Variable damping friction pair of base type metal shock absorber
Technical Field
The invention belongs to the field of structural design, and particularly relates to a variable damping friction pair of a base type metal shock absorber.
Background
With the rapid development of electronic science and technology, electronic devices have been widely used in national defense, science and technology, parts of national economy and various fields of people's life. Due to the difference of vehicles, the working environment of the electronic equipment is very complicated and severe, especially the electronic equipment on military vehicles. Therefore, in addition to meeting the electrical performance of the product, the electronic device should also be able to research and solve the operational reliability of the device in a dynamic environment and the capability of resisting a severe environment. The mechanical environmental conditions usually include mechanical vibration, shock, swing, centrifugal acceleration, jolt vibration and the like, wherein the vibration and shock environments are most harmful to the reliable operation of the vehicle-mounted electronic equipment. The damage to the vehicle-mounted electronic equipment caused by the vibration and impact environment is represented in two aspects: 1. the equipment generates resonance with larger amplitude under a certain excitation frequency; 2. the long-term vibration and impact easily cause fatigue damage to the electronic equipment.
Generally, the vibration-proof and shock-proof design of the vehicle-mounted electronic equipment is mainly designed for vibration-proof and shock-proof of the equipment on the basis of reinforcing the weak links of the electronic equipment, so that the vibration or shock magnitude transmitted to the equipment by external excitation through the attenuation of a vibration-proof and shock-proof system meets the safety allowable conditions of the equipment. The vehicle-mounted electronic equipment is generally arranged in a cabinet, and the whole safety protection is realized mainly by means of the damping and buffering effect of a cabinet damping system.
From the classical transmissibility curve, for the vehicle-mounted electronic cabinet, the first-order resonance frequency peak amplification factor of the system is large due to the mobility requirement, and equipment is likely to be failed or damaged. Thus, the conventional mode of vibration isolation is not suitable for military vehicles that are in a mobile environment and have stringent requirements on the system architecture. The shock absorbers currently used are metal shock absorbers made of metal parts having elastic and damping properties, wherein the metal springs provide stiffness and the damping is mainly provided by friction pairs.
Disclosure of Invention
The utility model provides a become damping friction pair adjusts frictional damping power through the normal pressure of adjusting contact surface.
The utility model adopts the following technical scheme: a variable damping friction pair of a base type metal shock absorber comprises a friction pair shell, a friction head, a metal shock absorption pad, a limiting piece and a gland nut, wherein the friction head is tightly pressed on the friction pair shell by the metal shock absorption pad, and damping is generated by mutual friction between the friction head and the friction pair shell; the inner diameter of the friction pair shell changes along with the change of the axial position; the metal vibration damping pad is fixed on the limiting part by the compression nut, and the friction heads are uniformly arranged on the outline of the metal vibration damping pad in a circular ring shape.
Furthermore, the friction pair shell is of an annular columnar structure, the inner diameter of the M section is constant in the center section of the inner wall of the friction pair shell, and the length of the M section is not more than 10 mm; the inner diameter of the connecting section N of the inner wall of the friction pair shell and the section M is linearly reduced, the inclination angle of the inner wall is alpha, alpha is more than or equal to 10 degrees and less than or equal to 15 degrees, and the length of the N section is not more than 50 mm.
Furthermore, the M section and the N section are main working areas of the variable damping friction pair, wherein the middle point of the M section is the balance position of the variable damping friction pair; when the vibration absorber is excited at high frequency, the vibration absorber has small amplitude, and the friction head floats up and down in the range of the M section, so that the friction damping of the friction head is small when the friction head is excited at high frequency; when low-frequency excitation is carried out, the vibration absorber has larger amplitude, the friction head enters the N section from the M section, the inner diameter of the friction pair shell is linearly reduced along the axial direction, and the friction damping is gradually increased; the size of the inclination angle alpha of the N sections of inner walls determines the linear change rate of the inner diameter of the friction pair shell and the damping change law of the friction pair.
Furthermore, the section of the friction head is of a concave structure, and the height h of a groove in the section of the friction head is greater than the thickness of the metal vibration damping pad; the sharp angle of the outline of the section of the friction head is chamfered, and the chamfer angle beta is larger than the inclination angle alpha of the inner wall of the
friction pair shell 1 by 0 DEG<β-α<5 degrees; the number of the friction heads annularly arranged along the metal vibration damping pad is X, and X is not less than two; the shape of the friction head is arc-shaped, and the arc angle gamma of the outline of the friction head is less than
Furthermore, the friction head and the friction pair shell are made of stainless steel material 0Cr17Ni4Cu4Nb, so that the wear resistance of the variable damping friction pair is enhanced; the metal vibration damping pad is made of metal rubber materials and provides radial rigidity for the friction head.
The utility model has the advantages that:
the structure is based on the design concept of friction damping self-adaptive variable damping, namely, the friction damping is changed along with the position change of the limiting piece. The structure has the advantages that the structure can obtain larger damping during low-frequency excitation and obtain smaller damping during high-frequency excitation, thereby meeting the vibration isolation requirements of different frequency bands and better realizing the function of axial variable damping. The structure has been successfully applied to the base composite metal shock absorber and mass production is realized, and the problems of large amplification factor and high resonant frequency peak value of the equipment in the working process are solved.
