A low-pressure turbine rotor over-rotation protection oil cut-off mechanism and method

Abstract

The present invention belongs to the technical field of turbine engines and discloses a low-pressure turbine rotor over-rotation protection oil cut-off mechanism and method thereof, wherein the protection oil cut-off mechanism includes an upper casing, an exhaust casing, a lower casing, a protection mechanism, a low-pressure shaft, and a turbine rotor. The present invention uses a protection mechanism to transmit displacement information of the turbine rotor, so that after the low-pressure shaft breaks, the fracture information can be promptly transmitted to the engine through a transmission mechanism, causing the engine to shut down in time, thereby avoiding the situation where the turbine disk is broken due to high rotation of the low-pressure shaft; the present invention calculates a first time, a second time, and a third time, and proposes controlling the axial distance L1 between the trigger screw and the turbine rotor, the preset distance L2 that the trigger screw moves axially after colliding with the turbine rotor, and the axial distance L3 of the outer rotating connecting rod, so that the protection time can be controlled within a target range, thereby avoiding the situation where the turbine rotor over-rotates and causes the turbine disk to break.

Description

Technical Field

[0001] The present invention belongs to the technical field of turbine engines, and in particular relates to a low-pressure turbine rotor over-rotation protection oil cut-off mechanism and a method thereof. Background Art

[0002] Loss of load on the low-pressure turbine rotor (e.g., a low-pressure shaft fracture) may cause the disc to spin and rupture, generating high-energy, uncontained fragments that could endanger engine safety. Engine airworthiness regulations stipulate that if certain component failures result in the overspeed protection device being unable to prevent rotor overspeed, a mechanical overspeed protection mechanism must be installed in addition to the electronic overspeed protection system. Currently, there are three main design methods for mechanical overspeed protection mechanisms:

[0003] 1) After the shaft breaks, the turbine rotor moves backward, and the over-speed protection mechanism triggers the fuel system, directly closing the throttle;

[0004] 2) After the shaft breaks, the turbine rotor moves backward, and the stator parts such as the guide vanes get stuck in the rotating parts, or the rotor blades are broken, preventing the wheel from continuing to over-rotate;

[0005] 3) After the shaft breaks, the turbine rotor over-rotates, and the blades break and fly out before reaching the wheel disc rupture speed, preventing the turbine disc speed from continuing to increase. This method is generally called blade shedding protection design.

[0006] However, the current mechanical over-rotation protection mechanism has the following disadvantages:

[0007] 1) In the electronic over-speed protection mode, the structural strength design of the wheel disc and blades is relatively simple. There is no need to consider that the disc must have a higher speed than the blade to break, but there is a certain risk of control system failure.

[0008] 2) The blade-off protection mode has high reliability, but the structural strength design is complex, which will increase the rotor weight and reduce the blade life.

[0009] 3) The risk of static parts such as guide vanes getting stuck in rotating parts or breaking rotor blades to prevent the wheel from continuing to over-rotate is high, and there is little experience in applying this to existing engines. Summary of the Invention

[0010] In order to solve at least one problem in the background technology, the present invention proposes a low-pressure turbine rotor over-rotation protection oil cut-off mechanism and method thereof.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A low-pressure turbine rotor over-rotation protection oil cut-off mechanism comprises an upper casing, an exhaust casing, a lower casing, a protection mechanism, a low-pressure shaft and a turbine rotor;

[0013] The protection mechanism is located on one side of the low-pressure shaft and is used to transmit displacement information of the turbine rotor after the low-pressure shaft breaks;

[0014] The turbine rotor is mounted on the low-pressure shaft, so that when the low-pressure shaft breaks, the turbine rotor collides with the protection mechanism and pushes the protection mechanism to move;

[0015] One end of the exhaust casing is fixedly connected to the upper casing, and the other end is connected to the protection mechanism;

[0016] One end of the protection mechanism away from the exhaust casing is connected to the lower casing;

[0017] The protection mechanism is also connected to a steel cable, and a displacement sensor is installed on one side of the steel cable. The displacement sensor is used to send an oil cut-off signal when the steel cable moves to a preset position;

[0018] The steel cable is also connected to an oil cut-off valve, which is used to receive an oil cut-off signal, and then cut off the oil and shut down the engine.

