A propeller speed limiter

Abstract

The present invention discloses a propeller speed limiter. The transmission shaft is slidably connected to the small-diameter hole of the housing through a bushing. Two L-shaped counterweights located in the large-diameter hole of the housing are installed at the upper end of the transmission shaft. The oil distributing valve is slidably assembled in the central hole of the transmission shaft, and a speed limiting spring is crimped at its upper end. The two hook parts of the two L-shaped counterweights abut against the outer ring of the bearing. The lower end of the cover is fixed to the upper end face of the housing, and an adjusting screw is threadedly locked and fixed in its small hole. The adjusting plunger is assembled together with the guide plate and the speed limiting spring seat and is installed in the large cylindrical hole of the cover. There is an annular oil groove I on the transmission shaft, and a plurality of oil distributing holes communicating with the lubricating oil inlet hole of the housing and an oil return hole I communicating with the oil return hole II of the housing are opened. The oil distributing valve is provided with an annular oil groove II. By moving the oil distributing valve, the annular oil groove II is made to be not communicated or communicated with the annular oil groove I. The propeller speed control of the present invention is accurate and fast, prevents the phenomenon of the propeller running at high speed when a failure occurs, and makes the flight safety factor higher.

Description

Technical Field

[0001] The present invention relates to a propeller speed limiter. Background Art

[0002] With the development of aviation propeller technology, the requirements for propeller control systems are also getting higher and higher. To ensure flight safety and prevent the propeller from overspeeding in case of a failure, a maximum speed limiting mechanism is provided in all propeller control systems. Some speed limiting mechanisms are included in the engine or the propeller's own structure. Sometimes, due to limited space in the engine and propeller, or due to the requirement of functional modularization, the speed limiting function is separated and designed as an independent product. The existing speed limiters, whether electronically controlled or hydraulic, have a simple structure, a single function, low reliability, slow response speed, and low control accuracy. Once a failure occurs, they cannot prevent the propeller from overspeeding in case of a failure, resulting in flight accidents. Therefore, it is very important to study a propeller speed limiter that can accurately and quickly control the propeller speed and improve the flight safety factor. Summary of the Invention

[0003] The object of the present invention is to solve the above problems existing in the prior art, and provide a propeller speed limiter that can accurately and quickly control the propeller speed, prevent the propeller from overspeeding in case of a failure, and improve the flight safety factor.

