Mechanical overspeed protection system for medium-speed and high-power diesel engines

Abstract

A mechanical overspeed protection system for medium-speed, high-power diesel engines is provided, belonging to the field of diesel engine control technology. The system comprises a mechanical overspeed protection device and an air-controlled stop valve. The mechanical overspeed protection device is fixed to the diesel engine body, and the connecting shaft of the mechanical overspeed protection device is connected to the camshaft installed on the diesel engine body. The main air inlet of the air-controlled stop valve is connected to the main compressed air source, and the main air outlet of the air-controlled stop valve is respectively connected to the injection pump plunger lifting mechanism of each cylinder on the diesel engine body. The main compressed air passes through the air-controlled stop valve to the injection pump plunger lifting mechanism. The compressed air inlet of the mechanical overspeed protection device is connected to the auxiliary compressed air source, and the compressed air outlet of the mechanical overspeed protection device is connected to the control air interface of the air-controlled stop valve. The present invention uses compressed air to push the injection pump plunger lifting mechanism of each cylinder, quickly cutting off the fuel supply to control the diesel engine shutdown, thereby achieving diesel engine overspeed protection. The system has a simple structure, low cost, and improved system reliability.

Description

Technical Field

[0001] The invention belongs to the technical field of diesel engine control, and in particular relates to a mechanical overspeed protection system for a medium-speed, high-power diesel engine. Background Art

[0002] Usually, diesel engines are equipped with overspeed protection to avoid damage to the machine and casualties caused by excessive engine speed, especially medium-speed and high-power diesel engines with high speed, high power and large inertia. Safety is the top priority in diesel engine operation.

[0003] Currently, there are two main types of overspeed protection for medium- and high-power diesel engines: mechanical and electronic. The mechanical overspeed protection device is installed at the end of the diesel engine's camshaft. A flyweight is installed inside the device. The centrifugal force generated by the rotation of the flyweight opens the hydraulic oil circuit. The hydraulic oil pushes the parking cylinder piston to push the fuel rack back to the "zero position", cutting off the fuel and stopping the diesel engine, thus achieving diesel engine overspeed protection. The electronic type uses a speed sensor to measure the diesel engine speed. The electrical and electronic circuit module controls the solenoid valve to connect compressed air. The compressed air pushes the piston cylinder to push the fuel rack back to the "zero position", cutting off the fuel and stopping the diesel engine. Alternatively, high-pressure compressed air is used to push the fuel pump lifting mechanism of each cylinder to cut off the fuel and stop the diesel engine, thus achieving diesel engine overspeed protection.

[0004] Since the mechanical overspeed protection device uses lubricating oil as its working medium, which is taken from the diesel engine's lubricating oil circuit, the increase of impurities and oil stains in the lubricating oil with use may cause the piston assembly of the parking cylinder to get stuck, affecting the normal operation of the parking cylinder, posing certain safety hazards. In addition, the aging of the seals will cause the lubricating oil to leak, affecting the cleanliness and appearance of the entire machine, and maintenance is also very troublesome.

[0005] The electronic overspeed protection device relies on a speed sensor and an electrical and electronic circuit module, which is expensive. In addition, once a power outage occurs, the diesel engine will lose its safety protection, directly threatening the operating safety of the diesel engine.

[0006] In view of the problems existing in the above-mentioned existing structures, it is necessary to propose improvements. Summary of the Invention

[0007] The technical problem solved by the present invention is to provide a mechanical overspeed protection system for medium-speed, high-power diesel engines. The present invention is based on a mechanical overspeed protection device and compressed air. The compressed air pushes the plunger lifting mechanism of the fuel injection pump of each cylinder to quickly cut off the fuel supply and control the diesel engine to stop, thereby realizing diesel engine overspeed protection. The system has a simple structure, low cost, and improved system reliability.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A mechanical overspeed protection system for a medium-speed, high-power diesel engine comprises a mechanical overspeed protection device and a pneumatically controlled parking valve. The mechanical overspeed protection device is fixed to the diesel engine body, and a connecting shaft of the mechanical overspeed protection device is connected to a camshaft mounted on the diesel engine body.

