JP2010163963A - Fuel injection pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce stress concentration at the crossing points of cylinder holes 27 and 29 with fuel discharge ports, which is caused according to thermal strain resulting from heat generated in a fuel force feeding step by plungers 14 and 15 in a fuel injection pump 1. <P>SOLUTION: In the fuel injection pump 1, inlet flow passages 48 and 49 for introducing fuel, before pressurization, to the cylinder holes 27 and 29 are formed in cylinder bodies 25 and 26, and each of the inlet flow passages 48 and 49 is disposed around the cylinder hole 27, 29 while being branched into two or more passages. Thereby, the cylinder bodies 25 and 26 can be efficiently cooled by carrying low-temperature fuel, before pressurization, to a wide range within the cylinder bodies 25 and 26. Thus, the temperature rise of the cylinder bodies 25 and 26 in the force feeding step can be suppressed, and the stress concentration by thermal strain at a crossing point 56 between the cylinder hole 27 and a first fuel discharge port 28 and a crossing point between the cylinder hole 29 and a second fuel discharge port can be reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection pump for an internal combustion engine.

  As shown in FIG. 4, as a conventional fuel injection pump 100, the fuel sent out by the feed pump 103 is pressurized in the cylinder holes 104 and 105 by the reciprocating movement of the plungers 101 and 102, and is externally supplied from the fuel discharge hole 107. There is something to pump. In such a fuel injection pump 100, a cylinder hole 104 and a fuel discharge hole 107 are provided in the cylinder body 108 so as to intersect with each other. For example, the fuel is orthogonal to the reciprocating direction (vertical direction in the figure) of the plunger 101. A discharge hole 107 is formed.

  For this reason, the temperature in the cylinder hole 104 rises with the pressurization of the fuel due to the movement of the plunger 101, so that the cylinder hole 104 and the fuel discharge hole 107 are distorted to the larger diameter side due to heat. There is a risk of stress concentration at the intersection 109 between the fuel discharge hole 107 and the fuel discharge hole 107. Since the cylinder body 110 is also provided with a fuel injection hole (not shown) that intersects with the cylinder hole 105, the cylinder hole 105 formed in the cylinder body 110 intersects with a fuel discharge hole (not shown). Similarly, there is a risk of stress concentration in the part.

As a cooling technique related to the fuel injection pump 100, the lubricating oil for the fuel injection pump 100 is cooled by engine cooling water (see Patent Document 1), and the fuel before pressurization is guided to an electromagnetic valve to electromagnetically. There is one that lowers the temperature of the valve (see Patent Document 2).
However, in the former technique, the structure is complicated and large because engine cooling water is used. Even in the latter technique, a pipe must be disposed in order to introduce fuel before pressurization to the electromagnetic valve, resulting in a complicated structure. Furthermore, neither the former technique nor the latter technique can reduce the stress concentration due to thermal strain at the intersection 109 and the intersection between the cylinder hole 105 formed in the cylinder body 110 and the fuel discharge hole.

JP 11-159350 A JP 2002-174154 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a cylinder hole and a fuel discharge due to the distortion of the cylinder hole and the fuel discharge hole due to heat generated in the fuel pumping process by the plunger. The purpose is to reduce the stress concentration at the intersection with the hole.

[Means of Claim 1]
According to a first aspect of the present invention, there is provided a fuel injection pump comprising: a housing having a cylinder hole and a fuel discharge hole that communicates across the cylinder hole; and a fuel that is supplied into the cylinder hole by reciprocating in the cylinder hole. And a plunger that pressurizes and pressurizes, and the fuel pressurized by the reciprocating motion of the plunger is pumped out of the fuel discharge hole.
The housing is formed with an introduction channel for introducing fuel before pressurization into the cylinder hole, and the introduction channel is branched into a plurality and arranged around the cylinder hole.

According to this, the housing can be efficiently cooled by branching the introduction flow path into a plurality of parts and allowing the low-temperature fuel before pressurization to flow into the housing. For this reason, the temperature rise of the housing by the heat | fever which generate | occur | produces in the process (pumping process) by which a fuel is pressurized and pumped with a plunger can be suppressed. As a result, it is possible to suppress the occurrence of distortion due to the heat of the cylinder hole and the fuel discharge hole, thereby reducing the stress concentration at the intersection between the cylinder hole and the fuel discharge hole.
Further, since the introduction flow path also serves as the housing cooling flow path, the structure is not complicated, and no separate member is required for cooling the housing.

[Means of claim 2]
In the fuel injection pump according to claim 2, at least a part of the introduction flow path is formed in the vicinity of the intersection of the cylinder hole and the fuel discharge hole.

