Turboprop engine and its variable pitch device

Abstract

The purpose of this invention is to provide a turboprop engine and its pitch control device. The pitch control device includes a housing, a piston, an adjusting member, a locking member, and a flow path. The piston divides the interior of the housing into a first chamber and a second chamber. A third chamber is formed between the adjusting member and the housing. The locking member is drivenly connected to the adjusting member. When the fluid pressure in the second chamber is greater than a pressure threshold, the adjusting member is driven to move towards the compression elastic member, which in turn moves the locking member to a first position. When the fluid pressure in the second chamber is less than the pressure threshold, the elastic member elastically resets and drives the adjusting member to actuate, causing the adjusting member to move the locking member to a second position. The locking member allows piston movement in the first position and restricts piston movement in the second position. This pitch control device can prevent the propeller from moving towards a horizontal position at any pitch angle.

Description

Technical Field

[0001] This invention relates to the field of turboprop engine technology, and more particularly to a turboprop engine and its pitch control device. Background Technology

[0002] Common turboprop engines and open rotor engines are equipped with variable pitch mechanisms to adjust the propfan pitch angle online, so that the propfan can work under the appropriate angle of attack of the incoming flow under different operating conditions, thereby improving working efficiency.

[0003] Current pitch control mechanisms for large pitch adjustment torque loads typically use a hydraulic actuator to drive a fork axially, which in turn rotates the propeller connected to the rocker arm to achieve pitch adjustment. However, the propeller generates significant resistance to the engine at small pitch positions, easily leading to over-revving and serious consequences. Therefore, considering engine safety requirements, when there is significant leakage in the actuator, it is necessary to be able to feather or lock the propeller in its current position.

[0004] Currently, the locking mechanism inside the actuator cylinder employs methods such as adding a spring, high-pressure gas, or installing a counterweight on the propeller shaft to allow the actuator cylinder to automatically move along the large-pitch direction without hydraulic actuation, thereby driving the propeller to feather. However, such methods can only provide a small feathering torque load. Schwartz Robert A. et al. designed a self-locking structure in the form of a trapezoidal lead screw (Schwartz Robert A., Carvalho Paul, Cutler Mark J.. Large-scale Advanced Prop-fan pitch change actuator and control design report. Hamilton Standard Division United Technologies Coproration, 1986.), but such a locking mechanism has a complex structure, posing challenges to reliability and manufacturing.

[0005] For hydraulically actuated pitch mechanisms operating under high adjustment torque, the urgent problem to be solved is how to prevent the propeller from moving towards the horizontal at any pitch angle. Summary of the Invention

[0006] The purpose of this invention is to provide a variable pitch device that can prevent the propeller from moving towards a horizontal position at any pitch angle.

[0007] A pitch control device for achieving the aforementioned objective includes:

[0008] outer shell;

[0009] A piston is disposed in the outer casing and is slidably and sealingly fitted with the outer casing, dividing the interior of the outer casing into a first chamber and a second chamber;

[0010] The adjusting member is elastically supported in the second chamber by an elastic member, and a third chamber is formed between the adjusting member and the outer shell.

[0011] A locking element, which is kinetically connected to the adjusting element; and

[0012] The flow path includes a first flow path communicating with the first chamber, a second flow path communicating with the second chamber, and a third flow path communicating with the third chamber;

[0013] When the fluid pressure in the second chamber is greater than the pressure threshold, the adjusting member is driven to move in the direction of compressing the elastic member and can drive the locking member to move to the first position. When the fluid pressure in the second chamber is less than the pressure threshold, the elastic member can elastically reset and drive the adjusting member to actuate, so that the adjusting member drives the locking member to move to the second position. The locking member allows the piston to move in the first position and restricts the piston to move in the second position.

[0014] In one or more embodiments, the pressure threshold is calculated using the following formula (1):

[0015]

[0016] Where, p Bmin f is the pressure threshold. max S is the maximum pressure within the compression stroke of the elastic element. b p0 is the cross-sectional area of ​​the third chamber and p0 is the oil pressure of the third chamber.

[0017] In one or more embodiments, the outer casing includes an outer cylindrical wall and a central rod disposed within the outer cylindrical wall. The piston includes a piston portion, a sleeve portion, and a mating portion. The piston portion is sleeved on the outside of the central rod and slidably and sealingly engaged with the central rod. The piston portion extends radially outward from the sleeve portion and slidably and sealingly engages with the outer cylindrical wall. The mating portion is disposed in the second chamber. In the second position, the locking member abuts against the mating portion to restrict the movement of the piston.