[0019] Preferably, the protection mechanism comprises a trigger screw, an inner rotating link, a moving link, an outer rotating link, a first mounting seat and a second mounting seat;

[0020] The trigger screw is threadedly connected to the inner rotating connecting rod;

[0021] One end of the inner rotating connecting rod close to the trigger screw is rotatably connected to the first mounting seat, and one end of the inner rotating connecting rod away from the trigger screw is rotatably connected to the moving connecting rod;

[0022] One end of the movable link away from the inner rotating link is rotatably connected to the outer rotating link;

[0023] The second mounting seat is rotatably connected to the outer rotating connecting rod.

[0024] Preferably, the trigger screw is arranged axially along the low-pressure shaft.

[0025] Preferably, the first mounting seat is fixedly connected to the exhaust casing;

[0026] The second mounting seat is fixedly connected to the lower receiver;

[0027] The exhaust casing and the lower casing are movable relative to each other.

[0028] Preferably, the outer rotating link is connected to a steel cable.

[0029] A method for cutting off oil supply for over-rotation protection of a low-pressure turbine rotor is provided, which is used for the above-mentioned oil cutting off mechanism for over-rotation protection of a low-pressure turbine rotor.

[0030] Preferably, the method comprises: after the low-pressure shaft breaks, calculating a first time, wherein the first time is the time required for the turbine rotor to move axially along the low-pressure shaft until it collides with the protection mechanism;

[0031] Calculating a second time, where the second time is the time it takes for the protection mechanism to move axially a preset distance after colliding with the turbine rotor; or calculating a third time, where the third time is the time it takes for the protection mechanism to transmit displacement information of the turbine rotor;

[0032] Calculating a protection time, where the protection time is the sum of the first time and the second time, or calculating the sum of the first time and the third time;

[0033] Based on the protection time, the fuel supply to the engine is cut off until the engine stops.

[0034] Preferably, calculating the first time includes:

[0035] Obtain the axial distance between the trigger screw in the protection mechanism and the turbine rotor before the low-pressure shaft breaks, recorded as L1;

[0036] The first time is calculated based on the following formula:

[0037] t1=L1 / v1, where t1 is the first time and v1 is the average speed of the turbine rotor moving L1.

[0038] Preferably, calculating the second time includes:

[0039] Obtain the preset distance that the trigger screw in the protection mechanism moves axially after colliding with the turbine rotor, recorded as L2;

[0040] The second time is calculated based on the following formula:

[0041] t2=L2 / v2, where t2 is the second time and v2 is the average speed of the trigger screw moving along the axial direction L2.

[0042] Preferably, calculating the third time includes:

[0043] Obtain the axial movement distance of the outer rotating connecting rod, recorded as L3;

[0044] Based on L3, the moving distance of the steel cable connected to the outer rotating link is obtained and recorded as L4;

[0045] The displacement sensor on one side of the cable detects the cable moving distance L4 and sends a signal to calculate the third time;

[0046] The third time t3 is calculated based on L3 using the following formula:

[0047] t3=L3 / v3, where t3 is the third time and v3 is the average speed of the outer rotating connecting rod moving along the axial direction L3.

[0048] Preferably, L3 / L2>1.

[0049] Beneficial effects of the present invention:

[0050] 1. The present invention uses a protective mechanism to transmit the displacement information of the turbine rotor. When the low-pressure shaft breaks, the transmission mechanism can promptly transmit the fracture information to the engine, causing the engine to shut down in time, thus preventing the turbine disc from breaking due to high rotation of the low-pressure shaft.

[0051] 2. The present invention calculates the first time, the second time, and the third time, and proposes controlling the axial distance L1 between the trigger screw and the turbine rotor, the preset distance L2 that the trigger screw moves axially after colliding with the turbine rotor, and the axial distance L3 of the outer rotating connecting rod, so that the protection time can be controlled within a target range, thereby avoiding the situation where the turbine rotor overrotates and causes the turbine disk to rupture, and avoiding the risk of control system failure.

[0052] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0054] Figure 1 A schematic structural diagram of a low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to the present invention is shown;

[0055] Figure 2 A schematic structural diagram of the protection mechanism of the present invention is shown;

[0056] Figure 3 A flow chart of a method for cutting off oil supply for over-speed protection of a low-pressure turbine rotor according to the present invention is shown.