  According to this, it is possible to prevent the cylinder hole and the fuel discharge hole from being deformed by heat by reliably cooling the intersection of the cylinder hole and the fuel discharge hole. For this reason, the stress concentration at the intersection of the cylinder hole and the fuel discharge hole can be reduced.

[Means of claim 3]
In the fuel injection pump according to claim 3, the introduction flow path includes an annular flow path formed so as to surround the cylinder hole, and a radiation flow path branched from the annular flow path to communicate the annular flow path with the cylinder hole. Consists of.

  According to this, the cylinder hole can be cooled more efficiently by the fuel before pressurization flowing through the introduction flow path. In addition, since the fuel before pressurization is supplied into the cylinder hole through the annular annular channel and the radiation channel composed of a plurality of channels communicating the annular channel with the cylinder hole, the fuel before pressurization is A flow can be formed without being blocked. For this reason, the cooling efficiency can be improved without being affected by the heat generated in the pumping process.

1 is a configuration diagram of a fuel injection pump (Example 1). FIG. (Example 1) which is explanatory drawing of the pressure accumulation type fuel injection system carrying the fuel injection pump of this invention. (Example 1) which is a top view of the cylinder body of a fuel injection pump. It is a block diagram of a fuel injection pump (conventional example).

The fuel injection pump of the present invention pressurizes the fuel supplied into the cylinder hole by reciprocating in the cylinder hole and the housing having the cylinder hole and the fuel discharge hole communicating with the cylinder hole. And a pressure-feeding plunger, and the fuel pressurized by the reciprocating motion of the plunger is pressure-fed from the fuel discharge hole to the outside.
The housing is formed with an introduction channel for introducing fuel before pressurization into the cylinder hole, and the introduction channel is branched into a plurality and arranged around the cylinder hole.

At least a part of the introduction flow path is formed in the vicinity of the intersection of the cylinder hole and the fuel discharge hole.
The introduction flow path includes an annular flow path formed so as to surround the cylinder hole, and a radiation flow path that branches from the annular flow path and communicates the annular flow path with the cylinder hole.

[Configuration of Example 1]
The structure of the fuel injection pump 1 of Example 1 is demonstrated using FIGS.
The fuel injection pump 1 is used, for example, in an accumulator fuel injection system for a diesel engine, and pressurizes the fuel and supplies it to the common rail 2. The fuel accumulated in the common rail 2 is injected into the combustion chamber of the engine by the injector 3.

  The fuel injection pump 1 includes a feed pump 7 that sucks up fuel from a fuel tank 4, a pumping unit 8 that pressurizes and pumps fuel sucked up by the feed pump 7, and the like inside the housing 9.

  The feed pump 7 is constituted by, for example, a well-known trochoid pump, is driven by the camshaft 10, sucks the fuel pumped up from the fuel tank 4 through the filter 13, pressurizes it to a predetermined pressure, and discharges it. For convenience of drawing the fuel path, the feed pump 7 is disclosed in a form developed 90 degrees in FIGS.

The pressure feeding unit 8 includes cam means (described in detail below) that converts the rotational motion of the camshaft 10 into reciprocating motion, and plungers 14 and 15 to which the reciprocating motion of the cam means is transmitted.
The cam means is composed of an eccentric cam 18 provided on the camshaft 10 and a ring cam 19 fitted to the outer periphery of the eccentric cam 18 so as to be relatively rotatable.
Two plungers 14 and 15 are arranged in a vertically symmetrical position of the ring cam 19, and the plungers 14 and 15 are pressed against the upper and lower end surfaces of the ring cam 19 by springs 20 and 21, respectively.

  When the cam shaft 10 rotates, the cam means converts the rotational motion into a reciprocating motion by the rotation of the eccentric cam 18 and the ring cam 19, and the reciprocating motion is transmitted to the plungers 14 and 15.

The housing 9 includes a housing main body 24 that houses the camshaft 10, the ring cam 19, and the feed pump 7, and cylinder bodies 25 and 26 (housing) that house the plungers 14 and 15 so as to reciprocate.
The cylinder body 25 includes a cylinder hole 27 formed in the vertical direction in the figure, and a first fuel discharge hole 28 that communicates perpendicularly to the cylinder hole 27 (in the horizontal direction in the figure) at the top of the cylinder hole 27. The cylinder body 26 has a cylinder hole 29 formed in the vertical direction in the figure and a second fuel discharge hole (not shown) communicating with the cylinder hole 29 at right angles.

  The plungers 14 and 15 are reciprocated in the cylinder holes 27 and 29 by the reciprocating motion transmitted from the cam means, and the intake stroke for sucking fuel into the cylinder holes 27 and 29 and the fuel in the cylinder holes 27 and 29 are performed. The pumping process of pressurizing and pumping is repeated. The upper part of the cylinder hole 27 and the lower part of the cylinder hole 29 function as a fuel pressurization chamber, and the first fuel discharge hole 28 and the second fuel discharge hole are provided in communication with the pressurization chamber.

