Background
The following problems generally exist with existing gears or anti-backlash gears:
1. the backlash affects the transmission accuracy when the gears rotate in the opposite direction. In theory, the gear meshing has no side clearance, but the gear side clearance is generated between the non-working surfaces of the gears due to dimensional errors caused by changes of manufacturing, installation, temperature and the like, and the main factor influencing the forward and reverse rotation transmission precision of the gears is the gear side clearance. The gear backlash is mainly influenced by factors such as temperature rise of gears, misalignment of gear shafting, unidirectional deviation of gear teeth such as tooth profile, tooth direction and tooth pitch, radial run-out and elastic deformation of bearings and the like. Due to the backlash, the gear will have a large error when rotating in reverse. Backlash, as shown in fig. 1, will produce an idle stroke due to the influence of the backlash when rotating in the reverse direction, resulting in poor accuracy and performance of the gear transmission.
2. The anti-backlash gear is not compact enough in structure. The common methods for eliminating the gear backlash mainly include a center distance adjusting method, a gear staggered-tooth tension spring method, an axial adjusting method and the like. These methods are mainly applied to a train wheel having a sufficient space for the layout of the structure. And the elimination of the forward and reverse rotating clearance in a small space needs to adopt a scientific method to realize the compact design of the gear structure.
3. There is no structural design method for eliminating the gear backlash. The design method for eliminating the gear clearance of the system needs to comprehensively consider materials, manufacturing processes, structural design, mechanical analysis and the like. The axial positioning of the main and auxiliary gears, the layout of the structural space and the relationship between the load and the displacement of the C-shaped spring are all the key factors influencing the reverse transmission precision, and the prior art has no systematic gear design method with a compact structure for eliminating backlash.
The utility model discloses a (application number CN201620711953.3) discloses a clearance that disappears gear structure of engine, clearance that disappears gear adopts the main and auxiliary gear structure, the tooth profile parameter of main and auxiliary gear is the same, the center of master gear is provided with the axial protrusion, the center setting of auxiliary gear and the through-hole of axial protrusion suit, and the suit is on the axial protrusion of master gear, the engine field is applied to this kind of technique, be used for reducing engine noise, but the axial retaining ring that this clearance that disappears gear structure set up leads to overall structure not compact, can't be applied to accurate transmission such as little space instrument and meter.
Disclosure of Invention
According to the technical problems that the transmission precision is influenced by the tooth side clearance when the gear rotates reversely, the anti-backlash gear structure is not compact enough and the like, the compact gear structure for eliminating the side clearance and the design method thereof are provided. The invention realizes compact clearance elimination gear train structural design through the internal C-shaped spring, can eliminate the gear backlash when the gear rotates reversely, and improves the influence on the transmission precision.
The technical means adopted by the invention are as follows:
a compact gear structure for eliminating lateral clearance comprises a fixed gear, a floating gear and a C-shaped spring;
the fixed gear comprises a central hole provided with a key groove; the gear shaft extends into the central hole and is connected with the fixed gear through a key;
the floating gear is rotatably arranged on a central hole hub of the fixed gear through clearance fit;
three threaded holes which are 120 degrees apart from each other are circumferentially arranged on the tooth surface of the fixed gear, three annular long-strip-shaped holes which are 120 degrees apart from each other are circumferentially arranged on the tooth surface of the floating gear, the fixed gear and the floating gear are axially fixed through step screws arranged in the threaded holes and the annular long-strip-shaped holes, and the length of each annular long-strip-shaped hole is 3 times of the diameter of each step screw; the C-shaped spring is fixedly arranged between the fixed gear and the floating gear through a pin shaft, and the C-shaped spring is in clearance fit with the fixed gear and the floating gear; the fixed gear is provided with a groove for placing the C-shaped spring.
Further, the clearance between the C-shaped spring and the fixed gear and the floating gear is 1 mm.