[0004] To achieve the above object, the technical solution of the present invention is: a propeller speed limiter, which comprises a housing, a cover, a transmission shaft, a metering valve, a bushing, two L-shaped counterweights, a U-shaped counterweight disc, a bearing, a speed limit spring, an adjusting plunger, a speed limit spring seat, a guide plate, a lock nut, an adjusting spring seat, an adjusting spring, and an adjusting screw with a nut at one end, a stepped smooth rod in the middle, and a thread at the other end; during use, the lower end of the housing is fixed on the engine mounting seat.A variable-diameter hole is opened at the center of the housing. The large-diameter hole at the upper end is the mounting hole for two L-shaped counterweights. The small-diameter hole at the lower end is in interference fit with the bushing, and the bushing is press-fitted into the small-diameter hole of the housing. The transmission shaft is rotatably installed in the bushing. The convex shoulder edge at its upper end has a small clearance overlap with the bottom surface of the large-diameter hole of the housing. An annular oil groove I is opened at the middle position of its outer circle. A central hole is opened at its center. Two oil distribution windows are opened on the wall at the position of the annular oil groove I. An external spline matching the internal spline of the engine output shaft is machined at its bottom end. Multiple oil return holes I communicating with the oil return holes II opened at the bottom of the housing are opened on the upper wall near the external spline. During use, the lower end of the transmission shaft is installed on the internal spline of the engine output shaft and is driven to rotate by the engine transmission mechanism. Oil inlet holes communicating with the annular oil groove I are opened at the lower end of the housing and on the bushing. During use, the oil inlet holes are connected to the oil inlet hole of the engine mounting seat, and the pressurized lubricating oil in the propeller cavity can be introduced. The oil return holes II are connected to the engine oil return tank. The oil distribution valve is slidably assembled in the central hole of the transmission shaft. An annular oil groove II is opened at its lower end. Its upper end is fixed to the inner ring of the bearing. When it is stationary, the thick-diameter part at the upper end of its annular oil groove II closes the oil distribution window on the transmission shaft. When it moves upward, its annular oil groove II communicates with the annular oil groove I on the transmission shaft through the oil distribution window. The U-shaped counterweight disk is assembled with a slight clearance on the shaft head at the upper end of the transmission shaft. The lower ends of the two L-shaped counterweights are hinged to both ends of the U-shaped counterweight disk, and their two hook parts abut against the bottom surface of the outer ring of the bearing. There is a small hole at the upper end of the cover, and the lower end is a cylindrical large hole. The bottom surface extends outward to form an annular connecting boss, and the annular connecting boss is installed and fixed on the upper end surface of the housing. There is a self-locking thread in the small hole or a self-locking wire thread insert is installed. The upper end of the adjusting plunger is a hollow cylinder with a bottom surface, the height of which is less than the height of the cylindrical large hole of the cover, and the diameter matches that of the cylindrical large hole. The lower end extends into a variable-diameter round rod. Its upper cylindrical part is slidably connected in the cylindrical large hole of the cover, and an oil passing hole is opened at its center. The guide plate is slidably assembled on the variable-diameter round rod of the adjusting plunger. Its outer circle is sealed and fixed at the end of the cylindrical large hole by a step in the cylindrical large hole of the cover, a snap ring clamped and fixed on the wall of the cylindrical large hole, and a sealing ring. The speed-limiting spring seat is clamped and positioned at the end of the variable-diameter round rod of the adjusting plunger. The speed-limiting spring is installed between the end face of the shaft head convex platform of the oil distribution valve and the speed-limiting spring seat. The adjusting spring seat is in a shape of a capital "J" with a central hole. Its lower end is pressed by the adjusting spring against the hollow bottom wall of the upper cylindrical part of the adjusting plunger. The central hole in its upper end wall passes through the nut end of the adjusting screw. The nut of the adjusting screw is tightened on the end face in the concave cavity of the "J" shape of the adjusting spring seat. The threaded end of its other end is threadedly connected to the small hole at the upper end of the cover. The thick-diameter part of its smooth rod is movably sealed and connected to the lower part of the small hole of the cover. There is a clamping groove for a screwdriver or a screwing handle on its upper end face. The lower end of the adjusting spring is placed on the adjusting spring seat, and the upper end is limited by the top wall of the cylindrical large hole of the cover.

[0005] Further preferably, the present invention further includes an electromagnetic switch I, which is fixed on the side wall of the housing; the lubricating oil inlet hole at the lower end of the housing is connected to the oil return hole II opened at the bottom of the housing through the electromagnetic switch I. When the electromagnetic switch I is turned on, the pressure lubricating oil in the propeller chamber flows through the electromagnetic switch I to the engine's oil return tank, the lubricating oil pressure in the propeller chamber drops, and the propeller changes to a large pitch to the feathering position, enabling the present embodiment to have a feathering function.

[0006] Further preferably, the present invention further includes an electromagnetic switch II. The lubricating oil inlet hole at the lower end of the housing is connected to the lubricating oil cavity between the bottom surface of the hollow cylinder of the adjusting plunger and the guide plate through the electromagnetic switch II and the radial oil inlet hole opened on the cover. When the electromagnetic switch II is turned on, the pressure lubricating oil in the propeller chamber flows through the electromagnetic switch II to the lubricating oil cavity, the adjusting plunger moves upward, and the speed limit spring is relaxed, enabling the speed limiter of the present invention to check whether the speed limit system is normal at 91% of the working speed and realizing the speed control during ground inspection test runs. The speed limiter checks whether the entire speed limit module functions normally when the speed is lower than the normal working speed, enabling the present embodiment to have a ground inspection function.