[0018] In one or more embodiments, the adjusting member is sleeved on the outer periphery of the central rod, the elastic member is a helical spring sleeved on the outer periphery of the central rod, and the locking member is a cam hinged to the outside of the central rod;

[0019] The adjusting member has a connecting opening, the cam has a rod portion, and the connecting opening is provided with a first protrusion and a second protrusion;

[0020] When the adjusting member moves toward the direction of compressing the elastic member, the first protrusion cooperates with the rod to cause the locking member to rotate in the first direction, so that the locking member located in the first position can move to the second position;

[0021] When the adjusting member moves away from the elastic member, the second protrusion engages with the rod to cause the locking member to rotate in the second direction, so that the locking member located in the second position can move to the first position;

[0022] Wherein, the first direction is opposite to the second direction.

[0023] In one or more embodiments, the connection opening has an inner ring wall and an outer ring wall, the inner ring wall protruding toward the locking member relative to the outer ring wall, a first protrusion disposed in the portion of the inner ring wall that protrudes from the outer ring wall and protrudes toward the connection opening, and a second protrusion disposed at the end of the outer ring wall and protrudes toward the connection opening;

[0024] The central rod is provided with a first step portion, and the outer side of the outer ring wall is provided with a second step portion. When the adjusting member moves along the central rod in the direction of compressing the elastic member, the first step portion can abut against the second step portion to limit the continued movement of the adjusting member.

[0025] In the second position, the first step portion abuts against the second step portion, and when the locking member moves between the first position and the second position, at least a portion of the rod portion contacts the second protrusion.

[0026] In one or more embodiments, the central rod has a first rod segment and a second rod segment, the outer diameter of the first rod segment being smaller than the outer diameter of the second rod segment, so as to form the first step portion between the first rod segment and the second rod segment;

[0027] The outer ring wall includes a first ring wall segment and a second ring wall segment, wherein the inner diameter of the first ring wall segment is smaller than the inner diameter of the second ring wall segment, so as to form a second step portion between the first ring wall segment and the second ring wall segment;

[0028] The first annular wall segment has a convex ring portion protruding radially inward on the side away from the second annular wall segment. In the assembled state, the convex ring portion is slidably sealed to the first rod segment, and the second annular wall segment is slidably sealed to the second rod segment. The inner diameter of the first annular wall segment is larger than the outer diameter of the first rod segment, but smaller than the outer diameter of the second rod segment. The axial sides of the third chamber are defined by the convex ring portion and the first stepped portion, and the radial sides are defined by the outer annular wall and the first rod segment.

[0029] In one or more embodiments, in the second position, the mating surface of the cam abuts against the mating portion to restrict the piston movement;

[0030] The mating surface is an arc surface, and the line connecting the center of the circle extending from the arc surface and the rotation center of the cam is parallel to the axial direction of the central rod.

[0031] In one or more embodiments, when the mating surface abuts against the mating part, along the axial direction of the central rod, there is a first distance between the abutment point of the mating surface and the mating part and the rotation center, and along the radial direction of the central rod, there is a second distance between the rotation center and the mating part, and the first distance and the second distance satisfy the following relationship (2):

[0032] μh>l (2);

[0033] Wherein, l is the first distance, h is the second distance, and μ is the coefficient of friction between the mating part and the mating surface.

[0034] In one or more embodiments, the first flow path, the second flow path, and the third flow path are formed in the central rod.

[0035] On the other hand, according to some embodiments of this application, a turboprop engine is also provided, which includes a propfan and a pitch control device as described above.

[0036] The piston is equipped with a fork, and the propeller is connected to the piston via the fork.

[0037] The beneficial effects of this invention are as follows:

[0038] The pitch control device with this configuration utilizes the hydraulic pressure and spring in the second chamber to drive the adjusting element, controlling the contact state between the locking element and the piston. In the event of leakage in the large-pitch oil chamber, one-way locking is achieved, preventing the propeller from moving in the horizontal direction. Simultaneously, the mechanism for achieving one-way locking comprises only four parts: a spring, adjusting element, locking element, and cam. Its simple structure and easy manufacturing effectively improve the reliability of the pitch control actuator with locking mechanism.

