SUMMERY OF THE UTILITY MODEL
To the not enough that exists among the prior art, the utility model aims to provide a simple structure, convenient to use just can realize constant speed reciprocating motion's combined mechanism.
In order to achieve the above purpose, the technical scheme of the utility model is that: a kind of combined mechanism which realizes the constant speed reciprocating motion, its characteristic lies in: the eccentric crank-slider mechanism comprises a non-circular gear mechanism and a connecting rod mechanism, wherein the connecting rod mechanism is a centering crank-slider mechanism, the centering crank-slider mechanism is connected with the non-circular gear mechanism in series, the non-circular gear mechanism comprises a driving non-circular gear and a driven non-circular gear, the driven non-circular gear is meshed with the driving non-circular gear, a crank of the centering crank-slider mechanism is connected to a central shaft of the driven non-circular gear, and the crank moves along with the driven non-circular gear.
Furthermore, the centering crank-slider mechanism comprises a crank, a connecting rod and a slider, wherein one end of the crank is connected to the center of the driven non-circular gear, the other end of the crank is connected with the connecting rod, and the other end of the connecting rod is connected with the slider.
Furthermore, the combined mechanism further comprises a rack, a guide rail for the sliding block to move is arranged on the rack, the sliding block is connected to the guide rail in a sliding mode, the driving non-circular gear drives the driven non-circular gear to rotate, and the driven non-circular gear drives the crank to rotate, so that the connecting rod drives the sliding block to do reciprocating linear motion.
Furthermore, the center of the driving noncircular gear is matched with the rotating shaft to be rotatably connected onto the rack, the center of the driven noncircular gear is matched with the rotating shaft to be rotatably connected onto the rack, and the rotating center of the driving noncircular gear and the rotating center of the driven noncircular gear are on the same horizontal line.
Furthermore, the moving center of the sliding block is collinear with the rotating center of the driving non-circular gear and the rotating center of the driven non-circular gear and is on the same horizontal line.
Adopt the utility model discloses technical scheme's advantage does:
1. the utility model adopts the series combination of the non-circular gear and the centering crank-slider mechanism, which can strictly realize the constant-speed reciprocating motion rule of the driven part and the adjustable change of the reciprocating motion stroke of the driven part; further expanding the application, the combined mechanism can theoretically realize any speed change rule of the driven part; and the length of the crank is changed, so that the motion stroke of the sliding block can be adjusted.
2. The utility model is formed by combining a pair of non-circular gear transmission mechanisms and a centering slider-crank mechanism, when the driving gear rotates at uniform speed, the centering slider-crank mechanism is driven through the transmission of the pair of non-circular gears, and the constant-speed reciprocating motion of the driven part of the sine mechanism can be strictly realized; the combined mechanism is formed by combining the non-circular gear and the crank slider mechanism in series, so that the combined mechanism can be applied to a main transmission system of a machine which needs to accurately realize the constant-speed motion law and transmit larger power, such as a mechanical transmission type tension and compression fatigue testing machine, a mechanical transmission type shock absorber testing machine and the like.
Detailed Description
In the present invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "plane direction", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.
As shown in fig. 1 to 4, a combined mechanism for realizing constant-speed reciprocating motion is characterized in that: including non-circular gear mechanism and link mechanism, link mechanism is to heart slider-crank mechanism, establishes ties to heart slider-crank mechanism and non-circular gear mechanism, and non-circular gear mechanism includes initiative non-circular gear 1 and driven non-circular gear 2, and driven non-circular gear 2 meshes with initiative non-circular gear 1, and on the center pin of driven non-circular gear 2 was connected to crank 3 to heart slider-crank mechanism, crank 3 is connected in the center of rotation department of driven non-circular gear 2, and crank 3 moves along with driven non-circular gear 2.
The centering crank-slider mechanism comprises a crank 3, a connecting rod 4 and a slider 5, wherein one end of the crank 3 is connected to the center of the driven non-circular gear 2, the other end of the crank 3 is connected with the connecting rod 4, and the other end of the connecting rod 4 is connected with the slider 5.
The combined mechanism further comprises a rack 6, a guide rail for the sliding block 5 to move is arranged on the rack 6, the sliding block 5 is connected with the guide rail in a sliding mode, the driving noncircular gear 1 drives the driven noncircular gear 2 to rotate, and the driven noncircular gear 2 drives the crank 3 to rotate, so that the connecting rod 4 drives the sliding block 5 to do reciprocating linear motion.
The center of initiative non-circular gear 1 rotates with the pivot cooperation and is connected in frame 6, and the center of driven non-circular gear 2 rotates with the pivot cooperation and is connected in frame 6, under normal condition, initiative non-circular gear 1 is vertical to be arranged, and the horizontal level of driven non-circular gear 2 arranges, and initiative non-circular gear 1 is perpendicular with driven non-circular gear 2. The rotation center of the driving non-circular gear 1 and the rotation center of the driven non-circular gear 2 are on the same horizontal line. The moving center of the slide block 5 is collinear and on the same horizontal line with the rotating center of the driving noncircular gear 1 and the rotating center of the driven noncircular gear 2.
