A proportional linkage mechanism for the rotation angle of precision instruments

Abstract

The invention discloses an angle proportional connecting rod mechanism for precision instrument rotation, which is composed of five movable connecting rods and a frame. By changing the length of the connecting rod or the position of the frame, the angle of rotation of the active rod and the angle of rotation of the driven rod can meet a certain proportional relationship within a certain range. The active rod rotates a large angle and the driven rod rotates a small angle, thereby achieving precise angle adjustment.

Description

Technical Field

[0001] The invention belongs to the field of precision machinery and relates to the angle adjustment of precision instruments in X-ray optics, in particular to an angle proportional connecting rod mechanism for rotating precision instruments. Background Art

[0002] Synchrotron radiation devices are devices that generate synchrotron radiation by deflecting relativistic charged particles in a magnetic field. Synchrotron radiation includes far infrared, visible light, ultraviolet light, and X-rays. A monochromator can be used to obtain light of a specific wavelength from synchrotron radiation. The angle of the crystal in the monochromator needs to be adjusted very finely. The angle of each rotation is at the micro-radian level, so a high-precision angle adjustment mechanism is required to meet the requirements.

[0003] The existing monochromator crystal angle adjustment mechanism is mainly a sinusoidal mechanism (see Figure 1 ) and sinusoidal linkages (see Figure 2 ). In the sine mechanism, the driving mechanism pushes the rocker to rotate, and the sine value of the rotation angle is approximately equal to the displacement of the driving mechanism divided by the length of the rocker. In the sine linkage mechanism, the rocker is rotated using a four-bar mechanism. There are two ways to improve the accuracy of the angle using these two mechanisms: 1. Make the driving mechanism push a smaller distance each time; 2. Make the mechanism larger. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes the following technical solutions:

[0005] An angle proportional connecting rod mechanism for rotating a precision instrument, the connecting rod mechanism comprising:

[0006] a first rack, a second rack, and a third rack;

[0007] a first link, a second link, a third link, a fourth link, and a fifth link;

[0008] Among them, the first connecting rod is an active rod, one end of the first connecting rod is fixed on the first frame, and the other end of the first connecting rod is hinged to the left end of the second connecting rod; the right end of the second connecting rod is hinged to the third connecting rod, and a rotating pair is arranged on the second connecting rod as a connection point, at which the second connecting rod and the fourth connecting rod are hinged; the lower end of the third connecting rod is hinged to the second frame; the lower end of the fourth connecting rod is hinged to the fifth connecting rod; the fifth connecting rod is hinged to the third frame, and the precision instrument that needs to be rotated is installed on the fifth connecting rod.

[0009] The ratio of the rotation angles of the first connecting rod and the fifth connecting rod can be adjusted by: adjusting the length ratio of the second connecting rod on both sides of the connection point; adjusting the length of the fifth connecting rod; adjusting the horizontal positions of the second rack and the third rack. The horizontal positions of the second rack and the third rack can be adjusted by lateral movement of the second rack or the third rack.

[0010] Furthermore, when the link mechanism is working, the first link is the active part, driving the other links to rotate, and when the first link rotates, its rotation angle is greater than the rotation angle of the fifth link driven by it. Usually, the angle of the first link is much greater than the rotation angle of the fifth link driven by it.

[0011] Furthermore, within the selected range, the rotation angle of the first link and the rotation angle of the fifth link satisfy a specific proportional relationship, and the selected range refers to the rotation angle interval of the first link that allows the angular velocity of the fifth link to be stable during one rotation of the first link.

[0012] Further, when the first connecting rod rotates at a constant speed within the selected range, the angular velocity of the fifth connecting rod is stable. Wherein, when the first connecting rod rotates at a constant speed, the angular velocity of the fifth connecting rod is always changing, but the change is very small within the selected range, and the angular velocity is considered to be stable. In actual use, the rotation angle of the first connecting rod should be within the selected range.

[0013] The present invention can realize that the angles of rotation of the first connecting rod and the fifth connecting rod meet the proportional relationship by designing the length of each connecting rod, the position of the connection point, and the position of the frame. During the design, modifying the length of the second connecting rod on both sides of the connection point; modifying the length of the fifth connecting rod; modifying the position of the second frame and the third frame in the horizontal direction can significantly increase or decrease the ratio of the angles of rotation of the first connecting rod and the fifth connecting rod. Modifying other dimensions of the mechanism has little effect on the angle ratio.

[0014] When the mechanism is working, the first connecting rod is the active part, driving the other connecting rods to rotate, and finally realizing the fifth connecting rod to rotate a very small angle. After the mechanism design is completed, the first connecting rod is rotated for one circle, and the angle interval of the first connecting rod that can stabilize the angular velocity of the fifth connecting rod is selected as the selected range. When the angle of rotation of the first connecting rod exceeds the selected range, the speed of rotation of the fifth connecting rod is unstable, and the rotation direction may change. Therefore, the present invention requires that the angle selected by the first connecting rod must be within the selected range.

