An engine starting system improvement method, starting system and engine

Abstract

The application relates to an engine starting system improvement method, a pneumatic system and an engine, and comprises the following steps: obtaining an initial resistance torque and a starting resistance torque of an engine; obtaining a first transmission ratio according to an initial torque of a pneumatic motor under a set intake air pressure and the obtained initial resistance torque of the engine, and obtaining a second transmission ratio according to a starting torque of the pneumatic motor under the set intake air pressure and the obtained starting resistance torque of the engine; selecting a larger one of the first transmission ratio and the second transmission ratio as a transmission ratio between a gear and a ring gear of the pneumatic motor; obtaining structure parameters of a new ring gear according to the transmission ratio; processing the new ring gear by using the structure parameters of the new ring gear, dismounting an original ring gear of the engine, replacing the original ring gear with the new ring gear, and installing the pneumatic motor, wherein the gear of the pneumatic motor is engaged with the new ring gear; and the improved method of the application realizes the application of an engine with higher starting air pressure requirement on an offshore drilling platform.

Description

Technical Field

[0001] This invention relates to the field of engine technology, specifically to an improved method for engine starting systems, a starting system, and an engine. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Currently, the starting system of megawatt-class four-stroke inline or V-type engines includes an air source, a pneumatic motor, and a gear ring. After the air source supplies gas at a certain pressure to the pneumatic motor, the gear of the pneumatic motor drives the gear ring to rotate. The rotation of the gear ring drives the inline engine to start. Currently, the minimum gas pressure required for starting an inline engine is 8-10 bar. When inline engines are used on offshore drilling platforms, the operating pressure of the compressed air system on these platforms is usually 5-6 bar due to safety regulations and operating conditions. This pressure mismatch means that conventional inline engine starting systems cannot meet the actual operating needs of offshore drilling platforms. Therefore, how to improve the inline engine starting system to meet the actual operating needs of offshore drilling platforms is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide an improved engine starting system method, starting system, and engine. The improved engine starting system enables the engine to start and operate on an offshore drilling platform.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, embodiments of the present invention provide an improved method for an engine starting system, comprising the following steps: Obtain the engine's initial resistance torque and starting resistance torque; The first transmission ratio is obtained based on the initial torque of the pneumatic motor under the set intake pressure and the initial resistance torque of the engine. The second transmission ratio is obtained based on the starting torque of the pneumatic motor under the set intake pressure and the starting resistance torque of the engine. The larger of the first and second transmission ratios is selected as the transmission ratio between the gear and the ring gear of the pneumatic motor. The structural parameters of the new gear ring are obtained based on the transmission ratio; A new gear ring is manufactured using the structural parameters of the new gear ring. The original gear ring of the engine is removed and replaced with the new gear ring. A pneumatic motor is then installed, and the gear of the pneumatic motor meshes with the new gear ring.

[0006] Optionally, the structural parameters of the gear ring include the number of teeth and the module, wherein the number of teeth of the gear ring is obtained based on the transmission ratio and the number of teeth of the pneumatic motor gear, and the module is obtained based on the initial center distance between the gear and the gear ring and the number of teeth of the gear and the gear ring.

[0007] Optionally, the initial value of the module is obtained based on the initial center distance between the gear and the gear ring and the number of teeth of the gear and the gear ring. The initial value of the module is rounded to obtain the final module value. The corrected center distance between the gear and the gear ring is obtained based on the final module value and the number of teeth of the gear and the gear ring. A new pneumatic motor mounting hole is machined on the engine cover based on the corrected center distance between the gear and the gear ring. The pneumatic motor is installed on the new pneumatic motor mounting hole.

[0008] Optionally, a turbine pneumatic motor may be used.

[0009] Optionally, the new gear ring is made of 40Cr material.

[0010] Optionally, during the machining of the new gear ring, the non-load-bearing side of the chamfered end of the gear ring is chamfered.

[0011] Optionally, the initial resistance torque of the engine can be obtained based on the engine's frictional torque, initial compression resistance torque, and the inertial torque overcome by the engine as it accelerates from a standstill to its starting speed.

[0012] Optionally, the starting resistance torque of the engine can be obtained based on the engine's frictional torque and the inertial torque overcome by the engine as it accelerates from a standstill to its starting speed.

[0013] Secondly, embodiments of the present invention provide an engine starting system, which is improved using the engine starting system improvement method described in the first aspect.

[0014] Thirdly, embodiments of the present invention provide an engine equipped with the engine starting system described in the second aspect.

