CN116378782A - A low-pressure turbine rotor over-rotation protection oil cut-off mechanism and method thereof - Google Patents

Abstract

The invention belongs to the technical field of turbine engines, and discloses a low-pressure turbine rotor over-rotation protection oil-break mechanism and a method thereof. According to the invention, the displacement information of the turbine rotor is transmitted by using the protection mechanism, so that after the low-pressure shaft is broken, the broken information can be transmitted to the engine in time through the transmission mechanism, the engine is stopped in time, and the condition that the turbine disc is broken due to the high rotation of the low-pressure shaft is avoided; the invention proposes by calculating the first time, the second time and the third time by controlling the axial distance L of the trigger screw from the turbine rotor ₁ A preset distance L for the trigger screw to move axially after the trigger screw collides with the turbine rotor ₂ And a distance L of axial movement of the outer rotary link ₃ The protection time can be controlled within the target range, and the occurrence of turbine rotor over-rotation is avoidedResulting in a condition of rupture of the turbine disc.

Description

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

technical field

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

Background technique

Loss of load on the low-pressure turbine rotor (such as a broken low-pressure shaft) may cause the disc to fly and break to produce high-energy non-contained debris, which will endanger the safety of the engine. In addition to the electronic over-rotation protection system, it is necessary to set up a mechanical over-rotation protection mechanism. At present, there are three main design methods based on the mechanical over-rotation protection mechanism:

1) After the shaft breaks, the turbine rotor moves backwards, and the over-rotation protection mechanism triggers the fuel system and directly closes the throttle;

2) After the shaft is broken, the turbine rotor moves backward, and the stator parts such as the guide vanes block the rotating parts, or break the rotor blades to prevent the wheel from continuing to over-rotate;

3) After the shaft breaks, the turbine rotor over-rotates, and the blades break and fly out before reaching the rupture speed of the disk, so as to prevent the speed of the turbine disk from continuing to increase. This method is generally called the blade shedding protection design.

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

1) In the electronic over-rotation protection mode, the design of the structural strength of the wheel and blade is relatively simple, and there is no need to consider that the disk must be higher than the rupture speed of the blade, but there is a certain risk of failure of the control system;

2) The blade shedding protection mode has high reliability, but the structural strength design is complicated, which will bring the risk of increasing the weight of the rotor and reducing the life of the blade;

3) Stator parts such as guide vanes block the rotating parts, or break the rotor blades to prevent the wheel from continuing to over-rotate. The risk is high, and there is little experience in the application of existing engines.

Contents of the invention

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 a method thereof.

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

An oil cut-off mechanism for low-pressure turbine rotor over-rotation protection, including an upper casing, an exhaust casing, a lower casing, a protection mechanism, a low-pressure shaft and a turbine rotor;

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

The turbine rotor is installed on the low-pressure shaft, and is used for colliding with the protection mechanism when the low-pressure shaft breaks, and pushing the protection mechanism to move;

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

The end of the protection mechanism away from the exhaust casing is connected to the lower casing;

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

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

Preferably, the protection mechanism includes a trigger screw, an inner rotating link, a moving link, an outer rotating link, a first mount and a second mount;

The trigger screw is threadedly connected with the inner rotating connecting rod;

The end of the inner rotating link close to the trigger screw is rotatably connected to the first mount, and the end of the inner rotating link far away from the trigger screw is rotatably connected to the moving link;

One end of the moving connecting rod away from the inner rotating connecting rod is rotationally connected with the outer rotating connecting rod;

The second mounting base is rotatably connected with the outer rotatable connecting rod.

Preferably, the trigger screw is arranged axially along the low pressure axis.

Preferably, the first mount is fixedly connected to the exhaust casing;

The second mount is fixedly connected to the lower casing;

The exhaust casing is relatively movable with the lower casing.

Preferably, the outer rotating link is connected with a steel cable.

A low-pressure turbine rotor over-rotation protection oil cut-off method is used in the above-mentioned low-pressure turbine rotor over-rotation protection oil cut-off mechanism.