[0039] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0040] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0041] Figure 1 A half-sectional schematic diagram of some embodiments of this pitch control device is shown;

[0042] Figure 2 for Figure 1 Enlarged schematic diagram of part A;

[0043] Figure 3 A partial schematic diagram of some embodiments of this pitch control device in the second position is shown;

[0044] Figure 4 for Figure 3 Enlarged schematic diagram of section B in the middle;

[0045] Figure 5 for Figure 3 Enlarged diagram of section C;

[0046] Figure 6 A partial schematic diagram of some embodiments of the pitch control device in the first position is shown;

[0047] Figure 7 for Figure 6 Enlarged schematic diagram of section D in the middle;

[0048] Figure 8 for Figure 6 Enlarged schematic diagram of section E in the middle. Detailed Implementation

[0049] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0051] To provide a turboprop engine capable of preventing the propeller fan from moving towards the horizontal propeller at any pitch angle, a variable pitch device is provided according to some embodiments of this application. Figure 1 A half-sectional schematic diagram of some embodiments of this pitch control device is shown. Figure 2 for Figure 1 Enlarged schematic diagram of part A; Figure 3 A partial schematic diagram of some embodiments of this pitch control device in the second position is shown; Figure 4 for Figure 3 Enlarged schematic diagram of section B in the middle; Figure 5 for Figure 3 Enlarged diagram of section C; Figure 6 A partial schematic diagram of some embodiments of the pitch control device in the first position is shown; Figure 7 for Figure 6 Enlarged schematic diagram of section D in the middle; Figure 8 for Figure 6 Enlarged schematic diagram of section E in the middle.

[0052] The pitch control device includes a housing 1, a piston 2, an adjusting component 3, and a locking component 4. The interior of the housing 1 provides space to accommodate the other components of the pitch control device. The piston 2 is housed within the housing 1 and is slidably and sealingly fitted with it. It is understood that the "slidably and sealingly fitted component A and component B" described herein means that component A and component B can be relatively displaced under external force, while maintaining a seal between their sliding surfaces even when component A is displaced relative to component B. Specific implementation methods include, but are not limited to, configuring component A and component B in a slidably fitted connection state and then placing a sealing ring between their mating surfaces.

[0053] The piston 2 divides the interior of the outer casing 1 into a first chamber 11 and a second chamber 12. It is understood that the first chamber 11 and the second chamber 12 are independent of each other; that is, the fluid in the first chamber 11 and the fluid in the second chamber 12 do not exchange with each other. Since the piston 2 is movable within the outer casing 1, during its movement, the internal spaces of the first chamber 11 and the second chamber 12 correspondingly increase or decrease, and the interiors of the first chamber 11 and the second chamber 12 remain independent during the movement of the piston 2.

[0054] The adjusting member 3 is elastically supported in the second chamber 12 by the elastic member 5, and a third chamber 30 is formed between the adjusting member 3 and the outer shell 1. The configuration of the third chamber 30 will be described in detail later and will not be repeated here. The locking member 4 is connected to the adjusting member 3 in a transmission manner, so that when the adjusting member 3 is actuated, it will drive the locking member 4 to actuate synchronously.

[0055] The pitch control device also includes flow paths, which include a first flow path 61 connected to the first chamber 11, a second flow path 62 connected to the second chamber 12, and a third flow path 63 connected to the third chamber 30. Fluids such as hydraulic oil can enter the first chamber 11, the second chamber 12, and the third chamber 30 through the first flow path 61, the second flow path 62, and the third flow path 63, respectively, thereby changing the fluid pressure in the three chambers.

[0056] When the fluid pressure in the second chamber 12 exceeds the pressure threshold, the adjusting member 3 is driven to move towards the compression elastic member 5, that is, towards the direction of closer proximity to the elastic member 5, causing the elastic member 5 to be compressed. During the movement, this can drive the locking member 4 to move to the first position (i.e., Figure 6 (as shown in the position state), when the fluid pressure in the second chamber 12 is less than the pressure threshold, the elastic element 5 elastically resets and can drive the adjusting element 3 to actuate, causing the adjusting element 3 to drive the locking element 4 to move to the second position (i.e., Figure 4 (As shown in the diagram), the locking element 4 allows the piston 2 to move in the first position and restricts the piston 2 to move in the second position.

[0057] With the aforementioned configuration, when the second chamber 12 leaks, causing the internal liquid pressure to decrease, once it decreases to below the pressure threshold, the locking element 4 can be moved synchronously to the second position to lock the piston, achieving one-way locking in the case of oil chamber leakage and preventing the propeller from moving in the direction of the horizontal propeller.

