Contour optimization composition method for crank on single-cylinder crankshaft

Abstract

The invention discloses a single-cylinder crankshaft upper crank contour optimization composition method which comprises the following steps: firstly, analyzing a single-cylinder inner crank-connecting rod-crosshead motion rule, and finding out a corresponding relation between each motion parameter and a crank contour; the crank, the connecting rod and the crosshead are integrally and reversely rotated, and point location data of the rotating center of the connecting rod and the crosshead are obtained; setting a safety interval and a vertical line to obtain point position data of an intersection point of the crosshead movement line and the crank contour limiting line and tangent point data of the crank contour limiting line on the crank contour; repeating the operation according to the adjusted angle value to obtain a plurality of groups of tangent point data; fitting and processing the multiple groups of tangent point data to obtain a first group of crank limit profile curves and a second group of crank limit profile curves, shifting the outer circle of the crank pin to obtain an auxiliary profile, and connecting the three to obtain a crank profile. According to the method, the contour of the crank can be designed to the maximum extent, the balance performance of the crank is effectively improved, and the application applicability of the crankshaft is enhanced.

Description

Technical Field

[0001] This invention belongs to the technical field of liquid hydrogen booster equipment, specifically relating to a method for optimizing the crank profile on a single-cylinder crankshaft. Background Technology

[0002] High-pressure liquid hydrogen pumps are core equipment in the liquid hydrogen industry chain, widely used in aerospace, new energy, and fuel cell fields. Their main function is to facilitate the flow and pressurization of liquid hydrogen from storage tanks to vaporizers. Single-cylinder reciprocating liquid hydrogen pumps provide power to the liquid hydrogen through mechanical reciprocating action, forcing it to pressurize and flow, thus raising the pressure from low to high.

[0003] The crankshaft is a key component of a high-pressure liquid hydrogen reciprocating pump, and the crank is an important structural part of the crankshaft. Its functions are twofold: firstly, it connects to the crankpin to form the entire crankshaft; secondly, it adjusts the crankshaft's center of gravity, balancing the crankshaft and thus ensuring its stability during rotation. High-pressure liquid hydrogen pumps use single-cylinder crankshafts, relying primarily on the crank to balance the crankpin. Because the crankpin bears heavy connecting rod loads, its design diameter is large. Simultaneously, the overall pump structure is relatively small, limiting the space available for the balancing crank. Conventional cranks are insufficient to effectively balance the crankpin within this confined space.

[0004] Therefore, the study of crankshaft and crank profile is carried out to enable the crank to obtain greater mass within a confined space, thereby ensuring the balance of the crankshaft. Summary of the Invention

[0005] The purpose of this invention is to provide a method for optimizing the crank profile on a single-cylinder crankshaft, which can maximize the design of the crank profile, effectively improve the balance performance of the crank, and enhance the applicability of the crankshaft.

[0006] The technical solution adopted in this invention is a method for optimizing the crank profile on a single-cylinder crankshaft, which specifically includes the following steps: Step 1: Analyze the motion law of crank-connecting rod-crosshead in a single cylinder and find the correspondence between each motion parameter and the crank profile. Step 2: Rotate the crank-connecting rod-cross head assembly in the reverse direction. Once the crank is at its initial position, obtain the positional data of the connecting rod and the center of rotation of the crosshead. Step 3: Set the safety clearance and obtain the point data of the intersection of the crosshead motion line and the crank profile limit line; Step 4: Set a vertical line and find the tangent point on the crank profile where the crank profile limit line is located. Obtain the tangent point data based on the point data in Step 2 and Step 3. Step 5, Adjust The angle value is obtained by repeating steps 2 to 4 to obtain multiple sets of tangent point data. Step 6: Fit multiple sets of tangent point data to obtain the first set of crank limit profile curves. Based on the first set of crank limit profile curves, obtain the second set of crank limit profile curves. Offset the outer circle of the crank pin to obtain the auxiliary profile. Connect the first set of crank limit profile curves, the second set of crank limit profile curves, and the auxiliary profile to obtain the crank profile.

