A cylinder head lifting device and method for large low speed diesel engines

Abstract

The present application relates to the field of mechanical assembly and hoisting, in particular to a cylinder head hoisting device and method for large low-speed diesel engines; the device comprises a main hook, a variable stiffness joint, a lifting tool frame, four double-acting hydraulic cylinders and cross pipelines; the device connects the rodless cavities of the four hydraulic cylinders diagonally through the cross pipelines to build two closed fluid networks; the core is that when the hoisting gravity center deviates, the eccentric load tension forces the hydraulic oil to flow spontaneously between the diagonal hydraulic cylinders, thereby synchronously extending the equivalent sling length of the eccentric weight side and the diagonal side, making the diagonal line as a whole sink to maintain a horizontal posture; the present application discards the complex external leveling mechanism, directly realizes the self-adaptive leveling of the lifting tool frame by using internal fluid physical flow, effectively overcomes the inclination problem caused by eccentric load in traditional hoisting, and provides a stable horizontal posture for cylinder head lowering.

Description

Technical Field

[0001] This invention relates to the field of mechanical assembly and lifting, specifically to a cylinder head lifting device and method for large low-speed diesel engines. Background Technology

[0002] With the continuous development of manufacturing and assembly technology for large low-speed diesel engines, the complexity of cylinder head hoisting operations has increased significantly. Due to the asymmetrical arrangement of valves and pipelines on the cylinder head surface, the actual center of gravity often deviates from the geometric center. Furthermore, hoisting operations are often carried out within the confined engine compartment space. This complex condition presents numerous challenges to spatial attitude control and load distribution during the hoisting process. Currently, cylinder head hoisting operations are generally performed using traditional flexible steel wire rope single-point suspension or a rigid lifting beam of fixed length. However, traditional purely flexible hoisting methods are prone to swaying, causing significant tilting of the cylinder head under eccentric loads, making precise lowering difficult. Maintaining a relatively stable posture between the bore and the slender double-ended stud is crucial. While traditional rigid lifting methods can limit posture drift, they directly and rigidly transmit the slight vibrations of the crane to the cylinder head. Furthermore, during the centering and lowering process, if the bore wall and the double-ended stud make slight lateral contact, the rigid structure cannot adapt to the slippage to release lateral stress, which can easily lead to thread jamming, scratching, or damage to the stud due to destructive lateral shear forces. Although these methods can meet basic lifting and handling requirements, they usually cannot balance the compliant vibration damping during the rough lifting stage with the rigid posture maintenance during the critical centering stage, and they cannot provide anti-jamming protection when micro-interference occurs.

[0003] Therefore, how to balance adaptive leveling of off-center load and stable maintenance of lowering posture during the lifting process of large low-speed diesel engine cylinder heads, and how to release local lateral stress in a timely manner when critical interference occurs, has become an urgent problem to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a cylinder head lifting device and method for large low-speed diesel engines. Existing lifting technologies often struggle to balance compliant vibration damping during the rough lifting phase with rigid posture maintenance during the critical alignment phase. When faced with eccentric loads, they are prone to causing significant tilting of the cylinder head, and they cannot achieve anti-jamming protection when micro-interference occurs. There is an urgent need to propose a cylinder head lifting device and method that can simultaneously achieve adaptive leveling under eccentric loads and stable posture maintenance during the cylinder head lifting process, and promptly release local lateral stress when critical interference occurs.

[0005] To solve the above-mentioned technical problems, the present invention provides a cylinder head lifting device and method for large low-speed diesel engines. Specifically, the technical solution of the present invention is as follows:

[0006] A cylinder head lifting device for a large low-speed diesel engine, comprising:

[0007] The main hook is connected to the bottom end of the crane's hoisting wire rope;

[0008] The variable stiffness joint includes a corresponding upper flange and a lower flange, wherein the upper flange is hinged to the main hook;

[0009] A lifting frame is fixedly connected to the bottom surface of the lower flange. Double-acting hydraulic cylinders are vertically fixedly connected to the ends of the lifting frame. The double-acting hydraulic cylinders are a left front hydraulic cylinder, a right front hydraulic cylinder, a left rear hydraulic cylinder, and a right rear hydraulic cylinder. The piston rod ends of the double-acting hydraulic cylinders are connected to branch steel cables. When lifting the cylinder head, the lower ends of the branch steel cables are respectively hooked into the lifting holes of the cylinder head.

[0010] The first cross pipe connects the rod chamber of the left front hydraulic cylinder and the rodless chamber of the right rear hydraulic cylinder to form a first closed fluid network; the second cross pipe connects the rod chamber of the right front hydraulic cylinder and the rodless chamber of the left rear hydraulic cylinder to form a second closed fluid network; and the internal pistons of the four double-acting hydraulic cylinders have equal effective pressure-bearing areas on both sides.

[0011] The first and second cross pipes are filled with anti-wear hydraulic oil.

[0012] Furthermore, the variable stiffness joint includes a flexible sealing cavity in the shape of a corrugated tube, the two ends of which are respectively vulcanized and bonded to the upper flange and the lower flange, and the interior of the flexible sealing cavity is filled with irregularly shaped polyhedral silicon carbide particles.

[0013] Furthermore, the side wall of the flexible sealed cavity is provided with an air extraction hole, which is connected to a vacuum pump through an air pipe, and an electromagnetic proportional valve is connected in series on the air pipe.

[0014] Furthermore, the lifting frame is a cross-shaped welded I-beam frame, the cylinder flange of the double-acting hydraulic cylinder is fixed to the bottom surface of the lifting frame, and the piston rod of the double-acting hydraulic cylinder extends vertically downward.

[0015] Furthermore, a first pressure measuring hole is provided in the middle section of the first intersecting pipe wall, and a second pressure measuring hole is provided in the middle section of the second intersecting pipe wall.

[0016] Furthermore, the flexible sealing cavity is formed by vulcanization of fabric-reinforced rubber material, and the particle size of the silicon carbide particles is distributed between 2 mm and 5 mm.

[0017] Furthermore, the upper flange of the variable stiffness joint is hinged to the main hook by a pin, the lower flange of the variable stiffness joint is fixedly connected to the lifting frame by high-strength bolts, and the end of the piston rod of the double-acting hydraulic cylinder is connected to the branch cable by a shackle.

[0018] A method for lifting the cylinder head of a large, low-speed diesel engine, comprising:

[0019] S1. Control the vacuum pump to stop working and open the electromagnetic proportional valve to connect the inside of the flexible sealed cavity with the outside atmosphere, so that the silicon carbide particles are in a loose fluidized state;

[0020] S2. Control the lifting action and achieve adaptive leveling of the lifting frame through the flow of oil in the first cross pipe and the second cross pipe;

[0021] S3. When the cylinder head hole and the slender double-ended stud on the diesel engine block enter the critical alignment zone, control the vacuum pump to start and adjust the opening of the electromagnetic proportional valve to extract the air inside the flexible sealing cavity to form a negative pressure, so that the variable stiffness joint is converted into a rigid locking state, and the cylinder head is lowered at a uniform speed.

[0022] S4. During the lowering process, the dynamic pressure pulse signals inside the first and second cross pipelines are collected in real time, and the pressure change rate is obtained by calculating the derivative of the dynamic pressure pulse signal with respect to time.

[0023] S5. When the pressure change rate is greater than or equal to the preset destructive lateral shear stress threshold, the duty cycle of the electromagnetic proportional valve is adjusted according to the pressure change rate to reduce the vacuum degree inside the flexible sealing cavity, so that the variable stiffness joint softens and produces compliant sliding.

[0024] S6. When the pressure change rate is less than the preset destructive lateral shear stress threshold, control the electromagnetic proportional valve to fully open, restore the ultimate vacuum inside the flexible sealing cavity, so that the variable stiffness joint can return to the rigid locking state and continue to lower.

[0025] Furthermore, in step S2, when the center of gravity of the cylinder head is biased towards the left front corner, the tension borne by the left front branch cable forces the piston and piston rod of the left front hydraulic cylinder to move downward. The pressurized hydraulic oil enters the rodless chamber of the right rear hydraulic cylinder through the first cross pipeline, forcing the piston and piston rod of the right rear hydraulic cylinder to extend downward, thereby simultaneously extending the equivalent cable length of the left front side and the right rear side, so that the two ends of the diagonal produce equal downward geometric displacement to complete the leveling.

[0026] Furthermore, step S5 is preceded by:

[0027] S0. Input the peak value of the pressure change rate into a pre-established pressure-stiffness adjustment model, wherein the pressure-stiffness adjustment model maps the pressure change rate to the corresponding stiffness adjustment coefficient.

[0028] The specific calculation process is as follows: the overshoot difference between the peak pressure change rate obtained in real time and the preset equivalent pressure change rate threshold is calculated. The overshoot difference is then substituted into the exponential mapping function after dimensionless processing to convert it into the stiffness adjustment coefficient. In the conversion process, the dimensionless processing eliminates the calculation coupling error caused by the fluid volume elastic modulus from a mathematical logic perspective. The duty cycle of the electromagnetic proportional valve is adjusted according to the calculated stiffness adjustment coefficient.

[0029] The present invention has the following beneficial effects:

[0030] 1. This invention connects the rodless chambers of four double-acting hydraulic cylinders through a first cross pipe and a second cross pipe to form a closed fluid network; when lifting the cylinder head, the hydraulic oil flows between the diagonal hydraulic cylinders, synchronously extending the equivalent sling length, thereby directly realizing the adaptive leveling of the lifting frame by utilizing the oil flow in the pipeline; this design effectively overcomes the tilting caused by off-center loading and provides a stable posture for lowering.

[0031] 2. The flexible sealed cavity of the variable stiffness joint of the present invention is filled with silicon carbide particles and connected to a vacuum pump with an electromagnetic proportional valve; during lifting, it is connected to the atmosphere to make the particles loose and fluidized; during lowering, air is pumped out to form a negative pressure to achieve a rigid locking state; when the pressure change rate measured during lowering is greater than or equal to the destructive lateral shear stress threshold, the vacuum degree is reduced by adjusting the duty cycle of the valve to soften the joint and produce compliant sliding. Attached Figure Description

[0032] The following drawings, illustrating embodiments of this application, are incorporated herein by reference and are used to understand this application. The drawings illustrate embodiments of this application and their descriptions, serving to explain the principles of this application. In the drawings,

[0033] Figure 1 This is a schematic diagram of the overall external structure of the device;

[0034] Figure 2 This is a schematic diagram of the overall structure of a double-acting hydraulic cylinder;

[0035] Figure 3 This is a schematic diagram of the external structure of the cylinder.

[0036] Figure 4 This is a schematic diagram of the cross-sectional structure of the cylinder.

[0037] Figure 5 This is a schematic diagram of the cross-sectional structure of a variable stiffness joint;

[0038] Figure 6 This is a flowchart of the cylinder head lifting method.

