KR20160150135A - Method for Determinating Optimal Clearance of Fuel Injection Pump - Google Patents
Method for Determinating Optimal Clearance of Fuel Injection Pump Download PDFInfo
- Publication number
- KR20160150135A KR20160150135A KR1020150086319A KR20150086319A KR20160150135A KR 20160150135 A KR20160150135 A KR 20160150135A KR 1020150086319 A KR1020150086319 A KR 1020150086319A KR 20150086319 A KR20150086319 A KR 20150086319A KR 20160150135 A KR20160150135 A KR 20160150135A
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- KR
- South Korea
- Prior art keywords
- gap
- plunger
- barrel
- machining
- analysis step
- Prior art date
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Classifications
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- G06F17/5018—
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
- F02M59/02—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
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- G06F17/5004—
Abstract
Description
The present invention relates to a fuel injection pump optimum gap determination method for determining an optimum gap of a fuel injection pump.
Generally, an engine is a device that converts heat energy generated by combustion of fuel into mechanical energy. That is, the engine is a device that generates propulsion force on a moving means such as a ship, an automobile, or the like. In such an engine, a plurality of cylinders are disposed on the engine block, an intake valve and an exhaust valve are provided in each cylinder, and a piston connected to the crankshaft by the connecting rod is installed, The crankshaft is rotated. At this time, the fuel injection pump provided in the engine injects the fuel into the cylinder at an appropriate timing through the injection nozzle provided in the cylinder. For this purpose, the fuel injection pump compresses the fuel to a high pressure.
On the other hand, the fuel injection pump is composed of a plunger serving as a piston to compress the fuel and a barrel serving as a cylinder. The fuel is compressed and sent to the cylinder by reciprocating the plunger inside the barrel. A clearance is formed between the plunger and the barrel by a difference in radius, and the gap is supplied with lubricant for lubricating the plunger and the barrel.
Here, the plunger and the barrel of the fuel injection pump are deformed due to the high pressure generated. Deformation by the pressure of the plunger and barrel causes a reduction in the clearance, and improper clearance causes abrasion and sticking of the plunger and barrel. Improper clearance means that deformation of the plunger and barrel is deformed beyond the design clearance.
Therefore, determining the optimum gap between the plunger and the barrel in the fuel injection pump is a very important factor in terms of improving the durability of the engine and reducing the operating cost of the engine. Therefore, a process for designing the optimum gap of the fuel injection pump is desperately required.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection pump optimum gap determination method capable of determining an optimum gap of a fuel injection pump.
In order to solve the above-described problems, the present invention can include the following configuration.
The method for determining the optimal gap of the fuel injection pump according to the present invention includes: a structural analysis step for grasping a maximum gap reduction amount due to deformation of a plunger and a barrel; A fluid lubrication analysis step of determining a gap by calculating an oil film coefficient which is a ratio of a minimum oil film thickness of the lubricating oil supplied between the plunger and the barrel to a surface roughness of the plunger and the barrel; A machining accuracy review step of calculating a gap machining limit which is a limit of gap machining between the plunger and the barrel and a machining error occurring at machining; And an optimal gap determination step of deriving an optimum gap from the structure analysis step, the fluid lubrication analysis step, and the machining precision review step.
In the fuel injection pump optimum gap determination method according to the present invention, the structural analysis step may include deriving the maximum gap reduction amount of the head portion that is the upper portion of the plunger, and deriving the maximum gap reduction amount of the stem portion that is the lower portion of the plunger .
In the fuel injection pump optimum gap determination method according to the present invention, the fluid lubrication analysis step may include the steps of: deriving a gap in which the film coefficient is not less than 3 in a head portion which is an upper portion of the plunger; And deriving a gap having an oil film coefficient of 3 or more.
In the method of determining the optimal gap of the fuel injection pump according to the present invention, the optimum gap determination step may derive an optimum gap in the gap range through the structure analysis step, the fluid lubrication analysis step, and the machining precision review step.
According to the present invention, the following effects can be achieved.
The present invention can be implemented to determine the optimum gap of the fuel injection pump, thereby improving the durability of the engine and the reliability of the fuel injection pump.
