阅读说明：本技术 平衡下落机构和重力仪 (Balanced falling mechanism and gravimeter ) 是由 伍康 文艺 郭梅影 于 2020-06-05 设计创作，主要内容包括：本发明涉及一种平衡下落机构和重力仪,所述驱动装置可以驱动所述调节件在竖直方向运动。当所述承载件和所述待测质量件在竖直方向运动,且所述待测质量件与所述承载件分离使所述待测质量件做自由落体运动时,可以通过质点系动量定理对所述重力仪整体进行分析,以所述重力仪整体质心保持不变为控制目标,得出所述调节件在竖直方向运动的状态。进而可以通过控制所述调节件的运动状态使得所述重力仪整体质心保持不变,从而得到的消除所述反冲振动对测量过程的影响。(The invention relates to a balance falling mechanism and a gravimeter, wherein a driving device can drive an adjusting piece to move in the vertical direction. When the bearing piece and the mass piece to be measured move in the vertical direction, and the mass piece to be measured is separated from the bearing piece to enable the mass piece to be measured to move in a free-fall mode, the whole gravity meter can be analyzed through the mass point system momentum theorem, so that the whole mass center of the gravity meter is kept to be not changed into a control target, and the state of the adjusting piece moving in the vertical direction is obtained. And the whole mass center of the gravity meter can be kept unchanged by controlling the motion state of the adjusting piece, so that the influence of the recoil vibration on the measurement process is eliminated.)

1. A balanced drop mechanism, comprising:

a housing (100) enclosing a receiving cavity (110), the receiving cavity (110) having a vertical central axis of symmetry (120);

the first rotating mechanism (210) and the second rotating mechanism (220) are arranged in the accommodating cavity (110) and are symmetrically arranged on two sides of the central symmetry axis (120) relative to the central symmetry axis (120);

the first balance piece (310) and the second balance piece (320) are arranged in the accommodating cavity (110), are respectively in transmission connection with the first rotating mechanism (210) and the second rotating mechanism (220), and are symmetrically arranged on two sides of the central symmetry axis (120);

the bearing piece (330) is used for placing a mass piece (340) to be measured, and the bearing piece (330) is arranged on the central symmetry axis (120) and is in transmission connection with the first rotating mechanism (210) and the second rotating mechanism (220);

the first rotating mechanism (210) and the second rotating mechanism (220) are used for driving the bearing part (330) and the first balancing part (310) and the second balancing part (320) to move in opposite directions in the vertical direction at the same speed;

a drive device (400) provided to the housing (100);

the adjusting piece (430) is in transmission connection with the driving device (400), and the driving device (400) is used for driving the adjusting piece (430) to move in the vertical direction so as to keep the integral mass center of the gravimeter unchanged when the mass piece (340) to be measured makes free-fall movement in the accommodating cavity (110).

2. The balanced drop mechanism of claim 1, wherein the drive means (400) comprises:

a cam (410) vertically rotatably disposed on the top of the housing (100);

the sliding rail (420) is vertically arranged at the top of the shell (100), the adjusting piece (430) is arranged on the sliding rail (420) in a sliding mode and abutted to the cam (410), and the cam (410) drives the adjusting piece (430) to move in the vertical direction along the sliding rail (420) when rotating.

3. The balanced drop mechanism of claim 2, characterized in that the cam (410) determines the displacement of the adjustment member (430) in the vertical direction based on the mass of the mass to be measured (340), the mass of the adjustment member (430), the displacement of the carrier member (330), and the displacement of the mass to be measured (340).

4. The balanced drop mechanism according to claim 2, wherein the drive means (400) comprises a base (450) and a support plate (440) arranged at a vertical spacing on top of the housing (100), the slide rail (420) being arranged between the base (450) and the support plate (440).

5. A balanced drop mechanism according to claim 4, wherein the support plate (440) is provided with an opening (442) for passage of the adjustment member (430).

6. The balanced drop mechanism of claim 4, wherein the drive device (400) further comprises a support base (460) disposed on the base (450), the cam (410) being rotatably disposed on the support base (460).

7. The balanced drop mechanism of claim 1, wherein the driving means (400) comprises a lead screw (470), the lead screw (470) is vertically rotatably disposed on the top of the housing (100), the adjusting member (430) is a nut, the nut is threadedly engaged with the lead screw (470), and the lead screw (470) drives the nut to move in a vertical direction when rotated.