[0039] In the diagram: 1. Main hook; 2. Lifting wire rope; 3. Variable stiffness joint; 4. Upper flange; 5. Lower flange; 6. Lifting frame; 7. Double-acting hydraulic cylinder; 8. Left front hydraulic cylinder; 9. Right front hydraulic cylinder; 10. Left rear hydraulic cylinder; 11. Right rear hydraulic cylinder; 12. Piston rod; 13. Branch cable; 14. Cylinder head; 15. Lifting hole; 16. First cross pipe; 17. Second cross pipe; 18. Rodless chamber; 19. Anti-wear hydraulic oil; 20. Flexible sealing cavity; 21. Silicon carbide particles; 22. Air extraction port; 23. Air pipe; 24. Vacuum pump; 25. Electromagnetic proportional valve; 26. Cylinder flange; 27. First pressure test hole; 28. Second pressure test hole; 29. ​​Pin; 30. High-strength bolt; 31. Shackle; 32. Piston; 33. Cylinder; 34. Slender double-ended stud. Detailed Implementation

[0040] In the following description, numerous specific details are set forth to provide a more thorough understanding of this application. However, it will be apparent to those skilled in the art that embodiments of this application may be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with embodiments of this application.

[0041] Example 1:

[0042] like Figure 1 As shown, a cylinder head lifting device for a large low-speed diesel engine includes:

[0043] The main hook 1 is connected to the bottom end of the hoisting wire rope 2 of the crane;

[0044] Combination Figure 5 As shown, the variable stiffness joint 3 includes an upper flange 4 and a lower flange 5, with the upper flange 4 hinged to the main hook 1.

[0045] Combination Figure 2 As shown, the lifting frame 6 is fixedly connected to the bottom surface of the lower flange 5. The ends of the lifting frame 6 are respectively vertically fixedly connected to double-acting hydraulic cylinders 7, namely the left front hydraulic cylinder 8, the right front hydraulic cylinder 9, the left rear hydraulic cylinder 10 and the right rear hydraulic cylinder 11. The piston rod 12 of the double-acting hydraulic cylinder 7 is connected to the branch steel cable 13. When lifting the cylinder head 14, the lower end of the branch steel cable 13 is respectively hooked to the lifting hole 15 of the cylinder head 14.

[0046] The first cross pipe 16 connects the rod chamber of the left front hydraulic cylinder 8 and the rodless chamber 18 of the right rear hydraulic cylinder 11 to form a first closed fluid network.

[0047] The second cross pipe 17 connects the rod chamber of the right front hydraulic cylinder 9 and the rodless chamber 18 of the left rear hydraulic cylinder 10 to form a second closed fluid network; and the internal pistons of the four double-acting hydraulic cylinders 7 have equal effective pressure-bearing areas on both sides.

[0048] Among them, the first cross pipe 16 and the second cross pipe 17 are filled with anti-wear hydraulic oil 19;

[0049] The variable stiffness joint 3 includes a flexible sealing cavity 20 in the shape of a corrugated tube. The two ends of the flexible sealing cavity 20 are respectively vulcanized and bonded to the upper flange 4 and the lower flange 5. The interior of the flexible sealing cavity 20 is filled with irregular polyhedral silicon carbide particles 21.

[0050] Main hook 1, variable stiffness joint 3, lifting frame 6, four double-acting hydraulic cylinders 7, first cross pipe 16, second cross pipe 17, and branch steel cable 13 connected to the end of piston rod 12 of double-acting hydraulic cylinder 7;

[0051] The main hook 1 is connected to the bottom end of the lifting wire rope 2 of the crane, serving as the upper force input end of the entire lifting device; the variable stiffness joint 3 is set between the main hook 1 and the spreader frame 6, used to change the mechanical transmission mode between the two during the lifting and centering stages.

[0052] The lifting frame 6 is located below the variable stiffness joint 3 and serves as the mounting base for four double-acting hydraulic cylinders 7. The four double-acting hydraulic cylinders 7 are the left front hydraulic cylinder 8, the right front hydraulic cylinder 9, the left rear hydraulic cylinder 10, and the right rear hydraulic cylinder 11. The piston rods 12 of the cylinders 7 are connected to branch steel cables 13 at their ends, and the lower ends of the branch steel cables 13 are respectively hooked to the four lifting holes 15 of the cylinder head 14.

[0053] The purpose of this arrangement is to convert the overall lifting force provided by the upper crane into a distributed suspension force on the four corners of the cylinder head 14, so as to avoid the obvious tilting caused by the shift of the center of gravity when the traditional single-point suspension is used, and to keep the cylinder head 14 in an adjustable posture during the lifting, translation and lowering process.

[0054] The main hook 1 and the variable stiffness joint 3 are connected by a hinge so that a certain degree of swing freedom is retained when the variable stiffness joint 3 is in a low stiffness state. The hinge connection adopts a pin 29 hinge method or a high-strength rotating shaft connection with lugs to realize vertical load transfer and allow relative angle changes.

[0055] The variable stiffness joint 3 and the spreader frame 6 are fixedly connected so that after the stiffness of the variable stiffness joint 3 increases, the attitude constraint on one side of the main hook 1 is effectively transferred to the spreader frame 6. The fixed connection adopts a high-strength bolt 30 connection method or a flange and positioning pin connection method to meet the tensile and torsional requirements under the lifting load.

[0056] Through the combination of the upper part being able to swing and the lower part being able to transmit force stably, the device does not directly and rigidly transmit the small vibrations of the crane to the cylinder head 14 during rough lifting, and can reduce attitude drift when fine lowering is required.

[0057] The lifting frame 6 can be a cross-shaped welded frame of I-beams, with four load-bearing lifting points at its four ends, which are vertically fixed to four double-acting hydraulic cylinders 7 respectively; the vertical fixed connection here is to enable the piston rod 12 of the double-acting hydraulic cylinder 7 to extend and retract in the vertical direction, directly changing the equivalent working length of the corresponding branch steel cable 13.

[0058] The fixing relationship is achieved by using the cylinder flange 26 bolt fixing method or by using the welded mounting seat and the pin 29 limiting method to ensure that the hydraulic cylinder axis is basically vertical and can withstand the lifting load; the branch steel cable 13 and the end of the piston rod 12 are connected by the shackle 31 method or by the rigging joint method to achieve a reliable tension connection;

[0059] Considering that the cylinder head 14 of a large low-speed diesel engine often has an asymmetrical arrangement of valves and pipelines, and the actual center of gravity is usually not at the geometric center, if the length of each lifting point cannot be adjusted, the cylinder head 14 will enter the subsequent work position in an off-center load posture at the beginning of the lifting, which is not conducive to the subsequent alignment with the double-ended stud.

[0060] The rod chamber of the left front hydraulic cylinder 8 and the rodless chamber 18 of the right rear hydraulic cylinder 11 are connected through the first cross pipe 16 to form a first closed fluid network; the rod chamber of the right front hydraulic cylinder 9 and the rodless chamber 18 of the left rear hydraulic cylinder 10 are connected through the second cross pipe 17 to form a second closed fluid network; the first cross pipe 16 and the second cross pipe 17 are filled with anti-wear hydraulic oil 19.

[0061] The cross-pipeline uses high-pressure steel wire braided hoses with an inner diameter of 15mm to 25mm. The length of the hose is matched according to the 6 diagonal dimensions of the spreader frame, usually between 2m and 4m. When the system is pre-filled with oil, it is necessary to strictly vent the gas through the exhaust valve located at the highest point of the hose to ensure that there is no residual gas in the closed fluid network. All four hydraulic cylinders adopt a double piston rod hydraulic cylinder structure or a hydraulic cylinder with an internal area compensation structure to ensure that the effective pressure area of ​​the rod chamber and the rodless chamber is completely equal. The effective pressure area and full stroke of the four hydraulic cylinders must be completely consistent to ensure the equal correspondence of diagonal displacement compensation.

[0062] By employing diagonal cross-connection, when the cylinder head 14 tilts, the dominant change is an increase in force at one corner, compensating for the force at its opposite corner; taking the left front corner as an example, combined with... Figure 3 and Figure 4The schematic diagram shows that the hydraulic cylinder in this embodiment is a double-acting hydraulic cylinder 7, which is divided into an upper rodless chamber and a lower rod chamber by a piston 32; the upper end of the piston rod 12 is connected to the piston 32 and extends vertically downward through the bottom of the cylinder to connect to the branch steel cable 13.

[0063] By connecting the lower rod chamber of the left front hydraulic cylinder 8 with the upper rodless chamber of the right rear hydraulic cylinder 11, a synchronous elongation fluid circuit with equal volume substitution is formed; when the branch steel cable 13 on one side is subjected to additional downward force, the force forces the piston rod 12 to move downward, directly compressing the hydraulic oil in the lower rod chamber and discharging it.

[0064] When the left front hydraulic cylinder 8 is pulled, it will push the hydraulic oil inside into the first cross pipe 16. The hydraulic oil flows along the first cross pipe 16 to the rodless chamber 18 of the right rear hydraulic cylinder 11, pushing the piston rod 12 of the right rear hydraulic cylinder 11 to move down.

[0065] When the left front corner is heavier, the left front cylinder piston 32 moves down to discharge oil. The discharged high-pressure oil is forcibly injected into the rodless chamber 18 of the right rear cylinder through the first cross pipe 16, forcing the right rear cylinder piston 32 to overcome the lighter load and extend downward synchronously.

[0066] Due to the equal volume displacement constraint of the first intersecting pipe 16, the double-acting hydraulic cylinders on the left front side and the right rear side will produce equal downward extension displacement, thereby maintaining the same horizontal settlement at both ends of the diagonal in terms of mechanical suspension relationship and offsetting the unilateral tilting trend of the left front corner.

[0067] The synchronous extension of the suspension relationship between the left front side and the right rear side means that under the forced coupling of the cross fluid network, the vertical downward displacement generated by the offset angle in the entire lifting device suspension system is copied equally to the diagonal position, realizing the adaptive leveling of the macro attitude; in this way, the original tilting trend is offset by the overall translation of the diagonal.

[0068] Since the anti-wear hydraulic oil 19 does not undergo significant volume compression in the pipeline, the change in tension can be directly converted into the displacement response of the diagonal hydraulic cylinder. Therefore, there is no need to configure an additional leveling motor or independent hydraulic station. The attitude correction can be triggered by the off-center load itself.

[0069] The effect of this structure is not that a single hydraulic cylinder extends and retracts independently, but that the forces at the four corners restrain each other on two diagonals, making it easier for the lifting frame 6 to approach a horizontal state during the lifting process, providing an initial attitude basis for subsequent precise lowering.

[0070] The variable stiffness joint 3 includes an upper flange 4 and a lower flange 5, with the upper flange 4 hinged to the main hook 1. The variable stiffness joint 3 also includes a corrugated flexible sealing cavity 20, with both ends of the flexible sealing cavity 20 vulcanized and bonded to the upper flange 4 and the lower flange 5, respectively. The interior of the flexible sealing cavity 20 is filled with irregularly shaped polyhedral silicon carbide particles 21. This structure uses the particle blocking principle to change the equivalent stiffness of the connection section.

[0071] The flexible sealing cavity 20 adopts a corrugated tube shape to allow a certain angle of deflection and slight displacement between the upper flange 4 and the lower flange 5 when the interior is not evacuated or the vacuum level is low, thereby absorbing the swinging, acceleration and deceleration impacts and collision interference in the confined cabin during the crane hoisting process.

[0072] The cavity is connected to the flange at both ends by vulcanized bonding in order to maintain the cavity's sealing and integrity when subjected to cyclic loads. This connection is made by vulcanized bonding or by using mechanical pressure rings in conjunction with the clamping and fixing of the sealing layer to ensure that the flexible sealing cavity 20 does not leak or detach from the flange.

[0073] The flexible sealing cavity 20 is filled with irregular polyhedral silicon carbide particles 21. Because the irregular polyhedral particles are more likely to form surface contact and edge interlocking when they are squeezed together, the frictional resistance between the particles is more obvious. In this way, when the pressure state inside the flexible sealing cavity 20 changes, the overall fluidity and overall locking of the particle group will be clearer.