Preferably, the method includes: after the low-pressure shaft breaks, calculating the first time, the first time being the time required for the turbine rotor to move axially along the low-pressure shaft until it collides with the protection mechanism;

Calculate the second time, the second time is the time for the protection mechanism to move the preset distance in the axial direction after colliding with the turbine rotor; or, calculate the third time, the third time is the displacement information of the turbine rotor by the protection mechanism the time it takes to deliver;

calculating a guard time, the guard time being 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 guard time, the fuel supply to the engine is cut off until the engine stops.

Preferably, calculating the first time includes:

Obtain the axial distance between the trigger screw in the protective mechanism and the turbine rotor before the low-pressure shaft breaks, denoted as _L1 ;

The first time is calculated based on the following formula:

t ₁ =L ₁ /v ₁ , where t ₁ is the first time, and v ₁ is the average speed of moving L ₁ of the turbine rotor.

Preferably, calculating the second time includes:

Obtain the preset distance moving axially after the trigger screw in the protection mechanism collides with the turbine rotor, denoted as L ₂ ;

The second time is calculated based on the following formula:

t ₂ =L ₂ /v ₂ , where t ₂ is the second time, and v ₂ is the average velocity of the trigger screw moving L ₂ along the axial direction.

Preferably, calculating the third time includes:

Obtain the axial movement distance of the outer rotating connecting rod, denoted as L ₃ ;

Obtain the moving distance of the steel cable connected with the outer rotating link based on L ₃ , denoted as L ₄ ;

The displacement sensor on one side of the cable sends a signal to calculate the third time after detecting the moving distance _L4 of the cable;

Calculate the third time t ₃ based on L ₃ , the formula is as follows:

t ₃ =L ₃ /v ₃ , where t ₃ is the third time, and v ₃ is the average speed of L ₃ moving the outer rotating connecting rod in the axial direction.

Preferably, said L ₃ /L ₂ >1.

Beneficial effects of the present invention:

1. The invention transmits the displacement information of the turbine rotor by using the protection mechanism, so that after the low-pressure shaft is broken, the fracture information can be transmitted to the engine in time through the transmission mechanism, so that the engine can be stopped in time, and the turbine disk is prevented from being broken due to the high rotation of the low-pressure shaft Case;

2. By calculating the first time, the second time and the third time, the present invention proposes to control the axial distance L ₁ from the trigger screw to the turbine rotor, and the preset distance L to move axially after the trigger screw collides with the turbine rotor ₂ and the distance L ₃ of the axial movement of the outer rotating connecting rod, so that the protection time can be controlled within the target range, avoiding the situation that the turbine rotor is over-rotating and causing the turbine disk to break, and avoiding the risk of failure of the control system.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure pointed out in the written description as well as the appended drawings.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 shows a structural schematic diagram of a low-pressure turbine rotor over-rotation protection oil cut-off mechanism of the present invention;

Fig. 2 shows the structural representation of the protection mechanism of the present invention;

Fig. 3 shows a flow chart of a method for oil cut-off of low-pressure turbine rotor over-rotation protection according to the present invention.

Among 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 Rod; 405, first mounting seat; 406, second mounting seat; 5, low-pressure shaft; 6, turbine rotor; 7, steel cable; 8, displacement sensor; 9, oil cut-off valve.

Detailed ways

In order to make the purpose, 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 It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

