CN-122014797-A - Load-adjustable vibration isolator and cam profile design method thereof

CN122014797ACN 122014797 ACN122014797 ACN 122014797ACN-122014797-A

Abstract

The invention discloses an adjustable load vibration isolator and a cam profile design method thereof, which belong to the technical field of vibration isolation and comprise a cam pair formed by a cam and a swing rod, a torsion spring, a worm and gear transmission mechanism, a speed reducing motor, a weighing sensor and a control unit, wherein the torsion spring is adopted in the cam pair to save space, and a plurality of groups of motion chains form a single-degree-of-freedom Sarrus mechanism. The load is detected through the weighing sensor, the control unit drives the gear motor and the worm gear mechanism, the pre-tightening angle of the torsion spring is automatically adjusted, the pre-tightening state is maintained by utilizing the self-locking characteristic of the worm gear, and continuous energy consumption is not needed. According to the cam profile design method, an equidistant spline curve is obtained through establishing a coordinate system and a mechanical equation through simultaneous deduction, and the cam profile is formed after offset correction, so that the positive stiffness bearing-quasi-zero stiffness vibration isolation segmentation function is realized. The invention has compact structure, small friction loss and long service life, can adapt to different loads, and ensures stable and reliable vibration isolation performance.

Inventors

XIONG ZHONGXIANG
WANG LINGWEI
HUANG LONG
QIU XIANG
ZENG LING
WANG LIZHEN
ZHOU YANING
WANG YIFAN

Assignees

中国安能集团第三工程局有限公司
长沙理工大学

Dates

Publication Date: 20260512
Application Date: 20251230

Claims (10)