[0074] For the hoisting of the cylinder head 14 of a large low-speed diesel engine, a certain degree of flexibility is required in the coarse positioning stage to absorb macroscopic sway, while a high rigidity is required in the centering stage to maintain the relative posture between the eyelet and the double-ended stud. A single material component can hardly meet both requirements at the same time. However, the flexible sealing cavity 20 filled with silicon carbide particles 21 can provide a physical basis for subsequent negative pressure regulation, so that the same connection part exhibits different mechanical characteristics under different working conditions.

[0075] The side wall of the flexible sealed cavity 20 is provided with an air extraction hole 22, which is connected to the vacuum pump 24 through an air pipe 23. An electromagnetic proportional valve 25 is connected in series on the air pipe 23. The air extraction hole 22, the air pipe 23, the vacuum pump 24 and the electromagnetic proportional valve 25 together form a channel for regulating the air pressure inside the flexible sealed cavity 20.

[0076] The channel uses a gas pipe 23 as a pressure-resistant flexible hose, or a metal rigid pipe with a flexible connection transition, to achieve air extraction and intake control; to ensure the closure of the vacuum control gas path logic, the electromagnetic proportional valve 25 connected in series on the gas pipe 23 is specifically a three-way electromagnetic proportional valve 25 with an integrated independent pressure relief and intake branch, which can be connected in series on the inlet side of the vacuum pump 24, or it can be arranged on a section of the gas path near the flexible sealing cavity 20;

[0077] Its working mechanism is that when the vacuum pump 24 stops working and the pressure relief channel of the three-way electromagnetic proportional valve 25 is opened, the interior of the flexible sealing cavity 20 is reliably connected to the external atmosphere through the air intake branch, which is close to the external atmospheric state. The normal extrusion pressure between the silicon carbide particles 21 is small, the particle group can be rearranged, the variable stiffness joint 3 exhibits high compliance, and the slight swing from the side of the main hook 1 is not easily directly amplified into a rigid collision at the lower end of the cylinder head 14.

[0078] When the vacuum pump 24 is working and the pumping degree is adjusted by the electromagnetic proportional valve 25, the internal pressure of the flexible sealing cavity 20 decreases, and the external atmospheric pressure causes the flexible sealing cavity 20 to tighten and compress the internal silicon carbide particles 21. The frictional interlock between the particles is enhanced, the overall deformation capacity of the variable stiffness joint 3 decreases, and the posture of the lifting frame 6 is easier to maintain.

[0079] The main hook 1, variable stiffness joint 3, lifting frame 6, four double-acting hydraulic cylinders 7 and two cross pipelines are not set up in isolation, but form a lifting structure that combines the switchable force transmission characteristics of the upper part with the adaptive leveling capability of the lower part: when vibration and obstacle avoidance are required, the variable stiffness joint 3 provides a compliant connection and the cross pipelines provide off-center load correction.

[0080] When precise lowering and posture maintenance are required, the variable stiffness joint 3 improves the constraint capacity through vacuum control, and the cross pipeline provides diagonal force balance; thereby, the contradiction between the easy swing of traditional flexible steel wire rope and the easy transmission of disturbance directly to the slender double-headed stud 34 by traditional rigid lifting tools can be alleviated, making the lifting of large low-speed diesel engine cylinder head 14 in the confined engine compartment more suitable for subsequent centering operations.

[0081] The lifting frame 6 is a cross-shaped welded frame of I-beams. The cylinder flange 26 of the double-acting hydraulic cylinder 7 is fixed to the bottom surface of the lifting frame 6, and the piston rod 12 of the double-acting hydraulic cylinder 7 extends vertically downward.

[0082] The first pressure measuring hole 27 is opened in the middle section of the pipe wall of the first cross pipe 16, and the second pressure measuring hole 28 is opened in the middle section of the pipe wall of the second cross pipe 17; the specific structure of the hanger frame 6 and the pressure measuring position are based on the requirements of bearing capacity, stable posture and detectability of differential pressure signal of the large low-speed diesel engine cylinder head 14 in the confined installation space, and the force path and signal path are constrained at the same time.

[0083] The cross-shaped arrangement of the lifting frame makes the four lifting holes 15 of the cylinder head 14 usually distributed in the four corner areas in the plane. The cross-shaped welded I-beam frame allows the four ends to naturally correspond to the installation positions of the left front hydraulic cylinder 8, right front hydraulic cylinder 9, left rear hydraulic cylinder 10 and right rear hydraulic cylinder 11, so that the concentrated load from the upper part from the variable stiffness joint 3 is distributed to the four corners along the two main beams.

[0084] Compared to ordinary plate beams, I-beams are more likely to provide higher bending and torsional resistance under the premise of controllable self-weight. Thus, when the cylinder head 14 generates eccentric load due to valve and pipeline offset, the spreader frame 6 body is less likely to experience additional torsional warping. The load changes received by the four double-acting hydraulic cylinders 7 are more reflected as the real difference in lifting force, rather than the pseudo-difference caused by the deformation of the spreader frame 6 itself. This is consistent with the working mechanism of leveling the first cross pipeline 16 and the second cross pipeline 17 using diagonal hydraulic cylinders.

[0085] If the rigidity of the spreader frame 6 is insufficient, the oil pressure changes in the cross pipeline that are intended to characterize the off-center load and micro-contact interference will be absorbed by the elastic torsion of the spreader frame 6 itself, which will interfere with the adaptive leveling and differential pressure pulse identification.

[0086] A cross-shaped welded frame of I-beams only needs to form a stress convergence zone at the center and load-bearing suspension points at the four ends. It can be formed by welding two I-beams perpendicularly to each other, or by using a central node plate in conjunction with four sections of I-beams welded together. If local installation strength is considered, stiffening plates or corner plates can also be added at the four ends.

[0087] The key point of this limitation is that the spreader frame 6 needs to simultaneously meet three conditions: connection with the lower flange 5 of the variable stiffness joint 3, installation with the four double-acting hydraulic cylinders 7, and diagonal force transmission, rather than being limited to a single weld type.

[0088] For the cylinder head 14 of a large low-speed diesel engine, this layout allows the upper variable stiffness joint 3 to make slight adjustments to its posture in a flexible state, without amplifying it into disordered deformation inside the lifting frame 6; and after the variable stiffness joint 3 enters a rigid locking state, the cross-shaped welded I-beam frame can transmit the locking posture to the four load-bearing lifting points in a relatively stable manner, providing a more stable geometric basis for the critical alignment of the cylinder head 14 holes and the slender double-ended studs 34.

[0089] The cylinder flanges 26 of the four double-acting hydraulic cylinders 7 are fixed to the bottom surface of the spreader frame 6, and the piston rod 12 of each double-acting hydraulic cylinder 7 extends vertically downward; the cylinder flanges 26 are set on the bottom surface of the spreader frame 6 so that the axis of each double-acting hydraulic cylinder 7 is basically consistent with the direction of gravity.

[0090] With this arrangement, the tension transmitted by the branch steel cable 13 can be directly converted into the axial movement of the piston rod 12, and the pressure change in the rodless chamber 18 inside the hydraulic cylinder is closer to the result of simple vertical force. It will not introduce a large lateral component force and additional friction due to the tilted arrangement of the hydraulic cylinder.

[0091] If the axis of the hydraulic cylinder deviates from the vertical direction, when the force on the left front corner or right rear corner increases, the piston 32 will not only compress the hydraulic oil, but will also be affected by the lateral force of the cylinder 33. This is not conducive to the oil in the first cross pipe 16 and the second cross pipe 17 flowing as expected, and will also cause the pressure pulse signal to be mixed with the mechanical disturbance component caused by the installation misalignment.

[0092] As long as the hydraulic cylinder is stable under the lifting load and the axial direction is maintained, the cylinder flange 26 and the bottom surface of the lifting frame 6 can be fixed by bolts or by welding the mounting base and tightening the bolts; when disassembly and maintenance are required, the positioning boss and bolt clamping method can also be used.

[0093] The connection of the piston rod 12 extending vertically downwards can be made so that the end of the piston rod 12 and the branch steel cable 13 form a stable tension path. In addition to the aforementioned shackle 31 connection, a lifting ring joint or a fork lug connector can also be used.

[0094] With this design, the effective stroke direction of the left front hydraulic cylinder 8, right front hydraulic cylinder 9, left rear hydraulic cylinder 10 and right rear hydraulic cylinder 11 is consistent with the working direction of the branch steel cable 13. The height change of the four corners of the cylinder head 14 can be directly converted into the axial displacement difference of the four hydraulic cylinders, and the hydraulic oil flow in the first cross pipe 16 and the second cross pipe 17 has a clear geometric meaning.

[0095] The mechanism of adaptive leveling using diagonal hydraulic cylinders makes it easier to perform in the preset direction under the limited conditions of fixed bottom surface and vertical extension, without weakening the compensation effect due to uncertain installation orientation.

[0096] To ensure that the dynamic differential pressure pulse during the subsequent lowering process can be reliably extracted, a first pressure measuring hole 27 is provided in the middle section of the first cross pipe 16, and a second pressure measuring hole 28 is provided in the middle section of the second cross pipe 17. The reason for setting the pressure measuring holes in the middle section of their respective cross pipes is as follows:

[0097] Firstly, the position near the hydraulic cylinder port is more susceptible to the effects of local throttling, joint impact, and near-field pressure waves caused by the instantaneous opening and closing of piston 32, and the measured signal will be biased towards local fluctuations near a single hydraulic cylinder; the middle position is relatively evenly distributed from both ends, making it more suitable for reflecting the overall pressure difference changes within the corresponding first closed fluid network or second closed fluid network.

[0098] Secondly, when the cylinder head 14 of the large low-speed diesel engine is lowered to the vicinity of the slender double-ended stud 34, if the bore wall is slightly touched, the overturning torque will propagate along the four double-acting hydraulic cylinders 7 and the two intersecting pipelines. The pressure measurement in the middle section is more likely to retain the pressure pulse characteristics caused by the overall attitude disturbance, which is convenient for subsequent judgment on whether the interference state has been entered based on the pressure change rate.

[0099] The first pressure measuring hole 27 and the second pressure measuring hole 28 only need to be able to communicate with the inner cavity of the corresponding pipeline and output pressure information. They can be connected by opening a threaded interface on the pipe wall and installing a pressure sensor, or they can be connected by reserving a pressure measuring connector and connecting an external pressure measuring hose or testing instrument.

[0100] For ease of disassembly and assembly, a quick-plug pressure probe can also be used; this structure retains the channel for extracting pressure information from the middle of the first cross pipe 16 and the second cross pipe 17; the first pressure probe 27 and the second pressure probe 28 can be structurally interconnected with the acquisition process of the dynamic differential pressure pulse signal.

[0101] When the cylinder head 14 is lowered at a constant speed in a rigidly locked state, if lateral interference occurs between the bore wall and the double-ended stud, the original hydrostatic balance of the four double-acting hydraulic cylinders 7 will be broken, and the hydraulic oil in the diagonal network will experience transient pressure fluctuations. After these fluctuations are drawn out through the first pressure measuring hole 27 and the second pressure measuring hole 28, the pressure change rate can be further calculated, and the duty cycle of the electromagnetic proportional valve 25 can be adjusted accordingly to change the vacuum degree inside the flexible sealing cavity 20, so that the variable stiffness joint 3 changes from higher stiffness to higher compliance.

