阅读说明：本技术 红外热像仪凸轮式变倍调焦系统双片薄齿轮错齿消隙机构 (Double-piece thin gear staggered tooth gap eliminating mechanism of cam type zoom focusing system of thermal infrared imager ) 是由 罗敏 陈吕吉 杨庆华 张生全 徐参军 李学宽 刘永杰 万启春 王海洋 杨林 徐瑞 于 2021-09-09 设计创作，主要内容包括：本发明涉及一种红外热像仪凸轮式变倍调焦系统双片薄齿轮错齿消隙机构,包括电机、第一齿轮、第二齿轮、扭簧和从动齿轮。第一齿轮固定连接电机的转轴,第二齿轮通过第一齿轮的齿轮轴间隙连接；第一齿轮和第二齿轮相配合的面留有扭簧的安装空间；第一齿轮和第二齿轮的齿轮盘上均设置有扭簧挂孔,扭簧的一端挂接在第一齿轮的扭簧挂孔内,其另外一端挂接在第二齿轮的扭簧挂孔内,第二齿轮自外向内贴近第一齿轮并从轴向固定住第二齿轮。通过旋转第一齿轮,让扭簧产生预紧力,通过把两片薄齿轮的齿进行错位的方式啮合在从动齿轮,用于消除齿轮正反旋转传递带来的间隙误差,达到多组透镜一起稳定高精度的相对运动。本机构具有结构简单、可靠性高等特点。(The invention relates to a double-piece thin gear staggered tooth clearance eliminating mechanism of a cam type zoom focusing system of a thermal infrared imager. The first gear is fixedly connected with a rotating shaft of the motor, and the second gear is connected through a gear shaft gap of the first gear; the surface of the first gear matched with the surface of the second gear is provided with an installation space of the torsion spring; the gear plate of the first gear and the gear plate of the second gear are both provided with torsion spring hanging holes, one end of each torsion spring is hung in the torsion spring hanging hole of the first gear, the other end of each torsion spring is hung in the torsion spring hanging hole of the second gear, and the second gear is pressed close to the first gear from outside to inside and axially fixes the second gear. Through rotatory first gear, let the torsional spring produce the pretightning force, through carrying out the mode meshing that misplaces the gear teeth of two film gears at driven gear for eliminate the clearance error that the gear positive and negative rotation transmission brought, reach the relative motion of multiunit lens stability high accuracy together. The mechanism has the characteristics of simple structure, high reliability and the like.)

1. The utility model provides a thermal infrared imager cam-type zoom focusing system biplate thin gear staggered teeth gap elimination mechanism which characterized in that:

the mechanism comprises a motor (1), a first gear (2), a second gear (3), a torsion spring (4) and a driven gear (5); the first gear (2) and the second gear (3) are both provided with gear inner holes; a gear inner hole of the first gear (2) is fixedly connected with a motor rotating shaft (11), a gear shaft (12) is arranged on the opposite surface of the first gear (2) connected with the motor (1), and the gear shaft (12) is in clearance connection with a gear inner hole of the second gear (3);

the surface of the first gear (2) matched with the first gear (3) is provided with an installation space of a torsion spring (4); torsion spring hanging holes (13) are formed in the gear discs of the first gear (2) and the first gear (3), one end of the torsion spring (4) is hung in the torsion spring hanging hole (13) of the first gear (2), the other end of the torsion spring (4) is hung in the torsion spring hanging hole (13) of the second gear (3), the second gear (3) is close to the first gear (2) from outside to inside, and is clamped in a retainer ring groove (14) of the first gear (2) through a shaft retainer ring (7) to limit the axial movement of the second gear (3);

the circle center of the torsion spring hanging hole (13) is positioned as follows: two end points which are in a straight line with the axle center on a circular ring taking the middle diameter Dm of the torsion spring as the diameter and the axle center on the first gear (2) and the second gear (3) as the centers;

the modulus, the tooth number and the reference circle diameter of the first gear (2) and the second gear (3) are the same;

the gear module m of the first gear (2) and the second gear (3) is calculated by the following formula:

in the formula: d₂-a pitch circle diameter; z-number of teeth;

the torsion of the torsion spring (4) is calculated by the following formula:

in the formula: m-torsion spring torsion; e-the wire stiffness modulus; d₁-a spring wire diameter; phi-rotation angle; dm-middle diameter of torsion spring; p-represents the circumference ratio; n-number of effective turns; r-load moment arm; judging whether the calculated torsion of the torsion spring (4) can meet the requirement of the torque of the motor (1) or not;

through rotating the first gear (3), the torsion spring (4) generates pretightening force, and the teeth of the two thin gears are meshed on the driven gear (5) in a staggered mode to eliminate clearance errors caused by forward and reverse rotation transmission of the gears.