[0057] In the figure: 1. Upper casing; 2. Exhaust casing; 3. Lower casing; 4. Protection mechanism; 401. Trigger screw; 402. Inner rotating connecting rod; 403. Moving connecting rod; 404. Outer rotating connecting rod; 405. First mounting seat; 406. Second mounting seat; 5. Low-pressure shaft; 6. Turbine rotor; 7. Steel cable; 8. Displacement sensor; 9. Oil shut-off valve. DETAILED DESCRIPTION

[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. 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 shall fall within the scope of protection of the present invention.

[0059] A low-pressure turbine rotor over-rotation protection oil cut-off mechanism, such as Figure 1 As shown, it includes an upper casing 1, an exhaust casing 2, a lower casing 3, a protection mechanism 4, a low-pressure shaft 5 and a turbine rotor 6; wherein the upper casing 1, the exhaust casing 2 and the lower casing 3 are all rotating body structures, the turbine rotor 6 is installed on the low-pressure shaft 5, and the protection mechanism 4 is located on one side of the low-pressure shaft 5. When the low-pressure shaft 5 breaks, the turbine rotor 6 will move Figure 1 The exhaust casing 2 is fixedly connected to the upper casing 1, and the other end is connected to the protective mechanism 4. The end of the protective mechanism 4 away from the exhaust casing 2 is connected to the lower casing 3, and the exhaust casing 2 and the lower casing 3 are relatively movable. The protective mechanism 4 is also connected to the steel cable 7, and a displacement sensor 8 is also installed on one side of the steel cable 7. The displacement sensor 8 is used to send an oil cut-off signal to the oil cut-off valve 9 connected to the steel cable 7 when the steel cable 7 moves to a preset position. Then the oil cut-off valve 9 cuts off the oil, the engine stops, and from Figure 1 It can be seen that the lower casing 3 and the upper casing 1 are not in contact, and there is a certain gap between them, which can ensure that the upper and lower ends of the protection mechanism 4 can move relative to each other.

[0060] It should be noted that the protection mechanism 4 is a displacement transmission mechanism, which can be a four-bar linkage mechanism, see Figure 2 .

[0061] Furthermore, if Figure 2As shown, the protection mechanism 4 includes a trigger screw 401, an inner rotating link 402, a movable link 403, an outer rotating link 404, a first mounting seat 405, and a second mounting seat 406, which together form a planar four-bar linkage. Its primary function is to trigger the fuel control system to shut off fuel after the low-pressure turbine shaft breaks, thereby preventing the casing from being uncontained due to the low-pressure turbine disk rupture caused by overspeeding of the low-pressure turbine rotor 6. In the protection mechanism 4, the trigger screw 401 is threadedly connected to the inner rotating link 402; the end of the inner rotating link 402 near the trigger screw 401 is rotatably connected to the first mounting seat 405 and is arranged axially along the low-pressure shaft 5. The end of the inner rotating link 402 away from the trigger screw 401 is rotatably connected to the movable link 403; the end of the movable link 403 away from the inner rotating link 402 is rotatably connected to the outer rotating link 404; and the second mounting seat 406 is rotatably connected to the outer rotating link 404. In addition, the first mounting seat 405 is fixedly connected to the exhaust casing 2 , the second mounting seat 406 is fixedly connected to the lower casing 3 , and the outer rotating connecting rod 404 is connected to the steel cable 7 .

[0062] It should be noted that when the trigger screw 401 moves axially along the low-pressure shaft 5, the inner rotating connecting rod 402 moves axially therewith, and then the inner rotating connecting rod 402 drives the upper end of the moving connecting rod 403 to move beyond the upper end. Figure 2 The middle right side moves, the lower end of the movable link 403 moves to the left, and then the outer rotating link 404 moves to the left. Finally, the outer rotating link 404 tightens the steel cable 7 connected thereto, and the steel cable 7 moves a distance, and the displacement sensor 8 monitors the distance.

[0063] It should be further explained that after the low-pressure turbine shaft breaks, since there is no ball bearing to bear the axial force, the turbine rotor 6 moves backward by L1 under the action of backward aerodynamic force. After time t1 (first time), it collides with the trigger screw 401. After time t2 (second time), the trigger screw 401 moves axially by a preset distance L2. After the connecting rod 402, the moving connecting rod 403, and the external rotating connecting rod 404 in the connecting rod mechanism, the external rotating connecting rod 404 can move axially by a distance L3. L3 / L2>1, that is, the transmission ratio. The external rotating connecting rod 404 drives the steel cable 7. After time t3, the steel cable 7 triggers the displacement sensor 8, which transmits an electrical signal to the oil shut-off valve 9. Then the oil shut-off valve 9 cuts off the fuel supply and the engine stops. After time t1+t2 or t1+t3, the low-pressure turbine disk speed is less than the rupture speed, thereby causing the low-pressure engine rotor to overspeed.

