JP2004340052A - Fuel injection pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection pump capable of effectively preventing seizure of a plunger and effectively recovering fuel oil which may leak. <P>SOLUTION: This fuel injection pump 1 includes a plunger barrel 2 and a plunger 3 which is inserted into the plunger barrel 2 so as to slide, a side wall of the plunger 3 is provided with a lead portion 4 for fuel metering and a plurality of centering grooves 5 formed in annular manner from near the lead portion 4. The plunger barrel 2 is provided with a first return passage 12 formed so as to communicate with a sliding area through which all the centering grooves 5 pass in a course ranging from its bottom dead center to top dead center and a second return passage 13 communicating with at least one of the centering grooves 5 near the bottom dead center of the plunger 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection pump used for a large vessel, a generator, and the like, and more particularly, to a fuel injection pump having a configuration for preventing seizure of a plunger and reducing fuel leakage from a plunger sliding portion.
[0002]
[Prior art]
When the pressurized fuel acts on the lead portion formed on the side wall of the plunger, a so-called side pressure is generated that presses the plunger against the plunger barrel, and the side pressure may cause seizure of the plunger. For this reason, in order to buffer the side pressure acting on such a plunger and to ensure good lubrication with the plunger barrel, fuel oil that attempts to leak between the sliding surfaces of the plunger and the plunger barrel is used. Is preferred.
[0003]
However, if the fuel that leaks between the sliding surfaces is actively used, a large amount of fuel oil leaks to the cam chamber through the gap between the sliding surfaces. Not only does it deteriorate, but in the case of low-viscosity fuel, the lubricating oil in the cam chamber is diluted with leak fuel, and in the case of low-quality oil such as heavy oil, the fuel oil enters sliding parts inside the pump, Inconveniences such as inducing sticking of the rack occur.
[0004]
Therefore, conventionally, a plurality of annular centering grooves are provided on the side wall of the plunger that slides in the plunger barrel near the lead portion, and the centering of the plunger is promoted while utilizing the high-pressure oil stored in the centering groove. By forming a lubricating oil film between sliding surfaces to prevent seizure, and by connecting at least one of the centering grooves to a return passage at a predetermined stroke position of the plunger, fuel oil is collected and leaked. Is considered (see Patent Document 1).
[0005]
[Patent Document 1]
Japanese Utility Model Publication No. 56-32608 (column 3, FIG. 2)
[0006]
[Problems to be solved by the invention]
However, in the above-described configuration, since at least one of the centering grooves is merely communicated with the return passage near the bottom dead center of the plunger, there is a limit in the fuel oil recovery capacity, and the fuel oil can always be efficiently recovered. It was not something. In addition, since there is only one return passage communicating with the centering groove, the number and formation position of the centering groove are largely determined in relation to the location of the return passage, and are determined according to the type and use of the injection pump. There was almost no degree of freedom that could be set arbitrarily.
[0007]
That is, if the number of centering grooves is increased by giving priority to prevention of seizure of the plunger, the amount of fuel oil accumulated between the plunger and the plunger barrel also increases, so only the return passage communicating with the centering groove near the bottom dead center is provided. In such a case, sufficient recovery capacity cannot be obtained, and there is a disadvantage that the amount of fuel oil leaked without being completely recovered increases. Conversely, if priority is given to reducing the amount of leaked fuel and the number of centering grooves is reduced, the amount of fuel oil accumulated between the sliding surfaces of the plunger and the plunger barrel is reduced, and the centering effect of the plunger is reduced and the distance between the sliding surfaces is reduced. Also, the fuel oil film formed on the surface becomes insufficient, and there is a possibility that seizure may occur.