[0007] Further preferably, the oil return hole II opened at the bottom of the housing is parallel to the horizontal axis, and the lubricating oil inlet hole opened at its lower end forms an angle of 30° with the vertical axis. This makes the oil flow more convenient.

[0008] Further preferably, there is a lubricating groove on the outer circle of the hollow cylinder with a bottom surface at the upper end of the adjusting plunger. During operation, the lubricating groove will be filled with lubricating oil, which plays a lubricating role for the adjusting plunger.

[0009] Further preferably, the structure in which the speed limit spring seat is snap-fitted and positioned on the stepped round rod of the adjusting plunger is: the speed limit spring seat is snap-fitted on the stepped round rod of the adjusting plunger and is locked and fixed on the stepped round rod by a self-locking nut threaded at the end of the stepped round rod, and the distance between it and the bottom surface of the hollow cylinder of the adjusting plunger is greater than the thickness of the guide plate.

[0010] Further preferably, the assembly structure of the U-shaped counterweight plate, the two L-shaped counterweights, and the transmission shaft is: the central hole of the U-shaped counterweight plate is assembled with a slight clearance on the shaft head at the upper end of the transmission shaft and is blocked by a baffle on the shaft disc; the two L-shaped counterweights have mounting holes that respectively cooperate with the mounting holes at both ends of the U-shaped counterweight plate and are hinged and connected by a pin shaft.

[0011] When the propeller is at a normal rotational speed, the position of the oil distribution valve in the transmission shaft hole is set by the adjusting screw. The component force exerted on the oil distribution valve by the centrifugal force generated by the rotation of the L-shaped counterweight is balanced with the elastic force of the speed-limiting spring. The thick-diameter part at the upper end of the annular oil groove II of the oil distribution valve closes the oil distribution hole on the transmission shaft, blocking the high-pressure lubricating oil from the propeller cavity. At this time, the rotational speed of the propeller is in a normal working state. When the rotational speed of the propeller increases, due to the increase in rotational speed, the centrifugal force of the L-shaped counterweight increases and exceeds the spring force of the pre-set speed-limiting spring, causing the oil distribution valve to lift upward. The annular oil groove I on the transmission shaft communicates with the valve annular oil groove II, and the pressure lubricating oil flows into the annular oil groove I through the oil distribution hole on the transmission shaft, flows through the annular oil groove II to the oil return hole of the transmission shaft, and then to the engine oil return tank. The lubricating oil pressure in the propeller cavity drops, the propeller increases its pitch, the rotational speed of the propeller no longer increases, the centrifugal force of the L-shaped counterweight decreases, and the component force exerted on the oil distribution valve also decreases accordingly. The oil distribution valve moves downward until it closes the oil distribution hole on the transmission shaft again, restricting the rotational speed of the propeller within a range not exceeding 104%.

[0012] The propeller rotational speed control of the present invention is precise and rapid, preventing the phenomenon of runaway when the propeller fails, making the flight safety factor higher. In particular, the present invention with the addition of electromagnetic switch I also has a feathering function; the present invention with the addition of electromagnetic switch II also has a ground inspection function; one present invention achieves multiple functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic structural diagram of the present invention;

[0014] Figure 2 is a schematic structural principle diagram of the present invention;

[0015] Figure 3 is a schematic connection structure diagram of the adjusting plunger, guide plate, speed-limiting spring seat and locking nut in the present invention;

[0016] Figure 4 is Figure 3 an exploded structural diagram of;

[0017] Figure 5 is a schematic connection structure diagram of the transmission shaft and the shaft disc in the present invention;

[0018] Figure 6 is Figure 5 an exploded structural diagram of;

[0019] Figure 7 is a schematic connection structure diagram of the U-shaped counterweight disc and the two L-shaped counterweights in the present invention;