The utility model discloses a to change at the uniform velocity rotation into constant velocity reciprocating motion, adopt non-circular gear mechanism and link mechanism to come the series connection combination to realize. Because the link mechanism is the preferred mechanism as the main transmission system of the machine, the simple link mechanism can not realize the constant-speed reciprocating motion law. Although the cam mechanism can strictly realize any motion law, the cam mechanism belongs to a high-auxiliary mechanism and has low bearing capacity, and generally cannot be used as a main transmission system. The non-circular gear mechanism and the crank block mechanism are combined in series to realize the conversion of the constant-speed rotation into the constant-speed reciprocating motion.
As shown in FIG. 1, the rotation center of the driving
non-circular gear 1 is O
1The rotation center of the driven
non-circular gear 2 is O
2The connecting point of the
crank 3 and the connecting
rod 4 is A, the connecting point of the connecting
rod 4 and the
sliding block 5 is B, and the connecting point is of a non-circular gear pairCenter distance O
1 O
2A (mm), the length O of the crank (3)
2A is r (mm), and the rotation angles of the driving
non-circular gear 1 and the driven
non-circular gear 1 are respectively
The instantaneous angular speeds of the driving and driven non-circular gears are omega respectively
1、ω
2The pitch circle radiuses of the meshing points of the driving and driven non-circular gears are r
1、r
2The length AB of the
link 4 is l.
Major quantitative relationship
Quantitative relationship of non-circular gear mechanism:
a pair of non-circular gear mechanisms can realize variable transmission ratio transmission between two wheels by utilizing different pitch curve shapes. Given ratio function
At any instant of time, there will always be a point P where the relative speed of motion is equal to zero, called the instant transmission node. The point P is positioned on the center line O
1 O
2And satisfies ω
1r
1=ω
2r
2Each using r
1、r
2To represent
Instantaneous transmission ratio i
12Comprises the following steps:
the pitch curve calculation formula of the driving gear is as follows:
the pitch curve calculation formula of the driven gear is as follows:
quantitative relation of the centering crank-slider mechanism:
crank O
2Corner of A
The relationship with the displacement x of the
slide 5 is:
1) equation of motion
Wherein:
thus, there are:
(crank link ratio)
) Beta is an included angle between the connecting rod and the frame;
2) speed of rotation
The relation between the rotation angle of the driving non-circular gear 1 and the sliding block 5 can be obtained by simultaneous solving of the formulas (1) and (5).
Design algorithm of non-circular gear pitch curve
Realize the constant-speed reciprocating motion rule
Then there are:
and then the pitch curve of the non-circular gear can be calculated by using the formulas (2) and (3).
The calculation steps are as follows:
step 1, inputting geometrical parameters such as crank length r, connecting rod length l, transmission center distance a of the non-circular gear and the like and rotation angular speed omega of the driving non-circular gear1(equal to a constant);
and 2, establishing a constant-speed motion rule of the sliding block 5 in a motion cycle [0,2 pi ] of the crank 3, namely a combined motion rule comprising a reciprocating constant-speed motion rule and a superposition of equal-acceleration equal-deceleration and sinusoidal motion rules in the starting and reversing stages, wherein the combined motion rule of equal-acceleration equal-deceleration and sinusoidal motion rule superposition is adopted in the starting and reversing stages, and the purpose of reducing the large impact caused by the sudden change of speed in the reversing process is achieved.
Step 3, calculating the transmission ratio i of the non-circular gear according to the formulas (7) and (8)12;
Step 4, calculating the pitch curve of the non-circular gear according to the formulas (2) and (3), and calculating the corresponding rotation angle of the driving non-circular gear and the driven non-circular gear according to the formula (8)
And then the process is finished.
Calculation example:
the crank length r is 0.3m, l is 0.9m, and a is 1.2 m.
The available non-circular gear pitch curve design is calculated as shown in fig. 4. Because the reciprocating motion rule of the crank connecting rod mechanism is asymmetric to the working stroke and the return stroke, the pitch curve is asymmetric, and the design scheme is unique.
The utility model adopts the series combination of the non-circular gear and the centering crank-slider mechanism, and can strictly realize the constant-speed reciprocating motion law of the driven part and the adjustable change of the reciprocating motion stroke of the driven part by properly designing the section curve of the non-circular gear; further expanding the application, the combined mechanism can theoretically realize any speed change rule of the driven part; and the length of the crank is changed, so that the motion stroke of the sliding block can be adjusted.
The utility model is formed by combining a pair of non-circular gear transmission mechanisms and a centering slider-crank mechanism, when the driving gear rotates at uniform speed, the centering slider-crank mechanism is driven through the transmission of the pair of non-circular gears, and the constant-speed reciprocating motion of the driven part of the sine mechanism can be strictly realized; the combined mechanism is formed by combining the non-circular gear and the crank slider mechanism in series, so that the combined mechanism can be applied to a main transmission system of a machine which needs to accurately realize the constant-speed motion law and transmit larger power, such as a mechanical transmission type tension and compression fatigue testing machine, a mechanical transmission type shock absorber testing machine and the like.
The present invention has been described above with reference to the accompanying drawings, and it is obvious that the present invention is not limited by the above-mentioned manner, and various insubstantial improvements can be made without the technical solutions of the present invention, or the present invention can be directly applied to other occasions without the improvements, and all are within the protection scope of the present invention.