1. An adjustable load vibration isolator, comprising: A vibration isolator main body; A cam pair consisting of a cam (10) and a swing rod (9); A torsion spring (8), the torsion spring (8) being provided in the cam pair; The staggered shaft spiral transmission mechanism is connected with the torsion spring (8); the speed reducing motor (6) is in spiral transmission connection with the staggered shaft; -a load cell (13), the load cell (13) being adapted to measure an actual load; and the control unit is respectively connected with the weighing sensor (13) and the speed reducing motor (6) in a signal manner.
2. The adjustable load vibration isolator according to claim 1, further comprising a preload adjustment device provided at the torsion spring (8) for adjusting a preload angle of the torsion spring (8), the preload adjustment device being any one of a lever-type precompression device, a cam-type precompression device, a wedge/ramp-type precompression device, an eccentric-type precompression device, or a screw-type precompression device.
3. The adjustable load vibration isolator according to claim 1, wherein the worm and gear transmission mechanism comprises a worm (5) and two worm gears (7) which are symmetrically distributed, the worm (5) is fixedly connected with an output shaft of the speed reduction motor (6), the worm (5) is meshed with the two worm gears (7), the vibration isolator further comprises a limiting shaft (14), limiting holes matched with the limiting shaft (14) are formed in each of the worm gears (7), the torsion springs (8) and the swinging rods (9), the limiting shafts (14) sequentially penetrate through the limiting holes to enable the worm gears (7) to be fixedly connected with the limiting shafts (14), the swinging rods (9) are rotationally connected with the limiting shafts (14), eccentric through holes are correspondingly formed in the worm gears (7) and the swinging rods (9), and thin rods at two ends of the torsion springs (8) are respectively inserted into the eccentric through holes, so that the three are achieved.
4. The adjustable load vibration isolator according to claim 1 or 3, further comprising a fixed wall (15), wherein a limiting hole matched with the limiting shaft (14) is formed in the fixed wall (15), the end portion of the limiting shaft (14) is arranged in the limiting hole in a penetrating mode and is in running fit through a bearing, the cam (10) is arranged in parallel with the fixed wall (15), the profile surface of the cam (10) is matched with the top end of the swinging rod (9), a roller (11) is assembled on the top end of the swinging rod (9) in a running mode through a pin shaft, the peripheral rolling surface of the roller (11) is matched with the profile surface of the cam (10) and keeps rolling contact, and the tail end of the profile surface of the cam (10) is integrally formed with a protruding structure.
5. The adjustable load vibration isolator according to claim 1, wherein the vibration isolator main body comprises a base (1), a movable platform (12) and a plurality of groups of moving chains, the moving chains are composed of an upper connecting rod (3), a lower connecting rod (2) and a revolute pair, the plurality of groups of moving chains are symmetrically distributed between the movable platform (12) and the base (1) and are combined to form a single-degree-of-freedom Sarrus mechanism, and the movable platform (12) is connected with the upper connecting rod (3), the base (1) and the lower connecting rod (2) through the revolute pair.
6. The adjustable load vibration isolator according to claim 1 or 5, wherein the number of the moving chains is four, the four moving chains are symmetrically distributed around the moving platform (12), a boss (4) is arranged on the base (1), the gear motor (6) is fixedly arranged on the boss (4), the cam (10) is fixedly connected with the bottom surface of the moving platform (12), the weighing sensor (13) is clamped between the cam (10) and the moving platform (12), the seat body (16) is fixedly arranged above the moving platform (12), the base (1) is fixedly connected with a chassis of the compacting equipment, and the boss (4) is integrally formed or fixedly connected with the base (1).
7. The design method of the cam profile of the adjustable load vibration isolator is characterized by comprising the following steps of: s1, firstly, a fixed coordinate system { O } is established by taking a connecting line midpoint O of hinge center points of two swing rods (9) as an original point, taking a vertical direction as a y axis and taking a horizontal direction as an x axis; In the initial state, the description equation of the equidistant line in the fixed coordinate system { O } after the right profile curve of the cam (10) is equidistantly shifted outwards by the roller radius r is recorded as y=f (x), and if the cam (10) moves downwards by delta y relative to the initial state, the description equation of the equidistant line in the fixed coordinate system { O } is changed into y=f (x) -delta y; S2, determining the stress relation between the cam (10) and the swing rods (9), wherein the resultant force F S of the cam (10) subjected to the swing rods (9) at two sides is as follows: ; Wherein F C is the acting force of the swing rod (9) on the cam (10), the direction is the normal direction of the equidistant line, and alpha is the included angle between the tangent line of the equidistant line at the central point of the fixed hinge of the swing rod (9) and the x axis; The moment balance equation at the center point of the motion hinge of the swing rod (9) is as follows ; Wherein l AB is the distance between the centers of two hinges on the swing rod (9), k is the rigidity of the torsion spring (8), theta 0 is the initial swing angle of the swing rod (9) in the initial state, phi 0 is the initial pre-torsion angle of the torsion spring (8) in the initial state, delta theta is the swing angle of the swing rod (9) which further rotates relative to the initial swing angle in the downward movement process of the cam (10), and the delta theta is the further torsion deformation angle of the torsion spring (8) relative to the initial pre-torsion angle in the downward movement process of the cam (10); S3, the coordinates of the center point of the fixed hinge of the swinging rod (9) are marked as (x A , 0), the coordinates of the center point of the moving hinge of the swinging rod (9) are marked as (x B ,y B ), and then the center coordinate relationship of the hinge of the swinging rod (9) is as follows: ; ; Equidistant lines at fixed coordinates slope of curve under { O }, system : ; The resultant force F S of the swing rods (9) on the two sides of the cam (10) is determined to be: 。
8. the vibration isolator cam profile design method according to claim 7, further comprising S4 of designing the resultant force F S applied to the cam (10) as a piecewise function of the displacement ay: ; wherein K is the positive rigidity of the first stage of self-definition, G 0 is the rated load, deltay 1 is the displacement threshold of the first stage of the cam (10), deltay 2 is the displacement upper limit threshold of the second stage of the cam (10), the piecewise function is substituted into the resultant force F S equation in S3, and the ordinate equation of the center point of the motion hinge of the swinging rod (9) is combined Obtaining a first-stage relation equation: ; ; And a second stage relationship equation: ; ; Wherein l AB is the distance between the two hinge centers on the swing rod (9), k is the rigidity of the torsion spring (8), theta 0 is the initial swing angle of the swing rod (9) in the initial state, phi 0 is the initial pretwist angle of the torsion spring (8) in the initial state, delta theta is the swing angle of the swing rod (9) relative to the initial swing angle in the downward movement process of the cam (10), which is equal to the further torsion deformation angle of the torsion spring (8) relative to the initial pretwist angle in the downward movement process of the cam (10), x A , 0) is the coordinate of the fixed hinge center point of the swing rod (9), x B ,y B is the coordinate of the motion hinge center point of the swing rod (9), The slope of the curve for the equidistant line in the fixed coordinate system { O }, f (x B ) is the value of the ordinate function of the equidistant line of the cam (10).
9. The vibration isolator cam profile design method of claim 8, further comprising S5: And solving a relation equation of two stages in the S4 by adopting a numerical algorithm, determining a discrete corresponding relation between an ordinate function value f (x B ) of an equidistant line of the cam (10) in the first stage and the second stage and an abscissa x B of a motion hinge center point of the swing rod (9), fitting based on the discrete corresponding relation to obtain a spline curve equation of the equidistant line of the cam (10), and shifting the spline curve equation to the left side by a roller radius r to obtain a curve equation of a right side contour of the cam (10).
10. The vibration isolator cam profile design method of claim 8, further comprising S6: When the initial pre-torsion angle of the torsion spring (8) is reduced to phi 0 ', phi 0 of the second-stage relation equation in the step S4 is replaced by phi 0 ', so as to determine the relation between the resultant force F S ' received by the second-stage cam (10) and the abscissa x B of the moving hinge center point of the swing rod (9).