[0020] Figure 8 is Figure 7 an exploded structural diagram of. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0022] As Figures 1 to 8As shown in the figure, this embodiment includes a housing 17, a cover 16, a transmission shaft 8, an oil distribution valve 10, a bushing 9, two L-shaped counterweights 7, a U-shaped counterweight disk 13, a bearing 6, a speed-limiting spring 5, an adjusting plunger 4, a speed-limiting spring seat 14, a guide plate 26, a locking nut 30, an adjusting spring seat 3, an adjusting spring 2, and an adjusting screw 1. During use, the lower end of the housing 17 is fixed to the engine mounting seat. A stepped hole is provided in the center of the housing 17. The large-diameter hole 18 at the upper end is the mounting hole for the two L-shaped counterweights 7. The small-diameter hole at the lower end is in interference fit with the bushing 9, and the bushing 9 is press-fitted into the small-diameter hole of the housing 17. The transmission shaft 8 is rotatably installed in the bushing 9. The shaft disk 29 with a baffle 35 fixed to its upper end has a small clearance lap on the bottom surface of the large-diameter hole 18 of the housing 17. An annular oil groove I 19 is provided in the middle position of its outer circumference. A central hole is provided in its center. Two oil distribution windows 21 are evenly provided on the wall at the position of the annular oil groove I 19. An external spline matching the internal spline of the engine output shaft is machined at its bottom end. Six oil return holes I 24 communicating with the oil return holes II provided at the bottom of the housing 17 are evenly provided on the upper wall near the external spline. During use, the lower end of the transmission shaft 8 is installed on the engine output shaft and is driven to rotate by the engine transmission mechanism. An oil inlet hole 22 communicating with the annular oil groove I 19 is provided at the lower end of the housing 17 and the bushing 9. Preferably, the oil return holes II provided at the bottom of the housing 17 are parallel to the horizontal axis, and the oil inlet hole 22 provided at its lower end forms an angle of 30° with the vertical axis. During use, the oil inlet hole 22 is connected to the oil inlet hole of the engine mounting seat, and the pressurized lubricating oil 23 in the propeller cavity can be introduced. The oil return holes II are connected to the engine oil return tank. The oil distribution valve 10 is slidably assembled in the central hole of the transmission shaft 8. An annular oil groove II 20 is provided at its lower end. Its upper end is fixed to the inner ring of the bearing 6. When it is stationary, the thick-diameter part at the upper end of its annular oil groove II 20 closes the oil distribution hole 21 on the transmission shaft 8. When it moves upward, its annular oil groove II communicates with the annular oil groove I 19 on the transmission shaft 8 through the oil distribution hole 21. The speed-limiting spring 5 is sleeved and pressed on the upper boss 15 of the oil distribution valve 10 and is pressed against the upper end of the inner ring of the bearing 6 by the locking nut locked on the upper end of the oil distribution valve 10. The central hole of the U-shaped counterweight disk 13 is assembled with a slight clearance on the upper end shaft head of the transmission shaft 8 and is blocked by the baffle 35 on the shaft disk 29. The two L-shaped counterweights 7 have mounting holes respectively cooperating with the mounting holes at both ends of the U-shaped counterweight disk 13 and are hinged by a pin shaft 25. Their two hook parts abut against the bottom surface of the outer ring of the bearing 6. The upper end of the cover 16 has a small hole, and the lower end is a large cylindrical hole. The bottom surface extends outward to form an annular connecting boss. The annular connecting boss is installed and fixed on the upper end surface of the housing 17 by six evenly distributed round head screws. A tailless self-locking wire screw insert 32 is installed in the small hole. The upper end of the adjusting plunger 4 is a hollow cylinder with a bottom surface, the height of which is less than the height of the large cylindrical hole of the cover 16, the diameter of which matches the large cylindrical hole, and there is a lubricating groove 34 on its outer circumference. The lower end extends into a stepped round rod. Its upper cylinder is slidably connected in the large cylindrical hole of the cover 16. An oil passing hole 33 is provided in its center.The guide plate 26 is slidably assembled on the stepped round rod of the adjusting plunger 4. Its outer circle is sealed and fixed at the end of the cylindrical large hole of the cover 16 by the step in the cylindrical large hole, the snap ring 31 clamped and fixed on the wall of the cylindrical large hole, and the O-ring seal. The speed-limiting spring seat 14 is clamped on the stepped round rod of the adjusting plunger 4 and is locked and fixed on the stepped round rod by the self-locking nut 30 screwed on the end of the stepped round rod. The distance between it and the bottom surface of the hollow cylinder of the adjusting plunger 4 is greater than the thickness of the guide plate 26. The speed-limiting spring 5 is installed between the end face of the boss 15 on the shaft head of the distributing valve 10 and the speed-limiting spring seat 14. The adjusting spring seat 3 is in a shape of a capital "J" with a central hole. Its lower end is pressed by the adjusting spring 2 against the bottom wall of the hollow center of the upper cylinder of the adjusting plunger 4. The central hole in its upper end wall passes through the nut end of the adjusting screw 1. The lower end of the adjusting spring 2 is placed on the adjusting spring seat 3, and the upper end is limited on the top wall of the cylindrical large hole of the cover 16. The nut of the adjusting screw 1 is tightened on the end face in the concave cavity of the "J" shape of the adjusting spring seat 3. The other threaded end of it is threadedly connected to the captive wire thread insert 32 in the small hole at the upper end of the cover 16 (or can be directly threadedly fixed in the threaded small hole). There is a sealing ring groove at the thick diameter of its smooth rod, and it is movably and sealingly connected with the lower part of the small hole of the cover 16 by an O-ring seal. There is a clamping groove or a screwing handle for the screwing tool on its upper end face; the clamping groove in this embodiment is the insertion hole for a hexagon wrench.