[0102] Without these two intermediate pressure measuring holes, even if the first cross pipe 16 and the second cross pipe 17 have adaptive leveling functions, the pressure changes in the cross pipes are difficult to be stably converted into usable detection signals, and the aforementioned action chain triggered by micro-contact stress to soften the variable stiffness joint 3 is difficult to establish.

[0103] Furthermore, the middle section of the pipe wall where the first pressure measuring hole 27 and the second pressure measuring hole 28 are located should avoid sharp bends, tees, and areas with obvious abrupt changes in cross-section. The reason for this is that sharp bends and areas with abrupt changes in cross-section will cause additional changes in the local flow state of the hydraulic oil, and the pressure waveform is prone to superimposed structural reflections and local disturbances, making it difficult to distinguish whether the overturning torque is generated by the contact between the cylinder head 14 hole wall and the double-ended stud, or irrelevant fluctuations caused by the shape of the pipeline itself.

[0104] Setting the pressure measurement position in the relatively straight middle section, combined with the aforementioned layout of the lifting frame 6 having high torsional resistance, vertical hydraulic cylinder axis, and cylinder flange 26 fixed to the bottom surface of the lifting frame 6, enables the pressure signals in the first cross pipe 16 and the second cross pipe 17 to better reflect the actual lifting status changes.

[0105] The effect of this is that the load-bearing stability of the lifting frame 6, the axial response characteristics of the double-acting hydraulic cylinder 7, and the arrangement of the pressure measuring holes work together to maintain the diagonal leveling function during the lifting process and provide a clearer pressure input source for interference identification in the critical centering zone. This allows the flexible and rigid switching of the aforementioned variable stiffness joint 3 to respond based on the pressure changes inside the cross pipeline without relying on external visual equipment.

[0106] Therefore, the cross-shaped welded I-beam frame, the cylinder flange 26 fixed to the bottom of the lifting frame 6, and the vertical downward extension of the piston rod 12, combined with the middle arrangement of the first pressure measuring hole 27 and the second pressure measuring hole 28, enable this lifting device to not only have load-bearing and leveling capabilities, but also enable the cross pipeline to have pressure signal output conditions.

[0107] For the hoisting operation of the cylinder head 14 of a large low-speed diesel engine, this structural arrangement enables the off-center load correction during the rough hoisting stage, the attitude maintenance during the critical alignment stage, and the differential pressure pulse detection when micro-interference occurs to be continuously realized along the same set of mechanical and hydraulic paths, which alleviates the problem that it is difficult to balance load-bearing stability and micro-stress identification in traditional rigid hoisting tools.

[0108] The flexible sealing cavity 20 is made of fabric-reinforced rubber material through vulcanization, and the particle size of the silicon carbide particles 21 is distributed between 2 mm and 5 mm.

[0109] The upper flange 4 of the variable stiffness joint 3 is hinged to the main hook 1 by a pin 29, and the lower flange 5 of the variable stiffness joint 3 is fixedly connected to the lifting frame 6 by a high-strength bolt 30. The end of the piston rod 12 of the double-acting hydraulic cylinder 7 is connected to the branch steel cable 13 by a shackle 31.

[0110] Based on the main hook 1, variable stiffness joint 3, lifting frame 6, four double-acting hydraulic cylinders 7, first cross pipe 16, second cross pipe 17, first pressure measuring hole 27, second pressure measuring hole 28, and branch steel cable 13, the material parameters and key connection relationships of the variable stiffness joint 3 are further defined. The purpose is to implement the principle that the aforementioned variable stiffness joint 3 can switch between flexible vibration absorption and rigid locking into a specific structure that can withstand the lifting load of large low-speed diesel engine cylinder head 14, while making the force transmission path between the main hook 1 and the cylinder head 14 have clearer mechanical boundaries at different stages.

[0111] The flexible sealing cavity 20 is made of fabric-reinforced rubber material vulcanized and molded. The particle size of silicon carbide particles 21 is distributed between 2mm and 5mm. The flexible sealing cavity 20 is made of fabric-reinforced rubber material vulcanized and molded, so that the variable stiffness joint 3 needs to produce a certain angle deflection and slight deformation with the main hook 1 during the rough lifting stage. In the critical centering zone, it also needs to withstand the external pressure pressing effect generated by the blockage of negative pressure particles and the continuous vertical load transmitted by the self-weight of the cylinder head 14.

[0112] If only a single layer of rubber is used, the cavity is prone to uneven local expansion, concentrated wrinkles or fatigue cracking during repeated vacuuming and depressurization. The change in the geometry of the cavity will lose stability, affecting the conversion of the internal silicon carbide particles 21 between the loose state and the interlocked state.

[0113] The fabric reinforcement layer inside the fabric-reinforced rubber material can limit excessive radial deformation of the cavity, so that the flexible sealed cavity 20 retains the deflectability of the corrugated tubular structure when it is not evacuated, and will not collapse disorderly due to the external atmospheric pressure after the vacuum pump 24 is working. Thus, the stiffness change of the variable stiffness joint 3 comes more from the change of normal pressure between silicon carbide particles 21 than from the unstable buckling of the cavity wall itself.

[0114] The fabric-reinforced rubber material is in the form of a natural rubber matrix with an embedded nylon cord layer, or in the form of a synthetic rubber matrix with an embedded polyester fiber cloth layer, in order to maintain sealing and flexibility when the flexible sealed cavity 20 is subjected to cyclic negative pressure and hoisting load.

[0115] Its molding method adopts the integral vulcanization molding method, or the segmented prefabrication followed by secondary vulcanization, so that the corrugated tube shape and the flange connection area at both ends form an integral seal; after this limitation, the aforementioned flexible sealing cavity 20 has a stable material basis for adjusting the internal vacuum degree through the air extraction hole 22, air pipe 23, vacuum pump 24 and electromagnetic proportional valve 25.

[0116] In other words, the flexible sealing cavity 20 is made of fabric-reinforced rubber material vulcanized and, together with the electromagnetic proportional valve 25 for adjusting the vacuum degree, the variable stiffness joint 3 can maintain high compliance in step S1, and can stably present the stiffness rise and fall caused by the change in vacuum degree in steps S3 and S5, so as not to mistake material fatigue or cavity instability as the result of stiffness adjustment.

[0117] The particle size distribution of silicon carbide particles 21 is limited to between 2mm and 5mm, which is determined to meet the requirements of both macroscopic flexibility and microscopic locking during the lifting of large low-speed diesel engine cylinder head 14. If the particle size of silicon carbide particles 21 is too small, the total surface area of ​​the particles will increase. Although the filling will be more compact, the particle group is more likely to exhibit a compacted state similar to a continuous medium under negative pressure. The change in the rearrangement resistance between particles is not obvious enough. When the variable stiffness joint 3 changes from a loose state to an interlocked state, the increase in stiffness will be affected. At the same time, particles with too small a particle size are also prone to clogging the local flow channels near the air extraction hole 22, which slows down the response of the vacuum pump 24 to the adjustment of the internal pressure of the flexible sealing cavity 20.

[0118] If the silicon carbide particles 21 are too large, the gaps between the particles will increase, and obvious local bridging will occur inside the flexible sealing cavity 20 under the pressure relief state. The flexibility of the variable stiffness joint 3 will decrease, and the ability to absorb the vibration and sway of the crane during the rough lifting stage will decrease. Moreover, under the rigid locking state, the force-bearing skeleton formed by a small number of large particles is relatively thick, and the posture after locking is more likely to show discretization changes, which is not conducive to the critical centering zone of the cylinder head 14 holes entering the slender double-ended stud 34.

[0119] With the particle size controlled between 2mm and 5mm, the irregular polyhedral silicon carbide particles 21 can still undergo a certain rearrangement when not vacuumed. After negative pressure is formed, they can generate obvious frictional interlocking through edge contact and surface contact, so that the variable stiffness joint 3 exhibits differentiated mechanical characteristics under the two working conditions of coarse positioning and fine lowering.

[0120] To ensure the claimed repeatable controllability, the preferred structural parameters are: the outer diameter of the flexible sealing cavity 20 is set to be between 200 mm and 350 mm, the effective length is between 300 mm and 500 mm, and the tube wall has 3 to 6 corrugations along the axial direction to ensure sufficient axial and angular deformation margin; the volume filling rate of silicon carbide particles 21 inside the cavity is controlled between 85% and 92%.

[0121] If the filling rate is less than 85%, the gaps between particles will be too large during vacuuming, making it difficult to quickly establish a dense force-bearing skeleton, resulting in lag and displacement deviation in rigid locking; if the filling rate is greater than 92%, there will be insufficient space for particle rearrangement under normal pressure, which will not provide the compliance required for the rough lifting stage; the rated pumping speed of vacuum pump 24 must match the net volume of flexible sealed cavity 20 to ensure that the pressure inside the cavity can be pumped from normal pressure to the target ultimate vacuum level within 5 seconds;

[0122] When silicon carbide particles 21 are selected with this particle size distribution, when combined with the adaptive leveling mechanism of the first cross pipe 16 and the second cross pipe 17, it can also alleviate a common problem: the spreader frame 6 has been leveled by the diagonal hydraulic cylinder compensation, but there is still a flexible disturbance in the wire rope above the main hook 1. If the variable stiffness joint 3 becomes too stiff too early in the coarse positioning stage, the disturbance will be directly transmitted to the spreader frame 6 along the main hook 1, the upper flange 4, and the lower flange 5.

[0123] If the variable stiffness joint 3 is still too soft in the critical centering region, the relative posture between the cylinder head 14 holes and the slender double-ended stud 34 will continue to drift. The silicon carbide particles 21 with a particle size distribution between 2 mm and 5 mm, together with the flexible sealing cavity 20 formed by vulcanization of the fabric-reinforced rubber material and the air path adjustment of the vacuum pump 24 and the electromagnetic proportional valve 25, enable the variable stiffness joint 3 to have a more controllable response amplitude to changes in vacuum. This makes the rigid locking in S3 and the softening and compliant sliding in S5 relatively clear. The dynamic differential pressure pulse signal extracted by the first pressure measuring hole 27 and the second pressure measuring hole 28 in the cross pipeline can also more accurately correspond to the state switching of whether the variable stiffness joint 3 should maintain rigidity or reduce stiffness.

[0124] Further defined, the upper flange 4 of the variable stiffness joint 3 is hinged to the main hook 1 by a pin 29, the lower flange 5 of the variable stiffness joint 3 is fixedly connected to the lifting frame 6 by a high-strength bolt 30, and the end of the piston rod 12 of the double-acting hydraulic cylinder 7 is connected to the branch steel cable 13 by a shackle 31.

[0125] These three connections correspond to the upper input end, the middle force transmission end, and the lower suspension end, respectively. They are not isolated but jointly determine the load path and attitude constraint path from the crane to the cylinder head 14.

[0126] The upper flange 4 is hinged to the main hook 1 via pin 29 in order to maintain a controlled relative swing degree of freedom between the main hook 1 and the spreader frame 6 when the variable stiffness joint 3 is in a low stiffness state. When the crane trolley moves, the main winch is finely adjusted, or there is a slight external disturbance in the nacelle, the slight attitude change of the main hook 1 will not be immediately regarded as a rigid command that the spreader frame 6 must follow synchronously. Instead, it can be released through the hinge of pin 29 and the compliant deformation of the flexible sealing cavity 20.

