A method for bullet-proof fly-by-wire braking in the event of a cylinder head stud fracture

Abstract

A method for preventing cylinder head stud breakage and subsequent flight braking is based on the principle of friction braking. A stud brake ring is installed on the cylinder head stud below the cylinder head, with a gap between the ring and the cylinder head to apply positive pressure and generate friction. When the cylinder head stud breaks, the brake ring, relying on the blocking force of the cylinder head, dynamically intercepts and dissipates the kinetic energy of the stud, converting the kinetic energy of the broken stud into frictional work, thus achieving frictional energy dissipation and preventing the cylinder head stud from flying out. This invention, by installing a directional energy dissipation device on the cylinder head stud, completely converts the kinetic energy of the ejected stud fragment into frictional work and heat at the moment of breakage, thereby preventing the stud fragment from flying out and effectively reducing the risk of secondary damage caused by the broken cylinder head stud, ensuring the reliability of the power equipment system and the safety of personnel, and ensuring the normal operation of the diesel engine.

Description

Technical Field

[0001] This invention relates to the cylinder structure of a marine low-speed diesel engine, and particularly to a bulletproof braking method for cylinder head stud fracture, belonging to the technical field of marine diesel engine. Background Technology

[0002] As is well known, the cylinder head of a marine diesel engine is fixed to the cylinder block by cylinder head studs. Multiple vertical cylinder head studs are fixedly connected to the cylinder block. During installation, the cylinder head studs pass through the cylinder head stud holes on the cylinder head. After the cylinder head and cylinder block are fitted together, the cylinder head nuts are connected to the cylinder head studs. Finally, the cylinder head nuts are tightened by a hydraulic tensioner, thereby fixing the cylinder head to the cylinder block.

[0003] As a core component of a marine propulsion system, the cylinder head stud is a crucial component ensuring the sealing and structural integrity of the combustion chamber. During operation, the cylinder head stud must withstand periodic burst pressures and alternating mechanical loads within the cylinder, thus directly affecting the operational safety and reliability of the main engine. However, under prolonged high loads or extreme operating conditions, the cylinder head stud may fracture due to material defects, preload relaxation, or fatigue limits. At the moment of fracture, the internal strain energy breaks the cylinder head stud into high-speed, high-energy splashes, which can not only damage engine room equipment but also cause fatal consequences to personnel, seriously threatening the operational safety of the ship.

[0004] Existing marine diesel engines are equipped with passive protection devices, such as nitrile rubber vibration damping brackets, which can reduce the vibration of cylinder head studs to some extent. However, due to the lack of a dynamic energy dissipation mechanism in their structural characteristics, they cannot dissipate all the kinetic energy that would cause the stud to break and fly off. Therefore, they are unable to effectively suppress the risk of the cylinder head stud flying off due to the instantaneous high kinetic energy impact of the breakage. Therefore, an active braking device designed based on the motion characteristics of the broken stud, to avoid the hazards caused by the stud fragment flying off, is of great engineering significance for improving the safety protection level of marine main engines and reducing operation and maintenance risks. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preventing the cylinder head stud from flying out of the cylinder head. Based on the principle of friction braking, by installing a directional energy dissipation device, the kinetic energy of the cylinder head stud is dynamically intercepted and dissipated at the moment of fracture. The kinetic energy of the stud fragment flying out is completely converted into frictional work, thereby achieving frictional energy dissipation and effectively avoiding the risk of secondary damage caused by the cylinder head stud flying out of the cylinder head.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preventing bullet-throwing braking of a broken cylinder head stud, wherein the cylinder head stud passes through a cylinder head stud hole on the cylinder head, and the cylinder head is fixed to the cylinder block by tightening the cylinder head nut; characterized in that: based on the principle of friction braking, a directional energy dissipation device is installed on the cylinder head stud below the cylinder head. When the cylinder head stud breaks, the blocking reaction force of the cylinder head dynamically intercepts and dissipates the kinetic energy of the cylinder head stud, completely converting the kinetic energy of the broken stud into frictional work, thereby achieving frictional energy dissipation and achieving bullet-throwing braking of the cylinder head stud to prevent the broken stud from flying out.