[0023] Preferably, this embodiment further includes an electromagnetic switch I 12, and the electromagnetic switch I 12 is fixed on the side wall of the housing 16; the lubricating oil inlet hole 22 at the lower end of the housing 17 is connected to the oil return hole II opened at the bottom of the housing 17 through the electromagnetic switch I 12. When the electromagnetic switch I 12 is turned on, the pressure lubricating oil 23 in the propeller cavity flows through the electromagnetic switch I 12 to the engine's oil return tank, and the lubricating oil pressure in the propeller cavity drops, and the propeller changes to the large pitch to the feathering position, so that this embodiment has the feathering function.

[0024] Preferably, this embodiment further includes an electromagnetic switch II 11, and the lubricating oil inlet hole 22 at the lower end of the housing 17 is connected to the lubricating oil cavity 28 between the bottom surface of the hollow cylinder of the adjusting plunger 4 and the guide plate 26 through the electromagnetic switch II 11 and the radial oil inlet hole 27 opened on the cover 16. When the electromagnetic switch II 11 is turned on, the pressure lubricating oil 23 in the propeller cavity flows through the electromagnetic switch II 11 to the lubricating oil cavity 28, the adjusting plunger 4 moves upward, and the speed-limiting spring 5 is relaxed, so that the speed limiter of the present invention checks whether the speed-limiting system is normal at 91% of the working speed, and realizes the speed control during the ground inspection test run. The speed limiter checks whether the functions of the entire speed-limiting module are normal under the condition of lower than the normal working speed, so that this embodiment has the ground inspection function.

[0025] Of course, the present invention has many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make corresponding changes and deformations according to the present invention. However, these corresponding changes and deformations should all belong to the improvements of equivalent technologies and fall within the protection scope of the claims of the present invention.