8. The balanced drop mechanism according to claim 1, further comprising two single-sided racks (510) and one double-sided rack (520), wherein the first rotating mechanism (210) and the second rotating mechanism (220) are both gears, the first balance member (310) and the second balance member (320) are each drivingly connected to one of the gears through one of the single-sided racks (510), and the carrier member (330) is drivingly connected to both of the gears through the double-sided racks (520).

9. The balanced drop mechanism of claim 1,

the first rotating mechanism (210) includes:

a first pulley (212) and a second pulley (214) disposed along a vertical direction;

a first steel belt (216) and a second steel belt (218), both ends of the first steel belt (216) are respectively connected with the first balance member (310) and the bearing member (330), both ends of the second steel belt (218) are respectively connected with the first balance member (310) and the bearing member (330), and the first steel belt (216), the second steel belt (218), the first balance member (310) and the bearing member (330) form a closed loop around the first pulley (212) and the second pulley (214);

the second rotating mechanism (220) includes:

a third pulley (222) and a fourth pulley (224) disposed along the vertical direction;

a third steel belt (226) and a fourth steel belt (228), both ends of the third steel belt (226) are respectively connected with the second balance member (320) and the bearing member (330), both ends of the fourth steel belt (228) are respectively connected with the second balance member (320) and the bearing member (330), and the third steel belt (226), the fourth steel belt (228), the second balance member (320) and the bearing member (330) form a closed loop around the third pulley (222) and the fourth pulley (224).

10. The balanced drop mechanism of claim 9, further comprising a servo motor drivingly connected to one of the first pulley (212), the second pulley (214), the third pulley (222), or the fourth pulley (224).

11. A gravimeter comprising the balanced drop mechanism of any of claims 1-10.

Technical Field

The invention relates to the technical field of precision instruments, in particular to a balance falling mechanism and a gravimeter.

Background

In the field of high-precision absolute gravity measurement, a classical free-fall absolute gravimeter adopts a frequency-stabilized laser interferometry technology to precisely measure the displacement and time of a test mass in free-fall motion in a vacuum environment, and finally, the parameters of the free-fall motion are fitted to obtain the absolute gravity acceleration. Therefore, the precise measurement of the movement displacement of the free falling body is the key for obtaining the high-precision absolute gravity acceleration value. In fact, the measurement process during free fall is often disturbed by vibration noise from the instrument itself and the instrument holder, which affects the accuracy of the absolute gravity measurement. The self-recoil vibration of the gravity meter caused by the gravity meter transmission mechanism in the process of realizing the free falling body movement of the test mass is a vibration interference with the largest influence, and the system deviation can be introduced into the gravity measurement.

Disclosure of Invention

In view of the above, it is desirable to provide a balanced drop mechanism and a gravimeter that address the above issues.

A balanced drop mechanism comprising:

the shell surrounds and forms an accommodating cavity, and the accommodating cavity is provided with a vertical central symmetry axis;

the first rotating mechanism and the second rotating mechanism are arranged in the accommodating cavity and are symmetrically arranged on two sides of the central symmetry axis relative to the central symmetry axis;

the first balance piece and the second balance piece are arranged in the accommodating cavity, are in transmission connection with the first rotating mechanism and the second rotating mechanism respectively, and are symmetrically arranged on two sides of the central symmetry axis;

the bearing piece is used for placing a mass piece to be measured, is arranged on the central symmetry axis and is in transmission connection with the first rotating mechanism and the second rotating mechanism;

the first rotating mechanism and the second rotating mechanism are used for driving the bearing piece and the first balancing piece and the second balancing piece to move in opposite directions in the vertical direction at the same speed;

the driving device is arranged on the shell;

the adjusting piece is in transmission connection with the driving device, and the driving device is used for driving the adjusting piece to move in the vertical direction, so that the integral mass center of the gravity meter is kept unchanged when the to-be-measured mass piece performs free-fall movement in the accommodating cavity.

In one embodiment, the driving device includes:

the cam is vertically and rotatably arranged at the top of the shell;

the sliding rail is vertically arranged at the top of the shell, the adjusting piece is arranged on the sliding rail in a sliding mode and abutted to the cam, and the cam drives the adjusting piece to move in the vertical direction along the sliding rail when rotating.

In one embodiment, the cam determines the displacement of the adjusting member in the vertical direction according to the mass of the mass member to be measured, the mass of the adjusting member, the displacement of the bearing member, and the displacement of the mass member to be measured.

In one embodiment, the driving device comprises a base and a supporting plate, the supporting plate is arranged at the top of the shell at intervals along the vertical direction, and the sliding rail is arranged between the base and the supporting plate.