Description

Load-adjustable vibration isolator and cam profile design method thereof Technical Field The invention belongs to the technical field of vibration isolation, and particularly relates to an adjustable load vibration isolator and a cam profile design method thereof. Background The roadbed compaction equipment realizes pavement compaction operation through vibration, an operator of the roadbed compaction equipment is exposed to a vibration environment for a long time, if the vibration isolation performance of the matched vibration isolator is insufficient, the operation comfort is reduced, and the occupational health problem of the operator is easily caused, so that the vibration isolator with excellent vibration isolation performance is needed to improve the operation experience of the operator. The vibration isolation effect of various vibration isolators in the prior art is directly related to the rigidity characteristic under the balanced state, the balanced state rigidity of the vibration isolator is more nearly zero, the vibration isolation effect is better, but the vibration isolator needs to meet the requirement of bearing capacity at the same time, so that the quasi-zero rigidity vibration isolator can be widely applied. In the prior art, the invention with the publication number of CN118462745B discloses a vibration isolator, and vibration isolation of a limited number of discrete loads is realized through the multi-section outline of a cam, but the vibration isolator lacks of adjustability, and has obvious positive rigidity and poor vibration isolation effect under the balanced state for loads with other values. And it is difficult to avoid friction between the cam and the moving follower. In the prior art, the invention with the publication number of CN117662671A discloses a load self-adaptive vibration isolation device, which detects load change in real time through a sensor, automatically adjusts the position of a spring and adapts to vibration isolation requirements under different loads. However, the load regulation depends on a control system, and compared with a passive vibration isolation device, the load regulation has the advantages of complex structure, increased fault points and lower reliability. In the prior art, the invention with the publication number of CN118128851A discloses a vibration isolator with adjustable load capacity, a wider quasi-zero stiffness vibration isolation area is realized through an inclined spring and a cantilever beam mechanism, and the vibration isolator can adapt to load conditions, but has a complex structure, occupies large space in linear motion, and is difficult to avoid abrasion between the cantilever beam and devices such as a clamp, a linear bearing and a guide rail. In the prior art, the utility model with the publication number of CN209309199U discloses an adjustable load wire mesh pad vibration isolator, which changes the compression amount of the wire mesh pad by pushing a wedge block through an adjusting bolt and adapts to different loads and vibration environments. However, the wire mesh pad is subjected to plastic deformation in use, so that the rigidity consistency is poor, the service life is possibly short, and the stability of the whole vibration isolation performance is affected. Furthermore, in practice, the weight change of the operator cannot be predicted in advance, so that the conventional quasi-zero stiffness vibration isolator cannot produce a good effect on the roadbed compacting equipment. Therefore, there is a need for an adjustable load vibration isolator which is compact in structure, small in occupied space, small in friction loss and long in service life, and can generate good vibration isolation effects for different loads through simple adjustment, so that the problems can be solved. Disclosure of Invention The embodiment of the invention aims to provide an adjustable load vibration isolator, which overcomes the defects of insufficient reliability, easiness in abrasion or poor performance stability of a vibration isolation device in the prior art, realizes stable and reliable load self-adaptive vibration isolation and ensures long-term service performance consistency. A second object of embodiments of the present invention is to provide a method for designing a cam profile of an adjustable load isolator; In order to solve the technical problems, the invention adopts the technical scheme that the load-adjustable vibration isolator comprises an isolator main body, a cam pair, a cam and a swinging rod, wherein the cam pair consists of a cam and a swinging rod; A torsion spring provided in the cam pair; The staggered shaft spiral transmission mechanism is connected with the torsion spring; the speed reducing motor is in spiral transmission connection with the staggered shaft; the device comprises a weighing sensor, a control unit and a speed reducing motor, wherein the weighing sensor is used for measuring actual load, and the