 reaches the valve opening pressure, the valve body 10 in the first passage 6 moves backward from the annular valve seat 8 in FIG. 1 to open the first passage 6 to open the pressure chamber R2. And the pressure chamber R1 can communicate with each other. The valve 4 functions as a normally closed damping valve. The other valve 5 is also the valve seat member 15, the valve body 17, the spring 18, and the spring seat 16 described above. The valve body 17 is always pressed against the valve seat member 15 by the spring 18 and is seated, and the valve body 17 in the second passage 7 reaches the valve opening pressure of the pressure chamber R1. then second passage 7 to the opening pressure chamber R1 and the pressure and retracted from the valve seat member 15 downward in FIG. 1 R2 and can be in communication with the valve 5 functions as a damping valve normally closed.

  That is, in the first passage 6, the valve 4 is opened for the flow of hydraulic oil from the pressure chamber R2 to the pressure chamber R1, and this is allowed, and the valve 4 is opened for the reverse flow. The other second passage 7 is set to be a one-way passage that prevents this, and the valve 5 is opened to allow the flow of hydraulic oil from the pressure chamber R1 to the pressure chamber R2, and this is reversed. The valve 5 is set to a one-way passage that prevents the valve 5 from opening in the direction of flow.

  The outer periphery of the spring seat 9 and the valve seat member 15 is sealed with the outer periphery of the spring seat 9, the inner periphery of the large diameter port 6b, and the outer periphery of the valve seat member 15 and the inner periphery of the large diameter port 7b. Rings 9a and 15a are respectively mounted, and the pressure chamber R1 and the pressure chamber are interposed between the outer periphery of the spring seat 9 and the inner periphery of the large-diameter port 6b and between the outer periphery of the valve seat member 15 and the inner periphery of the large-diameter port 7b. Communication with R2 is prevented, and a high damping force can be generated in the shock absorber even when high-frequency vibration is input.

  Further, when the spring seat 9 is fixed to the large diameter port 6b and the valve seat member 15 is fixed to the large diameter port 7b, a snap ring may be used. Specifically, a snap ring that engages with the large-diameter ports 6b and 7b is provided at the upper ends of the spring seat 9 and the valve seat member 15 in FIG. 1, and the spring seat 9 and the valve seat member 15 have a large diameter at the upper ends in FIG. If the dropout from the ports 6b and 7b is prevented, the spring seat 9 and the valve seat member 15 are pressed against the snap ring by the springs 11 and 18, respectively, so that they can be fixed to the large-diameter ports 6b and 7b.

  In this manner, the stepped rod 2 is inserted into the inner peripheral side of the piston 3 in which the valves 4 and 5 are incorporated, and the piston 3 is fixed to the rod 2 by the piston nut 30 screwed to the tip of the rod 2. Will be.

  Subsequently, an annular groove 22 is provided over the entire outer periphery of the piston 3, and a seal member 23 is fitted into the annular groove 22, and the seal member 23 is mounted on the outer periphery of the piston 3.

  The annular groove 22 is provided on the outer periphery of the piston 3 in a range from one end which is the lower end of the piston 3 in FIG. 1 to the length h of the small diameter ports 6a and 7a, that is, the small diameter port 6a, It is provided within the length range in which 7a is provided.

  As described above, by setting the position where the seal member 23 is mounted within the length range of the small-diameter ports 6a and 7a on the outer periphery of the piston 3, the seal member is disposed on the outer periphery of the piston 3 without increasing the size of the piston 3. 23 can be provided.

  That is, in the conventional piston in which the large diameter port is opened from the staggered ends above and below the piston 3, in order to provide an annular groove for mounting the seal member, the large diameter port must be avoided. Although the increase in the diameter of the piston could not be avoided, the first passage 6 and the second passage 7 in which the valves 4 and 5 are provided have the small diameter ports 6a and 7a opened from one end side of the piston 3 as described above. And the large diameter ports 6b and 7b opened from the other end of the piston 3, and the position where the seal member 23 is mounted is within the length range of the small diameter ports 6a and 7a on the outer periphery of the piston 3. Therefore, the annular groove 22 may be formed so as to avoid the small diameter ports 6a and 7a, and the outer diameter of the bottom portion 22a of the annular groove 22 is reduced correspondingly, and the seal member 23 is reduced even if the piston 3 is downsized. It can be mounted on the piston 23.

  That is, in particular, even when a high damping force is required and the valves 4 and 5 incorporated in the piston 3 are large, the seal member 23 is provided on the outer periphery of the portion surrounding the large-diameter ports 6b and 7b of the piston 3. Since it is not necessary to secure a space, the piston 3 can be reduced in size, and furthermore, a sufficient thickness can be secured when the annular groove 22 is provided on the outer periphery of the piston 3. There is no possibility of incurring a 3 strength drop.

Then, the Rukoto not sliding bordered seal member 23 on the inner periphery of the cylinder 1, a pressure chamber R1 and the pressure chamber R2 through the small gap formed between the piston 3 and the cylinder 1 is a piston sliding portion This communication is blocked by the seal member 23, whereby the piston sliding portion is sealed by the seal member 23.