In one embodiment, the support plate is provided with an opening for passage of the adjustment member.

In one embodiment, the driving device further includes a supporting seat disposed on the base, and the cam is rotatably disposed on the supporting seat.

In one embodiment, the driving device comprises a screw rod, the screw rod is vertically and rotatably arranged at the top of the shell, the adjusting piece is a nut, the nut is in threaded fit with the screw rod, and the screw rod drives the nut to move in the vertical direction when rotating.

In one embodiment, the bearing device further comprises two single-side racks and a double-side rack, the first rotating mechanism and the second rotating mechanism are both gears, the first balancing piece and the second balancing piece are in transmission connection with one gear through one single-side rack, and the bearing piece is in transmission connection with two gears through the double-side racks.

In one embodiment, the first rotation mechanism includes:

a first pulley and a second pulley disposed along a vertical direction;

the two ends of the first steel belt are respectively connected with the first balance piece and the bearing piece, the two ends of the second steel belt are respectively connected with the first balance piece and the bearing piece, and the first steel belt, the second steel belt, the first balance piece and the bearing piece form a closed loop surrounding the first pulley and the second pulley;

the second rotating mechanism includes:

a third pulley and a fourth pulley arranged along the vertical direction;

the two ends of the third steel belt are respectively connected with the second balance piece and the bearing piece, the two ends of the fourth steel belt are respectively connected with the second balance piece and the bearing piece, and the third steel belt, the fourth steel belt, the second balance piece and the bearing piece form a closed loop surrounding the third pulley and the fourth pulley.

In one embodiment, the device further comprises a servo motor in transmission connection with one of the first pulley, the second pulley, the third pulley or the fourth pulley.

A gravity meter comprises the balance falling mechanism.

According to the balance falling mechanism provided by the embodiment of the application, the driving device can drive the adjusting piece to move in the vertical direction. When the bearing piece with the quality spare that awaits measuring moves in vertical direction, just the quality spare that awaits measuring with the bearing piece separation makes when the quality spare that awaits measuring is the free fall motion, can be right through mass point system momentum theorem the balanced whereabouts mechanism is whole to carry out the analysis, with the whole barycenter of balanced whereabouts mechanism keeps not becoming control target, reachs the state of regulating part at vertical direction motion. And the whole mass center of the balance falling mechanism can be kept unchanged by controlling the motion state of the adjusting piece, so that the influence of the recoil vibration on the absolute gravity measurement process is eliminated, and the measurement precision is improved.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic view of a balanced drop mechanism provided in an embodiment of the present application;

fig. 2 is a schematic perspective view of a driving device according to an embodiment of the present application;

FIG. 3 is a front view of a drive device provided by an embodiment of the present application;

FIG. 4 is a front view of a cam structure provided by an embodiment of the present application;

FIG. 5 is a cross-sectional view of a cam configuration provided by an embodiment of the present application;

FIG. 6 is a schematic view of a screw structure according to another embodiment of the present application;

fig. 7 is a schematic view of a rack and pinion structure according to another embodiment of the present application.

Description of reference numerals:

balance drop mechanism 10

Case 100

Accommodating chamber 110

Central axis of symmetry 120

First rotating mechanism 210

First pulley 212

Second pulley 214

First steel belt 216

Second steel strip 218

Second rotating mechanism 220

Third pulley 222

Fourth pulley 224

Third steel strip 226

Fourth steel belt 228

First balance member 310

Second balance member 320

Carrier 330

Mass part to be measured 340

Driving device 400

Cam 410

Sliding rail 420

Sliding bar 421

Adjusting piece 430

Linear bearing 431

Supporting plate 440

Openings 442

Base 450

Supporting seat 460

Screw rod 470

Mounting unit 480

Single-sided rack 510

Double-sided rack 520

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Referring to fig. 1, the present embodiment provides a balanced drop mechanism 10. The balanced drop-down mechanism 10 includes a housing 100, a first rotating mechanism 210, a second rotating mechanism 220, a first balance member 310, a second balance member 320, a carrier 330, a driving device 400, and an adjusting member 430. The housing 100 encloses a receiving chamber 110. The receiving cavity 110 has a vertical central axis of symmetry 120. The first rotating mechanism 210 and the second rotating mechanism 220 are disposed in the accommodating cavity 110, and are symmetrically disposed on both sides of the central symmetry axis 120 with respect to the central symmetry axis 120. The first balance member 310 and the second balance member 320 are disposed in the accommodating chamber 110. The first balance member 310 and the second balance member 320 are respectively in transmission connection with the first rotating mechanism 210 and the second rotating mechanism 220, and are symmetrically arranged on two sides of the central symmetry axis 120. The bearing member 330 is used for placing a mass 340 to be measured. The bearing 330 is disposed on the central symmetry axis 120 and is in transmission connection with the first rotating mechanism 210 and the second rotating mechanism 220. The first rotating mechanism 210 and the second rotating mechanism 220 are used for driving the carrier 330 and the first balancing member 310 and the second balancing member 320 to move in opposite directions in a vertical direction at the same speed.