1 is a schematic flowchart of a fuel injection pump optimum gap determination method according to the present invention;
2 is a schematic plan view for explaining the deformation of the plunger and the barrel in the fuel injection pump optimum gap determination method according to the present invention
3 is a schematic flowchart for explaining the structural analysis in the fuel injection pump optimum gap determination method according to the present invention
4 is a schematic flowchart for explaining the fluid lubrication analysis in the fuel injection pump optimum gap determination method according to the present invention
FIG. 5 is a schematic flowchart for explaining machining analysis in the fuel injection pump optimum gap determination method according to the present invention
6 is a schematic flow chart for explaining the optimum gap determination in the fuel injection pump optimum gap determination method according to the present invention
The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and the inventor may properly define the concept of the term to describe its invention in the best possible way And should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a fuel injection pump optimum gap determination method according to the present invention will be described in detail with reference to the accompanying drawings.
2 is a schematic plan view for explaining deformation of a plunger and a barrel in a method of determining the optimum gap of the fuel injection pump according to the present invention, and Fig. 3 is a cross- FIG. 4 is a schematic flowchart for explaining the fluid lubrication analysis in the fuel injection pump optimum gap determination method according to the present invention, and FIG. 5 FIG. 6 is a schematic flow chart for explaining the optimum gap determination in the fuel injection pump optimum gap determination method according to the present invention, and FIG. 6 is a schematic flowchart for explaining the optimum gap determination in the fuel injection pump optimum gap determination method according to the present invention.
1 and 2, the method for determining the optimum gap of the fuel injection pump according to the present invention includes a plunger (shown in FIG. 2, a circle located inside) acting as a piston in the fuel injection pump of the engine, (Shown in Fig. 2, a circular shape located on the outer side) of the barrel (shown in Fig. 2).
The method for determining the optimal gap of the fuel injection pump according to the present invention mainly includes a structural analysis step S100, a fluid lubrication analysis step S200, a machining precision review step S300, and an optimal gap determination step S400.
Referring to FIGS. 1 and 2, the structure analysis step S100 is a step of determining a reduction in the gap generated by the deformation of the plunger and the barrel due to the maximum pressure inside the fuel injection pump, In order to design a larger value than the maximum value. The maximum pressure refers to the maximum pressure inside the fuel injection pump which is generated when the fuel is compressed within the fuel injection pump, that is, when the plunger is located near the top dead center. The operating condition of the fuel injection pump, ≪ / RTI > For example, the maximum pressure may be 1700 Bar. The plunger and the barrel can be deformed by the maximum pressure. Therefore, in the structure analysis step S100, the maximum clearance reduction amount of the plunger and the barrel can be grasped when the pressure is the maximum pressure, so that the design clearance can be set larger than the maximum clearance reduction amount.
Specifically, the structure analysis step S100 is performed by assuming that there is no clearance between the plunger (the inner circle) and the barrel (the outer circle) as shown in Fig. 2 and the plunger When the deformed portions of the barrel are overlapped with each other, the size of the overlapped portion (indicated by a dotted line) can be calculated through a commercial structure analysis program. The overlapped portion refers to a portion where the gap decreases by an amount corresponding to the actual gap. The maximum gap reduction amount can be derived from the calculated amount of deformation of the plunger and the deformation amount of the barrel.
Here, the maximum gap reduction amount of the head portion, which is the upper portion of the plunger, and the maximum gap decrease amount of the stem portion that is the lower portion of the plunger, are derived as different values. This is because the plunger and the barrel are deformed by the high pressure of the fuel to be compressed in the upper portion of the plunger, but the generated pressure in the gap is small at the portion corresponding to the lower portion of the plunger so that there is no deformation in the barrel. This is because only the deformation of the lower portion of the plunger appears due to the influence of the pressure. Thus, at the lower portion of the plunger, the maximum deformation amount of the plunger becomes the maximum gap decrease amount. The structural analysis step S100 may include a step S110 of deriving the maximum gap reduction amount of the head part and a step S120 of deriving the maximum gap reduction amount of the stem part.
Referring to FIG. 3, in step S110 of deriving the maximum gap reduction amount of the head portion, when the maximum pressure is applied, the deformation amount of the head portion of the plunger is larger than the deformation amount of the barrel, Is a step performed to derive the maximum gap reduction amount which is a large value. For example, the maximum gap reduction amount of the head portion can be derived through a commercial structural analysis program.