2. The thermal infrared imager cam-type zoom focusing system double-piece thin gear staggered tooth backlash elimination mechanism as claimed in claim 1, wherein the first gear (2) and the second gear (3) are miniature thin gears.

3. The thermal infrared imager cam-type zoom focusing system double-piece thin gear staggered tooth backlash elimination mechanism of claim 1, further comprising a gear pressing block (6) for fixedly connecting the first gear (2) and the motor rotating shaft (11).

4. The thermal infrared imager cam type zoom focusing system double-piece thin gear staggered tooth backlash elimination mechanism according to any one of claims 1 to 3, characterized by further comprising a shaft retainer ring (7) for being clamped in a retainer ring groove (14) formed in the first gear (2) to axially fix the first gear (3).

Technical Field

The invention relates to a double-piece thin gear staggered tooth gap eliminating mechanism of a cam type zoom focusing system of a thermal infrared imager, in particular to a double-piece micro gear staggered tooth gap eliminating mechanism, and belongs to the field of thermal infrared imagers.

Background

The optical system of the domestic and foreign high-precision thermal infrared imager largely uses a cam type zooming optical system, and a lens frame connected with the cam curve slot is driven by the designed cam curve slot to drive the lens to move back and forth according to a pre-designed curve, so that the requirements of zooming and focusing of the combination of multiple groups of lenses of the optical system are met.

Currently, cam type zoom and focus mechanisms are generally realized by transmission between gears. The gears are meshed too tightly, so that the low-temperature gears are locked; the meshing is too loose, so that the gap is increased, errors are brought to high-precision aiming of the thermal infrared imager, the observing and aiming precision of the thermal infrared imager is reduced, the difficulty of servo control is increased, and the situation that whether the position of the encoder is in the backlash gap or the lens is driven to move is difficult to judge.

Chinese patent CN102996757A discloses a double-gear backlash eliminating structure for adjusting the force of torsion springs in staggered teeth, which generates a pretightening force in a manner of multiple tension springs, thereby eliminating backlash. However, since the tension spring is hung on the two gears, both the two gears must have a space margin for the tension spring body and the stretched gear, and the gear is too large to be used for the transmission of the miniature thin gear of the miniaturized mechanism.

Disclosure of Invention

In order to solve the defects of the prior art, the invention provides a double-piece thin gear staggered tooth gap eliminating mechanism of a cam type zoom focusing system of a thermal infrared imager, which is used in a miniaturized zoom focusing gear transmission system required by the thermal infrared imager, can obviously improve the effect of eliminating transmission gaps among gears, helps to improve the transmission accuracy of the gears, further effectively improves the observing and aiming precision of the thermal infrared imager on the cam type zoom focusing system, and simultaneously reduces the difficulty of servo control.

The technical scheme for realizing the aim of the invention is as follows:

a double-piece thin gear staggered tooth gap eliminating mechanism of a thermal infrared imager cam type zoom focusing system comprises: the motor, first gear, second gear, torsional spring and driven gear. The first gear and the second gear are both provided with gear inner holes; the inner hole of the first gear is fixedly connected with a rotating shaft of the motor, the opposite surface of the first gear, which is connected with the motor, is provided with a gear shaft, and the gear shaft is in clearance connection with the inner hole of the second gear; the surface of the first gear matched with the surface of the second gear is provided with an installation space of the torsion spring; all be provided with the torsional spring hanging hole on the toothed disc of first gear and second gear, the one end of torsional spring articulates in the torsional spring hanging hole of first gear, and its other one end articulates in the torsional spring hanging hole of second gear, first gear is pressed close to from the extroversion to the inside and from the axial fixed second gear. The modulus, the tooth number and the reference circle diameter of the first gear and the second gear are the same. When the lens is used, the torsion spring generates pretightening force by rotating the first gear, and the teeth of the two thin gears are meshed on the driven gear in a staggered mode to eliminate clearance errors caused by forward and reverse rotation transmission of the gears and achieve the aim that a plurality of groups of lenses can stably move relatively with high precision.

Preferably, the position of the circle center of the torsion spring hanging hole is as follows: and the first gear and the second gear are provided with two end points which are in a straight line with the axle center and are positioned on a circular ring taking the middle diameter Dm of the torsion spring as the diameter.