[0015] The beneficial effects of this invention are as follows: 1. The improved engine starting system method of the present invention improves the transmission ratio so that the initial torque and starting torque of the pneumatic motor under the set intake pressure meet the requirements of the engine's initial resistance torque and starting resistance torque. Under the set intake pressure, the pneumatic motor can start the engine smoothly, enabling the engine to start even when the intake pressure is not met, thus realizing the application of megawatt-class four-stroke inline engines on offshore drilling platforms.

[0016] 2. The improved engine starting system method of the present invention involves chamfering the teeth of the new gear ring only on the non-load-bearing side, which facilitates the rapid engagement of the pneumatic motor gear with the load-bearing surface of the gear ring. Furthermore, it reduces the number of chamfers, thereby reducing processing time and labor, and improving processing efficiency. Chamfering only on the non-load-bearing side increases the width of the load-bearing surface of the gear ring teeth, reduces the force per unit area, and extends the service life of the gear ring.

[0017] 3. The improved engine starting system method of the present invention uses a turbine pneumatic motor instead of the original vane pneumatic motor, which can achieve lubrication-free operation, low air consumption, small size, light weight, high air efficiency, lubrication-free and maintenance-free power unit, and eliminates the need for accessories such as pressure reducing valve, oil-water separator, and oil mist lubricator, thus simplifying the structure of the starting system and reducing the manufacturing cost of the starting system. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 This is a flowchart of the method in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the engine starting system structure in Embodiment 2 of the present invention. Figure 1 ; Figure 3 This is a schematic diagram of the engine starting system structure in Embodiment 2 of the present invention. Figure 2 ; Among them, 1. gear ring, 2. flywheel, 3. housing, 4. pneumatic motor, 5. main start valve, 6. filter, 7. solenoid valve, 8. gear, 9. crankshaft. Detailed Implementation Example 1 This embodiment provides an improved method for engine starting systems, modifying the starting system of existing megawatt-class four-stroke inline engines, such as... Figure 1 As shown, the improved method includes the following steps: Step 1: Obtain the initial resistance torque and starting resistance torque of the engine.

[0020] The method for obtaining the initial resistance torque M0 of the engine is as follows: based on the engine's friction torque M... f Initial compression resistance torque M c And the inertial torque M that the engine overcomes when accelerating from a standstill to its starting speed. j The initial drag torque M0 of the engine is obtained.

[0021] Specifically: M0=Mf +M c +M j Engine starting resistance torque M st The method for obtaining it is: based on the engine's friction torque M f And the inertial torque M overcome during engine start-up time when accelerating from a standstill to starting speed. j The initial drag torque M0 of the engine is obtained.

[0022] M st =M f +M j M f — Frictional torque (Nm) M c —Initial compression resistance torque (Nm) M j — Engine start-up time t st The engine accelerates from a standstill to its starting speed n. st The inertial torque overcome (Nm) In this embodiment, when the engine approaches its ignition speed, the initial compression resistance torque M c Since the superposition of cylinders and inertia can be ignored, M is only considered in the initial drag torque calculation. c The impact.

[0023] Among them, the engine friction torque M f The method for obtaining it is as follows:

[0024] in: P f —Starting frictional resistance pressure (N / m) 2 Its value is derived from an empirical formula:

[0025] γ — kinematic viscosity of lubricating oil at starting temperature (m 2 / s) τ — number of engine strokes, take τ=4 V h —Engine single-cylinder working volume (m³) 3 ), take V h =h*π*D 2 / 4 D – Engine cylinder diameter (m), take D=0.19 i — Number of engine cylinders, take i=8 h—Engine stroke (m), take h=0.275 In this embodiment, the kinematic viscosity of the lubricating oil at the starting temperature was obtained using existing methods. The lubricating oil used was 15W / 40CD machine oil, and its kinematic viscosity at 100°C was 12.5–16.3 mm. 2 / s, its low-temperature dynamic viscosity at -15℃ is 7000 mPa·s. According to η t =γ·ρ,η t The dynamic viscosity of the lubricating oil is given by the lubricating oil density ρ = 900 kg / m³. 3 The corresponding kinematic viscosity is 7778 mm. 2 The viscosity-temperature curve shows that at an initiation boundary temperature of 5℃, its kinematic viscosity is 700-800 mm² / s. 2 / s, take γ=2500 mm 2 / s.

[0026] Therefore: P f =417.193×10⁵ N / m² Then M f =206.86 Nm.