Here, it is preferable that the gap of the head portion is set to be larger than the maximum gap decrease amount of the head portion. Accordingly, the method for determining the optimal gap of the fuel injection pump according to the present invention can reduce the friction between the plunger and the barrel of the head portion at the maximum pressure, thereby improving the durability of the engine.
Referring to FIG. 3, in step S120 of deriving the maximum gap reduction amount of the stem portion, the maximum gap reduction amount of the stem portion can be derived from the deformation amount of the plunger at the stem portion, which is the lower portion of the plunger, have. The deformation amount of the barrel is not considered because the barrel is hardly deformed even at the maximum pressure at the stem portion of the plunger. The maximum gap reduction amount of the stem portion can be derived through a commercial structural analysis program.
Here, the gap of the stem portion is preferably set to be larger than the maximum gap reduction amount of the stem portion. Accordingly, the method of determining the optimal gap of the fuel injection pump according to the present invention can reduce the friction between the plunger and the barrel of the stem portion at the maximum pressure, thereby improving the durability of the engine.
4, in the fluid lubrication analysis step S200, a gap is determined by calculating the oil film thickness which is the ratio of the minimum oil film thickness of the lubricating oil supplied between the plunger and the barrel to the surface roughness of the plunger and the barrel . Here, it is preferable that the gap has an oil film coefficient of 3 or more. The minimum oil film thickness means the smallest oil film thickness of the lubricant in the lubricating region between the plunger and the barrel. In addition, the minimum film thickness can be grasped under various gap and viscosity conditions in the operating conditions of the engine. The surface roughness refers to the degree of fine irregularity that occurs on the surface when finishing the metal surface.
The fluid lubrication analysis step (S200) may be performed through Reynolds Equation and Moment & Radial (Axial Force Equilibrium) in an abnormal state. Here, the fluid lubrication analysis step (S200) is performed under the following conditions.
First, the shape of the plunger and the barrel is the origin.
Second, the axes of the plunger and the barrel are always in the same plane. That is, the axis of the plunger only moves up and down on the centerline of the barrel.
Third, the bottom of the plunger is a fixed point and tilts freely.
Fourth, surface roughness and elastic deformation of the plunger and the barrel are neglected.
Fifth, the viscosity and density of the lubricating oil are constant.
Sixth, the inertia of the plunger and the barrel is neglected.
Seventh, helical grooves formed in the plunger and the barrel and existing grooves are not considered.
Assuming the above conditions, when the minimum film thickness exceeds the surface roughness, the plunger and the barrel are not in contact with each other. Further, assuming the above conditions, if the minimum film thickness is less than the surface roughness, the plunger and the barrel are in contact with each other. Accordingly, since the minimum oil film thickness is three times or more of the surface roughness of the gap having the oil film coefficient of 3 or more, it can be estimated that the plunger and the barrel are not in contact with each other, and therefore, the lubrication is good.
For example, when the minimum film thickness is 0.881 mu m and the surface roughness is 0.092 mu m, the film coefficient is 9.6. In this case, since the oil film coefficient is 3 or more, it can be said that the lubrication state of the gap is good.
The fluid lubrication analysis step (S200) includes a step (S210) of separating the head portion and the stem portion into a gap having an oil film coefficient of 3 or more, similar to the structure analysis step (S100) (S220) of obtaining a gap of 3 or more.
The step S210 of deriving a gap having an oil film coefficient of the head part of 3 or more and the step S220 of deriving a gap having an oil film coefficient of 3 or more of the stem part may be performed through the Reynolds equation and the force equilibrium equation in an abnormal state.
Accordingly, the gap between the plunger and the barrel is designed to improve the durability of the plunger and the barrel to improve the durability of the plunger and the barrel, The cost can be reduced.
Referring to Fig. 5, the machining precision review step S300 calculates a gap machining limit (S310), which is the limit of gap machining between the plunger and the barrel, and a machining error (S320) that occurs during machining.
The gap machining limit (S310) defines the machining limit according to the economical aspect of the product and the required precision in the gap machining. The smaller the gap between the plunger and the barrel is, the smaller the workability is, and the more the machining cost is increased. For example, if it costs 50 to process a gap of 4 μm and requires a cost of 100 to process a gap of 3 μm, and if a cost of 1000 is needed to process a gap of 2 μm, then a gap of 2 μm is 3 μm and 4 μm The value of utility falls from the economic point of view. Accordingly, in this case, the gap corresponding to the gap machining limit can be 3 占 퐉. Therefore, the gap machining limit is calculated in consideration of the economical aspect according to the required accuracy.
