JP2006118687A - Air spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air spring capable of preventing interference between a diaphragm and a piston and a peripheral member.
A cylindrical diaphragm is interposed between an upper surface plate and a piston located below the upper surface plate, and one end of the diaphragm is fixed to the upper surface plate, and the other end is folded inward so that the outer periphery of the piston The piston is fixed to the upper end portion of the piston through the side wall, and the piston has a large diameter portion formed at the lower end portion of the outer peripheral side wall that is larger in diameter than other portions, and a part of the large diameter portion has a piston periphery. A concave portion for preventing interference with the other member is formed, and the concave portion is installed on the piston peripheral member side in an assembled state to the vehicle to prevent interference between the piston large diameter portion and the piston peripheral member.
[Selection] Figure 1

Description

    The present invention relates to a suspension for a vehicle such as a truck or a bus, an anti-vibration support device for an industrial machine, and an air spring that is suitably used for a cylinder device.

  As this type of air spring, a cylindrical diaphragm that is elastically deformed with the relative displacement of both members is interposed between the piston and the upper surface plate above the piston, and one end of the diaphragm is fixed to the upper surface plate. A rolling lobe type air spring is known in which the other end is folded inward and fixed to the upper end of the piston through the outer peripheral side wall of the piston.

  A piston having a straight barrel shape is usually used, but Patent Document 1 discloses a piston having a lower end formed in a large diameter. The piston having a large lower end is capable of changing the spring constant of the air spring when the load applied to the diaphragm increases and the diaphragm rides on the large diameter.

In addition, the piston shape having a large diameter portion at the lower end portion has a diaphragm in close contact with the large diameter portion to increase the spring constant. Therefore, the air spring is stroked in the extending direction in a relatively low pressure state inside the diaphragm. It is also effective as a measure to prevent the phenomenon of diaphragm blistering.
Japanese Patent Laid-Open No. 10-299808

  However, when the lower end portion of the piston is formed to have a large diameter, the large diameter portion and the diaphragm may come into contact with the peripheral members of the air spring and be damaged. In particular, when the air spring is used as an anti-vibration support device between the vehicle body and the axle, there are other suspension members (for example, suspension rods) in the vicinity thereof, so it is necessary to prevent interference with these members. There is.

  In view of the above, an object of the present invention is to provide an air spring that can prevent interference between a diaphragm and a piston and a peripheral member.

  In order to achieve the above object, an air spring according to the present invention has a cylindrical diaphragm interposed between a top plate and a piston located below the top plate, and one end of the diaphragm is fixed to the top plate. The end is folded inward and is fixed to the upper end of the piston through the outer peripheral side wall of the piston, and the piston has a larger diameter part at the lower end of the outer peripheral side wall that is larger in diameter than other parts. In addition, a concave portion for preventing interference with members around the piston is formed in a part of the large diameter portion.

  The air spring having the above-described configuration supports a load equal to the product of the air pressure in the diaphragm and the effective area, and absorbs and attenuates vibration input from the vibration generating unit by a spring action due to air compressibility. Due to the input of vibration, a relative displacement along the axial direction occurs between the piston and the upper surface plate, and the folded inner portion of the cylindrical diaphragm rolls on the outer peripheral side wall of the piston due to this relative displacement, and vibration is generated. It will be attenuated.

  When the load on the air spring increases and the inner part of the diaphragm rolls on the outer peripheral side wall of the piston and rides on the large diameter part, the diaphragm closely adheres to the large diameter part, and at the same time the spring constant is increased, The phenomenon can be prevented.

  At the time of assembly to the vehicle, a concave portion formed in a part of the large diameter portion is installed on the piston peripheral member side to prevent interference between the piston large diameter portion and the piston peripheral member.

  The concave portion can be formed by forming a part of a circular large diameter portion in a flat shape. For example, a cylindrical large-diameter portion is formed, and then a part thereof is recessed inward. However, the circumferential length of the cross section surrounded by the concave portion and other large-diameter portions is set to a length that can prevent the diaphragm burr phenomenon, or a length that can achieve a desired spring characteristic.

  Further, it is desirable that the concave portion is retracted to the same level as the other part of the piston in the vertical direction of the piston, or to the inward side thereof. Thereby, interference with a piston peripheral member can be prevented reliably.

  As described above, according to the present invention, the lower end portion of the outer peripheral side wall of the piston is formed to have a larger diameter than other portions, and a recess is formed in a part of the large diameter portion. In the attached state, interference between the piston and the piston peripheral member can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of an air spring showing an embodiment of the present invention, and FIG. 2 is a bottom view of a piston.

  As shown in FIG. 1, the air spring 1 shown in the present embodiment is connected to a piston 2 connected to an axle side 40 (vibration generating portion) of a vehicle and a vehicle body side 41 (vibration receiving portion) disposed above the piston 2. And a cylindrical diaphragm 4 that is disposed between the piston 2 and the upper surface plate 3 and elastically deforms with the relative displacement of these members.