[0058] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0059] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0060] In some embodiments of this pitch control device, the pressure threshold is calculated using the following formula (1):

[0061]

[0062] Where, p Bmin f is the pressure threshold. max S represents the maximum pressure within the compression stroke of elastic element 5. b p0 is the cross-sectional area of ​​the third chamber 30; p0 is the oil pressure of the third chamber.

[0063] In some embodiments of this pitch-changing device, the outer casing 1 includes an outer cylindrical wall 13 and a central rod 14 disposed within the outer cylindrical wall 13. The piston 2 includes a piston portion 20, a sleeve portion 21, and a mating portion 22. The sleeve portion 21 and the mating portion 22 are respectively disposed on both sides of the piston portion 20 along the axial direction a. As shown in the figure, the piston portion 20 is sleeved on the outside of the central rod 14 and slidably and sealingly fitted with the central rod 14. The piston portion extends outward from the sleeve portion 21 toward the radial direction b and slidably and sealingly fits with the outer cylindrical wall 13. The mating portion 22 is disposed in the second chamber 12. In the second position, such as... Figure 4 As shown, the locking member 4 abuts against the mating part 22 to restrict the movement of the piston 2. In the first position, as Figure 6 As shown, there is a gap between the locking member 4 and the mating part 22 to allow the piston 2 to move. Specifically, the mating part 22 can be a sleeve-shaped structure that is arranged around the outer periphery of the locking member 4 and the adjusting member 3, as shown in the figure. The locking member 4 abuts against the inner periphery of the mating part 22 to lock by friction between the two.

[0064] In some embodiments of this pitch-changing device, the adjusting member 3 is sleeved around the outer periphery of the central rod 14, the elastic member 5 is a helical spring sleeved around the outer periphery of the central rod 14, and the locking member 4 is a cam hinged to the outside of the central rod 14. The adjusting member 3 has a connecting opening 31, the cam has a rod portion 41, and the connecting opening 31 is provided with a first protrusion 311 and a second protrusion 312. When the adjusting member 3 moves toward the direction of compressing the elastic member 5, the first protrusion 311 cooperates with the rod portion 41 to cause the locking member 4 to rotate along the first direction x1, so that the locking member 4 located in the first position can move to the second position, such as... Figure 5 As shown, in the second position, the second protrusion 312 contacts the rod 41. When the adjusting member 3 moves away from the elastic member 5, the second protrusion 312 engages with the rod 41, causing the locking member 4 to rotate along the second direction x2, so that the locking member 4 in the second position can move to the first position, as shown. Figure 8As shown, in the first position, the first protrusion 311 contacts the rod 41. In both the first and second positions, the first protrusion 311 and the second protrusion 312 restrict the rod 41 from disengaging. The first direction x1 and the second direction x2 are opposite. Specifically, when the first protrusion 311 moves from the rod body towards the end of the rod 41, it can drive the locking member 4 to rotate. Similarly, when the second protrusion 312 moves from the end of the rod 41 towards the rod body, it can also drive the locking member 4 to rotate. In a specific embodiment, both the first protrusion 311 and the second protrusion 312 are spherical protrusions, so as to drive the rod 41 to move through the arcuate outer surface. This configuration allows for one-way locking of the piston with a simple setup.

[0065] In one specific embodiment, a cam seat 48 is provided on the outer side of the central rod 14, and the locking member 4 is hinged to the outer periphery of the central rod 14 through the cam seat.

[0066] It is understood that in some other embodiments different from those shown in the figure, the locking element may also be other structural forms, such as a plug consisting of two inclined planes engaging a slider.

[0067] In some embodiments of this pitch-changing device, the connecting opening 31 has an inner ring wall 313 and an outer ring wall 314. The inner ring wall 313 protrudes toward the locking member 4 relative to the outer ring wall 314. A first protrusion 311 is disposed in the portion of the inner ring wall 313 that protrudes from the outer ring wall 314 and protrudes toward the connecting opening 31. A second protrusion 312 is disposed at the end of the outer ring wall 314 and protrudes toward the connecting opening 31. A first step portion 81 is provided on the center rod 14, and a second step portion 82 is provided on the outer side of the outer ring wall 314. When the adjusting member 3 moves along the center rod 14 toward the compression elastic member 5, the first step portion 81 can abut against the second step portion 82 to limit the continued movement of the adjusting member 3. In the second position, the first step portion 81 abuts against the second step portion 82, and when the locking member 4 moves between the first position and the second position, at least a portion of the rod portion 41 contacts the second protrusion 312 to prevent the rod portion 41 from completely disengaging from the connecting opening 31.