A low-pressure turbine rotor over-rotation protection oil cut-off mechanism, as shown in Figure 1, 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 Casing 1, exhaust casing 2 and lower casing 3 are all rotary structures. The turbine rotor 6 is installed on the low-pressure shaft 5, and the protection mechanism 4 is located on the side of the low-pressure shaft 5. When the low-pressure shaft 5 breaks, the turbine rotor 6 is It will move to the right side in Figure 1, and then collide with the protection mechanism 4 and move a certain distance. The protection mechanism 4 moves with the push of the turbine rotor 6, and transmits the displacement information until the engine cuts off the oil; the exhaust casing 2. One end is fixedly connected to the upper casing 1, and the other end is connected to the protection mechanism 4. The end of the protection mechanism 4 away from the exhaust casing 2 is connected to the lower casing 3, and the exhaust casing 2 is opposite to the lower casing 3. activity, the protection mechanism 4 is also connected with a steel cable 7, and a displacement sensor 8 is installed on one side of the steel cable 7. The displacement sensor 8 is used to send an oil cut signal to the engine connected to the steel cable 7 when the steel cable 7 moves to a preset position. The oil cut-off valve 9, and then the oil cut-off valve 9 cuts off the oil, and the engine stops, and it can be seen from Figure 1 that the lower casing 3 and the upper casing 1 are not in contact, and there is a certain gap between the two, which can ensure that the protection mechanism 4 The upper and lower ends can move relatively.

It should be noted that the protection mechanism 4 is a displacement transmission mechanism, specifically a four-bar linkage mechanism can be used, see FIG. 2 for details.

Further, as shown in FIG. 2, the protection mechanism 4 includes a trigger screw 401, an inner rotating link 402, a moving link 403, an outer rotating link 404, a first mounting base 405 and a second mounting base 406', which together form a plane The main function of the four-bar linkage mechanism is to trigger the fuel control system to cut off the fuel after the low-pressure turbine shaft is broken, so as to prevent the non-containment of the casing caused by the rupture of the low-pressure turbine disk due to the over-rotation of the low-pressure turbine rotor 6 . In the protection mechanism 4, the trigger screw 401 is threadedly connected with the inner rotating connecting rod 402; the end of the inner rotating connecting rod 402 close to the trigger screw 401 is rotatably connected with the first mount 405, and is arranged along the axial direction of the low pressure shaft 5, and the inner rotating The end of the connecting rod 402 away from the trigger screw 401 is rotationally connected with the moving connecting rod 403; the end of the moving connecting rod 403 away from the inner rotating connecting rod 402 is rotationally connected with the outer rotating connecting rod 404; the second mount 406 is rotating with the outer rotating connecting rod 404 connect. In addition, the first mounting base 405 is fixedly connected with the exhaust casing 2 , the second mounting base 406 is fixedly connected with the lower casing 3 , and the outer rotating connecting rod 404 is connected with the steel cable 7 .

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 along with it, and then the inner rotating connecting rod 402 drives the upper end of the moving connecting rod 403 to move beyond the right side in FIG. The lower end of the connecting rod 403 then moves to the left, and then the outer rotating connecting rod 404 moves to the left, and finally the outer rotating connecting rod 404 tightens the steel cable 7 connected thereto, and the steel cable 7 is displaced for a certain distance, and the displacement sensor 8 monitors the distance.

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 L ₁ under the action of the backward aerodynamic force, and the time t ₁ (the first time) passes , collides with trigger screw 401, after time t ₂ (the second time), trigger screw 401 axially moves preset distance L ₂ , through the linkage mechanism inner rotating link 402, moving link 403, outer rotating link 404 Finally, the axial distance of the outer rotating connecting rod 404 can be moved by L ₃ , L ₃ /L ₂ >1, that is, the transmission ratio, the outer rotating connecting rod 404 drives the steel cable 7, and the steel cable 7 triggers the displacement sensor 8 after time t ₃ , Transmit an electrical signal to the oil cut-off valve 9, then the oil cut-off valve 9 cuts off the fuel supply, the engine stops, and after the time t ₁ + t ₂ or t ₁ + t ₃ , the rotation speed of the low-pressure turbine disc is less than the rupture speed, thereby playing the role of low-pressure engine rotor The effect of overturning.