[0015] Advantages of the present invention:

[0016] 1. The present invention can design a mechanism according to the angle reduction ratio required by the project, and approximately obtain the required angle ratio mechanism;

[0017] 2. After the mechanism is manufactured, the angle ratio can still be modified by changing the position of the frame;

[0018] 3. Compared with existing solutions, the mechanism is small in size and saves space. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of an existing sinusoidal mechanism;

[0020] Figure 2 It is a schematic diagram of an existing sinusoidal linkage mechanism;

[0021] Figure 3 is a schematic diagram of the angle ratio mechanism of the present invention;

[0022] Figure 4 It is the working schematic diagram of the angle ratio mechanism;

[0023] Figure 5 It is the position diagram of the angle ratio mechanism before and after movement;

[0024] Figure 6 This is a specific example of the angle ratio mechanism of the present invention;

[0025] Figure 7 is a diagram showing the relationship between the angle of rotation of the active rod and the angle of rotation of the instrument in a specific example;

[0026] Figure 8 for Figure 7 A magnified view of the middle section;

[0027] Fig. 9 This is the relationship diagram between the connecting rod size and the frame coordinates before the mechanism moves;

[0028] Fig.10 This is the geometric relationship diagram after the mechanism moves.

[0029] Figure numerals: 1 - first link, 2 - second link, 3 - third link, 4 - fourth link, 5 - fifth link, 6 - connection point, 7 - second frame, 8 - third frame, 9 - first frame. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0031] The present invention relates to an angle proportional linkage mechanism for rotating precision instruments, such as Figure 3 As shown, the connecting rod mechanism includes:

[0032] A first rack 9, a second rack 7 and a third rack 8;

[0033] A first connecting rod 1, a second connecting rod 2, a third connecting rod 3, a fourth connecting rod 4, and a fifth connecting rod 5;

[0034] Among them, the first connecting rod is an active rod, one end of the first connecting rod is fixed on the first frame, and the other end of the first connecting rod is hinged to the left end of the second connecting rod; the right end of the second connecting rod is hinged to the third connecting rod, and a rotating pair is arranged on the second connecting rod as a connection point 6, at which the second connecting rod and the fourth connecting rod are hinged; the lower end of the third connecting rod is hinged to the second frame; the lower end of the fourth connecting rod is hinged to the fifth connecting rod; the fifth connecting rod is hinged to the third frame, and the precision instrument that needs to be rotated is installed on the fifth connecting rod.

[0035] The ratio of the rotation angles of the first connecting rod and the fifth connecting rod can be adjusted in the following ways: adjusting the length ratio of the second connecting rod on both sides of the connection point; adjusting the length of the fifth connecting rod; adjusting the positions of the second frame and the third frame in the horizontal direction, that is, moving the second or third frame laterally.

[0036] Furthermore, when the link mechanism is working, the first link is the active part, driving the other links to rotate, and when the first link rotates, its rotation angle is greater than the rotation angle of the fifth link driven by it. Usually, the angle of the first link is much greater than the rotation angle of the fifth link driven by it.

[0037] Furthermore, during one rotation of the first connecting rod, an angle interval of the first connecting rod that can stabilize the angular velocity of the fifth connecting rod is selected as the selected range.

[0038] Furthermore, when the first connecting rod rotates at a constant speed, the angular velocity of the fifth connecting rod is always changing, and the change is very small within the selected range, so the angular velocity is considered to be stable.

[0039] Furthermore, within the selected range, the rotation angle of the first connecting rod and the rotation angle of the fifth connecting rod satisfy a specific proportional relationship. In actual use, the rotation angle of the first connecting rod should be within the selected range.

[0040] like Figure 4 The figure shows the working diagram of the angle ratio mechanism. Figure 5 This is the position diagram of the angle proportional mechanism before and after movement.

[0041] The present invention can obtain the required angle ratio by establishing the geometric relationship equation of the connecting rod and designing the mechanism according to the engineering requirements. The suggested equation method is as follows:

[0042] First, establish a rectangular coordinate system, such as Fig. 9As shown. The origin of the coordinate system is at the position of the first frame, and the horizontal axis of the coordinate system is parallel to the fifth link. Let the coordinates of the third frame be (x, y) and the coordinates of the second frame be (z, w). The length of the first link is L1; the second link is divided into two sections at the connection point, with lengths of L2 and L3 respectively; the length of the third link is L4; the length of the fourth link is L5; the length of the fifth link is L6.