[0068] In some embodiments of this pitch control device, the center rod 14 has a first rod segment 141 and a second rod segment 142, the outer diameter of the first rod segment 141 being smaller than the outer diameter of the second rod segment 142, so as to form a first step portion 81 between the first rod segment 141 and the second rod segment 142. The outer annular wall 314 includes a first annular wall segment 3141 and a second annular wall segment 3142, the inner diameter of the first annular wall segment 3141 being smaller than the inner diameter of the second annular wall segment 3142, so as to form a second step portion 82 between the first annular wall segment 3141 and the second annular wall segment 3142. The first annular wall segment 3141, on the side away from the second annular wall segment 3142, is provided with a protruding ring portion 3143 protruding radially inward. In the assembled state, the protruding ring portion 3143 is slidably and sealingly fitted with the first rod segment 141, and the second annular wall segment 3142 is slidably and sealingly fitted with the second rod segment 142. The inner diameter of the first annular wall segment 3141 is larger than the outer diameter of the first rod segment 141, but smaller than the outer diameter of the second rod segment 142. The axial sides of the third chamber 30 are defined by the protruding ring portion 3143 and the first step portion 81, and the radial sides are defined by the outer annular wall 314 and the first rod segment 141. It can be understood that when in the first position, the first annular wall segment 3141 and the first rod segment 141 define the walls of the radial sides of the third chamber 30. When in the second position, the first annular wall segment 3141, the second annular wall segment 3142, and the first rod segment 141 together define the walls of the radial sides of the third chamber 30.

[0069] In some embodiments of this pitch control device, at the second position, such as Figure 4 As shown, the mating surface 400 of the cam abuts against the mating part 22 to restrict the movement of the piston 2. The mating surface 400 is an arc surface, and the line connecting the center O1 of the circle extending from this arc surface and the rotation center O2 of the cam is parallel to the axial direction a of the central rod 41. This configuration ensures that the locking member 4 can make smooth contact with the piston 2, preventing damage to the locking member 4 under impact loads. In a specific embodiment, the contact surface between the locking member 4 and the piston 2 is roughened to increase the coefficient of friction between them.

[0070] In some embodiments of this pitch-changing device, when the mating surface 400 abuts against the mating part 22, along the axial direction a of the central rod 41, there is a first distance l between the abutment point of the mating surface 400 and the mating part 22 and the rotation center O2, and along the radial direction b of the central rod 41, there is a second distance h between the rotation center O2 and the mating part 22. The first distance l and the second distance h satisfy the following relationship (2):

[0071] μh>l (2);

[0072] Wherein, μ is the coefficient of friction between the mating part 22 and the mating surface 400. With the above configuration, frictional self-locking can be generated between the mating surface 400 and the mating part 22, preventing the movement of the piston 2. This means that when the torque of the external load on the propeller is in the direction of small pitch, the propeller will be locked in the current position under the action of this variable pitch device; when the torque of the external load on the propeller is in the direction of large pitch, the propeller will move in the direction of large pitch, further reducing the drag on the engine.

[0073] In some embodiments of this pitch control device, the first flow path 61, the second flow path 62, and the third flow path 63 are formed in the center rod 41.

[0074] On the other hand, according to some embodiments of this application, a turboprop engine is also provided, which includes a propfan and a pitch control device as described in the preceding one or more embodiments. A fork 7 is provided on the piston 2, and the propfan is driven to the piston via the fork 7. In one specific embodiment, the piston 2 has a shoulder, and the fork 7 is pressed against the shoulder of the piston 2 by a clamping nut 71.

[0075] In one specific embodiment, the first cavity 11 is a small-pitch oil cavity and the second cavity 12 is a large-pitch oil cavity. When it is necessary to adjust the blade pitch towards the small pitch, it is achieved by increasing the fluid pressure in the first cavity 11. When it is necessary to adjust the blade pitch towards the large pitch, it is achieved by increasing the fluid pressure in the second cavity 12.