A method for oil cut-off of low-pressure turbine rotor over-rotation protection, which is used in the above-mentioned low-pressure turbine rotor over-rotation protection oil cut-off mechanism, as shown in Figure 3, specifically as follows:

S1: After the low-pressure shaft 5 breaks, calculate the first time, which 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;

S2: Calculate the second time, the second time is the time when the protection mechanism 4 moves the preset distance in the axial direction after colliding with the turbine rotor 6; or, calculate the third time, the third time is the time when the protection mechanism 4 moves the turbine rotor 6 The time required for the displacement information to be transmitted;

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

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

From steps S1-S4, it can be known 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 rupture of the low-pressure turbine disk, and the higher the safety. Therefore, how to protect the oil cut-off method needs to be considered To shorten the protection time, the specific calculation process is as follows:

Further, the calculation of the first time includes:

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, denoted as L ₁ ;

S102: Calculate the first time based on the following formula:

t ₁ =L ₁ /v ₁ , where t ₁ is the first time, and v ₁ is the average speed of moving L ₁ of the turbine rotor 6 .

It should be noted that, through the calculation process of the first time, it can be known 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.

Further, calculating the second time includes:

S201: Obtain the preset distance moved axially after the trigger screw 401 in the protection mechanism 4 collides with the turbine rotor 6, denoted as L ₂ ;

S202: Calculate the second time based on the following formula:

t ₂ =L ₂ /v ₂ , where t ₂ is the second time, and v ₂ is the average velocity of the trigger screw 401 moving L ₂ along the axial direction.

It should be noted that the moving speed of the trigger screw 401 is related to the speed when the turbine rotor 6 is in contact, so the second time _t2 is more convenient to adjust through L2, and when designing the movable distance of the trigger screw ₄₀₁ , L can be reduced as much as possible. ₂ , reduce the second time.

Further, the calculation of the third time includes:

S301: Acquire the axial movement distance of the outer rotating connecting rod 404, denoted as L ₃ ;

S302: Obtain the moving distance of the steel cable 7 connected to the outer rotating link 404 based on L ₃ , denoted as L ₄ ;

S303: the displacement sensor 8 on one side of the steel cable 7 sends a signal for calculating the third time after detecting the moving distance _L4 of the steel cable 7;

S304: Calculate the third time t ₃ based on L ₃ , the formula is as follows:

t ₃ =L ₃ /v ₃ , where t ₃ is the third time, and v ₃ is the average speed at which the outer rotating link 404 moves L ₃ in the axial direction.

It should be noted that since the trigger screw 401 is installed inside the upper casing 1, there are certain limitations in detecting its movement data. Therefore, the second time can also be deduced by calculating the third time, and at the same time, the accuracy of the second time can be verified. accuracy. Through steps S301-S304, it can be seen that the protection mechanism 4 can drive the steel cable 7 to move, so the protection mechanism 4 and the steel cable 7 move synchronously. At this time, the displacement sensor 8 is used to monitor the steel cable 7. When the steel cable 7 moves to the critical position , the displacement sensor 8 can send a signal to the system, and then cut off the fuel.

It should be further explained that, in the method for protecting the fuel cutoff of the present invention, it is necessary to adjust the values of L ₁ , L ₂ and L ₃ within a reasonable range, so as to realize the protection of the fuel cutoff mechanism while ensuring the stable operation of the protection fuel cutoff mechanism. effect.

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 perform equivalent replacements for some of the technical features; and these The modification or replacement does not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (11)