The invention also provides a design method of the gear structure, which comprises the following steps:
step 1: first of all by means of the gear reference circle radius r of the fixed gearpAccording to rcl=0.82×rpCalculating the circumferential arrangement radius r of the stepped screwcl;
Step 2: three threaded holes which are spaced by 120 degrees are arranged on the tooth surface of the fixed gear along the circumference, and the stepped screw and the threaded holes are fixed in a four-point riveting mode;
and step 3: the floating gear is rotatably arranged on the fixed gear through clearance fit, three annular long holes which are spaced by 120 degrees are circumferentially arranged on the tooth surface of the floating gear, and the length of each annular long hole is 3 times of the diameter of the stepped screw;
and 4, step 4: the flank of tooth of fixed gear sets up the recess that is used for placing C type spring, and C type spring and fixed gear and floating gear are clearance fit, and the clearance between C type spring and fixed gear and the floating gear is 1mm, and the external diameter r of recessf=0.75×rp;
And 5: radius r of C-shaped spring center circleavr,ravr=0.56×rp(ii) a The opening width of the C-shaped spring is s, and the opening angle alpha of the C-shaped spring is arcsin (0.5 s/r)avr);
Step 6: the C-shaped spring has a rectangular section, a thickness of b and a width of h, and the moment of inertia I (bh) of the C-shaped spring is bh312 bending section coefficient Z ═ bh2/6;
And 7: according to the set gear train transmission output torque T
oThe torque T is comprehensively influenced by factors such as transmission efficiency eta and transmission ratio i of a gear and a bearing, consideration of manufacturing and the like
otherDetermining gear shaft input drive torque
Wherein, n is 1 … … j, j is the jth gear and bearing;
and 8: the pin shaft is positioned in a plane rectangular coordinate system taking the center of the fixed gear as a dot, and the distance from the pin shaft to the y axis is lx=ravrX cos alpha, distance from x axis ly=ravr×sinα-0.5×dy;
And step 9: according to TkAnd lxCalculating the load F of the C-shaped spring0=Tk/lx;
Step 10: the maximum bending stress of the C-shaped spring is sigma under the action of bending moment
maxThe C-shaped spring material is spring steel with the lower yield strength of
The safety coefficient is more than 1.25, and the maximum bending stress
Step 11: c-type spring restoring force F
1Coefficient of 0.9, restoring force of spring
F
1>F
0;
Step 12: satisfy gear shaft input transmission torque T
kThe pressing displacement of the C-shaped spring end is
Wherein E is CThe modulus of elasticity of the material of the type spring.
Further, the opening angle α of the C-shaped spring is 30 °, and the opening width s of the C-shaped spring is ravr。
Compared with the prior art, the invention has the following advantages:
the compact gear structure for eliminating the lateral clearance and the design method thereof are applied to the technical field of precision transmission such as an indicating mechanism, can eliminate the gear backlash during the reverse rotation of the gear through the gear structure, improve the transmission precision, realize the compact gear train structure design for eliminating the backlash through the internal C-shaped spring, and can quickly and accurately complete the gear torque transmission without the lateral clearance.
Based on the reasons, the invention can be widely popularized in the fields of precision transmission and the like.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. Any specific values in all examples shown and discussed herein are to be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are used for convenience of description and simplicity of description only, and in the absence of any contrary indication, these directional terms are not intended to indicate and imply that the device or element so referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be considered as limiting the scope of the present invention: the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.
Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.
Example 1
As shown in fig. 1-3, the present invention provides a compact side play eliminating gear structure, which comprises a fixed gear 1, a floating gear 2 and a C-shaped spring 3;
the fixed gear 1 comprises a central hole provided with a key groove; the gear shaft extends into the central hole and is connected with the fixed gear 1 through a key;
the floating gear 2 is rotatably arranged on a central hole hub of the fixed gear 1 through clearance fit;
three threaded holes which are 120 degrees apart from each other are circumferentially arranged on the tooth surface of the fixed gear 1, three annular long holes which are 120 degrees apart from each other are circumferentially arranged on the tooth surface of the floating gear 2, the fixed gear 1 and the floating gear 2 are axially fixed through a step screw 4 which is arranged in the threaded holes and the annular long holes, and the length of each annular long hole is 3 times the diameter of the step screw 4; the C-shaped spring 3 is fixedly arranged between the fixed gear 1 and the floating gear 2 through a pin shaft 5, and the C-shaped spring 3 is in clearance fit with the fixed gear 1 and the floating gear 2; the fixed gear 1 is provided with a groove for placing the C-shaped spring 3.