[0076] The adjustment process according to some embodiments of this pitch control device is as follows:

[0077] Pitch adjustment process:

[0078] When adjusting to a larger distance, the second chamber 12 is pressurized, driving the adjusting component 3 to move to the right. The lower end of the adjusting component 3 contacts the locking component 4, causing the locking component 4 to rotate and separate from the piston 2, thus releasing the one-way locking state, as shown in the attached figure. Figure 4 As shown; at the same time, the hydraulic drive piston 2 of the second chamber 12 moves to the right, driving the shift fork 7 to drive the propeller to rotate in the direction of large distance.

[0079] When the adjustment is made to a smaller distance, the pressure in the second chamber 12 decreases but remains greater than p. Bmin (See formula (1)), but at this time the oil pressure p B Size p is generated on the adjusting element 3. B ·S b The pressure is still greater than the maximum pressure within the compression stroke of spring 3, driving the adjusting member 3 to move to the right. The first protrusion 311 at the lower end of the adjusting member 3 contacts the locking member 4, causing the locking member 4 to rotate and separate from the piston 2, releasing the one-way locking state, as shown in the attached figure. Figure 4As shown; at the same time, the hydraulic drive piston 2 of the second chamber 11 moves to the left, driving the shift fork 7 to drive the propeller to rotate in the direction of small distance.

[0080] Pitch unidirectional locking process:

[0081] When a large leak occurs in the second cavity 12, causing the internal oil pressure p B Rapidly less than p Bmin When the spring 5 drives the adjusting member 3 to move to the left, the second protrusion 312 at the upper end of the adjusting member 3 contacts the locking member 4, driving the locking member 4 to move until the locking member 4 hits the piston 2, and the two generate contact positive pressure.

[0082] When the external load on the propeller torque is directed towards the smaller pitch direction, the propeller will be locked in its current position by the locking element 4, as shown in the attached diagram. Figure 2 As shown, when the external load on the propfan has a torque in the direction of greater pitch, the propfan will move in the direction of greater pitch, further reducing the drag on the engine.

[0083] Other processes:

[0084] When the seal of the first chamber 11 fails while the second chamber 12 continues to operate normally, the oil pressure p B Still greater than p Bmin The driving adjustment component 3 moves to the right, and the first protrusion 311 at the lower end of the adjustment component 3 contacts the locking component 4, causing the locking component 4 to rotate and separate from the piston 2, thus releasing the one-way locking state, as shown in the attached figure. Figure 4 As shown; simultaneously, piston 2 is under oil pressure p B Under its influence, the propeller will move towards a greater distance, causing the propeller fan to feather and ensuring the safe operation of the engine.

[0085] The pitch control device with this configuration utilizes the hydraulic pressure and spring in the second chamber 12 to drive the adjusting element 3, controlling the contact state between the locking element 4 and the piston 2. In the event of leakage in the large-pitch oil chamber, one-way locking is achieved, preventing the propeller from moving in the horizontal direction. The mechanism for achieving one-way locking consists of only four parts: a spring, adjusting element 3, locking element 4, and a cam. Its simple structure and easy manufacturing effectively improve the reliability of the pitch control actuator with a locking mechanism.

[0086] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0087] It should be understood that the two directions mentioned in the text being "parallel" do not need to meet strict mathematical angle requirements, but rather allow for a certain tolerance range. For example, the difference from the mathematically required angle is within 5°. "Along" a certain direction means that there is at least a component in that direction. Preferably, the angle with that direction is within 10°, and more preferably, the angle is within 5°.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A variable pitch device, characterized in that, include: outer shell; A piston is disposed in the outer casing and is slidably and sealingly fitted with the outer casing, dividing the interior of the outer casing into a first chamber and a second chamber; The adjusting member is elastically supported in the second chamber by an elastic member, and a third chamber is formed between the adjusting member and the outer shell. A locking element, which is kinetically connected to the adjusting element; and The flow path includes a first flow path communicating with the first chamber, a second flow path communicating with the second chamber, and a third flow path communicating with the third chamber; When the fluid pressure in the second chamber is greater than the pressure threshold, the adjusting member is driven to move in the direction of compressing the elastic member and can drive the locking member to move to the first position. When the fluid pressure in the second chamber is less than the pressure threshold, the elastic member can elastically reset and drive the adjusting member to actuate, so that the adjusting member drives the locking member to move to the second position. The locking member allows the piston to move in the first position and restricts the piston to move in the second position.