The driving device 400 is disposed at the top of the housing 100. The adjusting member 430 is in transmission connection with the driving device 400. The driving device 400 is used for driving the adjusting member 430 to move in the vertical direction, so that the mass center of the balance falling mechanism 10 is kept unchanged when the mass piece to be measured 340 falls freely in the accommodating cavity 110.

The housing 100 may have a cubic structure. A vacuum may be present in the receiving chamber 110. In a vacuum environment, the air resistance generated when the object is lowered can be reduced, and in one embodiment, the vacuum environment can be an ultra-vacuum environment. Obtaining the displacement time pair of the free falling body track in the ultra-vacuum environment, and then using the formula S which is 1/2gt²The quadratic term obtained by fitting the series of displacement time pairs is more accurate gravity acceleration.

The first rotating mechanism 210 and the second rotating mechanism 220 may be disposed on the same horizontal line. The first rotating mechanism 210 and the second rotating mechanism 220 may rotate to drive the first balance member 310, the second balance member 320, and the bearing member 330 to move upward or downward in a vertical direction. The first rotating mechanism 210 and the second rotating mechanism 220 may be weights having a certain mass. The first rotating mechanism 210 and the second rotating mechanism 220 may be both circular structures, and the diameters of the circular structures may be the same.

The carrier 330 may be linked with the first balance member 310 and the second balance member 320 by the first rotating mechanism 210 and the second rotating mechanism 220. It is understood that when the first rotating mechanism 210 on the left side rotates counterclockwise and the second rotating mechanism on the right side rotates clockwise at the same speed, the carrier 330 ascends in the vertical direction, and the first balancing member 310 and the second balancing member 320 descend at the same speed in the vertical direction. When the first rotating mechanism 210 rotates clockwise and the second rotating mechanism rotates counterclockwise at the same speed, the first rotating mechanism 210 and the second rotating mechanism 220 may drive the first balancing member 310 and the second balancing member 320 to ascend synchronously in a vertical direction. At the same time, the carrier 330 descends at the same speed in the vertical direction. The mass 340 to be measured placed on the carrier 330 is separated from the carrier and performs free-fall motion, and the local gravitational acceleration is calculated by measuring the displacement time pair of the falling trajectory of the mass 340 to be measured.

It is understood that the sum of the masses of the first balance member 310 and the second balance member 320 may be set equal to the sum of the bearing member 330 and the mass member to be measured 340 placed on the bearing member 330. When the gravitational acceleration needs to be measured, the load bearing member 330 may drive the mass member to be measured 340 to ascend. After the mass piece is lifted to a certain height, the bearing member 330 may be controlled to accelerate downwards at an acceleration greater than g, so that the bearing member 330 is separated from the mass piece 340 to be measured. At this time, the mass member to be measured 340 starts to move in a free-fall manner.

It is understood that by controlling the descending speed of the carrier member 330, the separation distance between the carrier member 330 and the mass member to be measured 340 can be controlled to be kept within a set range. In one embodiment, the distance between the carrier 330 and the mass 340 to be measured is kept within 10mm, thereby reducing the distanceWhen the mass part 340 to be measured falls on the bearing part 330, a larger impact force is generated, so that the damage of the impact on the mass part 340 to be measured and the bearing part 330 is reduced, and the times of reusable measurement of parts are increased. The position accuracy of the mass member to be measured 340 falling on the bearing member 330 can be ensured, and the repetition accuracy of each falling measurement can be ensured. Further, the distance of linkage among the carrier 330, the first balance member 310 and the second balance member 320 can be controlled, and further, the distance that the mass 340 to be measured can freely fall can be controlled. In one embodiment, the mass to be measured 340 has a free fall distance greater than 20 cm. In the range, the displacement time obtained by measuring the mass part 340 to be measured has more data, the gravity acceleration value obtained by fitting has higher precision, and the precision can reach mu Gal (10)^-8m/s²) Precision of order of magnitude.