[0007] The invention is further characterized in that, In step 1, the correspondence is that the crank rotates around the center point O of the crankshaft and drives the crosshead to perform reciprocating linear motion through the connecting rod. The connection point Q between the crosshead and the connecting rod is located on the reciprocating motion path of the crosshead. During the rotation of the crank, the position of each point Q corresponds to a contour point of the crank.

[0008] In step 2, the initial position of the crank is when At that time, the crank is in the initial position.

[0009] In step 2, the specific positional data of the connecting rod and the center of rotation of the crosshead are as follows: when the crank returns to the initial position, the positional data of the connecting rod and the center of rotation of the crosshead at point Q is... , and It is calculated using the following expression: ; ; In the formula, L is the length of the connecting rod; l is the length of the crank. The angle between the crank and the connecting rod. ; The angle between the crosshead's line of motion and the X-axis; The angle between the connecting rod and the line of motion of the crosshead. .

[0010] The positional data of point S, the intersection of the crosshead motion line and the crank profile constraint line in step 3. The following formula is used for calculation: ; ; In the formula, L1 is the vertical distance between the rotation center Q of the connecting rod and the crosshead and the end face of the crosshead; For safe distance; The angle between the crosshead's movement line and the X-axis.

[0011] The point data of the tangent point T on the crank profile where the crank profile constraint line is located in step 4. It is calculated using the following formula: ; ; In the formula, l is the crank length; The angle between the crosshead's movement line and the X-axis.

[0012] In step 5 The value range is 0° to 90°.

[0013] Step 6 involves fitting multiple sets of tangent point data, specifically by changing multiple sets of data. Connect the tangent points determined by the values ​​of to obtain the first set of crank limit profile curves; mirror the first set of crank limit profile curves to obtain the second set of crank limit profile curves.

[0014] The beneficial effects of this invention are: The present invention relates to a method for optimizing the crank profile on a single-cylinder crankshaft. Based on the motion law of the crankshaft-connecting rod-crosshead mechanism, the method uses a reverse approach to analyze and fit the limit profile of the crankshaft and crank, which can maximize the design of the crank profile, effectively improve the balance performance of the crank, enhance the applicability of the crankshaft, and thus optimize the overall structure of the reciprocating pump.

[0015] It can also improve the space utilization between the crankshaft and the crosshead, making the overall structure of the reciprocating pump more compact, especially for small-structure reciprocating pumps, thus reducing production costs. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the method for optimizing the crank profile on a single-cylinder crankshaft according to the present invention. Figure 2 This is a schematic diagram of the motion of crank-connecting rod-crosshead in the crank profile optimization construction method on a single-cylinder crankshaft of the present invention; Figure 3 This is a schematic diagram of the multiple distribution states of crank-connecting rod-crosshead after the crank is rotated in reverse in the crank profile optimization construction method of the single-cylinder crankshaft of the present invention. Figure 4 This is a schematic diagram of the state of the crank-connecting rod-crosshead after the crank returns to the initial position in the crank profile optimization construction method of the single-cylinder crankshaft of the present invention. Figure 5 This invention relates to the method for optimizing the crank profile on a single-cylinder crankshaft. A schematic diagram showing the state of the crank-connecting rod-crosshead when different values ​​are taken; Figure 6 This is the intersection point during multiple positioning of crankshaft rotation in the crankshaft profile optimization construction method of the single-cylinder crankshaft of the present invention. A schematic diagram of the relative positions of points; Figure 7 This is the intersection point during multiple positioning of crankshaft rotation in the crankshaft profile optimization construction method of the single-cylinder crankshaft of the present invention. A schematic diagram of the relative positions of points; Figure 8 This is a schematic diagram of the first set of crank limit profile curves in the single-cylinder crankshaft crank profile optimization construction method of the present invention. Figure 9 This is a schematic diagram of the crank profile obtained by the crank profile optimization method on the single-cylinder crankshaft of the present invention. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0018] Example 1 The present invention provides a method for optimizing the crank profile on a single-cylinder crankshaft, as follows: Figure 1 As shown, the specific steps include: Step 1: Analyze the motion law of crank-connecting rod-crosshead in a single cylinder and find the correspondence between each motion parameter and the crank profile. Step 2: Rotate the crank-connecting rod-cross head assembly in the reverse direction. Once the crank is at its initial position, obtain the positional data of the connecting rod and the center of rotation of the crosshead. Step 3: Set the safety clearance and obtain the point data of the intersection of the crosshead motion line and the crank profile limit line; Step 4: Set a vertical line and find the tangent point on the crank profile where the crank profile limit line is located. Obtain the tangent point data based on the point data in Step 2 and Step 3. Step 5, Adjust The angle value is obtained by repeating steps 2 to 4 to obtain multiple sets of tangent point data. Step 6: Fit multiple sets of tangent point data to obtain the first set of crank limit profile curves. Based on the first set of crank limit profile curves, obtain the second set of crank limit profile curves. Offset the outer circle of the crank pin to obtain the auxiliary profile. Connect the first set of crank limit profile curves, the second set of crank limit profile curves, and the auxiliary profile to obtain the crank profile.