[0010] The main air inlet of the pneumatic stop valve is connected to the main compressed air source, and the main air outlet of the pneumatic stop valve is respectively connected to the injection pump plunger lifting mechanism of each cylinder on the diesel engine body, and the main compressed air passes through the pneumatic stop valve to the injection pump plunger lifting mechanism; the compressed air inlet of the mechanical overspeed protection device is connected to the auxiliary compressed air source, and the compressed air outlet of the mechanical overspeed protection device is connected to the control air interface of the pneumatic stop valve;

[0011] When the diesel engine speed is too high and exceeds the set value, the mechanical overspeed protection device will be activated to connect the auxiliary compressed air circuit, open the air-controlled parking valve, and the main compressed air will push the plunger lifting mechanism of the injection pump of each cylinder, cut off the fuel, control the diesel engine to stop, and realize the diesel engine overspeed protection.

[0012] To further limit the above solution, the main compressed air source adopts a 3MPa compressed air source, and the auxiliary compressed air source adopts a 0.7MPa compressed air source.

[0013] Further defining the above solution, the mechanical overspeed protection device includes a housing, and a compressed air inlet and a compressed air outlet are respectively provided on both sides of the upper part of the housing; a piston cylinder is axially slidably provided in the inner cavity of the upper part of the housing, and the piston head of the valve stem with a reset handle is adapted to the piston cylinder, and a spring I is provided inside the piston cylinder, and the spring I is sleeved on the outside of the valve stem with the reset handle, and the two ends of the spring I are respectively pressed on the inner end of the piston cylinder and the piston head of the valve stem with the reset handle, and the valve stem with the reset handle and the piston cylinder are provided with through holes for connecting with the compressed air inlet and the compressed air outlet;

[0014] A support shaft is fixedly provided in the middle of the inner cavity of the shell, and a locking block is movably sleeved on the support shaft. The locking block is used to lock the piston cylinder. The right end of the locking block and the shell are limited by an end face bearing provided on the support shaft. The support shaft sleeve of the left end of the locking block is provided with a positioning sleeve, and the support shaft sleeve of the left end of the positioning sleeve is provided with a spring II. The spring II presses the left end of the locking block through the positioning sleeve.

[0015] One end of the connecting shaft is movably adapted to the lower part of the inner cavity of the shell, and a speed setting screw is provided at the end of the connecting shaft. The speed setting screw is covered with a spring III on the outside and is inserted into the hole at the end of the connecting shaft and screwed with the nut at the other end of the hole. The connecting shaft is connected to the camshaft through a screw and a flat key.

[0016] To further define the above solution, a guide mounting plate is fixed to the upper part of the shell, the valve stem with the reset handle passes through the hole on the guide mounting plate to guide it, a position switch is fixed on the guide mounting plate, and the position switch contact head contacts the valve stem with the reset handle.

[0017] As a further limitation of the above solution, limit screws for limiting the swing position of the locking block are provided on the left and right sides of the upper portion of the housing.

[0018] The advantages of the present invention compared with the prior art are:

[0019] 1. This solution is based on a mechanical overspeed protection device and compressed air. The compressed air pushes the lifting mechanism of the fuel pump of each cylinder, quickly cutting off the fuel supply and controlling the diesel engine to stop, thus achieving diesel engine overspeed protection. It has a simple structure, low cost, and is independent of the electrical control system. This improves the reliability of the system and provides a strong guarantee for the safe operation of medium-speed, high-power diesel engines.

[0020] 2. This solution uses compressed air as the working medium, avoiding the problems of easy stagnation and leakage when using lubricating oil as the medium in the existing technology. It can be directly installed through the camshaft end of the diesel engine, with a simple structure and easy installation and maintenance.