When it is necessary to stop the measurement, the carrier 330 may be decelerated and then lightly caught by the mass 340 to carry the mass 340 back to the initial position of the ascent.

It will be appreciated that the moment in which the load bearing member 330 and the mass 340 are separated corresponds to a sudden decrease in the mass of the balance drop mechanism 10, resulting in the introduction of a mechanical impulse into the ground, the resulting momentum being transferred to the balance drop mechanism 10 and the ground, thereby causing vibration of the ground and the vibration of the isolation device and drop chamber in the gravimeter system to which the balance drop mechanism 10 belongs, such vibration noise being referred to as kick-back vibration. Since the recoil vibrations are highly reproducible and close in phase in each fall, systematic errors can be introduced into absolute gravity measurements.

In the embodiment of the present application, the driving device 400 may drive the adjusting member 430 to move in the vertical direction. When the bearing member 330 and the mass member 340 to be measured move in the vertical direction, and the mass member 340 to be measured is separated from the bearing member 330 so that the mass member 340 to be measured makes a free-fall motion, the whole balance falling mechanism 10 can be analyzed through the mass point system momentum theorem, so that the whole mass center of the balance falling mechanism 10 is kept not to become a control target, and the state of the adjusting member 430 moving in the vertical direction is obtained. The impact of the recoil vibration on the measurement process can be eliminated by controlling the motion state of the adjusting member 430 so that the overall center of mass of the balanced drop mechanism 10 is kept constant.

In one embodiment, during the process that the bearing member 330 carries the mass element 340 to be measured to ascend, the bearing member 330 and the mass element 340 to be measured move upward as a whole, the first balance member 310 and the second balance member 320 move downward at equal and opposite speeds, and considering the system formed by the balance falling mechanism 10 and the mass element 340 to be measured, the principle of mass system momentum can be obtained as follows:

∫(F_N-G_all)dt＝Δp＝m₁Δv₁+m₂Δv₂-m₃Δv₃-m₄Δv₄, (1)

G_all＝(m₁+m₂+m₃+m₄)g, (2)

F_Nis the supporting force, m, to which the balanced falling mechanism 10 is subjected₁,m₂,m₃,m₄Represents the mass of the mass part 340 to be measured, the bearing part 330 and the first balance part 310 and the second balance part 320 respectively, Δ p represents the momentum change of the system in any integral time period, and Δ ν₁,Δv₂,Δv₃,Δv₄Respectively represent the speed change amounts of the mass member to be measured 340, the bearing member 330, and the first and second balance members 310 and 320 in an arbitrary integration period. G_allThe gravity force applied to the mass to be measured 340, the bearing member 330, the first balance member 310 and the second balance member 320.

From the motion relationship of the ascent process, Δ v is easily obtained₁＝Δv₂＝-Δv₃＝-Δv₄. As can be seen from the formula (1), the supporting force F is maintained at Δ p equal to 0 only at any time during the rising process_NThe change is not generated, and the transmission of the recoil momentum to the ground is not generated so as not to cause the recoil vibration. Therefore, substituting Δ p of 0 into equation (1) can yield:

m₁+m₂＝m₃+m₄, (3)

as can be seen from the formula (3), as long as the mass sum of the first balancing member 310 and the second balancing member 320 is equal to the mass sum of the to-be-measured mass member 340 and the bearing member 330, the rising phase of the measurement process can be realized without the backlash effect.

Similarly, applying the particle system momentum theorem for the fall process can result in:

∫(F_N-G_all)dt＝Δp＝-m₁Δv₁-m₂Δv₂+m₃Δv₃+m₄Δv₄, (4)

the bearing member 330 is separated from the mass member 340 to be measured during the falling process, the two members move differently, and the speeds of the first balance member 310 and the second balance member 320 are equal to and opposite to the speed of the bearing member 330, so that the speed relationship of the four members satisfies v₁(t)≠v₂(t)＝-v₃(t)＝-v₄(t) of (d). Combining the formula (3) and the formula (4) can obtain

Δp(t)＝∫(F_N(t)-G_all)dt＝m₁·∫[a₁(t)-a₂(t)]dt (5)

Wherein a is₁(t),a₂(t) acceleration of the mass 340 and the carrier 330 during the fall, respectively. The mass to be measured 340 makes a free fall motion, so a₁(t) ═ g is a constant. While the carrier 330 is falling with an acceleration a₂(t) is a time-varying quantity. From the above, it is known that the release timing exists a₂(t)>g to separate the mass part 340 to be measured from the bearing part 330, a is provided before the bearing part 330 catches the mass part 340 to be measured₂(t)<g to ensure that the bearing member 330 can lightly catch the mass 340 to be measured. Thus during the fall a₁(t)-a₂The value of (t) varies with time. From equation (5), it is not guaranteed that Δ p (t) ═ 0 is satisfied at any time during the fall.