[0019] Example 2 The method for optimizing the crank profile on a single-cylinder crankshaft according to the present invention specifically includes the following steps: Step 1: Analyze the motion law of the crankshaft-connecting rod-crosshead in a single cylinder, such as... Figure 2 As shown, a reverse approach is used to find the correspondence between each motion parameter and the crank profile; Specifically, the following constraints also apply: 1) In multiple distribution states, there is no interference between the crosshead end face and the assumed crank profile; 2) In multiple distribution states, the minimum distance between the crosshead end face and the assumed crank profile remains consistent.

[0020] The specific correspondence between the various motion parameters and the crank profile is as follows: the crank rotates around the crankshaft center O, and drives the crosshead to perform reciprocating linear motion via the connecting rod. Let O be the clockwise rotation angle of the crankshaft around the center O. The time mark is used as the initial position of the crank. The crosshead is driven to reciprocate linearly through the connecting rod. The connection point Q between the crosshead and the connecting rod is located on the reciprocating motion path of the crosshead. During the rotation of the crank, the position of each point Q corresponds to a profile point of the crank, which is used as the basis for calculation.

[0021] Step 2: Rotate the crank-connecting rod-cross head assembly in the reverse direction. Upon reaching the initial crank position, the interrelationships between the crank-connecting rod-crosshead mechanism remain unchanged. Therefore, the angle between the crosshead's motion line and the X-axis is... ,and .

[0022] The positional data of the connecting rod and the center of rotation Q of the crosshead are as follows: , and The following expressions (1) and (2) are used to calculate: (1); (2); In the formula, L is the length of the connecting rod; l is the length of the crank. The angle between the crank and the connecting rod. ; The angle between the crosshead's line of motion and the X-axis; The angle between the connecting rod and the line of motion of the crosshead. .

[0023] Step 3, as follows Figure 3 As shown, a safety clearance is set here to avoid interference between the crank and the crosshead end face on the crosshead's movement line. That is, the distance between the crosshead end face line and the crank profile limiting line is Mark the intersection of the crosshead motion line and the crank profile constraint line as S. The position data of the intersection point S between the crosshead motion line and the crank profile constraint line are... The following formulas (3) and (4) are used to calculate: (3); (4); In the formula, L1 is the vertical distance between the rotation center Q of the connecting rod and the crosshead and the end face of the crosshead; For safe distance; The angle between the crosshead's movement line and the X-axis.