[0064] A method for cutting off oil supply for over-speed protection of a low-pressure turbine rotor is used for the above-mentioned oil-cutting mechanism for over-speed protection of a low-pressure turbine rotor, such as Figure 3 As shown, the details are as follows:

[0065] S1: After the low-pressure shaft 5 breaks, the first time is calculated. The first time is the time required for the turbine rotor 6 to move axially along the low-pressure shaft 5 until it collides with the protection mechanism 4;

[0066] S2: Calculating a second time, which is the time it takes for the protection mechanism 4 to move a preset distance axially after colliding with the turbine rotor 6; or calculating a third time, which is the time it takes for the protection mechanism 4 to transmit the displacement information of the turbine rotor 6;

[0067] S3: Calculate the protection time, which is the sum of the first time and the second time, or the sum of the first time and the third time;

[0068] S4: Based on the protection time, the fuel supply to the engine is cut off until the engine stops rotating.

[0069] From steps S1 to S4, it can be seen that the protection oil cut-off method is related to the protection time. Generally speaking, the shorter the protection time, the lower the risk of low-pressure turbine disk rupture and the higher the safety. Therefore, the protection oil cut-off method needs to consider how to shorten the protection time. The specific calculation process is as follows:

[0070] Furthermore, calculating the first time includes:

[0071] S101: Obtain the axial distance between the trigger screw 401 in the protection mechanism 4 and the turbine rotor 6 before the low-pressure shaft 5 breaks, recorded as L1;

[0072] S102: Calculate the first time based on the following formula:

[0073] t1=L1 / v1, where t1 is the first time, and v1 is the average speed of the movement L1 of the turbine rotor 6.

[0074] It should be noted that, through the calculation process of the first time, it can be seen that the smaller L1 is, the shorter the first time will be, because after the low-pressure shaft 5 breaks, the speed of v1 is uncontrollable, so L1 can be set to reduce the first time.

[0075] Furthermore, calculating the second time includes:

[0076] S201: Obtaining a preset distance, L2, that the trigger screw 401 of the protection mechanism 4 moves axially after colliding with the turbine rotor 6;

[0077] S202: Calculate the second time based on the following formula:

[0078] t2=L2 / v2, where t2 is the second time, and v2 is the average speed of the trigger screw 401 moving along the axial direction L2.

[0079] It should be noted that the moving speed of the trigger screw 401 is related to the speed at which the turbine rotor 6 contacts the trigger screw 401. Therefore, the second time t2 is more convenient to adjust through L2. When designing the movable distance of the trigger screw 401, L2 can be minimized to reduce the second time.

[0080] Furthermore, calculating the third time includes:

[0081] S301: Obtaining the axial movement distance of the outer rotating link 404, recorded as L3;

[0082] S302: Based on L3, the moving distance of the steel cable 7 connected to the outer rotating link 404 is obtained, which is recorded as L4;

[0083] S303: The displacement sensor 8 on one side of the steel cable 7 detects that the steel cable 7 has moved a distance L4 and sends a signal for calculating a third time;

[0084] S304: Calculate the third time t3 based on L3, using the following formula:

[0085] t3=L3 / v3, where t3 is the third time, and v3 is the average speed of the outer rotating link 404 moving along the axial direction L3.

[0086] It should be noted that because trigger screw 401 is mounted inside upper casing 1, detecting its movement data has certain limitations. Therefore, the second time can be inferred by calculating the third time, thereby verifying its accuracy. As can be seen from steps S301-S304, protection mechanism 4 can drive the movement of cable 7, and thus the protection mechanism 4 and cable 7 move synchronously. Displacement sensor 8 monitors cable 7. When cable 7 moves to a critical position, displacement sensor 8 sends a signal to the system, which then cuts off the fuel.

[0087] It should be further explained that, in the oil cut-off protection method of the present invention, the values of L1, L2 and L3 need to be adjusted within a reasonable range to achieve the oil cut-off protection effect while ensuring that the oil cut-off protection mechanism can operate stably.