The system can not completely eliminate the recoil vibration in the falling process only by being deduced according to the momentum theorem of the mass point system. Reconsidering the entirety of the first balance member 310, the second balance member 320, the mass member to be measured 340, the carrier member 330 and the regulating member 430. With the test mass, the carrier 330, the first balance 310, the second balance 320, and the adjustment member 430 as the subject of investigation, equation (5) can be rewritten as:

Δp(t)＝∫(F_N-G_all)dt＝∫[m₂·a₂(t)-m₁·a₁(t)+m₅·a₅(t)]dt (6)

G_all)＝(m₁+m₂+m₃+m₄+m₅)g, (7)

wherein m is₅And a₅(t) the mass of the conditioning member 430 and the acceleration of the conditioning member 430 during the fall, respectively. To achieve full backlash balance, substituting Δ p (t) to 0 into equation (6) may result in equation (8), where v₅(t) is the movement speed of the slider:

m₁·v₂(t)-m₁·v₁(t)+m₅·v₅(t)＝0, (8)

equation (8) is obtained by integrating the equal sign on both sides simultaneously:

m₁·s₂(t)-m₁·s₁(t)+m₅·s₅(t)＝0. (9)

wherein s is₁(t),s₂(t),s₅(t) are the movement displacements of the mass to be measured 340, the carrier 330 and the adjuster 430, respectively. Since these displacements are all time-derivative functions during the actual movement, deriving equation (9) also leads to equation (8). This indicates that satisfying equation (9) is equivalent to satisfying equation (8), and that any time Δ p (t) during the fall becomes 0. Therefore, the formula (9) is the motion condition that the slider 5 needs to satisfy, and can be further arranged as follows:

s₅(t)＝-m₁/m₅·[s₂(t)-s₁(t)]. (10)

from equation (10), the adjustment during the fall is knownThe motion displacement of the member 430 and the separation distance s between the mass 340 to be measured and the carrier 330₂(t)-s₁(t) correlating. In the actual measurement process, the rotation speeds of the first rotating mechanism 210 and the second rotating mechanism 220 can be controlled by servo motors. The movement displacement s of the carrier 330₂(t) can be obtained by an optical axis encoder of a servo motor, the movement displacement s of the mass part to be measured 340₁(t) can be represented by the free fall formula s₁(t)＝1/2·gt²And (6) approximate estimation.

Wherein the balanced drop mechanism 10 may be adapted for use in a gravimeter. The gravimeter may be an absolute gravimeter. The absolute gravimeter can obtain the displacement time pair of the free fall trajectory of the mass part to be measured 340 in the falling process through an interference measurement device. The displacement interferometry principle is similar to that of a Michelson interferometer, and the interferometry device can comprise a laser, a pyramid prism, a beam splitter and a photoelectric detector. The light beam emitted by the laser is divided into measuring light and reference light through the beam splitter, wherein the measuring light is transmitted upwards and reflected by the pyramid prism and the reference pyramid prism fixed inside the to-be-measured mass part 340 to finally converge with the reference light to generate interference, and an interference fringe signal containing falling displacement information is acquired by the photoelectric detector. The drop displacement theoretically obtained by interference measurement is the movement displacement of the mass to be measured 340 relative to the reference prism. The movement displacement s of the mass part to be measured 340₁(t) can also be obtained from falling interference fringes. Thus, the movement displacement of the regulating member 430 can be obtained. By controlling the displacement of the adjusting member 430 to satisfy the formula (10), the effect of keeping the center of mass of the balance falling mechanism 10 as a whole constant can be achieved.

It will be appreciated that the balanced drop mechanism 10 may also be adapted for use with other mechanisms where it is desirable to balance recoil vibrations.

Referring to fig. 2 and 3, in one embodiment, the driving device 400 includes a cam 410 and a slide rail 420. The cam 410 is vertically rotatably disposed at the top of the housing 100. The slide rail 420 is vertically disposed at the top of the housing 100. The adjusting member 430 is slidably disposed on the sliding rail 420. And abuts the cam 410. The cam 410 drives the adjusting member 430 to move in a vertical direction along the slide rail 420 when rotating. It will be appreciated that the profile of the cam 410 may determine the displacement of the adjustment member 430 as the cam 410 rotates. The profile and diameter of the cam 410 may be set by the displacement of the adjusting member 430, and thus it may be ensured that the displacement of the adjusting member 430 satisfies equation (10) when the cam 410 rotates.