Claims

1. A propeller speed limiter, characterized in that: It includes a housing, a cover, a transmission shaft, an oil distribution valve, a bushing, two L-shaped counterweights, a U-shaped counterweight plate, a bearing, a speed-limiting spring, an adjusting plunger, a speed-limiting spring seat, a guide plate, a locking nut, an adjusting spring seat, electromagnetic switch I, electromagnetic switch II, an adjusting spring, and an adjusting screw with a nut at one end, a stepped smooth rod in the middle, and a thread at the other end; A stepped hole is opened in the center of the housing. The large-diameter hole at the upper end is the installation hole for the two L-shaped counterweights. The small-diameter hole at the lower end is in interference fit with the bushing, and the bushing is press-fitted into the small-diameter hole of the housing; The transmission shaft is rotatably installed in the bushing. The convex shoulder edge at its upper end has a small clearance lapped on the bottom surface of the large-diameter hole of the housing. An annular oil groove I is opened at the middle position of its outer circle. A central hole is opened in its center. Two oil distribution windows are opened on the wall at the annular oil groove I. The bottom end is machined with an external spline matching the internal spline of the engine output shaft. Multiple oil return holes I communicating with the oil return hole II opened at the bottom of the housing are opened on the upper wall near the external spline; An oil inlet hole communicating with the annular oil groove I is opened at the lower end of the housing and on the bushing; The oil distribution valve is slidably assembled in the central hole of the transmission shaft. An annular oil groove II is opened at its lower end. The upper end is fixed to the inner ring of the bearing. When it is stationary, the thick-diameter part at the upper end of its annular oil groove II closes the oil distribution window on the transmission shaft. When it moves upward, its annular oil groove II communicates with the annular oil groove I on the transmission shaft through the oil distribution window; The U-shaped counterweight plate is assembled with a slight clearance on the shaft head at the upper end of the transmission shaft; The lower ends of the two L-shaped counterweights are hinged to both ends of the U-shaped counterweight plate, and their two hook parts abut against the bottom surface of the outer ring of the bearing; There is a small hole at the upper end of the cover, and a cylindrical large hole at the lower end. The bottom surface projects outwards with an annular connecting boss, and the annular connecting boss is installed and fixed on the upper end surface of the housing. There is a self-locking thread in the small hole or a self-locking wire thread insert is installed; The upper end of the adjusting plunger is a hollow cylinder with a bottom surface, the height of which is less than the height of the cylindrical large hole of the cover, and the diameter of which matches the cylindrical large hole. The lower end extends into a stepped round rod. The upper cylindrical part of it is slidably connected in the cylindrical large hole of the cover, and an oil passage hole is opened in its center; The guide plate is slidably assembled on the stepped round rod of the adjusting plunger. Its outer circle is sealed and fixed at the end of the cylindrical large hole by a step in the cylindrical large hole of the cover, a snap ring clamped and fixed on the wall of the cylindrical large hole, and a sealing ring; The speed-limiting spring seat is clamped and positioned at the end of the stepped round rod of the adjusting plunger; The speed-limiting spring is installed between the end face of the shaft head convex platform of the oil distribution valve and the speed-limiting spring seat; The adjusting spring seat is in a shape of a capital letter "J" with a central hole. Its lower end is pressed by the adjusting spring against the hollow bottom wall of the upper cylindrical part of the adjusting plunger. The central hole in its upper end wall passes through the nut end of the adjusting screw; The nut of the adjusting screw is tightened on the end face in the concave cavity of the "J" shape of the adjusting spring seat. The threaded end at the other end is threadedly connected to the small hole at the upper end of the cover. The thick-diameter part of its smooth rod is movably sealed and connected to the lower part of the small hole of the cover. There is a clamping groove for a screwdriver or a screwdriver handle on its upper end face; The lower end of the adjusting spring is placed on the adjusting spring seat, and the upper end is limited by the top wall of the cylindrical large hole of the cover; The electromagnetic switch I is fixed on the side wall of the housing. The oil inlet hole at the lower end of the housing is connected to the oil return hole II opened at the bottom of the housing through the electromagnetic switch I;The lubricating oil inlet hole at the lower end of the housing is connected to the lubricating oil cavity between the bottom surface of the hollow cylinder of the adjusting plunger and the guide plate through the electromagnetic switch II and the radial oil inlet hole opened on the cover; the oil return hole II opened at the bottom of the housing is parallel to the horizontal axis, and the lubricating oil inlet hole opened at its lower end forms an angle of 30° with the vertical axis. There is a lubricating groove on the outer circle of the hollow cylinder with a bottom surface at the upper end of the adjusting plunger; the structure in which the speed limit spring seat is clamped and positioned on the stepped round rod of the adjusting plunger is that the speed limit spring seat is clamped on the stepped round rod of the adjusting plunger and is locked and fixed on the stepped round rod by a self-locking nut screwed on the end of the stepped round rod, and the distance between it and the bottom surface of the hollow cylinder of the adjusting plunger is greater than the thickness of the guide plate.