[0088] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-pressure turbine rotor over-rotation protection oil cut-off mechanism, characterized in that: It includes an upper casing (1), an exhaust casing (2), a lower casing (3), a protection mechanism (4), a low-pressure shaft (5) and a turbine rotor (6); The protection mechanism (4) is located on one side of the low-pressure shaft (5) and is used to transmit displacement information of the turbine rotor (6) after the low-pressure shaft (5) breaks; The turbine rotor (6) is mounted on the low-pressure shaft (5) and is used to cause the turbine rotor (6) to collide with the protection mechanism (4) and push the protection mechanism (4) to move when the low-pressure shaft (5) breaks. One end of the exhaust casing (2) is fixedly connected to the upper casing (1), and the other end is connected to the protection mechanism (4); One end of the protection mechanism (4) away from the exhaust casing (2) is connected to the lower casing (3); The protection mechanism (4) is further connected to a steel cable (7), and a displacement sensor (8) is further installed on one side of the steel cable (7). The displacement sensor (8) is used to send an oil cut-off signal when the steel cable (7) moves to a preset position. The steel cable (7) is also connected to an oil cut-off valve (9), and the oil cut-off valve (9) is used to receive an oil cut-off signal, and then cut off the oil and stop the engine; The low-pressure turbine rotor over-rotation protection oil cut-off mechanism is used for: After the low-pressure shaft (5) breaks, a first time is calculated, wherein the first time is the time required for the turbine rotor (6) to move axially along the low-pressure shaft (5) until it collides with the protection mechanism (4); Calculating a second time, the second time being the time it takes for the protection mechanism (4) to move a preset distance in the axial direction after colliding with the turbine rotor (6); Alternatively, a third time is calculated, wherein the third time is the time required for the protection mechanism (4) to transmit the displacement information of the turbine rotor (6); Calculating a protection time, where the protection time is the sum of the first time and the second time, or calculating the sum of the first time and the third time; Based on the protection time, the fuel supply to the engine is cut off until the engine stops.

2. A low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to claim 1, characterized in that: The protection mechanism (4) comprises a trigger screw (401), an inner rotating connecting rod (402), a moving connecting rod (403), an outer rotating connecting rod (404), a first mounting seat (405) and a second mounting seat (406); The trigger screw (401) is threadedly connected to the inner rotating connecting rod (402); One end of the inner rotating link (402) close to the trigger screw (401) is rotatably connected to the first mounting seat (405), and one end of the inner rotating link (402) away from the trigger screw (401) is rotatably connected to the moving link (403); One end of the movable link (403) away from the inner rotating link (402) is rotatably connected to the outer rotating link (404); The second mounting seat (406) is rotatably connected to the outer rotating connecting rod (404).

3. A low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to claim 2, characterized in that: The trigger screw (401) is arranged axially along the low-pressure shaft (5).

4. A low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to claim 2, characterized in that: The first mounting seat (405) is fixedly connected to the exhaust casing (2); The second mounting seat (406) is fixedly connected to the lower casing (3); The exhaust casing (2) and the lower casing (3) are movable relative to each other.

5. The low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to claim 2, characterized in that: The outer rotating connecting rod (404) is connected to the steel cable (7).

6. A low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to any one of claims 2 to 5, characterized in that: Calculate the first time, including: Obtain the axial distance between the trigger screw (401) in the protection mechanism (4) and the turbine rotor (6) before the low-pressure shaft (5) breaks, which is recorded as L1; The first time is calculated based on the following formula: t1=L1 / v1, where t1 is the first time and v1 is the average speed of the turbine rotor (6) moving L1.

7. The low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to claim 6, characterized in that: Calculate the second time, including: Obtaining a preset distance that the trigger screw (401) in the protection mechanism (4) moves axially after colliding with the turbine rotor (6), which is recorded as L2; The second time is calculated based on the following formula: t2=L2 / v2, where t2 is the second time, and v2 is the average speed of the trigger screw (401) moving along the axial direction L2.

8. The low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to claim 7, characterized in that: Calculate the third time, including: Obtaining the axial movement distance of the outer rotating connecting rod (404), recorded as L3; Based on L3, the moving distance of the steel cable (7) connected to the outer rotating link (404) is obtained and recorded as L4; The displacement sensor (8) on one side of the steel cable (7) detects that the steel cable (7) has moved a distance L4 and then sends a signal for calculating the third time; The third time t3 is calculated based on L3 using the following formula: t3=L3 / v3, where t3 is the third time, and v3 is the average speed of the outer rotating connecting rod (404) moving along the axial direction L3.

9. The low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to claim 8, characterized in that: The L3 / L2>1.

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