  In the pumping unit 8, the fuel discharged from the feed pump 7 pushes the suction valves 32 and 33 open by the suction stroke of the plungers 14 and 15 (corresponding to the downward movement in the plunger 14 and the upward movement in the plunger 15). The fuel sucked into the cylinder holes 27 and 29 is sucked into the cylinder holes 27 and 29 by the pressure-feeding stroke of the plungers 14 and 15 (corresponding to the upward movement of the plunger 14 and the downward movement of the plunger 15). Pressurized fuel is pressurized and sent to the common rail 2 through the first fuel discharge hole 28 by pushing the discharge valve 34 open.

Here, the intake valves 32 and 33 are check valves that prevent the fuel from flowing back to the feed pump 7 side. The intake valve 32 is arranged above the cylinder hole 27, and the intake valve 33 is arranged below the cylinder hole 29. The cylinder bodies 25 and 26 are mounted as described above. The discharge valve 34 is a check valve that prevents the pumped fuel from flowing back into the cylinder holes 27 and 29, and the first fuel discharge hole 28 is provided to be openable and closable with respect to the outside (the common rail 2 side). It has been.
The second fuel discharge hole is also communicated to the outside by a fuel pipe (not shown) so as to be opened and closed.

  The fuel injection pump 1 adjusts the amount of fuel supplied to the cylinder hole 27 provided between the pressure adjustment valve 37 for adjusting the fuel pressure in the feed pump 7 and the feed pump 7 and the suction valve 32. An intake metering valve 38 is provided.

[Operation of fuel injection pump 1]
The operation of the fuel injection pump 1 will be described in detail below with reference to FIG.
As the camshaft 10 rotates and the feed pump 7 is driven, fuel is introduced from the fuel tank 4 through the filter 13 and the inlet 40 into the fuel introduction path 41 and sucked into the suction side of the feed pump 7. It is. Then, the feed pump 7 pressurizes the sucked fuel to a predetermined pressure and sends it to the fuel reservoir chamber 43 of the suction metering valve 38 through the fuel lead-out path 42.

  Further, surplus fuel discharged from the feed pump 7 is supplied to the cam chamber 45, and the fuel overflowing from the cam chamber 45 returns to the fuel tank 4 through the fuel return path 46. The cam chamber 45 is provided with the above cam means, and the fuel supplied to the cam chamber 45 is used for lubricating the sliding portion of the cam means.

The fuel in the fuel reservoir chamber 43 is supplied to the cylinder holes 27 and 29 through the intake metering valve 38, the introduction passages 48 and 49 (described later in detail), and the intake valves 32 and 33.
Then, the fuel supplied into the cylinder hole 27 is pressurized by the pressure feeding stroke of the plunger 14, and the pressurized fuel is pressure-fed to the common rail 2 by pushing the discharge valve 34 through the first fuel discharge hole 28. The Similarly, the fuel in the cylinder hole 29 is pressurized by the pressure-feeding stroke of the plunger 15, and the pressurized fuel is pressure-fed to the common rail 2 through the second fuel discharge hole.

[Features of Example 1]
An introduction flow path 48 for introducing the fuel before pressurization into the cylinder hole 27 is formed in the cylinder body 25, and this introduction flow path 48 is branched into a plurality and disposed around the cylinder hole 27. ing.
In the present embodiment, the introduction channel 48 is formed so as to surround the cylinder hole 27, and extends from the annular channel 50 to the inner peripheral side of the annular channel 50. And a radiation flow path 51 composed of a plurality of flow paths for communicating with the cylinder hole 27 via the suction valve 32.

  In the cylinder body 25, an introduction passage 48 is formed so as to communicate the fuel passage 54 of the fuel delivered from the intake metering valve 38 and the fuel passage 55 of the intake valve 32. Since the fuel flow path 54 is located on the camshaft side (lower side in the drawing) with respect to the intake valve 32, the introduction flow path 48 connecting the fuel flow path 54 and the fuel flow path 55 passes through the vicinity of the cylinder hole 27. .

The annular channel 50 is provided, for example, in an annular shape (see FIG. 3A) or a quadrangular shape (see FIG. 3B) immediately downstream of the fuel channel 54. Further, the radial flow path 51 is provided radially so as to be branched into a plurality from the annular flow path 50 and communicate with the fuel flow path 55. In the present embodiment, there are four radiation channels 51, for example, and the intervals between the radiation channels 51 are equal (see FIG. 3).
Further, at least a part of the radiation channel 51 is formed in the vicinity of the intersection 56 between the cylinder hole 27 and the first fuel discharge hole 28.