[0008]
Therefore, in the present invention, the degree of freedom of the design of the plunger is increased to effectively prevent the seizure of the plunger, and the fuel oil to be leaked is effectively collected, so that the seizure of the plunger and the effective use of the fuel oil are prevented. It is a main object to provide a fuel injection pump that can achieve both recovery and recovery. Another object is to suppress the mixing of fuel oil and lubricating oil and to avoid a decrease in lubricating effect due to dilution of lubricating oil.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a fuel injection pump according to the present invention has a plunger barrel and a plunger slidably inserted into the plunger barrel, and a fuel metering lead is provided on a side wall of the plunger. And a plurality of centering grooves formed in an annular shape in the vicinity of the lead portion. A slide through which all of the centering grooves pass through the plunger barrel in the process of moving the plunger from bottom dead center to top dead center. A first return passage formed to communicate with a moving part; and a second return passage formed to communicate with at least one of the centering grooves near a bottom dead center of the plunger. (Claim 1).
[0010]
Therefore, when the plunger rises and enters the pumping stroke, the fuel pressure in the space defined by the plunger and the plunger barrel and the fuel pressure in the lead portion rises, and a side pressure is applied to the plunger and the sliding surface between the plunger and the plunger barrel. The high-pressure fuel attempts to leak from between, but the leak oil moving between the sliding surfaces is introduced into a centering groove provided in the plunger and is temporarily stored, so that the plunger coincides with the center of the plunger barrel. The lubrication oil film is formed between the sliding surfaces with the plunger barrel to promote lubrication.
[0011]
Each centering groove is communicated with the first return passage in the course of the reciprocating movement of the plunger, so that the fuel oil introduced into the centering groove is recovered through the first return passage. . Of these, a small amount of leaked oil cannot be completely recovered from the first return passage and attempts to leak between the sliding surfaces toward the opening end side of the plunger barrel. Since the second return passage communicating with at least one of the centering grooves is formed, an opportunity to be further collected through the second return passage is obtained.
[0012]
Therefore, the fuel oil that leaks along the sliding surface between the plunger and the plunger barrel is recovered through the first return passage and the second return passage, and is leaked without being completely recovered. Fuel oil can be significantly reduced. In addition, since the fuel oil can be recovered through the two return passages, the number and position of the centering grooves can be set arbitrarily without impairing the fuel oil recovery ability.
[0013]
Here, the first return passage is formed so as to communicate with the centering groove closest to the lead portion among the plurality of centering grooves at the bottom dead center of the plunger, and the second return passage is provided below the plunger. At the dead point, the centering groove may be formed so as to communicate with the centering groove farthest from the lead portion among the plurality of centering grooves (claims 2 and 3). Instead, the communicating part may be appropriately changed depending on the type of the pump and the like.
[0014]
Further, the first return passage may be communicated with a supply / discharge port formed so as to be able to communicate with the lead portion, and the fuel recovered through the first return passage may be reused (claim 4).
[0015]
Further, the plunger barrel is provided with a lubricating oil supply passage communicating with the opening end side where the plunger is inserted relative to a region where the centering groove slides, and between the sliding surface with the plunger via the lubricating oil supply passage. When supplying the lubricating oil, it is preferable that the second return passage be communicated between a portion where the first return passage between the sliding surfaces communicates and a portion where the lubricating oil supply passage communicates. 5).
[0016]
According to such a configuration, the lubricating oil supplied to the sliding surface is prevented from being mixed and diluted with the fuel oil, and also penetrated between the sliding surfaces to reach the second return passage. Since the lubricating oil can be recovered together with the fuel oil through this return passage, the lubricating oil does not permeate between the sliding surfaces beyond the second return passage, and a decrease in the lubricating effect can be avoided. It becomes.
[0017]
It is preferable that a seal member is interposed between the sliding surfaces of the plunger and the plunger barrel on the opening end side of the plunger barrel relative to a portion where the lubricating oil supply passage communicates. With such a configuration, the portion between the sliding surface and the second return passage communicating with the second return passage and the seal member can be filled with the lubricating oil, so that the lubricating oil makes it difficult for the fuel oil to leak. Even if it leaks to the opening end side without being collected in the return passage, it can be reliably prevented by the seal member.
[0018]
Here, the seal member includes an O-ring provided in an annular groove formed on the outer periphery of the plunger, and a ring member provided on the outer periphery of the O-ring and having higher hardness than the O-ring. Is preferable for maintaining the sealing effect (claim 7).