[0027] Engine initial compression resistance torque M c The method for obtaining it is as follows:

[0028] T max —The maximum tangential force (Pa) per unit piston area during pure piston compression: In this embodiment, T max =4.864×10 5 r—crank radius (m), r=0.1375 D—Cylinder diameter (m), D=0.190 At this moment: M c =1896.24Nm The inertial torque M overcome during engine start-up time when accelerating from a standstill to starting speed. j (Engine shaft inertia moment M) j The method to obtain ) is as follows:

[0029] in: I0 — Moment of inertia of the engine moving parts referred to the crankshaft (kgm) 2 ) In this embodiment, the calculation method for I0 can use existing technology, and will not be described in detail here. It is 56.3868 kgm. 2 n st —Starting speed (r / min), take n st=150 ω st —The angular velocity (rad / s) corresponding to the starting speed, take ω st =8.378 t st —Startup time (s), taken as t st =3 Therefore: M j =295.24Nm Therefore: the initial resistance torque of the engine is: M 0=M f +M c +M j =2398.34 Nm The starting resistance torque of the engine is: M st =M f +M j =502.12 Nm Step 2: Determine the initial torque M of the pneumatic motor under the set intake pressure. s0 and the obtained initial drag torque of the engine M 0 yields the first transmission ratio i 1. The starting torque M of the pneumatic motor under the set intake pressure. sst and the obtained engine starting resistance torque M st Obtain the second transmission ratio i 2.

[0030] Specifically:

[0031]

[0032] In this embodiment, the intake pressure is set to 5-6 bar. Under an intake pressure of 5-6 bar, the initial torque M of the pneumatic motor is... s0 and starting torque M sst Since these are known quantities, they will not be described in detail here.

[0033] Step 3: Select the first transmission ratio i 1 and second transmission ratio i The larger one in 2 is the transmission ratio between the pneumatic motor and the gear ring. i。

[0034] In this embodiment, the transmission ratio i =16, the transmission ratio has been increased from the original 10:1 to 16:1.

[0035] Step 4: Obtain the structural parameters of the gear ring based on the transmission ratio.

[0036] Specifically: If the number of teeth Z2 of the pneumatic motor gear is the same as the number of teeth of the original pneumatic motor gear, and remains unchanged, then the number of teeth Z1 of the gear ring is 16xZ2.

[0037] If the initial center distance L between the original pneumatic motor gear and the gear ring is known, then: According to L=(Z1+Z2)*m / 2, where m is the module of the gear ring, since the initial center distance L between the original pneumatic motor gear and the gear ring is known, the initial value of the module m of the gear ring can be calculated using this formula.

[0038] Round the initial value of the module m to obtain the final module m of the gear ring.

[0039] In this embodiment, the module of the gear ring is 4.

[0040] Substituting the module 4 of the gear ring into the formula L=(Z1+Z2)*m / 2, we obtain the improved center distance between the gear ring and the gear.

[0041] The tooth tip circle diameter B of the gear ring can be obtained using the formula B=m*(Z1+2).

[0042] The structural parameters of the gear ring were finally obtained, including the number of teeth Z1, the module m, and the tip circle diameter B.

[0043] Step 5: Fabricate the gear ring according to the structural parameters obtained in Step 4.

[0044] In this embodiment, the gear ring is made of 40Cr, and its hardness is increased from 25HRC of traditional 45# steel gear ring to 48HRC, ensuring the hardness and strength of the gear ring.

[0045] In traditional gear ring machining, both the load-bearing and load-bearing surfaces of the chamfered ends of the teeth are chamfered. In this embodiment, only the non-load-bearing surfaces of the chamfered ends are chamfered. This method facilitates the rapid engagement of the pneumatic motor gear with the load-bearing surface of the gear ring, and reduces the number of chamfers, thereby reducing machining and labor time and improving machining efficiency. Chamfering only on the non-load-bearing surfaces increases the width of the load-bearing surface of the gear ring teeth, reduces the force per unit area, and extends the service life of the gear ring.

[0046] Step 6: Remove the original gear ring of the engine, replace it with a new gear ring, and install the pneumatic motor. The gear of the pneumatic motor meshes with the new gear ring.

[0047] Specifically, the flywheel of the engine is removed, the original gear ring is removed, and the new gear ring manufactured in step 5 is installed. The center distance between the new gear and the gear ring is obtained by combining the module of the new gear ring, the number of teeth of the gear ring and the number of teeth of the pneumatic motor gear with the formula L=(Z1+Z2)*m / 2. Based on the new center distance, the pneumatic motor mounting hole is machined on the engine cover, and the pneumatic motor is installed on the pneumatic motor mounting hole.

[0048] In this embodiment, a turbine pneumatic motor is used instead of the original vane-type pneumatic motor, achieving lubrication-free operation, low air consumption, small size, light weight, high air efficiency, and a lubrication-free and maintenance-free power unit. Furthermore, it eliminates the need for accessories such as pressure reducing valves, oil-water separators, and oil mist lubricators, simplifying the starting system structure and reducing manufacturing costs. The remaining engine structure remains unchanged and will not be described in detail here. After the modification, the gap between the outer edge of the gear ring and the inner wall of the housing is ≥2mm; when the pneumatic motor is mounted on the housing, the distance between the outer edge of the pneumatic motor and the engine crankcase is ≥5mm.