[0007] Furthermore, the bulletproof braking method specifically includes: a stud brake ring, serving as a directional energy dissipation device, is tightly installed on the outer periphery of the cylinder head stud below the cylinder head, with a certain gap between the stud brake ring and the cylinder head. The stud brake ring applies a uniform circumferential normal force to the cylinder head stud and generates a frictional force for braking. When the cylinder head stud breaks, the broken stud moves upward along with the stud brake ring. When the stud brake ring is blocked by the reaction force generated by the cylinder head, it stops below the cylinder head. If the broken stud continues to move upward, the frictional force generated by the stud brake ring on the cylinder head stud will convert work into heat energy, which is used to consume the kinetic energy of the broken stud flying outward, until the broken stud exhausts its kinetic energy and stops in the cylinder head stud hole of the cylinder head, thereby achieving bulletproof braking of the cylinder head stud.

[0008] Furthermore, the inner wall of the stud brake retainer is coated with an HVOF coating.

[0009] Furthermore, a 10mm gap is left between the stud brake retaining ring and the cylinder head.

[0010] Furthermore, the stud brake retaining ring includes a wear-resistant bushing and a clamp. The wear-resistant bushing is tightly fitted to the outer circumference of the cylinder head stud, and the clamp is a standard split hose clamp that is wrapped around the lower part of the wear-resistant bushing. The wear-resistant bushing is tightly clamped to the cylinder head stud by tightening the bolts.

[0011] Furthermore, the wear-resistant bushing adopts a split structure, comprising two mating half-bushings. The upper part of the wear-resistant bushing is conical with an outer conical surface, and the lower part is cylindrical with a central hole. The diameter of the hole matches the outer diameter of the cylinder head stud to tightly fit the cylinder head stud. The diameter of the upper part of the outer conical surface is smaller than the diameter of the cylinder head stud hole so as to extend into the cylinder head stud hole, and the diameter of the lower part is larger than the diameter of the cylinder head stud hole. An annular clamp mounting groove for installing and positioning the clamp is provided on the cylindrical surface of the lower part of the wear-resistant bushing.

[0012] Furthermore, the inclination angle of the outer conical surface of the wear-resistant bushing is 8.5°.

[0013] Furthermore, the wear-resistant bushing has several long grooves evenly distributed along the axial direction from top to bottom, and the inner surface of the central hole is provided with a stress groove.

[0014] Furthermore, the length of the long groove accounts for 55-60% of the height of the wear-resistant bushing, the lower root adopts an arc transition, and the position interval between two adjacent long grooves is 60°.

[0015] Furthermore, the surfaces of the inner bore walls in the center hole of the wear-resistant bushing, except for the stress groove, are treated with an HVOF coating.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention, by installing a directional energy dissipation device on the cylinder head stud, dynamically intercepts and dissipates the kinetic energy of the stud fragments that fly out at the moment of cylinder head stud breakage. The kinetic energy of the stud fragments is completely converted into frictional work and heat, thereby achieving anti-flying braking of the cylinder head stud, avoiding the flying out of the stud fragments, effectively reducing the risk of secondary damage caused by the cylinder head studs flying out, ensuring the reliability of the power equipment system and the safety of personnel, and ensuring the normal operation of the diesel engine. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the stud brake retaining ring.

[0018] Figure 2 This is a schematic diagram of half a wear-resistant bushing.

[0019] Figure 3 This is a schematic diagram of the installation of the stud brake retaining ring.

[0020] Figure 4 This is a cross-sectional view of the installation of the stud brake retaining ring.

[0021] Figure 5 This is a schematic diagram of the mechanism of action of the present invention.

[0022] In the picture, 01—Cylinder head, 02—Cylinder head stud, 03—Cylinder head nut, 04—Cylinder head stud hole, 05—Stud brake ring, 1—Wear-resistant bushing, 2—Clamp, 11—Inner hole wall, 12—Outer conical surface, 13—Cylindrical surface, 14—Clamp mounting groove, 15—Long groove, 16—Stress groove. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following embodiments are not intended to limit the scope of the present invention. All equivalent substitutions and modifications made based on the content of this specification should fall within the scope of protection claimed by the present invention.