[0021] 3. This solution uses an air-controlled parking valve, which uses low-pressure compressed air to control high-pressure compressed air. It is safe and reliable. The entire system is a mechanical structure and does not rely on speed sensors or electrical and electronic circuit modules. This reduces costs and avoids the risk of speed sensor and electrical and electronic circuit module failure or system power failure. It improves the reliability of the diesel engine overspeed protection system and ensures the safety of diesel engine operation.

[0022] 4. This solution uses compressed air to push the plunger lifting mechanism of each cylinder fuel injection pump instead of the previous method of using lubricating oil piston cylinder to push the fuel rack, avoiding the risk of piston or fuel rack getting stuck and unable to stop quickly, improving the reliability of the system, simplifying the structure, and facilitating installation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention;

[0024] Figure 2 Schematic diagram of the internal structure of the mechanical overspeed protection device of the present invention;

[0025] Figure 3 It is a right view of the mechanical overspeed protection device in the present invention. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0028] See also Figure 1-3 , details the embodiments of the present invention.

[0029] Mechanical overspeed protection system for medium- and high-power diesel engines, see Figure 1 As shown, it includes a mechanical overspeed protection device 1 and a pneumatic parking valve 3, the mechanical overspeed protection device 1 is fixed on the diesel engine body 5, and the connecting shaft 1-10 of the mechanical overspeed protection device 1 is connected to the camshaft 2 installed on the diesel engine body 5;

[0030] The main air inlet of the pneumatic stop valve 3 is connected to the main compressed air source, and the main air outlet of the pneumatic stop valve 3 is respectively connected to the injection pump plunger lifting mechanism 4 of each cylinder on the diesel engine body 5, and the main compressed air passes through the pneumatic stop valve 3 to the injection pump plunger lifting mechanism 4; the compressed air inlet 1-17 of the mechanical overspeed protection device 1 is connected to the auxiliary compressed air source, and the compressed air outlet 1-18 of the mechanical overspeed protection device 1 is connected to the control air interface of the pneumatic stop valve 3.

[0031] The main compressed air source adopts a 3MPa compressed air source, and the auxiliary compressed air source adopts a 0.7MPa compressed air source.

[0032] When the diesel engine speed exceeds the set value, the mechanical overspeed protection device 1 activates, connects the 0.7MPa compressed air circuit, and opens the air-controlled shutoff valve. The 3MPa compressed air pushes the plunger lifting mechanism of each cylinder's fuel injection pump, cutting off fuel and shutting down the diesel engine, thus implementing overspeed protection. This solution, based on the mechanical overspeed protection device and compressed air, provides diesel engine overspeed protection with a simple structure, low cost, and independence from electrical control systems. This improves system reliability and provides a strong guarantee for the safe operation of medium- and high-speed, high-power diesel engines.

[0033] This embodiment uses compressed air as the working medium, avoiding the problems of easy sticking and leakage when using lubricating oil as the medium in the prior art, and avoiding the risk of the piston or fuel rack getting stuck and unable to shut down quickly, thereby improving the reliability of the system, simplifying the structure, and facilitating installation and maintenance.

[0034] In one embodiment, see Figure 2 and 3 As shown, the mechanical overspeed protection device 1 includes a shell 1-1, and a compressed air inlet 1-17 and a compressed air outlet 1-18 are respectively provided on both sides of the upper part of the shell 1-1; a piston cylinder 1-2 is axially slidably provided in the inner cavity of the upper part of the shell 1-1, and the piston head of the valve stem 1-4 with a reset handle is adapted to the piston cylinder 1-2, and a spring I 1-3 is provided inside the piston cylinder 1-2, and the spring I 1-3 is sleeved on the outside of the valve stem 1-4 with the reset handle, and the two ends of the spring I 1-3 are respectively pressed on the inner end of the piston cylinder 1-2 and the piston head of the valve stem 1-4 with the reset handle, and the valve stem 1-4 with the reset handle and the piston cylinder 1-2 are provided with through holes corresponding to the compressed air inlet 1-17 and the compressed air outlet 1-18;