Further, the clearance between the C-shaped spring 3 and the fixed gear 1 and the floating gear 2 is 1 mm.
When the gear structure is installed, firstly, the fixed gear 1 is meshed with the transmission gear, then the pin shaft 5, the C-shaped spring 3 and the floating gear 2 are installed, the floating gear 2 is reversely meshed with the teeth of the transmission gear, the fixed gear 1 is positively meshed with the teeth of the transmission gear, when the gear structure works, the floating gear 2 is reversely meshed with the transmission gear, the C-shaped spring 3 is subjected to a pre-tightening load (restoring force), and the floating gear 2 is matched with the transmission gear through the restoring force of the C-shaped spring 3, so that the clearance of the gear is eliminated.
As shown in fig. 4, the present invention further provides a design method of the above gear structure, including the following steps:
step 1: first of all by means of the gear reference circle radius r of the fixed gearpAccording to rcl=0.82×rpCalculating the circumferential arrangement radius r of the stepped screwcl;
Step 2: three threaded holes which are spaced by 120 degrees are arranged on the tooth surface of the fixed gear along the circumference, and the stepped screw and the threaded holes are fixed in a four-point riveting mode;
and step 3: the floating gear is rotatably arranged on the fixed gear through clearance fit, three annular long holes which are spaced by 120 degrees are circumferentially arranged on the tooth surface of the floating gear, and the length of each annular long hole is 3 times of the diameter of the stepped screw;
and 4, step 4: the flank of tooth of fixed gear sets up the recess that is used for placing C type spring, and C type spring and fixed gear and floating gear are clearance fit, and the clearance between C type spring and fixed gear and the floating gear is 1mm, and the external diameter r of recessf=0.75×rp;
And 5: radius r of C-shaped spring center circleavr,ravr=0.56×rp(ii) a The opening width of the C-shaped spring is s, and the opening angle alpha of the C-shaped spring is arcsin (0.5 s/r)avr);
Step 6: the C-shaped spring has a rectangular section, a thickness of b and a width of h, and the moment of inertia I (bh) of the C-shaped spring is bh312 bending section coefficient Z ═ bh2/6;
And 7: according to the set gear train transmission output torque T
oThe torque T is comprehensively influenced by factors such as transmission efficiency eta and transmission ratio i of a gear and a bearing, consideration of manufacturing and the like
otherDetermining gear shaft input drive torque
Wherein, n is 1 … … j, j is the jth gear and bearing;
wherein the gear train transmits the output torque ToThe torque T is comprehensively influenced by factors such as transmission efficiency eta and transmission ratio i of a gear and a bearing, consideration of manufacturing and the likeotherInput conditions known to the user when designing the gear structure;
and 8: the pin shaft is positioned in a plane rectangular coordinate system taking the center of the fixed gear as a dot, and the distance from the pin shaft to the y axis is lx=ravrX cos alpha, distance from x axis ly=ravr×sinα-0.5×dy;
And step 9: according to TkAndlxcalculating the load F of the C-shaped spring0=Tk/lx;
Step 10: the maximum bending stress of the C-shaped spring is sigma under the action of bending moment
maxThe maximum bending stress occurs at the position A, the C-shaped spring material is spring steel, and the lower bending strength is
The safety coefficient is more than 1.25, and the maximum bending stress
Step 11: c-type spring restoring force F
1Coefficient of 0.9, restoring force of spring
F
1>F
0;
Step 12: satisfy gear shaft input transmission torque T
kThe pressing displacement of the C-shaped spring end is
Wherein E is the elastic modulus of the material of the C-shaped spring.
Further, the opening angle α of the C-shaped spring is 30 °, and the opening width s of the C-shaped spring is ravr。
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 the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will 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; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.