[0024] This invention relates to a braking system that prevents the broken stud from flying off when a cylinder head stud breaks. Please refer to [link to relevant documentation]. Figure 3 The cylinder head stud 02 passes through the cylinder head stud hole 04 on the cylinder head 01, and the cylinder head 01 is fixed to the cylinder block by pumping the cylinder head nut 03.

[0025] The bulletproof braking method of the present invention is based on the principle of friction braking. A directional energy dissipation device is installed on the cylinder head stud below the cylinder head. When the cylinder head stud breaks, the blocking reaction force of the cylinder head is used to dynamically intercept and dissipate the kinetic energy of the cylinder head stud, and the kinetic energy of the stud fracture is completely converted into frictional work, thereby achieving frictional energy dissipation and achieving bulletproof braking of the cylinder head stud to prevent the stud fracture from flying out.

[0026] The bulletproof braking method specifically includes: a stud brake ring, serving as a directional energy dissipation device, is tightly installed on the outer periphery of the cylinder head stud below the cylinder head, with a certain gap between the stud brake ring and the cylinder head. The stud brake ring applies a uniform circumferential normal force to the cylinder head stud and generates a frictional force for braking. When the cylinder head stud breaks, the broken stud moves upward along with the stud brake ring. When the stud brake ring is blocked by the reaction force generated by the cylinder head, it stops below the cylinder head. If the broken stud continues to move upward, the frictional force generated by the stud brake ring on the cylinder head stud will convert into heat energy to consume the kinetic energy of the broken stud, until the broken stud exhausts its kinetic energy and stops in the cylinder head stud hole, thereby achieving bulletproof braking of the cylinder head stud.

[0027] Furthermore, in order to increase the coefficient of friction and improve the braking effect, the inner wall of the stud brake retainer is coated with an HVOF coating.

[0028] Please see Figure 1 The illustrated stud brake ring includes a wear-resistant bushing 1 and a clamp 2. The wear-resistant bushing 1 is tightly fitted to the outer circumference of the cylinder head stud 02, and the clamp 2 is wrapped around the lower part of the wear-resistant bushing 1, tightly holding the wear-resistant bushing 1 onto the cylinder head stud 02.

[0029] The wear-resistant bushing 1, as a key component of the bulletproof brake for fractured studs, needs to balance high energy efficiency and structural reliability. Its specific structure is as follows: Figure 2As shown, the upper part of the wear-resistant bushing 1 is conical, the lower part is cylindrical, and the center has a central hole with a diameter that matches the cylinder head stud 02 for a tight fit. The wear-resistant bushing 1 adopts a split structure, that is, it is split 180° along the diameter direction, and 2mm is machined off on both opposite surfaces to form two half bushings for easy disassembly, assembly, and clamping. Please refer to... Figure 2 The wear-resistant bushing 1 has an outer conical surface 12 on its upper part with an inclination angle of 8.5°. The diameter of the lower part of the outer conical surface 12 is larger than the diameter of the cylinder head stud hole 04, and the diameter of the upper part is smaller than the diameter of the cylinder head stud hole 04, so that the upper part of the wear-resistant bushing 1 can extend into the cylinder head stud hole 04. The wear-resistant bushing 1 has several long grooves 15 evenly distributed axially from the top down to reduce axial stiffness, so that under the reaction force of the cylinder head, the upper part of the wear-resistant bushing 1 can be compressed and further extend into the cylinder head stud hole 04. See Figure 5 The length of the long groove 15 accounts for approximately 55%-60% of the height of the wear-resistant bushing 1, and the lower root adopts an arc transition. The positional interval between the two long grooves 15 can be set to 60°. A stress groove 16 is provided on the inner surface of the center hole of the wear-resistant bushing 1 to achieve directional tightening of the upper part of the wear-resistant bushing 1. Except for the stress groove 16, the surface of the inner hole wall 11 of the center hole of the wear-resistant bushing 1 is treated with HVOF coating, mainly to enhance the wear resistance and corrosion resistance of the wear-resistant bushing 1. After coating, the inner diameter of the center hole of the wear-resistant bushing 1 must match the outer diameter of the cylinder head stud 02 to ensure correct installation. An annular clamp mounting groove 14 is provided on the cylindrical surface 13 at the lower part of the wear-resistant bushing 1 for installing and positioning the clamp 2.