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2, a fuel injection pump 1 includes a plunger barrel 2 and a plunger 3 slidably inserted into the plunger barrel 2. A lead portion 4 is formed, which comprises two positive leads formed symmetrically with respect to the central axis.
[0020]
On the side wall of the plunger 3, there are formed a plurality of annular centering grooves 5 which are sequentially shifted at a predetermined pitch in a direction away from the vicinity of the lead portion 4, and are spaced apart from this group of centering grooves 5. Is formed. In this example, five centering grooves (5a to 5e) are formed.
[0021]
On the other hand, a supply / discharge port 7 for supplying and discharging fuel, which is formed to be communicable with the lead portion 4 of the plunger 3, is opened on the sliding surface of the plunger barrel 2 with the plunger 3, and further has an annular shape. First and second return grooves 8 and 9 and an annular lubricating oil supply groove 10 are formed.
[0022]
The supply / discharge port 7 is opened and closed by the land portion 11 of the plunger 3. When the plunger 3 moves from the bottom dead center to the top dead center, the supply / discharge port 7 is closed by the land portion 11 and the land portion 11 comes off. A state communicating with the part 4 is formed.
[0023]
The first return groove 8 communicates with the supply / discharge port 7 via a first return passage 12 formed in the plunger barrel 2, while the plunger 3 moves from the bottom dead center to the top dead center. It is formed at a position that passes through the entire centering groove 5. In this example, the first return groove 8 is formed at the bottom dead center of the plunger 3 at a position communicating with the centering groove 5a closest to the lead portion 4 among the plurality of centering grooves 5 (5a to 5e). I have.
[0024]
The second return groove 9 communicates with a collection tank (not shown) through a second return passage 13 formed in the plunger barrel 2, and at least one of the centering grooves 5 near the bottom dead center of the plunger 3. It is formed so that it may communicate with. In this example, the second return groove 9 is formed at the bottom dead center of the plunger 3 at a position communicating with the centering groove 5e farthest from the lead portion 4 among the plurality of centering grooves 5 (5a to 5e). ing.
[0025]
The lubricating oil supply groove 10 is formed on the opening end 14 side of the plunger barrel 2 where the plunger 3 is inserted, relative to the area A where the centering groove 5 slides on the sliding surface with the plunger 3. The lubricating oil is introduced through a lubricating oil supply passage 15 formed in the plunger 2 to supply the lubricating oil between the sliding surfaces of the plunger 3 and the plunger barrel 1.
[0026]
In addition, the seal groove 6 is located at a position on the side wall of the plunger 3 where the lubricating oil is supplied through the lubricating oil supply passage 15, that is, the opening end 14 of the plunger barrel 2 than the sliding range of the lubricating oil supply groove 10. The plunger 3 is formed in a ring shape at a position where the plunger 3 is not exposed to the outside from the open end 14 at the bottom dead center thereof. An annular seal member 20 is housed in the seal groove 6 to seal between the plunger 3 and the plunger barrel 2.
[0027]
In this example, as shown in FIG. 3, the seal member 20 includes an O-ring 20a provided in a seal groove 6 formed on the outer periphery of the plunger 3, and an O-ring 20a provided on the outer periphery of the O-ring 20a. A ring member 20b having a higher hardness than the ring 20a prevents the easily wearable O-ring 20a from directly abutting on the plunger barrel 2. Here, the ring member 20b may be made of abrasion-resistant material such as Teflon (registered trademark) or metal.
[0028]
In the above configuration, when the plunger 3 lifts up by closing and closing the supply / discharge port 7 provided in the plunger barrel 2 by the land portion 11, when the plunger 3 enters the pressure feeding stroke, the operation defined by the plunger 3 and the plunger barrel 2. The fuel pressure in the chamber 21 and the reed portion 4 increases, and the fuel is pumped through a delivery valve (not shown). In such a case, the compressed high-pressure fuel is supplied to the plunger 3 and the plunger 3. An attempt is made to leak to a cam chamber (not shown) through a gap between the sliding surface with the barrel 2.