  Therefore, in the piston structure of the present invention, it is possible to reduce the size of the piston 3 as compared with the conventional one. Therefore, the outer diameter of the hydraulic device, in this embodiment, the shock absorber can be further reduced. Therefore, the mounting property of the hydraulic equipment to the application location is improved.

  Furthermore, since the inner diameter of the cylinder 1 can be reduced, the sliding resistance between the seal member 23 and the cylinder 1 can be reduced, so that smooth expansion and contraction of the hydraulic equipment can be realized, and the hydraulic oil temperature due to sliding friction can be achieved. Since the increase can be suppressed, the decrease in the viscosity of the hydraulic oil due to the increase in the hydraulic oil temperature can be suppressed, and even when used for a long time, the damping force does not decrease, and the hydraulic device can exhibit a stable damping function. .

  Further, as shown in FIG. 2, since it is only necessary to provide the annular groove 22 on the outer peripheral side of the small-diameter ports 6a and 7a, the annular groove 22 can be set deeper, so that the inner peripheral side of the seal member 23 has a higher pressure. It is also possible to adopt a seal configuration in which the backup ring 24 is inserted so that it can withstand, there is no problem of increasing the outer diameter of the piston 3 or the cylinder 1, and the degree of freedom in the seal design is increased. It is possible to adopt an optimal seal configuration for hydraulic equipment while avoiding an increase in size.

  Furthermore, since it is possible to adopt the optimum seal configuration for the hydraulic equipment while avoiding an increase in size of the hydraulic equipment, a small gap between the cylinder 1 and the piston 3 in the pressure chamber R1 and the pressure chamber R2 is interposed. Therefore, when a high frequency vibration is input to the shock absorber, a high damping force can be generated.

  Even if a larger valve is provided on the piston 3, the seal member 23 is mounted on the outer periphery of the piston 3 so as to avoid the large-diameter ports 6b and 7b into which the valve is inserted. The design flexibility of the valve is improved.

  Further, as shown in FIG. 3, a cylindrical socket 25 rising from the outer peripheral portion of one end of the piston may be provided, and an annular slide bearing 26 may be mounted on the outer periphery of the socket 25. By providing the slide bearing 26 on the outer periphery of the socket 25 in this manner, the outer diameter of the piston 3 is not increased, and a smoother expansion and contraction of the shock absorber as a hydraulic device is realized while preventing a decrease in strength. Is possible.

 This concludes the description of the embodiment of the seal structure in the piston sliding portion. This seal structure in the piston sliding portion seals the gap between the piston and the cylinder in which the valve is provided. Therefore, it goes without saying that the present invention can be applied to a hydraulic device having a structure including the piston and the cylinder in addition to the shock absorber.

 It should be noted that the scope of the present invention is not limited to the details shown or described.

It is a longitudinal cross-sectional view of the piston part of the hydraulic equipment with which the piston structure in one embodiment was embodied. It is a longitudinal cross-sectional view of the disk with which the piston structure in the modification of one Embodiment was embodied. It is a longitudinal cross-sectional view of the disk with which the piston structure in the other modification of one Embodiment was embodied.

Explanation of symbols

1 Cylinder 2 Rod 3 Piston 4, 5 Valve 6 First Passage 7 Second Passage 6a, 7a Small Diameter Port 6b, 7b Large Diameter Port 8 Annular Valve Seat 9, 16 Spring Seat 10, 17 Valve Element 11, 18 Spring 12, 19 Shafts 13 and 20 Valve bodies 14 and 21 Notch 15 Valve seat member 22 Annular groove 23 Seal member 24 Backup ring 25 Socket 26 Ride bearing 30 Nut R1 and R2 Pressure chamber

Claims (3)

Hydraulic oil that is connected to a rod that is movably inserted into the cylinder and that is slidably inserted into the cylinder to separate the two pressure chambers from the one pressure chamber toward the other pressure chamber. The first passage having a valve that gives resistance to the flow of hydraulic fluid that allows only the flow of the hydraulic fluid and the flow of hydraulic fluid that passes only from the other pressure chamber to the one pressure chamber. In a piston structure of a hydraulic device having a second passage having a valve for resistance to flow, two small-diameter ports are opened from one end side of the piston, and two small-diameter ports are respectively communicated from the other end side of the piston. the large port is opened to form the first passage and the second passage of these small ports and the large-diameter port as sets, small port with valve provided in the first passage is accommodated in the large-diameter port And a valve body seated on a step formed by the large-diameter port, and a valve provided in the second passage is accommodated in the large-diameter port and fixed to the large-diameter port A piston structure comprising a valve body seated on an end portion of a valve seat member , wherein a seal member is mounted on the outer periphery of the piston within the length range of the small diameter port. The valve provided in the first passage is interposed between the valve body, a cylindrical spring seat fixed to the large-diameter port, and the spring seat and the valve body, and directs the valve body toward the stepped portion. And a valve provided in the second passage is a step formed by the valve body, the valve seat member, the valve body, a small diameter port, and a large diameter port. 2. The piston structure according to claim 1 , further comprising a spring interposed between the first portion and the second portion to urge the valve body toward the valve seat member. 3. The piston structure according to claim 1 , wherein a cylindrical socket rising from an outer peripheral portion of one end of the piston is provided, and an annular slide bearing is mounted on the outer periphery of the socket.

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