  The cylinder body 26 is also formed with an introduction channel 49, similar to the introduction channel 48 of the cylinder body 25, and an annular channel 57 and a radiation channel 58 are formed.

[Effect of Example 1]
According to the fuel injection pump 1 of the present embodiment, the cylinder bodies 25 and 26 are formed with the introduction passages 48 and 49 for introducing the fuel before pressurization into the cylinder holes 27 and 29. 48 and 49 are branched into a plurality and are arranged around the cylinder holes 27 and 29, respectively.

  According to this, since the low-temperature fuel before pressurization can flow over a wide range in the cylinder bodies 25 and 26, the cylinder bodies 25 and 26, particularly, the periphery of the cylinder holes 27 and 29 can be efficiently cooled. Can do. For this reason, the temperature rise of the cylinder bodies 25 and 26 accompanying the heat | fever generate | occur | produced by the fuel pressurization at a pumping process can be suppressed.

As a result, the occurrence of distortion due to heat in the cylinder hole 27, the first fuel discharge hole 28, the cylinder hole 29, and the second fuel discharge hole can be suppressed, so that the intersection of the cylinder hole 27 and the first fuel discharge hole 28 can be suppressed. 56, stress concentration at the intersection of the cylinder hole 29 and the second fuel discharge hole can be reduced. For this reason, the reliability of the fuel injection pump 1 is improved.
Further, since the introduction passages 48 and 49 also serve as cylinder body cooling passages, the structure is not complicated, and no separate member is required for cooling the cylinder body.

Further, in the fuel injection pump 1 of the present embodiment, at least a part of the radiation channel 51 is formed in the vicinity of the intersection 56 between the cylinder hole 27 and the first fuel discharge hole 28, and at least a part of the radiation channel 58. Is formed in the vicinity of the intersection of the cylinder hole 29 and the second fuel discharge hole.
According to this, the cylinder holes 27 and 29 can be more efficiently cooled by the fuel before pressurization flowing through the introduction flow paths 48 and 49.

  In addition, since the fuel before pressurization is supplied into the cylinder holes 27 and 29 through the annular channels 50 and 57 and the radiation channels 51 and 58, the fuel before pressurization forms a flow without being blocked. can do. For this reason, the cooling efficiency can be improved without being affected by the heat generated in the pumping process.

[Modification]
In the fuel injection pump 1 of the first embodiment, the introduction flow path is provided by providing the radiation flow path 51 in such a positional relationship that the two fuel flow paths 51 sandwich the first fuel discharge hole 28 in the circumferential direction of the cylinder hole 27. At least a part of 48 may be formed in the vicinity of the intersection 56 between the cylinder hole 27 and the first fuel discharge hole 28. In the first embodiment, the four radiation flow paths 51 are provided at equal intervals. However, the number is not limited to four. Further, the intervals between the radiation channels 51 may not be equal.

  In the first embodiment, the introduction flow path 48 includes the annular flow path 50 and the radiation flow path 51, but it is sufficient that the introduction flow path 48 is branched into a plurality around the cylinder hole 27. Is not limited. For example, a plurality of branched introduction channels 48 may be circulated around the cylinder hole 27. The same applies to the introduction flow path 49.

  Further, the fuel injection pump 1 of the first embodiment has the pressure feeding portion 8 composed of the two plungers 14 and 15 and the cam means, but is a fuel injection pump provided with a pressure feeding mechanism having a pressure mechanism by the plunger. The present invention can be applied if it exists, and the pressure feeding mechanism is not limited to the embodiment.

1 Fuel injection pump 14, 15 Plunger 25, 26 Cylinder body (housing)
27, 29 Cylinder hole 28 1st fuel discharge hole 48, 49 Introduction flow path 50, 57 Annular flow path 51, 58 Radiation flow path 56 Crossing part

Claims (3)

A housing having a cylinder hole and a fuel discharge hole crossing and communicating with the cylinder hole;
A plunger that pressurizes and feeds fuel supplied into the cylinder hole by reciprocating in the cylinder hole;
In the fuel injection pump in which the fuel pressurized by the reciprocating motion of the plunger is pumped to the outside from the fuel discharge hole,
The housing is formed with an introduction flow path for introducing fuel before pressurization into the cylinder hole,
The fuel injection pump characterized in that the introduction flow path is branched into a plurality and arranged around the cylinder hole. The fuel injection pump according to claim 1, wherein
At least a part of the introduction flow path is formed in the vicinity of an intersection of the cylinder hole and the fuel discharge hole. The fuel injection pump according to claim 1 or 2,
The introduction channel is
An annular channel formed so as to surround the cylinder hole;
A fuel injection pump comprising: a radial flow path branched from the annular flow path and communicating the annular flow path with the cylinder hole.

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