2. The propeller speed limiter according to claim 1, characterized in that: The oil return hole II opened at the bottom of the housing is parallel to the horizontal axis, and the lubricating oil inlet hole opened at its lower end forms an angle of 30° with the vertical axis.

3. The propeller speed limiter according to claim 1 or 2, characterized in that: There is a lubricating groove on the outer circle of the hollow cylinder with a bottom surface at the upper end of the adjusting plunger.

4. The propeller speed limiter according to claim 3, characterized in that: The structure in which the speed limit spring seat is clamped and positioned on the stepped round rod of the adjusting plunger is: the speed limit spring seat is clamped on the stepped round rod of the adjusting plunger, and is locked and fixed on the stepped round rod by a self-locking nut screwed on the end of the stepped round rod, and the distance between it and the bottom surface of the hollow cylinder of the adjusting plunger is greater than the thickness of the guide plate.

5. The propeller speed limiter according to claim 4, characterized in that: The assembly structure of the U-shaped counterweight plate, the two L-shaped counterweights and the transmission shaft is: the central hole of the U-shaped counterweight plate is assembled with a small clearance on the shaft head at the upper end of the transmission shaft and is blocked by the baffle on the shaft disc; the two L-shaped counterweights have mounting holes respectively cooperating with the mounting holes at both ends of the U-shaped counterweight plate and are hinged and connected by a pin shaft.

6. The propeller speed limiter according to claim 1 or 2, characterized in that: The structure in which the speed limit spring seat is clamped and positioned on the stepped round rod of the adjusting plunger is: the speed limit spring seat is clamped on the stepped round rod of the adjusting plunger, and is locked and fixed on the stepped round rod by a self-locking nut screwed on the end of the stepped round rod, and the distance between it and the bottom surface of the hollow cylinder of the adjusting plunger is greater than the thickness of the guide plate.

7. The propeller speed limiter according to claim 6, characterized in that: The assembly structure of the U-shaped counterweight plate, the two L-shaped counterweights and the transmission shaft is: the central hole of the U-shaped counterweight plate is assembled with a small clearance on the shaft head at the upper end of the transmission shaft and is blocked by the baffle on the shaft disc; the two L-shaped counterweights have mounting holes respectively cooperating with the mounting holes at both ends of the U-shaped counterweight plate and are hinged and connected by a pin shaft.

8. The propeller speed limiter according to claim 3, characterized in that: The assembly structure of the U-shaped counterweight plate, the two L-shaped counterweights and the transmission shaft is: the central hole of the U-shaped counterweight plate is assembled with a small clearance on the shaft head at the upper end of the transmission shaft and is blocked by the baffle on the shaft disc; the two L-shaped counterweights have mounting holes respectively cooperating with the mounting holes at both ends of the U-shaped counterweight plate and are hinged and connected by a pin shaft.

9. The propeller speed limiter according to claim 1 or 2, characterized in that: The assembly structure of the U-shaped counterweight plate, the two L-shaped counterweights and the transmission shaft is: the central hole of the U-shaped counterweight plate is assembled with a small clearance on the shaft head at the upper end of the transmission shaft and is blocked by the baffle on the shaft disc; the two L-shaped counterweights have mounting holes respectively cooperating with the mounting holes at both ends of the U-shaped counterweight plate and are hinged and connected by a pin shaft.

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