  The piston 2 is composed of a thin steel cylinder, and has an upper end face plate 2b and a lower end face plate 2c at the upper and lower end portions as well as the outer peripheral side wall 2a. A boundary portion between the upper end face plate 2b of the piston 2 and the outer peripheral side wall 2a is a shoulder portion 2d of the piston. The shoulder 2d is formed in a substantially triangular cross-section with a rounded corner at the entire circumference of the piston 2, and is higher than the center of the upper end plate 2b.

  The upper end face plate 2b of the piston 2 is formed in a concave shape having a bottom portion lower than the shoulder portion 2d continuously from the piston shoulder portion 2d, and an opening 11 is formed at the center thereof.

  The lower end face plate 2c of the piston 2 is formed in a bowl shape, and its outer peripheral portion is welded and fixed to the outer peripheral side wall 2a of the piston 2 in a lid shape. As a result, a second space S2 is formed inside the piston and communicates with the first space S1 formed by the diaphragm 4 through the central opening 11 of the upper end face plate 2b. Further, a headed bolt 13 for connecting to the axle side 40 is inserted into the lower end face plate 2c, and is fixed by welding.

  A large-diameter portion 12 having a larger diameter than other cylindrical portions is formed at the lower end portion of the outer peripheral side wall 2a of the piston 2, and a member around the piston (for example, a suspension rod) is formed on a part of the large-diameter portion 12. A recess 14 is formed for preventing interference with the above.

  The large diameter portion 12 is obtained by expanding the outer peripheral side wall 2a of the piston 2 outward to form a concentric cylindrical portion. Further, the recess 14 is formed by recessing a part of the cylindrical large-diameter portion 12 in a planar shape. The recess 14 is formed by retreating to the same level as the outer peripheral side wall 2a of the piston 2 in the vertical direction of the piston. For example, the lower end portion of the outer peripheral side wall 2a of the piston 2 is expanded outward to form the large diameter portion 12 concentric with the outer peripheral side wall 2a, and then a part thereof is recessed in a planar shape so as to be perpendicular to the outer peripheral side wall 2a. Thus, it is possible to form the concave portion 14 that is linear (same level).

  However, the circumferential length of the cross section surrounded by the concave portion 14 and the other large-diameter portion 12 is set to a length that can prevent the diaphragm 4 from curling and a length that provides desired spring characteristics. The recess 14 may be retracted inward so as to be smaller than the diameter of the outer peripheral side wall 2a of the piston 2 positioned on the upper side. Moreover, in the said embodiment, although the outer peripheral side wall 2a of piston 2 illustrated the thing of a straight body shape, it may not be restricted to this but a truncated cone cylinder shape may be sufficient.

  The lower holding tool 6 is formed in a dish shape, and an opening communicating with the opening 11 of the upper end face plate 2b and a bolt insertion hole are formed in the center of the bottom portion 6a. The bottom portion 6a is formed on the upper surface of the upper end face plate 2b. Fastened with bolts 17.

  Further, a presser flange 15 extends outwardly on the outer peripheral edge of the lower holding tool 6 so as to be one step higher than the bottom 6a. The other end of the diaphragm 4 is formed by the presser flange 15 and the upper end face plate 2b of the piston 2. 4b is clamped to the piston shoulder 2d to prevent the diaphragm 4 from being blistered.

  On the other hand, an upper surface plate 3 connected to the vehicle body side is disposed at a position directly above the piston 2. On the lower side of the upper surface plate 3, an upper holding tool 21 formed in a disk shape is fastened by a bolt 22, and on the outer peripheral side of the upper holding tool 21, a flange 23 formed one step lower over the entire circumference. The one end 4a of the diaphragm 4 is sandwiched between the flange 23 and the outer peripheral portion of the upper surface plate 3.

  A cylindrical diaphragm 4 disposed between the upper surface plate 3 and the piston 2 is an elastic film made of a cylindrical rubber material reinforced by a reinforcing cord (not shown), and is formed at both ends 4a and 4b. Includes a bead portion (not shown) formed in a ring shape from a steel wire rod. And the one end part 4a of the diaphragm 4 provided with the upper side bead part is clamped between the upper surface board 3 and the flange 23 of the upper side clamping tool 21, and the upper end side of the diaphragm 4 is sealed. Further, the other end 4b of the diaphragm 4 provided with the lower bead portion is sandwiched between the upper end face plate 2b of the piston 2 and the holding flange 15 of the lower holding tool 6, and the lower end side of the diaphragm 4 is sealed. An internal space S1 is formed.

  The diaphragm 4 has one end portion 4a fixed to the upper surface plate 3 side, and the other end portion 4b is disposed along the outer peripheral side wall 2a of the piston 2 with the lower side of the diaphragm 4 folded inward. 2 is fixed to the inner side of the upper end face plate 2b of the piston 2 (the edge of the opening 11) through the shoulder 2d.

  Further, the upper plate 3 and the upper holding tool 21 are provided with a communication pipe 26 penetrating them, and the communication pipe 26 communicates the space outside the air spring 1 with the space S1 in the diaphragm 4 so that air or the like Thus, the diaphragm 4 is elastically deformed.