[0024] Substituting formulas (1) and (2) into formulas (3) and (4) yields new formulas (5) and (6), which are used to obtain the point data of the intersection point S of the crosshead motion line and the crank profile limit line. Formulas (5) and (6) are shown below: (5); (6); The above-mentioned safety distance This ensures that point S on the crosshead motion line does not interfere with the crosshead end face line. However, when moving away from the crosshead motion line, some points on the crankshaft profile may still interfere with the crosshead end face line. To avoid this, the crank profile limiting line can be made tangent to the crank profile curve. In this case, no point on the crank profile will interfere with the crosshead end face line. Thus, during crank rotation, the minimum distance between its profile and the crosshead end face remains a safe distance. However, the position of the minimum spacing will deviate from the crosshead movement line.

[0025] Step 4, as follows Figure 4 As shown, find a perpendicular line on the crank profile limiting line, and this line passes through the rotation center P of the crank and connecting rod. The intersection of this perpendicular line and the crank profile limiting line is marked as point T. This perpendicular line is parallel to the crosshead motion line. Point T is the tangent point on the crank profile where the crank profile limiting line is located. The tangent point data is obtained based on the point position data in steps 2 and 3. Specifically, the point position data of tangent point T... The following formulas (7) and (8) are used to calculate: (7); (8); In the formula, l is the crank length; The angle between the crosshead's movement line and the X-axis.

[0026] Substituting formulas (5) and (6) into formulas (7) and (8) yields new formulas (9) and (10) used to obtain the positional data of the tangent point T. Formulas (9) and (10) are shown below: (9); (10); Step 5: A single rotational state cannot describe the entire crank profile; it needs to be extended to multiple rotational angles to obtain multiple distribution states, such as... Figure 5 As shown, in order to fit the crank limit profile curve, multiple data points are established, and the crank rotation angle is set. The value range is 0° to 90°. The specific values ​​are shown in formula (11): (11); In the formula, x is an integer, that is... The value can be 0 to 9 times a certain integer.

[0027] Repeat steps 2 through 4 to obtain multiple sets of tangent point data.

[0028] Step 6: Based on multiple sets of tangent point data, fit the first set of crank limit profile curves and remove the redundant parts, i.e., remove the parts outside the first quadrant. Then, based on the first set of crank limit profile curves, obtain the second set of crank limit profile curves, and offset the outer circle of the crank pin to obtain an auxiliary profile. Connect the first set of crank limit profile curves, the second set of crank limit profile curves, and the auxiliary profile to obtain the crank profile.

[0029] Example 3 Based on Example 2, the acquisition of multiple sets of tangent point data in step 5 of the single-cylinder crankshaft crank profile optimization method of the present invention is specifically shown in the following formulas (12), (13) and (14); (12); (13); (14); In the formula, The angle between the crank and the connecting rod. ; The angle between the crosshead's line of motion and the X-axis; The angle between the connecting rod and the line of motion of the crosshead. , This refers to the number of times the location was located.

[0030] The first can be obtained by using formulas (12), (13) and (14). During the second positioning: Center of rotation of the crosshead and connecting rod The location data is as follows: Specifically, as shown in the following formulas (15) and (16): (15); (16); The intersection of the crosshead motion line and the crank profile limit line The location data is as follows: As shown in the following formulas (17) and (18): (17); (18); The intersection of the vertical line and the crank profile limiting line The location data is as follows: As shown in the following formulas (19) and (20): (19); (20); like Figure 6 and Figure 7 As shown, according to , , The point data is used to obtain the distribution positions of the crank-connecting rod-crosshead mechanism at multiple positioning angles, among which... Point and The points of overlap.

[0031] Step 6, as detailed below Figure 8 As shown, according to The point data is used to fit the first set of crank limit profile curves, and the excess parts are removed, that is, the parts outside the first quadrant are removed.

[0032] like Figure 9 As shown, The point is the center of the crankpin. Since the crank profile is symmetrically distributed about the extension of line OO1, the second set of crank limit profile curves is obtained by mirroring the extension of OO1 as a symmetrical curve. On one side of the crankpin, in order to leave sufficient clearance to limit the connecting rod position, the outer circle of the crankpin is offset. The auxiliary profile is obtained, and the crank profile is obtained by connecting the first set of crank limit profile curves, the second set of crank limit profile curves, and the auxiliary profile. Specifically, as follows: Figure 9 The connection between the first set of crank limit profile curves, the second set of crank limit profile curves, and the auxiliary profile shown is achieved through fillets and straight lines, thus completing the overall crank profile.