The machining error (S320) means a machining error of a gap generated when the plunger and the barrel are machined to form a gap, and the machining error may vary depending on the processing capability of the machining company. For example, the machining error can be reduced as skilled machinists use precise machining equipment. Therefore, the machining accuracy review step (S300) can calculate the gap machining limit and the machining error according to the economic aspect and the machining capability of the machining company. Here, in the machining accuracy review step S300, since the gap is calculated in consideration of the economic aspect and the machining capability, it is not necessary to divide the head portion and the stem portion to calculate the gap.
Referring to FIG. 6, the optimal gap determination step (S400) derives an optimal gap in the structural analysis step (S100), the fluid lubrication analysis step (S200), and the machining precision review step (S300).
More specifically, the optimal gap determination step (S400) may include a design gap between the head portion and the stem portion derived from the maximum gap reduction amount of the head portion and the maximum gap reduction amount of the stem portion in the structure analysis step (S100) A gap having an oil film coefficient of 3 or more in the head part derived in step S200 and a gap having an oil film coefficient of 3 or more in the stem part and a gap satisfying the gap machining limit derived in the machining precision review step S300 is determined . Accordingly, the optimal gap determination step S400 determines the optimal gap in consideration of gap restriction conditions and useful gaps derived from the respective steps S100, S200, and S300. In this case, the optimal gap determination step (S400) can derive the range of the optimum gap specified in the design drawing in consideration of the machining error. Since the deformation amounts of the head part and the stem part are different from each other like the structure analysis step S100 and the fluid lubrication analysis step S200, the optimum gap determination step S400 is divided into the head part and the stem part The optimal gap is determined.
Here, the optimal gap determination step (S400) derives the optimum gap to the gap range. If the optimum gap is a specific value rather than a range, not only is the probability of machining error occurring, but also it is difficult for the machining company to process it to a specific value.
Therefore, the method for determining the optimal gap of the fuel injection pump according to the present invention is realized to derive the optimal gap to the range of gap, thereby shortening the processing time and improving the productivity of the fuel injection pump.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. .
S100: Structural analysis S200: Fluid lubrication analysis
S300: machining analysis S400: optimum clearance determination
Claims (4)
A fluid lubrication analysis step of determining a gap by calculating an oil film coefficient which is a ratio of a minimum oil film thickness of the lubricating oil supplied between the plunger and the barrel to a surface roughness of the plunger and the barrel;
A machining accuracy review step of calculating a gap machining limit which is a limit of gap machining between the plunger and the barrel and a machining error occurring at machining; And
And determining an optimum gap from the structural analysis step, the fluid lubrication analysis step, and the machining precision review step.
Deriving a maximum gap reduction amount of the head portion that is the upper portion of the plunger; And
And deriving a maximum clearance reduction of the stem portion that is the lower portion of the plunger.
Deriving a gap in which the film coefficient is equal to or greater than 3 in a head portion which is an upper portion of the plunger; And
And deriving a gap at the stem portion, which is the lower portion of the plunger, of the oil film coefficient of 3 or more.
Wherein the optimal gap determination step derives an optimal gap in a gap range through the structure analysis step, the fluid lubrication analysis step, and the machining precision review step.
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| Application Number | Priority Date | Filing Date | Title |
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| KR1020150086319A KR20160150135A (en) | 2015-06-18 | 2015-06-18 | Method for Determinating Optimal Clearance of Fuel Injection Pump |
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| KR1020150086319A KR20160150135A (en) | 2015-06-18 | 2015-06-18 | Method for Determinating Optimal Clearance of Fuel Injection Pump |
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| KR20160150135A true KR20160150135A (en) | 2016-12-29 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109029334A (en) * | 2018-07-12 | 2018-12-18 | 雍睿 | Harshness coefficient size effect of rock structural face universe searches for measurement method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109029334A (en) * | 2018-07-12 | 2018-12-18 | 雍睿 | Harshness coefficient size effect of rock structural face universe searches for measurement method |
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