Drawings
FIG. 1 is a sectional view of a variable damping friction pair;
FIG. 2 is a top view of a variable damping friction pair structure;
FIG. 3 is a schematic structural view of a friction pair housing;
FIG. 4 sectional view of friction pair housing structure
FIG. 5 is a schematic view of a friction head structure;
FIG. 6 is a cross-sectional view of the friction head construction.
Icon:
1-friction pair housing;
2-a friction head;
3-a metal vibration damping pad;
4-a limiting member;
and 5, pressing the nut.
Detailed Description
The technical solution of the present invention will be described clearly and completely with reference to the accompanying drawings, and obviously, the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
A variable damping friction pair of a base type metal shock absorber comprises a friction pair shell 1, a friction head 2, a metal shock absorption pad 3, a limiting piece 4 and a gland nut 5, wherein the friction head 2 is tightly pressed on the friction pair shell 1 by the metal shock absorption pad 3, and damping is generated by mutual friction between the friction head 2 and the friction pair shell 1; the inner diameter of the friction pair shell 1 changes along with the change of the axial position; the metal damping pad 3 is fixed on the limiting part 4 by the compression nut 5, and the friction heads 2 are uniformly arranged on the outline of the metal damping pad 3 in a circular ring shape. The variable damping friction pair structure is shown in fig. 1 and 2.
The friction pair shell 1 is of an annular columnar structure, the inner diameter of the friction pair shell 1 is constant in the center section M of the inner wall of the friction pair shell, and the length of the section M is not more than 10 mm; the inner diameter of the connecting section N of the inner wall of the friction pair shell 1 and the section M is linearly reduced, the inclination angle of the inner wall is alpha, alpha is more than or equal to 10 degrees and less than or equal to 15 degrees, and the length of the N section is not more than 50 mm. The structural form of the friction pair housing 1 is shown in fig. 3 and 4.
In fig. 4, M and N sections are main working areas of the variable damping friction pair, wherein a midpoint of the M section is a balance position of the variable damping friction pair; when the vibration absorber is excited at high frequency, the vibration absorber has small amplitude, and the friction head 2 floats up and down in the range of the M section, so that the friction damping of the friction head 2 is small when the friction head is excited at high frequency; when low-frequency excitation is carried out, the vibration absorber has larger amplitude, the friction head 2 enters the N section from the M section, the inner diameter of the friction pair shell 1 is linearly reduced along the axial direction, and the friction damping is gradually increased; the size of the inclination angle alpha of the N sections of inner walls determines the linear change rate of the inner diameter of the friction pair shell 1 and also determines the damping change law of the friction pair.
The section of the
friction head 2 is of a concave structure, so that the height h of the groove is greater than the thickness of the metal
vibration damping pad 3 for facilitating the assembly of the
friction head 2 and the metal
vibration damping pad 3; the section outline sharp angle of the
friction head 2 is chamfered, the chamfer angle beta is larger than the inner wall inclination angle alpha of the
friction pair shell 1, 0 DEG<β-α<5 degrees; the number of the
friction heads 2 annularly arranged along the metal
vibration damping pad 3 is X, and X is not less than two; the shape of the
friction head 2 is arc-shaped, and the arc angle gamma of the outline of the
friction head 2 is less than
The outline and section of the
friction head 2 are shown in fig. 5 and 6。
The materials of the friction head 2 and the friction pair shell 1 are all stainless steel 0Cr17Ni4Cu4Nb, so that the wear resistance of the variable damping friction pair is enhanced. The metal damping pad 3 is a metal rubber material and provides radial stiffness to the friction head 2.
The working principle and implementation steps of the friction pair are as follows:
when the vibration environment of a working system in which the friction pair structure is located is under low-frequency excitation, the amplitude of the limiting piece 4 is large, the limiting piece 4 drives the friction head 2 to move to the N sections of the friction pair shell 1 through the metal vibration damping pad 3, the inner diameter of the section is linearly reduced along the axial direction, the compression amount of the metal vibration damping pad 3 is increased, and the positive pressure between the friction contact surfaces is increased;
according to the description of an ideal friction model, the friction damping force is in direct proportion to the positive pressure of the contact surface, so the friction damping is correspondingly increased;
when the vibration environment of a working system in which the friction pair structure is positioned is in high-frequency excitation, the amplitude of the limiting part 4 is small, the friction head 2 mainly moves up and down at the balance position of the M section of the friction pair shell 1, the inner diameter of the section is large and constant all the time, the compression amount of the metal vibration damping pad 3 is small, the positive pressure between the friction contact surfaces is small, and therefore the friction damping is small;
keeping the friction coefficient and the rigidity of the metal vibration damping pad 3 constant, and determining the change law of the system damping according to the ideal friction model by the rule that the inner diameter of the friction pair shell 1 gradually changes along the axial direction; different damping change laws can be obtained by changing the shape of the inner wall of the friction pair shell 1.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the embodiments of the present invention.