[0035] A support shaft 1-5 is fixedly provided in the middle of the inner cavity of the shell 1-1, and a locking block 1-6 is movably sleeved on the support shaft 1-5. The locking block 1-6 is used to lock the piston cylinder 1-2. The right end of the locking block 1-6 is limited by an end bearing 1-7 provided on the support shaft 1-5 and the left end of the locking block 1-6 is sleeved with a positioning sleeve 1-8. A spring II 1-9 is sleeved on the support shaft 1-5 at the left end of the positioning sleeve 1-8. The spring II 1-9 presses the left end of the locking block 1-6 through the positioning sleeve 1-8.

[0036] One end of the connecting shaft 1-10 is movably adapted to the lower part of the inner cavity of the shell 1-1, and a speed setting screw 1-11 is provided at the end of the connecting shaft 1-10. The speed setting screw 1-11 is covered with a spring III 1-12 on the outside and is inserted into the hole at the end of the connecting shaft 1-10 and screwed with the nut 1-13 at the other end of the hole. The connecting shaft 1-10 is connected to the camshaft 2 by a screw and a flat key.

[0037] A guide mounting plate 1-14 is fixed to the upper portion of the housing 1-1. The valve stem 1-4 with a reset handle passes through a hole in the guide mounting plate 1-14, guiding the valve stem 1-4 with the reset handle. A position switch 1-15 is fixed to the guide mounting plate 1-14. The contact of the position switch 1-15 contacts the valve stem 1-4 with the reset handle, thereby outputting an activation signal of the diesel engine mechanical overspeed protection device to the control system.

[0038] Limit screws 1-16 are provided on the left and right sides of the upper portion of the housing 1-1 for limiting the swing position of the locking block 1-6 to prevent the limit screws 1-16 from swinging too much.

[0039] The operating principle of mechanical overspeed protection device 1 is as follows: Mechanical overspeed protection device 1 is mounted on the end of the diesel engine's camshaft 2 via connecting shaft 1-10 and is driven to rotate by the diesel engine's camshaft 2. Adjusting the preload of spring III 1-12 by adjusting speed setting screw 1-11 changes the centrifugal force exerted by speed setting screw 1-11 during its rotation. When the engine speed reaches the overspeed protection value, the centrifugal force generated by speed setting screw 1-11 overcomes the preload of spring III 1-12, causing it to swing out. During rotation, it strikes locking block 1-6, causing it to shift position. Valve stem 1-4 with a reset handle, which is locked by locking block 1-6, now slides inward (rightward in the diagram) under the action of spring I 1-3. A through hole is machined into valve stem 1-4 with reset handle. At this point, 0.7 MPa compressed air is supplied, causing valve stem 1-4 with reset handle to slide inward (rightward in the diagram), triggering position switch 1-15 and outputting an actuation signal for the diesel engine's mechanical overspeed protection device to the control system. When the diesel engine stops and the fault is confirmed, the mechanical overspeed protection device can be reset by pulling out the valve stem 1-4 with the reset handle outward (to the left in the figure). At the same time, the position switch 1-15 is reset, and the locking block 1-6 is reset under the action of the spring II 1-9. The limit screw 1-16 is used to limit the swing position of the locking block 1-6.

[0040] In this embodiment, the entire system is a mechanical structure and does not rely on a speed sensor or an electrical and electronic circuit module, which reduces costs, avoids the risk of failure of the speed sensor and the electrical and electronic circuit module or system power failure, improves the reliability of the diesel engine overspeed protection system, and ensures the safety of diesel engine operation.