[0029]
At this time, the fuel oil that moves between the sliding surfaces of the plunger 3 and the plunger barrel 2 is introduced into a centering groove provided in the plunger and is temporarily stored, so that the plunger is aligned with the center of the plunger barrel. At the same time, a plentiful lubricating oil film is positively formed between the sliding surfaces with the plunger barrel to prevent the seizure of the plunger. In addition, all the centering grooves 5 are communicated with the first return passage 12 while the plunger 3 moves from the bottom dead center to the top dead center, so that the centering groove 5 flows between the sliding surfaces of the plunger 3 and the plunger barrel 2. After being introduced into the centering groove 5 of the plunger 3, the fuel is recovered via the first return passage 12.
[0030]
Among them, a small amount of leaked oil cannot be completely recovered by the first return passage 12 and tries to leak between the sliding surfaces of the plunger 3 and the plunger barrel 2 toward the opening end 14. At the dead point, the second return groove 9 is communicated with the centering groove 5 e furthest from the lead portion 4, so that the fuel that cannot be completely recovered through the first return passage 13 is supplied to the second return groove 9. There will be an opportunity to be further recovered from the second return passage 13 via 9.
[0031]
That is, in the above-described configuration, per one forward movement or one backward movement of the plunger 3, the centering grooves 5a to 5d communicate with the first return groove 8 once each, and the plunger 3 communicates with the centering groove 5e. Since there is an opportunity to communicate with the first return groove 8 and the second return groove 9, the fuel oil that tries to leak from the working chamber 21 between the sliding surfaces of the plunger 3 and the plunger barrel 2 is There is an opportunity to be recovered via the first return passage 12 and the second return passage 13, and it is possible to increase the recovery capacity and greatly reduce the leakage of fuel oil.
[0032]
When the plunger is lifted by a predetermined amount and the closed state of the supply / discharge port 7 by the land 11 is released, the supply / discharge port 7 communicates with the lead portion 4, and the fuel pressure in the working chamber 21 and the lead portion 4 is reduced. It is released at a stretch and the pumping process is completed.
[0033]
Further, in the above-described configuration, the lubricating oil introduced between the sliding surfaces of the plunger 3 and the plunger barrel 2 from the lubricating oil supply passage 15 via the lubricating oil supply groove 10 causes the plunger 3 to reciprocate as the plunger 3 reciprocates. The lubricating oil permeates toward the open end 14 of the barrel 2 and the second return groove 9, but reaches the second return groove 9 together with the fuel oil leaking from the working chamber 21 side to the second return groove 9. Since the liquid is recovered through the passage 13, the liquid does not permeate beyond the second return groove 9, and the oil is lubricated between the sliding surfaces on the supply / drain side from the second return groove 9. Then, the opening end side of the plunger barrel can be lubricated with the lubricating oil. Therefore, the lubricating oil is not unnecessarily diffused to cause poor lubrication, and the opening end 14 side of the second return groove 9 is filled with the lubricating oil, so that the fuel oil fills the second return groove 9. Over the opening end 14 side.
[0034]
Even if the fuel oil cannot be completely recovered through the first and second return passages 12 and 13 and further leaks between the sliding surfaces of the plunger 3 and the plunger barrel 2 toward the open end 14, Since the seal member 20 is provided in front of 14, the seal member 20 prevents further movement and prevents fuel oil from leaking to a cam chamber (not shown).