[0033] Furthermore, the present invention can adjust parameters and Adjust the overall crank profile to obtain the overall crank profile for different needs.

Claims

1. A method for optimizing the crank profile on a single-cylinder crankshaft, characterized in that, Specifically, the following steps are included: Step 1: Analyze the motion law of crank-connecting rod-crosshead in a single cylinder and find the correspondence between each motion parameter and the crank profile. Step 2: Rotate the crank-connecting rod-cross head assembly in the reverse direction. Once the crank is at its initial position, obtain the positional data of the connecting rod and the center of rotation of the crosshead. Step 3: Set the safety clearance and obtain the point data of the intersection of the crosshead motion line and the crank profile limit line; Step 4: Set a vertical line and find the tangent point on the crank profile where the crank profile limit line is located. Obtain the tangent point data based on the point data in Step 2 and Step 3. Step 5, Adjust The angle value is obtained by repeating steps 2 to 4 to obtain multiple sets of tangent point data. Step 6: Fit multiple sets of tangent point data to obtain the first set of crank limit profile curves. Based on the first set of crank limit profile curves, obtain the second set of crank limit profile curves. Offset the outer circle of the crank pin to obtain the auxiliary profile. Connect the first set of crank limit profile curves, the second set of crank limit profile curves, and the auxiliary profile to obtain the crank profile.

2. The method for optimizing the crank profile on a single-cylinder crankshaft according to claim 1, characterized in that, In step 1, the correspondence is that the crank rotates around the center point O of the crankshaft and drives the crosshead to perform reciprocating linear motion through the connecting rod. The connection point Q between the crosshead and the connecting rod is located on the reciprocating motion path of the crosshead. During the rotation of the crank, the position of each point Q corresponds to a contour point of the crank.

3. The method for optimizing the crank profile on a single-cylinder crankshaft according to claim 1, characterized in that, In step 2, the initial position of the crank is when At that time, the crank is in the initial position.

4. The method for optimizing the crank profile on a single-cylinder crankshaft according to claim 1, characterized in that, In step 2, the specific positional data of the connecting rod and the center of rotation of the crosshead are as follows: when the crank returns to the initial position, the positional data of the connecting rod and the center of rotation of the crosshead at point Q are... , and It is calculated using the following expression: ； ； In the formula, L is the length of the connecting rod; l is the length of the crank. The angle between the crank and the connecting rod. ; The angle between the crosshead's line of motion and the X-axis; The angle between the connecting rod and the line of motion of the crosshead. .

5. The method for optimizing the crank profile on a single-cylinder crankshaft according to claim 1, characterized in that, The point data of the intersection point S of the crosshead motion line and the crank profile limitation line in step 3. It is calculated using the following formula: ； ； In the formula, L1 is the vertical distance between the rotation center Q of the connecting rod and the crosshead and the end face of the crosshead; For safe distance; The angle between the crosshead's movement line and the X-axis.

6. The method for optimizing the crank profile on a single-cylinder crankshaft according to claim 1, characterized in that, The point data of the tangent point T on the crank profile where the crank profile limiting line is located in step 4. It is calculated using the following formula: ； ； In the formula, l is the crank length; The angle between the crosshead's movement line and the X-axis.

7. The method for optimizing the crank profile on a single-cylinder crankshaft according to claim 1, characterized in that, In step 5 The value range is 0° to 90°.

8. The method for optimizing the crank profile on a single-cylinder crankshaft according to claim 1, characterized in that, In step 6, fitting multiple sets of tangent point data specifically involves modifying multiple sets of data... Connect the tangent points determined by the values ​​of to obtain the first set of crank limit profile curves; mirror the first set of crank limit profile curves to obtain the second set of crank limit profile curves.

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