Preferably, the first gear and the second gear adopt a micro-thin-sheet straight gear.

Preferably, the gear pressing block is used for fixedly connecting the first gear and the motor rotating shaft.

Preferably, the shaft retaining ring is used for being clamped in a retaining ring groove arranged on the first gear, so that the second gear is axially fixed.

The mechanism and the beneficial effects of the invention are as follows:

the selection of the torsion spring needs to be calculated and determined by combining the torsion force of the motor, the diameter of a torsion spring wire, the pitch diameter of the torsion spring, the rotating angle and the like, and the torsion force required by rotating the torsion spring by a corresponding angle is as follows:

in the formula: m: torsion of a torsion spring; e: the rigidity modulus of the wire; d₁: the diameter of the spring wire; phi: rotating the angle; dm is the middle diameter of the torsion spring; p: representing the circumferential ratio; n: effective number of turns; r: a load acting arm. And judging whether the calculated torsion of the torsion spring can meet the torque requirement of the motor.

By combining parameters such as frictional resistance, rotational inertia, motor torque and the like, the maximum torque of the torsional spring in operation can be givenThen selecting the corresponding diameter d of the spring wire according to the middle diameter Dm of the torsion spring₁Corresponding material (modulus of elasticity E).

This mechanism is used for the transmission of high accuracy infrared visual field switching structure, and the gear need be through accurate calculation, combines reference circle diameter, tooth ratio, improves the gear precision, and the modulus is not imitated too big, can suitably increase the number of teeth, chooses corresponding modulus, and the modulus, the number of teeth, the reference circle diameter of first gear and second gear must be the same, and the modulus computational formula is as follows:

in the formula: d₂: pitch circle diameter; z: the number of teeth.

Compared with the prior art, the invention has the following advantages:

(1) the invention only uses one torsion spring, which can be applied to a larger gear and a miniature thin gear;

(2) for the mode of adopting a plurality of tension springs, because the plurality of tension springs are matched, the original length of the tension springs must be stretched when the gear is used, the tension of the tension springs is not uniform due to the inconsistency or assembly errors of the plurality of tension springs, and the gear precision is not uniform due to the change of the meshing staggered tooth positions of the gears and the generation of gaps in the rotation process of the gears; the tension spring is a spiral torsion spring which is subjected to axial tension, the diameter of the spring wire is generally thin due to the fact that multiple coils of the spring wire are wound, the distance between every two coils of the spring wire is increased due to the tensile force, the original length of the tension spring needs to be recovered due to the deformation of the tension spring, pre-tightening force is generated, hooks at two ends of the tension spring are easy to deform, the reliability is low after the tension spring is stretched for a long time, and fatigue is prone to causing the tension spring to lose efficacy. The torsion spring has fewer turns and thicker diameter, generates torque or rotating force, is not easy to generate fatigue to cause performance reduction or even failure, and has higher reliability than the tension spring in the application of miniature high-precision gear backlash elimination; therefore, the mechanism has the advantages of simple structure, high reliability and the like.

In a word, the mechanism is used on a thermal imager of a cam barrel or cam shaft type infrared zoom focusing and backlash eliminating gear transmission mechanism system with high precision and miniaturization requirements, can obviously improve the elimination of transmission clearances among gears, improve the gear transmission accuracy, improve the observing and aiming precision of the thermal imager on the cam type zoom focusing system, reduce the servo control difficulty, save the space and achieve the miniaturization requirements.

Drawings

FIG. 1: the mechanism of the invention is composed schematically.

FIG. 2: the structure schematic diagram of the double-piece gear backlash eliminating mechanism.

FIG. 3: the first gear structure is a schematic diagram, wherein (a) is a front view, and (b) is a left view.

FIG. 4: the second gear structure diagram, wherein (a) is a front view and (b) is a left view.

FIG. 5: the three-dimensional structure schematic diagram of the torsion spring.

FIG. 6: two-dimensional dimension schematic diagram of torsion spring

In the figure: 1-a motor, 2-a first gear, 3-a second gear, 4-a torsion spring and 5-a driven gear; 6-gear briquetting; 7-a retaining ring for a shaft, 11-a motor rotating shaft, 12-a gear shaft, 13-a torsion spring hanging hole and 14-a retaining ring groove.