[0030] The clamp 2 is a standard split-type hose clamp, tightened on both sides by bolts, such as Figure 1 As shown, the initial normal force is provided between the wear-resistant bushing 1 and the cylinder head stud 02 to ensure effective contact between the outer surfaces of the wear-resistant bushing 1 and the cylinder head stud 02, thereby constraining the axial or circumferential displacement of the wear-resistant bushing 1. Furthermore, the circumferential preload of the bolt also applies a certain vertical normal force to the friction surface with the cylinder head stud 02, further increasing the normal force on the friction surface. Given a constant coefficient of friction, this generates greater frictional force, which helps to prevent the broken stud from flying out. The elastic deformation capability of the hose clamp can absorb high-frequency vibration energy, reducing the risk of bolt loosening, while simultaneously making the circumferential preload applied by the clamp 2 more uniform, compensating for the assembly gap between the wear-resistant bushing 1 and the cylinder head stud 02.

[0031] When the stud brake retaining ring 05 is installed, as follows: Figure 4As shown, firstly, the two half-sleeves of the wear-resistant bushing 1 are aligned and tightly fitted against the outer surface of the cylinder head stud 02 located below the cylinder head stud hole 04, with the inner wall 11 of the central hole facing inward. Then, the clamp 2 is used to position and surround the wear-resistant bushing 1 in the clamp mounting groove 14 at its lower part. Next, the height position of the stud brake ring 05 is moved up and down along the cylinder head stud 02, first so that the outer conical surface 12 of the wear-resistant bushing 1 extends into the cylinder head stud hole 04 and is close to the lower edge of the cylinder head stud hole 04, then it is moved downwards a suitable distance h, approximately 10mm, leaving a certain gap between the stud brake ring 05 and the cylinder head 01. Finally, the bolts of the clamp 2 are tightened, tightly clamping the stud brake ring 05 onto the cylinder head stud 02 below the cylinder head stud hole 04. Figure 3 As shown, the wear-resistant bushing 1, with its inner wall 11 coated with HVOF, applies a uniform circumferential normal pressure to the cylinder head stud 02 to generate frictional force that prevents the brake stud from flying off. The clamp 2 can adjust the preload at any time during the clamping process of the wear-resistant bushing 1 to avoid local stress concentration that could cause the HVOF coating inside the wear-resistant bushing 1 to crack.

[0032] When the cylinder head stud 02 breaks unexpectedly, please refer to [the relevant documentation]. Figure 3 If the broken stud of cylinder head stud 02 bounces downwards, it will be restrained by cylinder head nut 03 and cylinder head 01, and will remain trapped in cylinder head stud hole 04. If the broken stud of cylinder head stud 02 bounces upwards, please refer to... Figure 5 This will cause the stud brake ring 05 on it to move upwards. When the diameter of the outer conical surface 12 on the wear-resistant bushing 1 is larger than that of the cylinder head stud hole 04, and is blocked by the lower edge of the cylinder head stud hole 04, the stud brake ring 05 will be subjected to the reaction force of the cylinder head 01 and will be stuck in the cylinder head stud hole 04 and stop below the cylinder head 01. This reaction force is equal in magnitude and opposite in direction to the total load on the cylinder head stud 02. At this time, the broken stud of the cylinder head stud 02 will continue to move upwards, and the friction force generated by the stopped wear-resistant bushing 1 on the cylinder head stud 02 will do work and be converted into heat energy to consume the kinetic energy of the cylinder head stud 02 flying away, until the cylinder head stud 02 exhausts its flying kinetic energy and stops in the cylinder head stud hole 04 of the cylinder head 01, thereby inhibiting the flying out of the broken cylinder head stud 02 and realizing the anti-flying braking of the cylinder head stud 02.