1. A low-pressure turbine rotor over-rotation protection oil cut-off mechanism is characterized in that it comprises an upper casing (1), an exhaust casing (2), a lower casing (3), a protection mechanism (4), a low-pressure shaft ( 5) and the turbine rotor (6); The protection mechanism (4) is located on one side of the low-pressure shaft (5), and is used to transmit the displacement information of the turbine rotor (6) after the low-pressure shaft (5) breaks; The turbine rotor (6) is installed on the low-pressure shaft (5), and is used for colliding the turbine rotor (6) with the protection mechanism (4) when the low-pressure shaft (5) breaks, and pushing the protection mechanism (4) to move; 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 with the lower casing (3); The protection mechanism (4) is also connected with a steel cable (7), and a displacement sensor (8) is also installed on one side of the steel cable (7), and the displacement sensor (8) is used for when the steel cable (7) moves After reaching the preset position, an oil cut-off signal is sent; The steel cable (7) is also connected with an oil cut-off valve (9), and the oil cut-off valve (9) is used to receive the oil cut-off signal, and then the oil is cut off, and the engine is shut down. 2. A low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to claim 1, characterized in that, the protection mechanism (4) includes a trigger screw (401), an inner rotating connecting rod (402), a moving connecting rod (403), the outer rotating link (404), the first mount (405) and the second mount (406); The trigger screw (401) is threadedly connected with 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 mount (405), and the end of the inner rotating link (402) away from the trigger screw (401) is connected to the moving link ( 403) rotating connection; One end of the moving connecting rod (403) away from the inner rotating connecting rod (402) is rotationally connected with the outer rotating connecting rod (404); The second mounting base (406) is rotatably connected with the outer rotatable link (404). 3. The oil cut-off mechanism for low-pressure turbine rotor over-rotation protection 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 base (405) is fixedly connected to the exhaust casing (2); The second mounting seat (406) is fixedly connected with the lower casing (3); The exhaust casing (2) is relatively movable with the lower casing (3). 5. The oil cut-off mechanism for low-pressure turbine rotor over-rotation protection according to claim 2, characterized in that, the outer rotating connecting rod (404) is connected with a steel cable (7). 6. A method for oil cut-off of low-pressure turbine rotor over-rotation protection, characterized in that it is used in a low-pressure turbine rotor over-rotation protection oil cut-off mechanism according to any one of claims 2-5. 7. A method for oil cut-off of low-pressure turbine rotor over-rotation protection according to claim 6, characterized in that it comprises: After the low-pressure shaft (5) breaks, calculate the first time, which 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); Calculate the second time, the second time is the time for the protection mechanism (4) to move the preset distance axially after colliding with the turbine rotor (6); or, calculate the third time, the third time is the protection mechanism (4) the time required for transmitting the displacement information of the turbine rotor (6); calculating a guard time, the guard time being 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 guard time, the fuel supply to the engine is cut off until the engine stops. 8. A method for oil cut-off of low-pressure turbine rotor over-rotation protection according to claim 7, characterized in that calculating the first time includes: Obtain the axial distance from the trigger screw (401) in the protection mechanism (4) to the turbine rotor (6) before the fracture of the low-pressure shaft (5), denoted as L ₁ ; The first time is calculated based on the following formula: t ₁ =L ₁ /v ₁ , where t ₁ is the first time, and v ₁ is the average speed of moving L ₁ of the turbine rotor (6). 9. A method for oil cut-off of low-pressure turbine rotor over-rotation protection according to claim 8, characterized in that calculating the second time includes: Obtain the preset distance moved axially after the trigger screw (401) in the protection mechanism (4) collides with the turbine rotor (6), denoted as L ₂ ; The second time is calculated based on the following formula: t ₂ =L ₂ /v ₂ , where t ₂ is the second time, and v ₂ is the average velocity of the trigger screw ( 401 ) moving L ₂ along the axial direction. 10. A method for oil cut-off of low-pressure turbine rotor over-rotation protection according to claim 9, characterized in that calculating the third time includes: Obtain the distance moved along the axial direction of the outer rotating connecting rod (404), which is denoted as L ₃ ; Obtain the moving distance of the steel cable (7) connected with the outer rotating link (404) based on L ₃ , denoted as L ₄ ; The displacement sensor (8) on one side of the cable (7) sends a signal to calculate the third time after detecting the moving distance _L4 of the cable (7); Calculate the third time t ₃ based on L ₃ , the formula is as follows: t ₃ =L ₃ /v ₃ , where t ₃ is the third time, and v ₃ is the average speed at which the outer rotating link (404) moves L ₃ in the axial direction. 11 . The method for oil cut-off of low-pressure turbine rotor over-rotation protection according to claim 10, characterized in that, said L ₃ /L ₂ >1.

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