[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0042] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. Mechanical overspeed protection system for medium-high-speed and high-power diesel engines, characterized by: It comprises a mechanical overspeed protection device (1) and a pneumatically controlled parking valve (3), wherein the mechanical overspeed protection device (1) is fixed on a diesel engine body (5), and a connecting shaft (1-10) of the mechanical overspeed protection device (1) is connected to a camshaft (2) mounted on the diesel engine body (5); The main air inlet of the pneumatic stop valve (3) is connected to the main compressed air source, and the main air outlet of the pneumatic stop valve (3) is respectively connected to the fuel injection pump plunger lifting mechanism (4) of each cylinder on the diesel engine body (5), and the main compressed air passes through the pneumatic stop valve (3) to the fuel injection pump plunger lifting mechanism (4); the compressed air inlet (1-17) of the mechanical overspeed protection device (1) is connected to the auxiliary compressed air source, and the compressed air outlet (1-18) of the mechanical overspeed protection device (1) is connected to the control air interface of the pneumatic stop valve (3); The main compressed air source adopts a 3MPa compressed air source, and the auxiliary compressed air source adopts a 0.7MPa compressed air source; When the diesel engine speed is too high and exceeds the set value, the mechanical overspeed protection device (1) is activated to connect the auxiliary compressed air circuit, open the air-controlled parking valve (3), and the main compressed air pushes the plunger lifting mechanism of the injection pump of each cylinder to cut off the fuel, control the diesel engine to stop, and realize the diesel engine overspeed protection; The mechanical overspeed protection device (1) comprises a shell (1-1), wherein the upper two sides of the shell (1-1) are respectively provided with a compressed air inlet (1-17) and a compressed air outlet (1-18); a piston cylinder (1-2) is axially slidably provided in the inner cavity of the upper part of the shell (1-1), the piston head of the valve stem (1-4) with a reset handle is adapted in the piston cylinder (1-2), a spring I (1-3) is provided inside the piston cylinder (1-2), the spring I (1-3) is sleeved on the outside of the valve stem (1-4) with the reset handle, and the two ends of the spring I (1-3) are respectively pressed on the inner end of the piston cylinder (1-2) and the piston head of the valve stem (1-4) with the reset handle, and the valve stem (1-4) with the reset handle and the piston cylinder (1-2) are provided with through holes corresponding to the compressed air inlet (1-17) and the compressed air outlet (1-18); A support shaft (1-5) is fixedly positioned in the middle of the inner cavity of the shell (1-1) by a pin, a locking block (1-6) is movably sleeved on the support shaft (1-5), and the locking block (1-6) is used to lock the piston cylinder (1-2). The right end of the locking block (1-6) and the shell (1-1) are limited by an end face bearing (1-7) provided on the support shaft (1-5), a positioning sleeve (1-8) is sleeved on the support shaft (1-5) at the left end of the locking block (1-6), and a spring II (1-9) is sleeved on the support shaft (1-5) at the left end of the positioning sleeve (1-8), and the spring II (1-9) presses the left end of the locking block (1-6) through the positioning sleeve (1-8); One end of the connecting shaft (1-10) is movably adapted to the lower part of the inner cavity of the housing (1-1). A speed setting screw (1-11) is provided at the end of the connecting shaft (1-10). The speed setting screw (1-11) is covered with a spring III (1-12) on the outside and is inserted into a hole at the end of the connecting shaft (1-10) and screwed with a nut (1-13) at the other end of the hole. The connecting shaft (1-10) is connected to the camshaft (2) via a screw and a flat key.

2. The mechanical overspeed protection system for a medium-high-speed, high-power diesel engine according to claim 1, characterized in that: A guide mounting plate (1-14) is fixed to the upper portion of the housing (1-1), and the valve stem (1-4) with the reset handle passes through a hole on the guide mounting plate (1-14) to guide it.

3. The mechanical overspeed protection system for a medium-high-speed, high-power diesel engine according to claim 2, characterized in that: A position switch (1-15) is fixed on the guide mounting plate (1-14), and a contact joint of the position switch (1-15) contacts a valve stem (1-4) with a reset handle.

4. The mechanical overspeed protection system for a medium-high speed, high power diesel engine according to claim 1, characterized in that: Limit screws (1-16) for limiting the swing position of the locking block (1-6) are provided on the left and right sides of the upper portion of the housing (1-1).

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