  FIG. 3 is a sectional view of the diaphragm. The diaphragm 4 has a shape at the time of manufacture, that is, a shape at the time when the diaphragm is vulcanized, and the outer diameter DU near the upper surface plate 3 is the largest as shown in FIG. The outer diameter DS of the part in contact with is formed in a tapered shape having the smallest diameter, and includes an upper opening 30 and a lower opening 31.

  And the outer diameter DS of the site | part which contacts the shoulder part 2d of a piston is formed smaller diameter than the largest outer diameter DP (refer FIG. 1) of the upper part of the piston 2. As shown in FIG. As a result, the diaphragm 4 is brought into close contact with the piston 2 so that the diaphragm 4 reliably rolls and does not cause a burr phenomenon.

  More specifically, the diaphragm 4 has a tapered shape (taper angle α1) in which the first taper portion 4e contacting the upper end side of the piston 2 from the shoulder portion 2d of the piston 2 gradually spreads from the minimum diameter portion (outer diameter DS). Formed. The second taper portion 4f, which is continuous with the first taper portion 4e and is in contact with the lower region of the outer peripheral side wall 2a of the piston 2, is also formed in a taper shape (taper angle α2), and further continuous with the second taper portion 4f. Thus, the third tapered portion 4g extending from the folded portion 27 to the upper surface plate 3 side is also formed in a tapered shape (taper angle α3). Each taper angle is set to α1> α2> α3.

  And among the 1st taper part 4e, the 2nd taper part 4f, and the 3rd taper part 4g, the lower side part from folding part 27 constitutes the inner side part which contacts outer peripheral side wall 2a of piston 2, Among the three taper portions 4g, the upper portion of the folding portion 27 constitutes an outer portion that is disposed at an interval outside the inner portion. By setting the taper angle of each of the taper portions 4e, 4f, and 4g, contact between the inner part and the outer part when the diaphragm 4 is used can be avoided, and the diaphragm 4 can be prevented from being blistered.

  The air spring 1 having the above configuration supports a load equal to the product of the air pressure in the diaphragm 4 and the effective area, and absorbs and attenuates vibrations input from the vibration generating part by a spring action due to air compressibility. By the input of vibration, a relative displacement along the axial direction occurs between the piston 2 and the upper surface plate 3, and the folded inner portion of the cylindrical diaphragm 4 rolls around the outer peripheral side wall 2 a of the piston 2 by this relative displacement. Will move and damp the vibration.

  Here, if the load applied to the air spring 1 increases when the piston 2 has a straight body shape, the inner part of the diaphragm 4 rolls on the lower part of the outer peripheral side wall 2 a of the piston 2. At this time, since the diameter is gradually increased from the first taper portion 4e to the third taper portion 4g, the inner portion of the diaphragm 4 is separated from the outer peripheral side wall 2a of the piston 2, and the blistering phenomenon is caused. There is a possibility of waking up. However, in this embodiment, since the large diameter portion 12 is formed at the lower end portion of the piston 2, even if the lower end side of the third taper portion 4g rides on the large diameter portion 12, the close contact state is maintained, and the spring At the same time as increasing the constant, the diaphragm 4 is prevented from being blurred.

  The air spring 1 may interfere with a peripheral member (for example, a suspension rod) of the piston 2 by the large diameter portion 12 in a state where the air spring 1 is assembled to a vehicle. The flat concave portion 14 has a structure that prevents interference with piston peripheral members. Therefore, an air spring having desired spring characteristics can be provided without affecting the behavior characteristics of the air spring at all.

  Of course, the present invention is not limited to the above-described embodiment, and many modifications and changes can be made within the scope of the present invention. For example, although the number of recessed portions formed is one in this embodiment, a plurality of recessed portions may be formed so as to prevent interference with a plurality of piston peripheral members.

The longitudinal cross-sectional view of the air spring which shows embodiment of this invention Bottom view of piston Diaphragm longitudinal section

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air spring 2 Piston 2a Side wall 2b Upper end face plate 2c Lower end face plate 2d Shoulder part 3 Upper face board 4 Diaphragm 4a One end part 4b Other end part 4e 1st taper part 4f 2nd taper part 4g 3rd taper part 6 Lower clamping tool 11 Opening 12 Large diameter part 14 Recessed part

Claims (3)

A cylindrical diaphragm is interposed between the upper surface plate and the piston located below the upper surface plate, one end of the diaphragm is fixed to the upper surface plate, and the other end is folded inward, and the piston passes through the outer peripheral side wall of the piston. An air spring fixed to the upper end of the
The piston is formed with a large-diameter portion having a larger diameter than other portions at the lower end portion of the outer peripheral side wall thereof, and a recess for preventing interference with members around the piston is formed in a part of the large-diameter portion. An air spring characterized by being formed. 2. The air spring according to claim 1, wherein the recess is formed by recessing a part of a circular large-diameter portion in a planar shape. 3. The air spring according to claim 1, wherein the concave portion is retracted to the same level as or inward of other portions of the piston in the vertical direction of the piston.

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