[0127] If the upper flange 4 is directly and rigidly connected to the main hook 1, in stages S1 and S2, even if the silicon carbide particles 21 are in a loose fluidized state, the swing on one side of the main hook 1 will be more transformed into the local twist of the flexible sealing cavity 20 due to the lack of rotational margin at the connection end, and the actual usable compliance range of the variable stiffness joint 3 will be reduced.

[0128] After the pin 29 is used for hinge, the variable stiffness joint 3 mainly undertakes the function of compliant connection under low vacuum, while under high vacuum, it undertakes the function of attitude locking by means of particle interlocking and the overall flange. The connection properties between the upper flange 4 and the main hook 1 show different effects as the state of the variable stiffness joint 3 changes, which is more in line with the requirements of vibration absorption and obstacle avoidance and attitude maintenance in the critical centering zone during the rough hoisting stage in the technical disclosure.

[0129] The pin 29 is hinged by a cylindrical pin that passes through the lug plate of the main hook 1 and the connecting lug plate of the upper flange 4, and a locking structure is used, or a hinged pin structure with a self-lubricating bushing is used, so as to realize the vertical force transmission between the main hook 1 and the upper flange 4 and allow relative rotation.

[0130] Regardless of the specific form of the pin 29 used, the purpose is to ensure that the change in the direction of force on the main hook 1 can be partially absorbed in the form of rotational degrees of freedom, rather than creating an unnecessary additional bending moment between the upper flange 4 and the lower flange 5.

[0131] The upper flange 4 is hinged to the main hook 1 by the pin 29. Combined with the feature that the silicon carbide particles 21 inside the flexible sealing cavity 20 can be rearranged under low vacuum, slight disturbances on one side of the main hook 1 are not easily amplified into lateral collisions between the lower end of the cylinder head 14 and the slender double-ended stud 34.

[0132] The lower flange 5 is fixedly connected to the spreader frame 6 by high-strength bolts 30 in order to transfer the attitude constraint formed by the variable stiffness joint 3 in the rigid locking state to the spreader frame 6 in a more stable manner. Unlike the upper flange 4, which needs to retain a certain relative rotation, the lower flange 5 and the spreader frame 6 emphasize the connection stiffness more, because the spreader frame 6 not only bears the total lifting load from the main hook 1, but also bears the off-center load difference fed back by the four double-acting hydraulic cylinders 7 and the branch steel cable 13.

[0133] If the connection stiffness between the lower flange 5 and the hanger frame 6 is insufficient, even if negative pressure has been established inside the flexible sealing cavity 20 and the silicon carbide particles 21 have formed frictional interlock in stage S3, the lower flange 5 may still move slightly relative to the hanger frame 6, resulting in the locked position not being the actual spatial orientation that the cylinder head 14 needs to maintain, but only the local state of the variable stiffness joint 3 body.

[0134] After being fixedly connected with high-strength bolts 30, a relatively stable flange connection surface is formed between the lower flange 5 and the cross-shaped H-beam welded frame. The stiffness of the variable stiffness joint 3 is increased by the increase in vacuum, which can be transmitted along the lower flange 5 to the lifting frame 6, and then from the lifting frame 6 to the four load-bearing lifting points corresponding to the left front hydraulic cylinder 8, right front hydraulic cylinder 9, left rear hydraulic cylinder 10 and right rear hydraulic cylinder 11, so that the cylinder head 14 maintains a relatively stable level and spatial posture in the critical centering area.

[0135] The high-strength bolts 30 are used for fixing the connection by directly connecting the lower flange 5 to the top reinforcing plate of the spreader frame 6 with six evenly distributed high-strength bolts 30, or by using high-strength bolts 30 in conjunction with locating pins to fix them together on the central connecting seat of the spreader frame 6, so as to meet the tensile, shear and torsional resistance requirements under the lifting load; the key point is that a fixed connection relationship with low clearance, reusable assembly and disassembly and high load-bearing capacity should be established between the lower flange 5 and the spreader frame 6;

[0136] With this setup, the central force convergence area formed by the cross-shaped welded I-beam frame of the aforementioned lifting frame 6 can form a continuous main force-bearing path with the fixed connection of the lower flange 5; and the dynamic differential pressure pulses extracted by the aforementioned first pressure measuring hole 27 and second pressure measuring hole 28 are closer to the hydraulic network changes caused by the actual force on the cylinder head 14, and are less likely to be mixed with the mechanical false disturbances caused by the loose connection of the lower flange 5.

[0137] The end of the piston rod 12 of the double-acting hydraulic cylinder 7 is connected to the branch steel cable 13 via the shackle 31 in order to ensure reliable transmission of tension while allowing for a moderate installation compensation between the branch steel cable 13 and the end of the piston rod 12.

[0138] The actual position of the four lifting holes 15 of the cylinder head 14 may be affected by casting tolerance, tooling manufacturing error or the angle of the hanging cable during operation. If the end of the piston rod 12 is rigidly connected to the branch steel cable 13 with no swing margin, and the force direction of the branch steel cable 13 deviates slightly from the axis of the piston rod 12, the end of the piston rod 12 will bear an additional bending moment, the smoothness of the piston 32 in the hydraulic cylinder will decrease, and the oil flow in the first cross pipe 16 and the second cross pipe 17 will also be affected.

[0139] With the connection of shackle 31, the branch steel cable 13 can make a small range of angle adjustment around the pin 29 of shackle 31 after being stretched, so that the tension is transmitted more closely along the axis of piston rod 12. The response of the hydraulic cylinder to the height change of the four corners of cylinder head 14 is closer to pure axial displacement. This is in conjunction with the layout of piston rod 12 extending vertically downward, which makes the leveling effect achieved between diagonal hydraulic cylinders through the first cross pipe 16 and the second cross pipe 17 more stable.

[0140] The shackle 31 is connected by either an arc-shaped shackle 31 in conjunction with a cable ring, or by a straight shackle 31 in conjunction with a pressing cable sleeve, so as to achieve a reliable tensile connection between the end of the piston rod 12 and the branch steel cable 13 while retaining a certain angle compensation.

[0141] With this limitation, the end of the piston rod 12 is connected to the branch steel cable 13 via the shackle 31, which not only facilitates the attachment and removal of the cylinder head 14, but also helps to transfer the load at the four lifting holes 15 of the cylinder head 14 to the four double-acting hydraulic cylinders 7 more smoothly.

[0142] Correspondingly, when the cylinder head 14 bore wall slightly touches the slender double-ended stud 34 during the lowering process and generates a flipping torque, this torque will be directly manifested as a dynamic differential pressure pulse signal through the branch steel cable 13, shackle 31, piston rod 12, rodless chamber 18, first cross pipe 16 and second cross pipe 17. This signal is collected through the first pressure measuring hole 27 and the second pressure measuring hole 28 and then used to judge the pressure change rate and adjust the duty cycle of the electromagnetic proportional valve 25.

[0143] If the connection between the branch cable 13 and the end of the piston rod 12 is too rigid or there is a significant gap, the mechanical transmission chain may experience additional friction, impact, or idle stroke, which will reduce the fidelity of the differential pressure pulse signal.

[0144] The flexible sealing cavity 20 is made of fabric-reinforced rubber material vulcanized and molded. The silicon carbide particles 21 have a particle size distribution between 2mm and 5mm. It is combined with the upper flange 4, which is hinged to the main hook 1 by the pin 29, and the lower flange 5, which is fixedly connected to the lifting frame 6 by the high-strength bolts 30. The end of the piston rod 12 of the double-acting hydraulic cylinder 7 is connected to the branch steel cable 13 by the shackle 31. This structure limits the connection between the main hook 1, the variable stiffness joint 3, the lifting frame 6, the four double-acting hydraulic cylinders 7 and the two intersecting pipelines to form a relatively continuous mechanical conversion path.

[0145] As a result, during the rough lifting stage, disturbances on one side of the main hook 1 can be partially released through the hinge pin 29 and the flexible sealed cavity 20 formed by vulcanization of the fabric-reinforced rubber material, and the silicon carbide particles 21 remain in a rearrangeable state; in the critical centering zone, the negative pressure causes the silicon carbide particles 21 with a particle size distribution between 2 mm and 5 mm to form a more obvious frictional interlock, and the lower flange 5 then transmits this locking posture to the lifting frame 6 through the high-strength bolts 30;

[0146] When slight interference occurs between the bore wall and the slender double-ended stud 34, the branch steel cable 13 transmits the torque change to the double-acting hydraulic cylinder 7 and the cross pipeline via the shackle 31. The pressure change can then serve as the input for subsequent vacuum adjustment. The defined material parameters and connection methods are interconnected with the adaptive leveling structure and pressure measuring structure, enabling the lifting, leveling, centering, and anti-jamming processes of the large low-speed diesel engine cylinder head 14 within the confined engine compartment to be continuously realized along the same set of mechanical and hydraulic paths.

[0147] Example 2:

[0148] like Figure 6 As shown, a method for lifting the cylinder head of a large low-speed diesel engine includes:

[0149] S1. Control the vacuum pump 24 to stop working and open the electromagnetic proportional valve 25 to connect the inside of the flexible sealed cavity 20 with the outside atmosphere, so that the silicon carbide particles 21 are in a loose fluidized state.

[0150] S2. Control the lifting action and achieve adaptive leveling of the spreader frame 6 through the flow of oil in the first cross pipe 16 and the second cross pipe 17.

[0151] S3. When the cylinder head 14 hole and the slender double-ended stud 34 on the diesel engine block enter the critical alignment zone, the vacuum pump 24 is started and the opening of the electromagnetic proportional valve 25 is adjusted to extract the air inside the flexible sealing cavity 20 to form a negative pressure, so that the variable stiffness joint 3 is converted into a rigid locking state and the cylinder head 14 is lowered at a uniform speed.

[0152] S4. During the lowering process, the dynamic pressure pulse signals inside the first cross pipe 16 and the second cross pipe 17 are collected in real time, and the pressure change rate is obtained by calculating the derivative of the dynamic pressure pulse signal with respect to time.

[0153] S5. When the pressure change rate is greater than or equal to the preset destructive lateral shear stress threshold, the duty cycle of the electromagnetic proportional valve 25 is adjusted according to the pressure change rate to reduce the vacuum inside the flexible sealing cavity 20, so that the variable stiffness joint 3 softens and produces compliant sliding.

[0154] S6. When the pressure change rate is less than the preset destructive lateral shear stress threshold, control the electromagnetic proportional valve 25 to fully open, restore the ultimate vacuum inside the flexible sealing cavity 20, so that the variable stiffness joint 3 can return to the rigid locking state and continue to lower.

[0155] In step S2, when the center of gravity of the cylinder head 14 is biased to the left front corner, the tension of the left front branch cable 13 forces the piston 32 and piston rod 12 of the left front hydraulic cylinder 8 to move downward. The pressurized hydraulic oil enters the rodless chamber 18 of the right rear hydraulic cylinder 11 through the first cross pipe 16, forcing the piston 32 and piston rod 12 of the right rear hydraulic cylinder 11 to extend downward, thereby simultaneously extending the equivalent cable length of the left front side and the right rear side, so that the two ends of the diagonal produce equal downward geometric displacement to complete the leveling.

[0156] The steps preceding S5 include:

[0157] S0. Input the peak value of the pressure change rate into the pre-established pressure-stiffness adjustment model. The pressure-stiffness adjustment model maps the pressure change rate to the corresponding stiffness adjustment coefficient.