[0035]
The fuel and the lubricating oil recovered through the second return passage 13 may be recovered in a recovery tank (not shown) or may be reused after being separated using a centrifuge or the like. Is also good. Further, in the above-described configuration, the first return passage 12 communicates with the centering groove 5a closest to the lead at the bottom dead center of the plunger, and the second return passage is furthest away from the lead at the bottom dead center of the plunger. The centering groove 5e communicates with the centering groove 5e. However, the present invention is not limited to this. In the first return passage 12, all of the centering groove is moved while the plunger moves from the bottom dead center to the top dead center. The same effect can be obtained if the second return passage 13 is formed at a position near the bottom dead center of the plunger so as to communicate with at least one of the centering grooves. It is possible to obtain
[0036]
【The invention's effect】
As described above, according to the present invention, on the side wall of the plunger slidably inserted into the plunger barrel, a fuel metering lead and a plurality of centering grooves formed annularly from near the lead. A first return passage formed in the plunger barrel so as to communicate with a sliding portion through which all of the centering grooves pass in the process of moving the plunger from bottom dead center to top dead center. And a second return passage formed near the bottom dead center of the plunger so as to communicate with at least one of the centering grooves. The position can be set arbitrarily, effectively preventing seizure of the plunger and being introduced into the centering groove via two return passages. It becomes possible to recover postal oil, it is possible to effectively recover the fuel oil to be leak. Further, since the amount of leaked fuel oil is reduced, it is possible to avoid a decrease in lubrication effect due to dilution of the lubricating oil.
[0037]
When the plunger barrel is provided with a lubricating oil supply passage communicating with the opening end side of the region where the centering groove slides, the second return passage is provided with the first return passage between the sliding surface with the plunger. By communicating between the portion where the return passage communicates and the portion where the lubricating oil supply passage communicates, it is possible to prevent mixing of the leaking fuel oil and lubricating oil as much as possible, thereby avoiding a decrease in the lubricating effect. It is possible to do.
[0038]
Further, when a seal member is interposed between the sliding surfaces of the plunger and the plunger barrel on the opening end side of the plunger barrel with respect to a portion where the lubricating oil supply passage communicates, the second return passage communicates. The lubricating oil filled between the part and the seal member makes it difficult for fuel oil to leak, and even if it leaks to the open end side without being collected in the return passage, the seal member reliably prevents the leak It is possible to do.
[Brief description of the drawings]
FIG. 1 is a sectional view showing one embodiment of a fuel injection pump according to the present invention.
FIG. 2 is a view showing a plunger of the fuel injection pump used in FIG. 1;
FIG. 3 is a diagram illustrating a configuration example of a seal member interposed between a plunger and a plunger barrel;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel supply pump 2 Plunger barrel 3 Plunger 4 Lead part 5 Centering groove 12 First return passage 13 Second return passage 15 Lubricating oil supply passage 20 Seal member 20a O-ring 20b Ring member

Claims (7)

Having a plunger barrel and a plunger slidably inserted into the plunger barrel,
On the side wall of the plunger, a fuel metering lead portion and a plurality of centering grooves formed annularly in the vicinity of the lead portion are provided.
A first return passage formed in the plunger barrel so as to communicate with a sliding portion through which all of the centering grooves pass while the plunger moves from bottom dead center to top dead center; A second return passage formed near the dead center so as to communicate with at least one of the centering grooves. The said 1st return path is formed so that it may communicate with the centering groove closest to the said lead part among the said centering grooves at the bottom dead center of the said plunger, The said 1st return path. Fuel injection device. The second return passage is formed so as to communicate with a centering groove farthest from the lead portion among the plurality of centering grooves at a bottom dead center of the plunger. Fuel injector. The fuel injection pump according to claim 1, wherein the first return passage communicates with a supply / discharge port formed to be able to communicate with the lead portion. A lubricating oil supply passage which communicates with the plunger barrel at an opening end side where the plunger is inserted relative to a region where the centering groove slides and supplies lubricating oil to a sliding surface between the plunger and the plunger; Is provided,
The second return passage is formed so as to communicate between a portion where the first return passage between the sliding surfaces communicates and a portion where the lubricating oil supply passage communicates. The fuel injection pump according to claim 1, wherein 6. The fuel injection device according to claim 5, wherein a seal member is interposed between an opening end of the plunger barrel and a portion where the lubricating oil supply passage between the sliding surfaces communicates. The seal member includes an O-ring provided in an annular groove formed on an outer periphery of the plunger, and a ring member provided on the outer periphery of the O-ring and having higher hardness than the O-ring. 7. The fuel injection device according to claim 6, wherein:

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