[0043] After the mechanism moves to a certain angle, set some variables on the coordinate graph. Fig.10 As shown, capital letters represent angles, where the angle between the first link and the horizontal axis of the coordinate system is A. Draw a horizontal line parallel to the horizontal axis at the left end of the second link, draw a connecting line between the left end of the second link and the second frame, the length of the connecting line is set to m, the angle between the connecting line and the horizontal line is B, and the angle between the second link and the horizontal line is C. Draw a straight line between the connection point and the third frame, the length of the straight line is set to n, the angle between the straight line and the horizontal direction is D, and the angle between the straight line and the fifth link is E. Because before the mechanism moves, the fifth link is parallel to the horizontal axis of the coordinate system and is horizontal, angle E minus angle D is the angle F of rotation of the fifth link. The equation is established as follows:

[0044] Equation 1:

[0045]

[0046] From the Pythagorean theorem we get equation 2:

[0047]

[0048] From the law of cosines, we get equation 3:

[0049]

[0050] Equation 4:

[0051]

[0052] From the Pythagorean theorem we get equation 5:

[0053]

[0054] Equation 6:

[0055]

[0056] Equation 7:

[0057]

[0058] During the movement of the mechanism, the lengths of the connecting rods L1 to L6 and the positions x, y, z, and w of the frame remain unchanged and are considered constants. Only the angle between the connecting rod and the coordinate axis changes. The formula is a step-by-step substitution relationship. Substitute the value of the angle A between the first connecting rod and the horizontal axis of the coordinate system before the movement into equation one to obtain the value of B, substitute the value of B in equation one and the value of m in equation two into equation three to obtain C, substitute the value of C into equation four and equation five to obtain D and n, substitute the value of n into equation six to obtain E, and substitute the values ​​of E and D into equation seven to obtain F. Then substitute the value of A after the movement of the mechanism into the above formula, and solve it step by step to obtain the value of F after the movement of the mechanism. Through the above formula, after the size of the mechanism is designed, the angle of the fifth connecting rod can be calculated according to the angle of rotation of the first connecting rod. From this, the relationship between A and F can be obtained. The ratio of the difference between the two values ​​of A before and after the movement of the mechanism to the difference between the two values ​​of F before and after the movement, that is, the ratio of the angle of rotation of the first connecting rod to the angle of rotation of the fifth connecting rod, is the angle ratio. B, C, D, E, m and n are all intermediate variables introduced for the convenience of expression and can be eliminated by substitution.

[0059] As can be seen from the formula, the equation has eleven variables, including L1 to L6, the coordinates (x, y) and (z, w) of the two racks, and angle A. These eleven variables will affect the angle F of the fifth connecting rod. After analysis, when the range of rotation of A remains unchanged, there are four factors that have a greater impact on the angle ratio: 1. The length of the second connecting rod on both sides of the connection point, namely L2 and L3; 2. The length of the fifth connecting rod, namely L6; 3. The horizontal position of the second rack, namely the horizontal coordinate z; 4. The horizontal position of the third rack, namely the horizontal coordinate x. According to the scenario in which the mechanism is used, the preliminary size is determined, and then the size is modified and optimized later, using the method of controlling variables to change one unknown quantity each time. If the first connecting rod rotates a large angle and exceeds the selected range, the fifth connecting rod will also reverse. Therefore, the present invention has requirements for the rotation range of the first connecting rod, which cannot exceed the selected range. According to the four factors that have a greater impact on the angle ratio, the following four design methods are summarized.

[0060] Method 1: Change the lengths on both sides of the connection point of the second link, and keep the lengths of the other links and the position of the frame unchanged. This method can be implemented in three ways: 1. Keep the length of the second link unchanged, and change the position of the connection point on the second link, that is, the sum of L2 and L3 remains unchanged, and one of L2 and L3 increases while the other decreases; 2. Change the length of L2 and keep L3 unchanged; 3. Change the length of L3 and keep L2 unchanged. Within a certain range, the shorter L2 is, the longer L3 is, and the greater the angle ratio is.

[0061] Method 2: Changing the length of the fifth connecting rod, that is, the value of L6, while keeping the lengths of the other connecting rods and the positions of the frame unchanged, within the selected range, as L6 increases, the angle ratio increases first and then decreases.

[0062] Method three: changing the horizontal position of the second frame, that is, the horizontal coordinate z of the second frame, and keeping the lengths of the other connecting rods and the frame positions unchanged, within the selected range, as z increases, the angle ratio first increases and then decreases.

[0063] Method 4: changing the horizontal position of the third frame, that is, the horizontal coordinate x of the third frame, and keeping the lengths of the other connecting rods and the frame positions unchanged, within the selected range, as x increases, the angle ratio first increases and then decreases.