[0158] The specific calculation process is as follows: the overshoot difference between the peak pressure change rate obtained in real time and the preset equivalent pressure change rate threshold is calculated. The overshoot difference is then substituted into the exponential mapping function after dimensionless processing to convert it into a stiffness adjustment coefficient. In the conversion process, the dimensionless processing eliminates the calculation coupling error caused by the fluid volume elastic modulus from a mathematical logic perspective. The duty cycle of the electromagnetic proportional valve 25 is adjusted according to the calculated stiffness adjustment coefficient.

[0159] Based on the main hook 1, variable stiffness joint 3, lifting frame 6, left front hydraulic cylinder 8, right front hydraulic cylinder 9, left rear hydraulic cylinder 10, right rear hydraulic cylinder 11, first cross pipe 16, second cross pipe 17, first pressure measuring hole 27, second pressure measuring hole 28, vacuum pump 24, electromagnetic proportional valve 25 and branch steel cable 13, this lifting method connects the vacuum adjustable characteristics of variable stiffness joint 3, the fluid coupling characteristics of the two cross pipes and the displacement response characteristics of four double-acting hydraulic cylinders 7 in series, so that the cylinder head 14 can continuously complete attitude control at each stage, and all mechanical components jointly participate in attitude generation, differential pressure signal formation and stiffness switching;

[0160] In step S1, the vacuum pump 24 is stopped and the electromagnetic proportional valve 25 is opened, so that the interior of the flexible sealed cavity 20 is connected to the external atmosphere, and the silicon carbide particles 21 are in a loose fluidized state.

[0161] The opening of the electromagnetic proportional valve 25 here specifically refers to controlling the three-way electromagnetic proportional valve 25 to switch to the pressure relief channel open state, establishing a communication path between the cavity and the atmosphere. This is achieved by inputting a fully open control current into the electromagnetic proportional valve 25, or by maintaining the duty cycle in the high opening range, so that the flexible sealed cavity 20 forms a sufficient gas exchange path with the outside.

[0162] Its purpose is to make the internal pressure of the flexible sealed cavity 20 close to the external environmental pressure, thereby reducing the squeezing effect between silicon carbide particles 21 caused by the external atmospheric pressure.

[0163] At this time, the gauge pressure inside the flexible sealing cavity 20 is between -5kPa and 0kPa. The irregular polyhedral silicon carbide particles 21 can rearrange inside the flexible sealing cavity 20. The corrugated flexible sealing cavity 20 can also deflect at a certain angle as the relative posture between the upper flange 4 and the lower flange 5 changes.

[0164] The variable stiffness joint 3 exhibits high compliance, meaning that it can allow a lateral displacement of not less than 15 mm under a lateral external force of 10 kN. The small swing transmitted from the main hook 1 through the hinge pin 29 and the attitude changes of the crane lifting wire rope 2 caused by starting, stopping and slight vibration will not be directly transmitted to the lifting frame 6 and the cylinder head 14 below in a rigid form.

[0165] In conjunction with the aforementioned flexible sealing cavity 20, which is made of fabric-reinforced rubber material and vulcanized, and the upper flange 4, which is hinged to the main hook 1 via pin 29, the low-rigidity connection state formed in step S1 provides a basis for vibration and obstacle avoidance when the cylinder head 14 enters the narrow assembly area, and also prevents the adaptive leveling process dominated by cross pipelines from being repeatedly disturbed by the upper rigid disturbance.

[0166] In step S2, the lifting action is controlled by the oil flow in the first cross pipe 16 and the second cross pipe 17 to achieve adaptive leveling of the spreader frame 6. The lifting action is controlled by the continuous and uniform lifting of the main winch of the crane, or by alternating lifting and lateral movement, so that the main hook 1 drives the spreader frame 6 and cylinder head 14 to lift, move horizontally, or slowly approach the installation position. The four double-acting hydraulic cylinders 7 and the two cross pipes provide fluid response to the eccentric load during the lifting process.

[0167] Based on the aforementioned structure, when the cylinder head 14 experiences a shift in center of gravity due to the asymmetrical distribution of valves and pipelines, the tension borne by the four branch cables 13 will not be completely uniform. If the left front corner is heavier, the tension of the left front branch cable 13 will increase, the piston 32 of the left front hydraulic cylinder 8 will move downward, and the anti-wear hydraulic oil 19 in the rodless chamber 18 of the left front hydraulic cylinder 8 will be forced into the first cross pipeline 16. Since the first cross pipeline 16 is connected to the rodless chamber 18 of the right rear hydraulic cylinder 11, the piston 32 of the right rear hydraulic cylinder 11 will extend downward under the push of the oil.

[0168] The equivalent sling lengths on the left front side and the right rear side tend to lengthen synchronously, and the spreader frame 6 and the cylinder head 14 below it form an equal amount of overall settlement compensation along the diagonal, thereby maintaining a horizontal attitude; if the off-center load occurs at the right front corner, the second cross pipe 17 generates the same diagonal compensation between the right front hydraulic cylinder 9 and the left rear hydraulic cylinder 10.

[0169] Since the two intersecting pipes are filled with anti-wear hydraulic oil 19 and strictly vented, the change in oil volume is small. The force difference caused by the off-center load of the cylinder head 14 will be directly converted into the displacement distribution between the diagonal hydraulic cylinders. Step S2 uses the eccentric pulling force itself to drive the flow of oil in the first intersecting pipe 16 and the second intersecting pipe 17, making it easier for the lifting frame 6 to maintain a near-horizontal posture.

[0170] This process, in conjunction with the aforementioned cross-shaped welded I-beam frame, the double-acting hydraulic cylinder 7 cylinder flange 26 fixed to the bottom surface of the lifting frame 6, and the vertically downward extending piston rod 12, can reduce additional errors caused by the twisting of the lifting frame 6 body or the misalignment of the hydraulic cylinder installation, and provide a more stable initial geometric relationship for entering the critical centering zone near the slender double-headed stud 34.

[0171] In step S3, when the cylinder head 14 hole and the slender double-ended stud 34 on the diesel engine block enter the critical alignment zone, the vacuum pump 24 is started and the opening of the electromagnetic proportional valve 25 is adjusted to extract the air inside the flexible sealing cavity 20 to form a negative pressure, so that the variable stiffness joint 3 is converted into a rigid locking state and the cylinder head 14 is lowered at a uniform speed.

[0172] The operator determines the critical alignment zone by judging the relative height between the cylinder head 14 and the diesel engine block, or by combining the crane lifting displacement information and the installation reference height. A locking command is issued before the hole is about to approach the inlet end of the slender double-ended stud 34.

[0173] Specifically, the critical alignment zone can be determined by measuring the distance between the bottom surface of the cylinder head 14 and the top of the slender double-ended stud 34, which is between 10mm and 50mm, using a laser rangefinder set at the bottom of the hanger frame 6.

[0174] The combined use of vacuum pump 24 and electromagnetic proportional valve 25 is to ensure that the vacuum level inside flexible sealed cavity 20 is not limited to only two extreme states of vacuuming or not vacuuming, but can be adjusted within a certain range; ultimate vacuum refers to the maximum negative pressure state that vacuum pump 24 can achieve under this system, or the upper limit gauge pressure of the process set for a certain target high rigidity, such as -80kPa, which corresponds to an absolute pressure of approximately 20kPa.

[0175] As air is extracted, the external atmospheric pressure of the flexible sealed cavity 20 increases the compressive effect on the cavity wall and silicon carbide particles 21. The irregular polyhedral silicon carbide particles 21 gradually change from point contact to more obvious edge interlocking and surface contact. The relative sliding resistance of the particle group increases, and the equivalent elastic modulus of the variable stiffness joint 3 increases.

[0176] When the pressure inside the cavity reaches the above-mentioned ultimate vacuum level and the pressure is maintained stably, it is confirmed that the variable stiffness joint 3 has entered the rigid locking state. At this time, the equivalent lateral stiffness of the variable stiffness joint 3 is increased to more than 10 times that of the compliant state.

[0177] Since the upper flange 4 is hinged to the main hook 1 by the pin shaft 29 and the lower flange 5 is fixedly connected to the lifting frame 6 by the high-strength bolts 30, after the stiffness of the variable stiffness joint 3 increases, the originally large degree of attitude freedom between the main hook 1 and the lifting frame 6 is significantly reduced, and the horizontality and spatial posture maintained by the lifting frame 6 are more stably transmitted to the four corners of the cylinder head 14 corresponding to the four branch steel cables 13.

[0178] At this time, a uniform speed is used to reduce the disturbance of the pressure state in the first cross pipe 16 and the second cross pipe 17 by the additional acceleration during the lowering process, so that the dynamic differential pressure pulse signal collected later reflects more the real contact between the hole wall and the slender double-ended stud 34, rather than the background fluctuations caused by the crane's movement itself.

[0179] In step S4, during the lowering process, the dynamic differential pressure pulse signal inside the first cross pipe 16 and the second cross pipe 17 is collected in real time, and the pressure change rate is obtained by calculating the derivative of the dynamic differential pressure pulse signal with respect to time.

[0180] The real-time data acquisition here uses the first pressure measuring hole 27 and the second pressure measuring hole 28 as pressure sampling locations. The method is to install pressure sensors at the first pressure measuring hole 27 and the second pressure measuring hole 28 respectively and connect them to the controller, or to use the pressure measuring connector to connect an external sampling module to extract the pressure changes in the corresponding pipeline section.

[0181] In this embodiment, the control actions are uniformly scheduled by the controller; the controller can be an industrial programmable logic controller or a high-performance microcontroller with built-in analog-to-digital and digital-to-analog conversion modules.

[0182] High-frequency dynamic pressure sensors with a response frequency of not less than 2kHz are installed at the first pressure measuring port 27 and the second pressure measuring port 28 respectively. Their signals are connected to the A / D input terminal of the controller through shielded cables. The pulse width modulation output pin of the controller is connected to the control terminal of the electromagnetic proportional valve 25 through the power amplifier module, and the digital output terminal is connected to the start / stop relay of the vacuum pump 24.

[0183] The controller's program execution cycle is set to no more than 5ms to ensure real-time capture and execution response to dynamic differential pressure pulses; the pressure is taken from the middle section rather than from near the hydraulic cylinder connector because the middle section position can better reflect the overall pressure changes of the first and second closed fluid networks and is less likely to be amplified by local impact signals near a single hydraulic cylinder port.

[0184] The dynamic pressure pulse signal is the transient pressure fluctuation formed when the cylinder head 14 hole wall and the slender double-ended stud 34 make slight contact, and the overturning torque breaks the original hydrostatic balance of the four double-acting hydraulic cylinders 7.

[0185] The dynamic pressure pulse signal of this invention does not refer to the spatial pressure difference between the two ends of the same network or between two different pipelines, but rather to the dynamic sequence signal of the pressure at the current moment within a single intersecting pipeline relative to its initial steady-state pressure over time, i.e., the pressure increment pulse in the time dimension. The rate of pressure change is reflected as the ratio of the pressure difference between adjacent sampling periods at the same measuring point to the corresponding time interval.

[0186] Specifically, within the first 2 seconds after the variable stiffness joint 3 is rigidly locked and the crane enters the uniform speed lowering state, the controller collects and calculates the average pressure as the initial steady-state pressure baseline; during the lowering process, if the pressure change rate is less than 0.1 MPa / s for 10 consecutive sampling periods, the current moving average pressure is updated to the new steady-state baseline, thereby eliminating the low-frequency background drift caused by the gradual change of the system.