2. The pitch control device as described in claim 1, characterized in that, The pressure threshold is calculated using the following formula (1): Where, p Bmin f is the pressure threshold. max S is the maximum pressure within the compression stroke of the elastic element. b p0 is the cross-sectional area of ​​the third chamber and p0 is the oil pressure of the third chamber.

3. The pitch control device as described in claim 1, characterized in that, The outer casing includes an outer cylindrical wall and a central rod disposed within the outer cylindrical wall. The piston includes a piston portion, a sleeve portion, and a mating portion. The piston portion is sleeved on the outside of the central rod and slidably and sealingly engaged with the central rod. The piston portion extends radially outward from the sleeve portion and slidably and sealingly engages with the outer cylindrical wall. The mating portion is disposed in the second chamber. In the second position, the locking member abuts against the mating portion to restrict the movement of the piston.

4. The pitch control device as described in claim 3, characterized in that, The adjusting component is sleeved on the outer periphery of the central rod, the elastic component is a helical spring sleeved on the outer periphery of the central rod, and the locking component is a cam hinged to the outside of the central rod; The adjusting member has a connecting opening, the cam has a rod portion, and the connecting opening is provided with a first protrusion and a second protrusion; When the adjusting member moves toward the direction of compressing the elastic member, the first protrusion cooperates with the rod to cause the locking member to rotate in the first direction, so that the locking member located in the first position can move to the second position; When the adjusting member moves away from the elastic member, the second protrusion engages with the rod to cause the locking member to rotate in the second direction, so that the locking member located in the second position can move to the first position; Wherein, the first direction is opposite to the second direction.

5. The pitch control device as described in claim 4, characterized in that, The connection opening has an inner ring wall and an outer ring wall. The inner ring wall protrudes toward the locking member relative to the outer ring wall. The first protrusion is disposed in the portion of the inner ring wall that protrudes from the outer ring wall and protrudes toward the connection opening. The second protrusion is disposed at the end of the outer ring wall and protrudes toward the connection opening. The central rod is provided with a first step portion, and the outer side of the outer ring wall is provided with a second step portion. When the adjusting member moves along the central rod in the direction of compressing the elastic member, the first step portion can abut against the second step portion to limit the continued movement of the adjusting member. In the second position, the first step portion abuts against the second step portion, and when the locking member moves between the first position and the second position, at least a portion of the rod portion contacts the second protrusion.

6. The pitch control device as described in claim 5, characterized in that, The central rod has a first rod segment and a second rod segment, wherein the outer diameter of the first rod segment is smaller than the outer diameter of the second rod segment, so as to form the first step portion between the first rod segment and the second rod segment; The outer ring wall includes a first ring wall segment and a second ring wall segment, wherein the inner diameter of the first ring wall segment is smaller than the inner diameter of the second ring wall segment, so as to form a second step portion between the first ring wall segment and the second ring wall segment; The first annular wall segment has a convex ring portion protruding radially inward on the side away from the second annular wall segment. In the assembled state, the convex ring portion is slidably sealed to the first rod segment, and the second annular wall segment is slidably sealed to the second rod segment. The inner diameter of the first annular wall segment is larger than the outer diameter of the first rod segment, but smaller than the outer diameter of the second rod segment. The axial sides of the third chamber are defined by the convex ring portion and the first stepped portion, and the radial sides are defined by the outer annular wall and the first rod segment.

7. The pitch control device as described in claim 4, characterized in that, In the second position, the mating surface of the cam abuts against the mating part to restrict the piston movement; The mating surface is an arc surface, and the line connecting the center of the circle extending from the arc surface and the rotation center of the cam is parallel to the axial direction of the central rod.

8. The pitch control device as described in claim 7, characterized in that, When the mating surface abuts against the mating part, along the axial direction of the central rod, there is a first distance between the abutment point of the mating surface and the mating part and the rotation center, and along the radial direction of the central rod, there is a second distance between the rotation center and the mating part. The first distance and the second distance satisfy the following relationship (2): μh>l (2); Wherein, l is the first distance, h is the second distance, and μ is the coefficient of friction between the mating part and the mating surface.

9. The pitch control device as described in claim 3, characterized in that, The first flow path, the second flow path, and the third flow path are formed in the central rod.

10. A turboprop engine, characterized in that, Includes a propeller and a pitch control device as described in any one of claims 1 to 9; The piston is equipped with a fork, and the propeller is connected to the piston via the fork.

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