[0033] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. All equivalent changes and modifications made in accordance with the content of the present invention should be within the technical scope of the present invention.

Claims

1. A method for bullet-proof flywheel braking in the event of a cylinder head stud breaking, the cylinder head stud passing through a cylinder head stud hole in a cylinder head, the cylinder head being secured to a cylinder block by a pump-up cylinder head nut; characterised in that: Based on the principle of friction braking, a directional energy dissipation device is installed on the cylinder head stud below the cylinder head. When the cylinder head stud breaks, the blocking reaction force of the cylinder head is used to dynamically intercept and dissipate the kinetic energy of the cylinder head stud, completely converting the kinetic energy of the stud fracture into frictional work, thereby achieving frictional energy dissipation and achieving anti-flying braking of the cylinder head stud to prevent the stud fracture from flying out.

2. The bulletproof braking method for cylinder head stud fracture according to claim 1, characterized in that: The bulletproof braking method specifically includes: a stud brake ring, serving as a directional energy dissipation device, is tightly installed on the outer periphery of the cylinder head stud below the cylinder head, with a certain gap between the stud brake ring and the cylinder head. The stud brake ring applies a uniform circumferential normal force to the cylinder head stud and generates a frictional force for braking. When the cylinder head stud breaks, the broken stud moves upward along with the stud brake ring. When the stud brake ring is blocked by the reaction force generated by the cylinder head, it stops below the cylinder head. If the broken stud continues to move upward, the frictional force generated by the stud brake ring on the cylinder head stud will convert work into heat energy, which is used to consume the kinetic energy of the broken stud flying outward, until the broken stud exhausts its kinetic energy and stops in the cylinder head stud hole of the cylinder head, thereby achieving bulletproof braking of the cylinder head stud.

3. The bulletproof braking method for cylinder head stud fracture according to claim 2, characterized in that: The inner wall of the stud brake retaining ring is coated with an HVOF coating.

4. The bulletproof braking method for cylinder head stud fracture according to claim 2, characterized in that: A 10mm gap is left between the stud brake retaining ring and the cylinder head.

5. The bulletproof braking method for cylinder head stud fracture according to claim 2, characterized in that: The stud brake retainer includes a wear-resistant bushing and a clamp. The wear-resistant bushing is tightly fitted to the outer circumference of the cylinder head stud, and the clamp is a standard split hose clamp that is wrapped around the lower part of the wear-resistant bushing. The wear-resistant bushing is tightly clamped to the cylinder head stud by tightening the bolts.

6. The bulletproof braking method for cylinder head stud fracture according to claim 5, characterized in that: The wear-resistant bushing adopts a split structure, including two mating half bushings. The upper part of the wear-resistant bushing is conical with an outer conical surface, and the lower part is cylindrical with a central hole. The diameter of the hole matches the outer diameter of the cylinder head stud to fit tightly against the cylinder head stud. The diameter of the upper part of the outer conical surface is smaller than the diameter of the cylinder head stud hole so that it can extend into the cylinder head stud hole, and the diameter of the lower part is larger than the diameter of the cylinder head stud hole. An annular clamp mounting groove for installing and positioning the clamp is provided on the cylindrical surface of the lower part of the wear-resistant bushing.

7. The bulletproof braking method for cylinder head stud fracture according to claim 6, characterized in that: The inclination angle of the outer conical surface of the wear-resistant bushing is 8.5°.

8. The bulletproof braking method for cylinder head stud fracture according to claim 5, characterized in that: The wear-resistant bushing has several long grooves evenly distributed along the axial direction from top to bottom, and the inner surface of the central hole is provided with a stress groove.

9. The bulletproof braking method for cylinder head stud fracture according to claim 8, characterized in that: The length of the long groove accounts for 55-60% of the height of the wear-resistant bushing, and the lower root adopts an arc transition. The position interval between two adjacent long grooves is 60°.

10. The bulletproof braking method for cylinder head stud fracture according to claim 8, characterized in that: The inner wall surface of the wear-resistant bushing, except for the stress groove, is treated with HVOF coating.

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