[0187] To prevent the steady-state baseline update from overlapping with abnormal pulses, when the pressure deviation from the steady-state baseline is detected to exceed the dead zone threshold of 0.5 MPa, the controller immediately locks the update of the initial steady-state pressure baseline until the pressure change rate is below 0.05 MPa / s for 20 consecutive sampling periods and the absolute pressure value recovers to within the dead zone, before resuming the moving average update logic of the baseline. During the acquisition process, in order to satisfy the Nyquist sampling theorem and fully capture high-frequency pulses, the sampling frequency can be set to no less than 4000 Hz, with a time window of 50 ms, and a moving average filtering algorithm is used to remove high-frequency background mechanical vibration noise.

[0188] To ensure the synchronization and high-frequency fidelity of the pressure signals from the two intersecting pipelines, the dynamic pressure sensors at the first and second pressure measuring ports 27 and 28 employ a hard-wired synchronous triggering mechanism. Their A / D sampling is triggered by the same hardware timer on the controller, with a time alignment error not exceeding 10 μs. The sensor range is set to... to The overall accuracy reaches 0.1% of the full scale, and it has an impact overload resistance of 150% of the full scale. It can clearly distinguish dead zone fluctuations and transient high-frequency pulses of 0.5MPa.

[0189] In terms of data processing, a sampling frequency of 1000Hz corresponds to a data output cycle of 1ms, while the controller's program cycle of no more than 5ms adopts a multi-point batch processing mode. That is, within each program cycle, the array of the past 5 sampling points is extracted for differentiation and filtering calculations to ensure that each sampling point participates in the control decision without being missed. When abnormal communication or single-channel sampling distortion occurs, the system automatically degrades to relying on another normal signal for single-sided monitoring. If both channels fail, the current valve opening is locked and an audible and visual alarm is issued.

[0190] In addition, the controller is also set with a dead zone threshold. When the pressure deviates from the steady-state baseline by less than 0.5 MPa, it is considered as background fluctuation caused by normal uniform descent and is not included in the differential calculation. Only sudden changes exceeding the dead zone threshold are input into the differential module to calculate the pressure change rate, thereby clearly distinguishing between real contact pulses and background fluctuations.

[0191] Because the cylinder head 14 is in a rigidly locked state of variable stiffness joint 3, the overall posture is relatively stable. Once a certain hole and a certain slender double-headed stud 34 collide locally, the lateral contact stress will be transmitted to the first cross pipe 16 or the second cross pipe 17 through the corresponding branch steel cable 13, piston rod 12 and the rodless chamber 18 of the hydraulic cylinder, causing the originally flat pressure curve to suddenly change.

[0192] The controller continuously compares the acquired pressure signals to determine how quickly the pressure value at a given moment rises or falls relative to the previous moment, thus obtaining the pressure change rate. The differential calculation here does not require a specific mathematical expression; simply comparing the pressure change between adjacent sampling points with the sampling interval in chronological order allows it to determine whether the pressure change is a gradual accumulation or a rapid, abrupt change. The pressure change rate is the derivative of the denoised single-channel pressure signal, i.e., calculating the pressure difference between adjacent sampling periods divided by the time interval. Its discretized calculation formula is:

[0193] ;

[0194] in, The rate of change of pressure, The pressure value for the current sampling period. This is the pressure value from the previous sampling period. The sampling time interval; the peak value of the aforementioned pressure change rate is denoted as [value] in subsequent calculations. ;

[0195] Since the time derivative of the single-channel pressure dynamic signal is extracted, when the two intersecting pipelines fluctuate at the same time, the controller uses the pressure change rate of the channel with the larger absolute value as the subsequent judgment basis to ensure that the most unfavorable interference state is captured, thereby unifying the signal definition with the physical representation of the actual measurement.

[0196] Step S4 transforms the microscopic contact stress between the hole wall and the slender double-ended stud 34, which is not easily observed directly, into a measurable rate of pressure change in the first cross pipe 16 and the second cross pipe 17, providing a basis for whether to release stiffness in the future.

[0197] In step S5, when the pressure change rate is greater than or equal to the preset destructive lateral shear stress threshold, the duty cycle of the electromagnetic proportional valve 25 is adjusted according to the pressure change rate to reduce the vacuum inside the flexible sealing cavity 20, so that the variable stiffness joint 3 softens and produces compliant sliding; the preset threshold is used to determine the elastic bearing capacity of the slender double-ended stud 34 under allowable lateral load.

[0198] When the pressure change is determined to be close to a level that could cause thread jamming, scratching, or lateral damage to the stud, the controller triggers a softening action. Specifically, the preset destructive lateral shear stress threshold corresponds to the equivalent pressure change rate threshold in the control program, expressed in MPa / s. The conversion relationship is as follows:

[0199] ;

[0200] in, The equivalent pressure change rate threshold. To allow for lateral shear stress, The cross-sectional area of ​​the stud is... As the guide angle, This refers to the effective pressure-bearing area of ​​the rodless chamber in the hydraulic cylinder. The allowable lateral shear stress is set based on the yield strength of the material of the slender double-ended stud 34 of the diesel engine, and is usually taken as 15% to 25% of the material yield strength.

[0201] The guide angle tangent is directly calculated from the chamfer geometry of the stud top, for example, tan30° is used when the chamfer is 30 degrees; the calibration time constant is obtained through no-load lateral jacking calibration test, which represents 63.2% of the time required for the pressure in the hydraulic cylinder chamber to jump from zero to a stable value, and is taken as 0.05s to 0.15s in this embodiment;

[0202] The specific calibration steps are as follows: When the lifting device is suspended without load, use a push-pull force gauge to apply a step thrust to the side of the lifting frame 6, and at the same time record the pressure response curve in the cross pipeline. The time point when the steady-state pressure reaches 63.2% is the calibration time constant, and the tolerance is required to be controlled within ±5%.

[0203] Before comparison, the controller first takes the absolute value of the actual calculated pressure change rate and then compares it with the equivalent pressure change rate threshold to complete the logical judgment under a unified dimension. The duty cycle adjustment of the electromagnetic proportional valve 25 is achieved by changing the valve core opening by pulse width modulation signal or by continuously adjusting the valve core position by proportional current, so as to change the flow capacity of the electromagnetic proportional valve 25 and correspondingly change the pumping strength of the flexible sealing cavity 20.

[0204] Specifically, by adjusting the duty cycle of the three-way electromagnetic proportional valve 25, the connection ratio between its pressure relief intake branch and the air extraction channel is controlled, and an appropriate amount of external air is actively introduced into the air path, thereby reliably reducing the vacuum level inside the flexible sealing cavity 20.

[0205] In the pump-valve coordinated control sequence, the controller prioritizes adjusting the duty cycle of the electromagnetic proportional valve 25 to quickly respond to changes in pipeline pressure, while the vacuum pump 24 keeps running continuously throughout the entire lowering phase. Only when abnormal conditions such as single-channel sensor distortion or serious pipeline leakage are detected will the vacuum pump 24 be triggered to stop urgently and the proportional valve be fully opened to release pressure in order to implement a safety degradation strategy.

[0206] The physical process is that after the vacuum level inside the flexible sealed cavity 20 is reduced, the pressing effect of the external atmospheric pressure on the silicon carbide particle group 21 is reduced, the original frictional interlock between the silicon carbide particles 21 is partially released, and the equivalent elastic modulus of the variable stiffness joint 3 decreases.

[0207] The cylinder head 14, which was originally locked, will gain a limited degree of freedom of compliance. Under the combined action of its own weight and the guide angle at the end of the slender double-ended stud 34, the cylinder head 14 can slide slightly in a direction that is conducive to eliminating interference.

[0208] With the basic leveling completed in step S2 and the attitude locking completed in step S3, the connection stiffness that resolves local jamming is released during the compliant sliding.

[0209] In this way, step S5 transfers the lateral stress that would be directly applied to the slender double-ended stud 34 in a conventional rigid lifting device into a controllable change in the state of the particle group inside the variable stiffness joint 3, thereby reducing the rigid collision between the hole wall and the slender double-ended stud 34.

[0210] The purpose of setting step S0 before step S5 is to ensure that the duty cycle adjustment of electromagnetic proportional valve 25 is not simply based on experience to reduce the vacuum level, but rather based on the interference intensity corresponding to the pressure change rate for graded control.

[0211] Specifically, the peak value of the pressure change rate is input into a pre-established pressure-stiffness adjustment model, which maps the pressure change rate to the corresponding stiffness adjustment coefficient.

[0212] The pressure-stiffness adjustment model here is pre-stored in the controller or in the industrial computing unit that communicates with the controller, so as to output a corresponding stiffness adjustment coefficient according to the input pressure change rate;

[0213] Its establishment logic comes from the force transmission relationship of the aforementioned mechanical and hydraulic structures: the greater the pressure change rate, the faster the lateral contact stress between the hole wall and the slender double-ended stud 34 accumulates. If a high vacuum is maintained, the variable stiffness joint 3 continues to maintain high stiffness, and the risk of lateral shearing borne by the slender double-ended stud 34 will continue to increase.

[0214] If the pressure change rate is small, it indicates that the contact is more likely to be in a slight guiding and corrective stage. At this time, it is only necessary to release a small amount of stiffness, and it is not necessary to make the flexible sealing cavity 20 completely return to the loose fluidized state.

[0215] The specific calculation process is as follows: Calculate the peak pressure change rate obtained from real-time data acquisition. Compared with the preset equivalent pressure change rate threshold The overshoot value is then transformed into a stiffness adjustment coefficient by substituting it into an exponential mapping function after dimensionless processing. The specific conversion formula is as follows:

[0216] ;

[0217] in, is the base of the natural logarithm; The empirical calibration coefficient is dimensionless; in this embodiment, it is taken as a value of [value missing]. to It is used to adjust the sensitivity of the softening response of variable stiffness joints.

[0218] In the above calculation process, the ratio formula is used. The dimensional physical quantity of pressure change rate was transformed into a purely numerical variable, ensuring that the independent variable of the exponential function is strictly dimensionless, thus eliminating the calculation coupling error caused by the fluid volumetric elastic modulus from a mathematical perspective; based on the calculated dimensionless stiffness adjustment coefficient... Control the duty cycle of the electromagnetic proportional valve 25;

[0219] Output stiffness adjustment coefficient The value is between 0 and 1. The controller multiplies this coefficient by the duty cycle corresponding to the maximum opening. This yields the final duty cycle control command for the electromagnetic proportional valve:

[0220] ;

[0221] in, This is the final duty cycle control command for the electromagnetic proportional valve. Duty cycle corresponding to maximum opening; decoupling coefficient The larger the duty cycle, the higher the duty cycle. The larger the value, the more the pumping force weakens, and the more significant the decrease in vacuum level.

[0222] The maximum opening corresponds to the duty cycle. The value is usually set to 90% to 95% to reserve the control dead zone of the electromagnetic proportional valve 25 and prevent the coil from overheating. As a result, the degree of softening of the variable stiffness joint 3 in step S5 can be adapted to the current severity of interference, which avoids the problem of insufficient release causing the jam to not be released, and also reduces the problem of excessive release causing the cylinder head 14 to drift again.

[0223] In step S6, when the pressure change rate is less than the preset destructive lateral shear stress threshold, the electromagnetic proportional valve 25 is fully opened to restore the ultimate vacuum inside the flexible sealing cavity 20, so that the variable stiffness joint 3 returns to the rigid locking state and continues to lower.