[0064] According to the above four methods, the parameters of the mechanism can be iteratively optimized, and then a size can be obtained using the formula. Due to the error caused by the calculation, this method can only obtain a mechanism with an angle ratio close to the design requirements.

[0065] The following is further described in conjunction with specific embodiments:

[0066] First, according to the actual use space of the mechanism, determine a rough size parameter, then use the above four methods to iteratively optimize, determine the preliminary size of the mechanism, and finally use the formula to determine the parameters of the mechanism. Due to the error caused by the calculation, finally get a mechanism with an angle ratio close to the design requirements. The following example illustrates. If the design requires a mechanism with an angle ratio of 50:1, after iterative optimization, get a preliminary size, as shown in the attached figure. Figure 6 As shown, the length of the first link L1 is 100 mm, the sum of the lengths of the second link L2 and L3 is 265 mm, the length of the third link L4 is 150 mm, the length of the fourth link L5 is 145 mm, the length of the fifth link L6 is 240 mm, the position coordinates of the second rack are (295, -60); the position coordinates of the third rack are (30, -15). Assume that the length of L2 is k times that of L3, k is a positive constant, that is, L2=k L3. We substitute the parameters of each link and frame into the formula.

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074] Assume that the first link is Go to , the design requires an angle ratio of 50:1, so the range of F rotation is .Will and Substituting into the above formulas, we get the corresponding two expressions of F. At this time, both expressions contain only one unknown number k. The subtraction of the two expressions of F is equal to , find the value of k; there are two values ​​of k found, or When the value of k is 7.86, the value of L2 is 29.9 mm, the value of L3 is 235.1 mm, and the angle ratio is 50.36:1; when the value of k is 14.23, the value of L2 is 17.4 mm, the value of L3 is 247.6 mm, and the angle ratio is 49.72:1. In this way, two mechanisms that approximately meet the angle ratio requirements are obtained.

[0075] Figure 7 is the relationship between the angle of the first link (horizontally, in radians) and the angle of the instrument (vertically, in radians). When the first link rotates once, it can be seen that the image is an undulating curve. The speed of the fifth link is uneven, and it also rotates in the opposite direction. Take a relatively straight section on the image, such as 0.8 to 1.6 radians, which is a selected range. At this time, the image is close to a straight line, the speed of the fifth link is stable, and the angle ratio is about 49.69, such as Figure 8 As shown, the active rod rotates 0.8 radians (about 45.83°), and the fifth connecting rod rotates 0.0161 radians (about 0.92°). Therefore, the angle of rotation of the first connecting rod and the angle of rotation of the fifth connecting rod meet the proportional relationship within the selected range. When the rotation angle of the first connecting rod exceeds the selected range, the angle ratio will also change.

[0076] The parts of the present invention that are not described in detail belong to the known technology in the art. The above-described embodiments are only descriptions of the preferred implementation of the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation described. Under the premise of not departing from the design spirit of the present invention, various modifications and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A proportional linkage mechanism for the rotation angle of a precision instrument, characterized in that: The connecting rod mechanism comprises: A first rack, a second rack, and a third rack; a first link, a second link, a third link, a fourth link, and a fifth link; Among them, the first connecting rod is an active rod, one end of the first connecting rod is fixed on the first frame, and the other end of the first connecting rod is hinged to the left end of the second connecting rod; the right end of the second connecting rod is hinged to the third connecting rod, and a rotating pair is arranged on the second connecting rod as a connection point, at which the second connecting rod and the fourth connecting rod are hinged; the lower end of the third connecting rod is hinged to the second frame; the lower end of the fourth connecting rod is hinged to the fifth connecting rod; the fifth connecting rod is hinged to the third frame, and the precision instrument that needs to be rotated is installed on the fifth connecting rod. The ratio of the rotation angles of the first connecting rod and the fifth connecting rod can be adjusted by: adjusting the length ratio of the second connecting rod on both sides of the connection point; or adjusting the length of the fifth connecting rod; or adjusting the position of the second frame in the horizontal direction; or adjusting the position of the third frame in the horizontal direction.

2. The proportional linkage mechanism for the rotation angle of a precision instrument according to claim 1, characterized in that: When the link mechanism is working, the first link is an active component, driving the other links to rotate. When the first link rotates, its rotation angle is greater than the rotation angle of the fifth link driven by it.

3. The proportional linkage mechanism for the rotation angle of a precision instrument according to claim 2, characterized in that: In the selected range, the rotation angle of the first link and the rotation angle of the fifth link satisfy a specific proportional relationship. The selected range refers to the rotation angle interval of the first link that allows the angular velocity of the fifth link to be stable during one rotation of the first link.

4. The proportional linkage mechanism for the rotation angle of a precision instrument according to claim 3 is characterized in that: When the first link rotates at a constant speed within a selected range, the angular velocity of the fifth link is stable.

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