[0049] The modification method in this embodiment improves the transmission ratio between the gear ring and the pneumatic motor gear, ensuring that the initial torque and starting torque of the pneumatic motor at the set intake pressure meet the requirements of the engine's initial resistance torque and starting resistance torque. At a set intake pressure of 4.5-5 bar, the pneumatic motor can smoothly start the engine, enabling it to start even when the intake pressure is not met. This realizes the application of megawatt-class four-stroke inline engines on offshore drilling platforms. This starting system modification method can be used for 0.5-1.5MW inline engines and 0.5-2.4MW V-type engines. Furthermore, by adjusting the pneumatic motor mounting holes and increasing the strength of the gear ring, and by adopting a single-sided chamfer structure for the gear ring teeth, the reliability of the transmission is improved, and the manufacturing cost is reduced.

[0050] Example 2 This embodiment provides an engine starting system, such as Figure 2-3 As shown, the engine starting system is improved using the method described in Example 1. The engine starting system includes a crankshaft 9, flywheel 2, gear ring 1, housing 3, pneumatic motor 4, gear 8, main starting valve 5, solenoid valve 7, filter 6, pipes, fasteners, ball valve, air source, etc. The gear 8 connected to the pneumatic motor 4 meshes with the gear ring 1. The pneumatic motor 4 is connected to the air source through a pipe. The pipe is equipped with filter 6, solenoid valve 7, main starting valve 5, etc. In this embodiment, the structure of the engine starting system can adopt existing technology. Only the gear ring 1 and pneumatic motor 4 are improved according to the method described in Example 1. The rest of the structure is not modified and will not be described in detail here.

[0051] In this embodiment, the parts of the engine starting system not described in detail can be achieved using existing technologies.

[0052] Example 3 This embodiment provides an engine equipped with the engine starting system described in Embodiment 2. The remaining structure of the engine can be achieved using existing technology and will not be described in detail here.

[0053] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An improved method for an engine starting system, characterized in that, Includes the following steps: Obtain the engine's initial resistance torque and starting resistance torque; The first transmission ratio is obtained based on the initial torque of the pneumatic motor under the set intake pressure and the initial resistance torque of the engine. The second transmission ratio is obtained based on the starting torque of the pneumatic motor under the set intake pressure and the starting resistance torque of the engine. The larger of the first and second transmission ratios is selected as the transmission ratio between the gear and the ring gear of the pneumatic motor. The structural parameters of the new gear ring are obtained based on the transmission ratio; A new gear ring is manufactured using the structural parameters of the new gear ring. The original gear ring of the engine is removed and replaced with the new gear ring. A pneumatic motor is installed, and the gear of the pneumatic motor meshes with the new gear ring. The initial resistance torque of the engine is obtained from the engine's friction torque, initial compression resistance torque, and the inertial torque overcome by the engine when accelerating from a standstill to its starting speed. The starting resistance torque of the engine is obtained from the frictional torque of the engine and the inertial torque that the engine overcomes when accelerating from a standstill to the starting speed.

2. The improved engine starting system method as described in claim 1, characterized in that, The structural parameters of the gear ring include the number of teeth and the module. The number of teeth is obtained based on the transmission ratio and the number of teeth of the pneumatic motor gear, and the module is obtained based on the initial center distance between the gear and the gear ring, as well as the number of teeth of the gear and the gear ring.

3. The improved engine starting system method as described in claim 2, characterized in that, The initial value of the module is obtained based on the initial center distance between the gear and the gear ring and the number of teeth of the gear and the gear ring. The initial value of the module is rounded to obtain the final module value. The corrected center distance between the gear and the gear ring is obtained based on the final module value and the number of teeth of the gear and the gear ring. New pneumatic motor mounting holes are machined on the engine cover based on the corrected center distance between the gear and the gear ring. The pneumatic motor is installed on the new pneumatic motor mounting holes.

4. The improved engine starting system method as described in claim 1, characterized in that, The pneumatic motor is a turbine pneumatic motor.

5. The improved engine starting system method as described in claim 1, characterized in that, The new gear ring is made of 40Cr material.

6. The improved engine starting system method as described in claim 1, characterized in that, When machining a new gear ring, the non-load-bearing side of the chamfered end of the gear ring is chamfered.

7. An engine starting system, characterized in that, It is an improvement on the engine starting system method according to any one of claims 1-6.

8. An engine, characterized in that, The engine starting system as described in claim 7 is provided.

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