In one embodiment, the cam 410 may be driven to rotate by a servo motor. The servo motor has good control precision. In one embodiment, the cam 410 may be driven by the servo motor to rotate at a constant speed, and the profile and diameter of the cam 410 may be set to ensure that the displacement of the adjusting member 430 satisfies the formula (10).

In one embodiment, the driving device 400 includes a base 450 and a support plate 440. The base 450 and the support plate 440 may be spaced apart in a vertical direction at the top of the case 100. The slide rail 420 is disposed between the base 450 and the support plate 440.

The base 450 and the support plate 440 may each be a disk structure. The base 450 and the support plate 440 may be disposed in parallel. The slide rail 420 comprises two slide bars 421, and the two slide bars 421 are disposed between the base 450 and the supporting plate 440 at intervals. Two ends of the adjusting member 430 are slidably disposed on one of the sliding bars 421 respectively. The cam 410 may also be disposed between the two sliding bars 421. When the cam 410 rotates, the adjusting member 430 can be driven to move along the two sliding bars 421 in the vertical direction.

Referring to fig. 4 and 5, in one embodiment, linear bearings 431 may be installed at both ends of the adjusting member 430. The linear bearings 431 may be respectively sleeved outside the one sliding bar 421.

In one embodiment, the support plate 440 is provided with an opening 442. For passage of the adjusting member 430. The openings 442 may be square or circular in shape, etc. When the cam 410 drives the adjusting member 430 to move up and down, the adjusting member 430 can pass through the opening 442, so that the stroke range of the adjusting member 430 can be increased.

In one embodiment, the driving device 400 further comprises a supporting seat 460. The support seat 460 is disposed on the base 450, and the cam 410 is rotatably disposed on the support seat 460.

Referring to fig. 6, the driving device 400 includes a screw 470. The lead screw 470 is vertically and rotatably disposed at the top of the housing 100. The adjusting member 430 is a nut. The nut is threadedly engaged with the lead screw 470. The lead screw 470 drives the nut in a vertical direction when rotated.

It will be appreciated that the lead screw 470 may be controlled by a servo motor. The rotating speed of the screw rod 470 can be controlled by controlling the rotating speed of the servo motor, so that the displacement of the nut in the vertical direction can be controlled. The rotation speed of the lead screw 470 can be controlled by setting a program of a servo motor, so that the displacement of the adjusting member 430 meets the above requirements. In one embodiment, two mounting units 480 may be respectively disposed at two ends of the lead screw 470, and the servo motor may drive the lead screw 470 to rotate through one mounting unit.

Referring to fig. 7, in one embodiment, the balanced drop-down mechanism 10 further includes two single-sided racks 510 and a double-sided rack 520. The first rotating mechanism 210 and the second rotating mechanism 220 are both gears. The first balance member 310 and the second balance member 320 are respectively in transmission connection with one of the gears through one of the single-sided racks 510. The carrier 330 is in driving connection with both of the gears via the double-sided rack 520. It is understood that the double-sided rack 520 may be disposed at the central symmetry axis 120. The first balance member 310 and the second balance member 320 may be respectively provided at one end of one single-sided rack 510. The carrier 330 is disposed at one end of the double-sided rack 520. The double-sided rack 520 is located between the two gears, and both sides of the double-sided rack 520 are respectively engaged with the two gears.

It will be appreciated that the double-sided rack 520 carries the carrier 330 down as the left gear rotates clockwise and the right gear rotates counterclockwise. The two single-sided racks 510 respectively lift the first balance member 310 and the second balance member 320. The movement of the carrier 330 can be controlled by controlling the rotation speed of the gears so as to realize the ascending and descending process of the mass member to be measured 340. Since the lengths of the single-sided rack 510 and the double-sided rack 520 may be set as required, the long-distance free-fall movement of the mass 340 to be measured during the falling process may be ensured, so that the measurement accuracy may be improved.

In one embodiment, the first rotating mechanism 210 includes a first pulley 212 and a second pulley 214, a first steel belt 216 and a second steel belt 218, which are disposed in a vertical direction. The first steel belt 216 is connected to the first balance member 310 and the carrier member 330 at both ends thereof, respectively. The first steel belt 216 may be disposed around an upper semicircle of the first pulley 212. The two ends of the first steel belt 216 can symmetrically hang down from the two ends of the first pulley 212 and are connected to the first balancing member 310 and the supporting member 330, respectively.