[0224] The drop in the rate of pressure change here usually indicates that the abnormal lateral contact between the borehole wall and the slender double-ended stud 34 has disappeared or has been reduced to a safe range, and there are no longer high-frequency abrupt changes in the cross-pipeline that require triggering compliant release;

[0225] Controlling the electromagnetic proportional valve 25 to be fully open specifically means closing the pressure relief and air intake branch of the three-way electromagnetic proportional valve 25 and fully opening its air extraction channel. This is to restore the vacuum pump 24's ability to extract air from the flexible sealed cavity 20 to a higher level, thereby quickly rebuilding the normal extrusion force and frictional interlock between the silicon carbide particles 21.

[0226] When the cavity reaches the ultimate vacuum again and the particle interlocking is confirmed, the variable stiffness joint 3 switches to a higher stiffness state again, that is, the softening and compliance state ends and the rigid locking state is restored. In order to prevent the variable stiffness joint 3 from frequently switching back and forth near the preset destructive lateral shear stress threshold, the controller introduces a hysteresis band and minimum holding time de-jittering strategy between S5 and S6.

[0227] Specifically, an upper limit threshold for the pressure change rate that triggers the softening action and a lower limit threshold for restoring rigidity are set, with the lower limit threshold being 70% of the upper limit threshold. When the pressure change rate reaches the upper limit threshold and triggers the compliant sliding of S5, the pressure change rate must simultaneously drop below the lower limit threshold, and this low-stress state must be maintained for more than the preset minimum holding time, which is set to 1.5s in this embodiment, before the controller allows the execution of S6 to restore the ultimate vacuum.

[0228] The corrected cylinder head 14 posture can be maintained, and the uniform lowering action can continue. Since step S6 is performed after the compliant sliding that eliminates interference in step S5, when the variable stiffness joint 3 returns to rigid locking, the cylinder head 14 holes and the slender double-ended studs 34 have usually returned to a more favorable alignment relationship, and it is not easy for the same position to be stuck repeatedly when the lowering continues.

[0229] If a new interference position causes the pressure change rate to increase again during the continued descent, the control logic can still adjust the duty cycle of the electromagnetic proportional valve 25 according to the relationship between S4, S0 and S5, so that the flexible sealing cavity 20 can release part of the vacuum again.

[0230] After steps S1 to S6 and step S0 work together, a continuous action chain is formed between the main hook 1, the variable stiffness joint 3, the lifting frame 6, the four double-acting hydraulic cylinders 7, the first cross pipe 16, the second cross pipe 17, the first pressure measuring hole 27, and the second pressure measuring hole 28: in the rough lifting stage, the low stiffness state of S1 is used to absorb the upper disturbance, and in S2, the diagonal hydraulic network is used to correct the attitude tilt caused by the eccentric load.

[0231] The critical alignment zone relies on S3 to establish high stiffness and maintain the spatial orientation between the cylinder head 14 holes and the slender double-ended studs 34. Once local interference occurs during the lowering process, S4 converts the micro-contact stress into a dynamic differential pressure pulse, S0 converts the peak pressure change rate into a stiffness adjustment coefficient, S5 reduces the vacuum inside the flexible sealing cavity 20 and releases an appropriate amount of compliance, and S6 restores rigidity locking and continues the lowering process after the interference is resolved.

[0232] The method for lifting the cylinder head 14 of a large low-speed diesel engine in a confined installation area, by coordinating mechanical structure and control steps, allows pressure changes in the cross pipelines to participate in attitude leveling, interference identification, and determination of the release amplitude of the variable stiffness joint 3. This ensures that the centering accuracy, protection of the slender double-ended studs 34, and continuous operational stability are all taken into account during the lowering process of the cylinder head 14.

[0233] To verify the technical effect of the present invention, a lifting comparison test was conducted. Under the condition that the offset load is 15% of the total weight, the cylinder head initially tilted at an angle of 3.5° when using the traditional four-point rigid lifting scheme. However, when using the device of the present invention, the cross-pipe adaptive leveling system corrected the initial tilt angle and stabilized it within 0.2° within 4.2 seconds.

[0234] During the simulated centering and lowering process, with a preset lateral contact force of 500N triggering interference, the pressure-stiffness adjustment model of this invention reduced the equivalent stiffness by 65% ​​within 0.15s, and the measured peak value of the maximum lateral shear force was 680N, far below the allowable yield limit of 2500N for the stud. In contrast, the traditional method experienced hard jamming under the same conditions, with the peak lateral force exceeding 3200N. Experimental data demonstrate that this invention can effectively achieve automatic leveling under off-center loads and compliant micro-interference avoidance.

[0235] This application has been described through the above embodiments; however, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit this application to the described embodiments. Those skilled in the art will understand that many more variations and modifications can be made based on the teachings of this application, and all such variations and modifications fall within the scope of protection claimed in this application.

Claims

1. A cylinder head lifting device for a large low-speed diesel engine, characterized in that, include: The main hook (1) is connected to the bottom end of the hoisting wire rope (2) of the crane; The variable stiffness joint (3) includes an upper flange (4) and a lower flange (5) respectively, wherein the upper flange (4) is hinged to the main hook (1); The lifting frame (6) is fixedly connected to the bottom surface of the lower flange (5). The ends of the lifting frame (6) are respectively vertically fixedly connected to double-acting hydraulic cylinders (7). The double-acting hydraulic cylinders (7) are the left front hydraulic cylinder (8), the right front hydraulic cylinder (9), the left rear hydraulic cylinder (10), and the right rear hydraulic cylinder (11). The piston rod (12) of the double-acting hydraulic cylinder (7) is connected to the branch steel cable (13). When lifting the cylinder head (14), the lower end of the branch steel cable (13) is respectively hooked to the lifting hole (15) of the cylinder head (14). The first cross pipe (16) connects the rod chamber of the left front hydraulic cylinder (8) and the rodless chamber (18) of the right rear hydraulic cylinder (11) to form a first closed fluid network; the second cross pipe (17) connects the rod chamber of the right front hydraulic cylinder (9) and the rodless chamber (18) of the left rear hydraulic cylinder (10) to form a second closed fluid network; and the internal pistons of the four double-acting hydraulic cylinders (7) have equal effective pressure-bearing areas on both sides; The first cross pipe (16) and the second cross pipe (17) are filled with anti-wear hydraulic oil (19). The variable stiffness joint (3) includes a flexible sealing cavity (20) in the shape of a corrugated tube. The two ends of the flexible sealing cavity (20) are respectively vulcanized and bonded to the upper flange (4) and the lower flange (5). The interior of the flexible sealing cavity (20) is filled with irregular polyhedral silicon carbide particles (21). The flexible sealed cavity (20) has an air extraction hole (22) on its side wall. The air extraction hole (22) is connected to a vacuum pump (24) through an air pipe (23). An electromagnetic proportional valve (25) is connected in series on the air pipe (23).

2. The cylinder head lifting device for a large low-speed diesel engine according to claim 1, characterized in that, The lifting frame (6) is a cross-shaped welded I-beam frame. The cylinder flange (26) of the double-acting hydraulic cylinder (7) is fixed to the bottom surface of the lifting frame (6). The piston rod (12) of the double-acting hydraulic cylinder (7) extends vertically downward.

3. A cylinder head lifting device for a large low-speed diesel engine according to claim 1, characterized in that, The first cross pipe (16) has a first pressure measuring hole (27) in the middle section of the pipe wall, and the second cross pipe (17) has a second pressure measuring hole (28) in the middle section of the pipe wall.

4. A cylinder head lifting device for a large low-speed diesel engine according to claim 1, characterized in that, The flexible sealing cavity (20) is made of fabric-reinforced rubber material through vulcanization, and the particle size of the silicon carbide particles (21) is distributed between 2 mm and 5 mm.

5. A cylinder head lifting device for a large low-speed diesel engine according to claim 1, characterized in that, The upper flange (4) of the variable stiffness joint (3) is hinged to the main hook (1) by a pin (29), the lower flange (5) of the variable stiffness joint (3) is fixedly connected to the lifting frame (6) by a high-strength bolt (30), and the end of the piston rod (12) of the double-acting hydraulic cylinder (7) is connected to the branch cable (13) by a shackle (31).

6. A method for lifting the cylinder head of a large low-speed diesel engine, applied to the cylinder head lifting device for a large low-speed diesel engine as described in claim 1, characterized in that, include: S1. Control the vacuum pump (24) to stop working and open the electromagnetic proportional valve (25) so that the interior of the flexible sealed cavity (20) is connected to the external atmosphere and the silicon carbide particles (21) are in a loose fluidized state. S2. Control the lifting action and achieve adaptive leveling of the lifting frame (6) through the flow of oil in the first cross pipe (16) and the second cross pipe (17); S3. When the hole of the cylinder head (14) and the slender double-headed stud (34) on the diesel engine block enter the critical alignment zone, the vacuum pump (24) is started and the opening of the electromagnetic proportional valve (25) is adjusted to extract the air inside the flexible sealing cavity (20) to form a negative pressure, so that the variable stiffness joint (3) is converted into a rigid locking state and the cylinder head (14) is lowered at a uniform speed. S4. During the lowering process, the dynamic pressure pulse signals inside the first cross pipe (16) and the second cross pipe (17) are collected in real time, and the pressure change rate is obtained by calculating the derivative of the dynamic pressure pulse signal with respect to time. S5. When the pressure change rate is greater than or equal to the preset destructive lateral shear stress threshold, the duty cycle of the electromagnetic proportional valve (25) is adjusted according to the pressure change rate to reduce the vacuum inside the flexible sealing cavity (20) and soften the variable stiffness joint (3) to produce compliant sliding. S6. When the pressure change rate is less than the preset destructive lateral shear stress threshold, control the electromagnetic proportional valve (25) to fully open, restore the ultimate vacuum inside the flexible sealing cavity (20), so that the variable stiffness joint (3) can return to the rigid locking state and continue to lower.

7. The lifting method according to claim 6, characterized in that, In step S2, when the center of gravity of the cylinder head (14) is biased to the left front corner, the tension of the left front branch cable (13) forces the piston (32) and piston rod (12) of the left front hydraulic cylinder (8) to move downward. The pressurized hydraulic oil enters the rodless chamber (18) of the right rear hydraulic cylinder (11) through the first cross pipe (16), forcing the piston (32) and piston rod (12) of the right rear hydraulic cylinder (11) to extend downward, thereby simultaneously extending the equivalent cable length of the left front side and the right rear side, so that the two ends of the diagonal produce equal downward geometric displacement to complete the leveling.

8. The lifting method according to claim 6, characterized in that, The steps preceding S5 include: S0. Input the peak value of the pressure change rate into a pre-established pressure-stiffness adjustment model, wherein the pressure-stiffness adjustment model maps the pressure change rate to the corresponding stiffness adjustment coefficient. The specific calculation process is as follows: calculate the overshoot difference between the peak value of the pressure change rate obtained in real time and the preset equivalent pressure change rate threshold, and then input the overshoot difference into the exponential mapping function through dimensionless processing to convert it into the stiffness adjustment coefficient. In the conversion process, the calculation coupling error caused by the fluid volume elastic modulus is eliminated from the mathematical logic through dimensionless processing. The duty cycle of the electromagnetic proportional valve (25) is adjusted according to the calculated stiffness adjustment coefficient.

Images