Detailed Description

Example 1

As shown in fig. 1-5, a dual-blade gear staggered tooth gap eliminating mechanism of a thermal infrared imager cam type zoom focusing system comprises: the gear pressing block comprises a motor 1, a first gear 2, a second gear 3, a torsion spring 4, a driven gear 5, a gear pressing block 6 and a shaft retainer ring 7. The first gear 2 and the second gear 3 are both provided with gear inner holes; the gear inner hole of the first gear 2 is fixedly connected with a motor rotating shaft 11 through a gear pressing block 6, a gear shaft 12 is arranged on the opposite surface of the first gear 2 connected with the motor 1, and the gear shaft 12 is in clearance connection with the gear inner hole of the second gear 3; the surface of the first gear 2 matched with the surface of the second gear 3 is provided with an installation space of a torsion spring 4; torsion spring hanging holes 13 are formed in gear discs of the first gear 2 and the second gear 3, one end of the torsion spring 4 is hung in the torsion spring hanging hole 13 of the first gear, the other end of the torsion spring 4 is hung in the torsion spring hanging hole 13 of the second gear 3, the second gear 3 is close to the first gear 2 from outside to inside and is clamped in a retainer ring groove 14 of the first gear 2 through a retainer ring 7 for a shaft, and the axial moving position of the second gear 3 is limited; through rotating the first gear 3, the torsion spring 4 generates pretightening force, and the teeth of the two thin gears are meshed on the driven gear 5 in a staggered mode, so that clearance errors caused by forward and reverse rotation transmission of the gears are eliminated, and the aim of stabilizing high-precision relative motion of a plurality of groups of lenses is fulfilled.

The torsion spring 4 needs to be calculated and determined by combining the motor torsion, the torsion spring wire diameter, the torsion spring pitch diameter, the rotation angle and the like when being selected, and as shown in fig. 6, the torsion required by the corresponding angle is rotated:

in the formula: m: torsion of a torsion spring; e: the rigidity modulus of the wire; d₁: the diameter of the spring wire; phi: rotating the angle; dm is the middle diameter of the torsion spring; p: representing the circumference ratio (e.g., value 3.1416); n: effective number of turns; r: a load acting arm. The torsion spring 4 can be selected by checking the above formula to determine that it can meet the design requirements.

By combining parameters such as friction resistance, rotational inertia, motor torque and the like, the maximum torque of the torsional spring in operation can be given, and then the corresponding diameter d of the spring wire is selected according to the middle diameter Dm of the torsional spring₁Corresponding material (wire stiffness modulus E).

Gear torsion spring hanging hole position designs according to the pitch diameter Dm of torsional spring: on the gear, the axle center is used as the center, the middle diameter Dm of the torsion spring is used as the diameter of two end points, and one torsion spring hanging hole 13 (1 torsion spring hanging hole is designed in figure 2, and 2 torsion spring hanging holes are designed in figures 3 and 4) can be designed at any end point, and the aperture of the torsion spring hanging hole is slightly larger than the diameter of the torsion spring wire. When the torsion spring 4 is installed, one end of the torsion spring is installed in the torsion spring hanging hole 13 of the first gear 2, and the other end of the torsion spring is installed in the torsion spring hanging hole 13 of the second gear 3. Thus, the two torsion spring hanging holes respectively positioned on the two gears are used for supporting and fixing the two ends of the torsion spring.

Example (c):

e: the rigidity modulus of the wire; the stainless steel wire E for the torsion spring is 19000kg/mm ^ 2; d₁: spring wire straightDiameter, intended to select d₁0.8 mm; phi: rotating the disc at an angle of 30 degrees; dm is the middle diameter of the torsion spring, and the Dm is 0.8 mm; p: representing the circumference ratio (e.g., value 3.1416); n: taking the effective number of turns to be 0.8; r: the load acting arm R is 2; substituting the formula to calculate the torsion of the torsion spring

Combine the selected torque of the motor 1 and convert the torque output by the corresponding motor and determine whether the selection of the torsion spring 4 meets the requirement (for example, the calculated torsion spring torque should be larger than the motor output torque).

This mechanism is used for the transmission of the infrared visual field of high accuracy switching structure, and the gear need be through accurate calculation, combines reference circle diameter, tooth ratio, improves the gear precision, and the modulus is not imitated too big, can suitably increase the number of teeth, chooses corresponding modulus, and first gear 2 must be the same with second gear 3's modulus, number of teeth, reference circle diameter, and the modulus computational formula is as follows:

in the formula: d₂: pitch circle diameter; z: the number of teeth;

example (c): taking out the reference circle diameter d₂The number of teeth Z is 18, 36, and m is calculated to be 0.5.