The second steel strip 218 is connected at both ends thereof to the first balance member 310 and the carrier member 330, respectively. The second steel belt 218 may be disposed around a lower semicircle of the second pulley 214. Both ends of the second steel belt 218 may be connected to the first balance member 310 and the carrier member 330, respectively. The first steel belt 216, the second steel belt 218, the first balancing member 310 and the carrier member 330 thus constitute a closed loop around the first pulley 212 and the second pulley 214, and the first steel belt 216, the second steel belt 218, the first balancing member 310 and the carrier member 330 are constituted as a tensioned closed loop structure by the first pulley 212 and the second pulley 214.

The second rotating mechanism 220 includes a third pulley 222 and a fourth pulley 224, a third steel belt 226 and a fourth steel belt 228, which are disposed in a vertical direction. The third steel belt 226 is connected at both ends thereof to the second balance member 320 and the carrier member 330, respectively. The third steel belt 226 may pass around an upper semicircle of the third pulley 222. The third steel strip 226 extends downward at both ends and is connected to the second balance member 320 and the carrier member 330, respectively.

The fourth steel belt 228 passes around the fourth pulley 224 at both ends and extends upward to be connected to the second balancing member 320 and the carrier member 330, respectively. The fourth pulley 224 and the third pulley 222 tension the fourth steel belt 228 and the third steel belt 226. The fourth steel belt 228, the second counterweight 320 and the load bearing member 330 thus form a tensioned closed loop around the third pulley 222 and the fourth pulley 224.

In one embodiment, the balanced drop mechanism 10 further includes a servo motor. The servo motor is in transmission connection with one of the first pulley 212, the second pulley 214, the third pulley 222 or the fourth pulley 224. That is, as long as one of the first pulley 212, the second pulley 214, the third pulley 222 or the fourth pulley 224 rotates, the other remaining pulleys rotate along with the first steel belt 216, the second steel belt 218, the third steel belt 226 or the fourth steel belt 228. The bearing 330 can be controlled to displace upward or downward. In one embodiment, the servo motor is drivingly connected to the fourth pulley 224. Therefore, when the fourth pulley 224 rotates, the third pulley 222 is driven to rotate by the third steel belt 226 and the fourth steel belt 228. At the same time, the bearing member 330 also rotates, and the first steel belt 216 and the second steel belt 218 are driven to rotate by the bearing member 330. The rotation of the first steel belt 216 and the second steel belt 218 can drive the rotation of the first pulley 212 and the second pulley 214.

It will be appreciated that by providing a distance between the first pulley 212 and the second pulley 214, and a distance between the third pulley 222 and the fourth pulley 224, the distance that the load bearing member 330 can be raised or lowered can be increased. Therefore, the distance of the mass part 340 to be measured in free falling can be increased, the data acquisition amount is increased, and the measurement precision can be improved.

It is understood that the ascending stage of the measurement process can only operate the steel belt transmission mechanism formed by the first pulley 212, the second pulley 214, the third pulley 222 and the fourth pulley 224 to drive the first steel belt 216, the second steel belt 218, the third steel belt 226 and the fourth steel belt 228, and the mass member to be measured 340 is conveyed to the position of the drop release point through the bearing member 330. As can be seen from the above analysis, the backlash effect in the rising phase can be completely eliminated by the steel belt transmission mechanism having the first balance member 310 and the second balance member 320. And in the falling stage, a steel belt transmission mechanism and a cam 410 mechanism comprising a cam 410 and an adjusting piece 430 are simultaneously operated, wherein the steel belt transmission mechanism is mainly used for realizing the long-distance free falling motion of the tested mass and partially eliminating the recoil effect, and the cam 410 drives the piece to be tested to realize the motion displacement meeting the formula (10) so as to realize that the balance falling mechanism 10 and the integral mass center of the piece to be tested 340 are kept unchanged, thereby completely eliminating the recoil effect and further achieving the purpose of improving the measurement precision.

The embodiment of the application also provides a gravity meter. The gravimeter may be an instrument for measuring the absolute value of gravitational acceleration. The gravimeter includes the balanced drop mechanism 10. The gravimeter may further comprise the interferometric measuring device. The displacement time pair of the free falling trajectory of the mass part to be measured 340 in the falling process is obtained by the interferometric measuring device, so that the motion state of the mass part to be measured 340 can be obtained.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.