JP2013151902A - Fuel injection pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection pump capable of effectively suppressing erosion generated caused by cavitation generated in fuel discharged from a plunger barrel to an inlet/outlet fuel chamber in a fuel injection pump of a diesel engine or others.SOLUTION: In an fuel injection pump 1 having a cylindrical plunger barrel 2 formed by an inlet/outlet port 11 passing through, a plunger 3 defining a plunger chamber 21 with the plunger barrel 2, and an inlet/outlet fuel chamber 4 and carrying out fuel supply and fuel discharge by the reciprocating movement of the plunger 3, a solid deflector 40 extending to the plunger 3 side is arranged in the inlet/outlet port 11, a step is formed in the plunger chamber 21 side more than a reed 31 in the plunger 3, an inclining part 34 with a step angle of 45° or less in a crosssection including a center axis of the plunger is formed in the step.

Description

  The present invention relates to a fuel injection pump that is used in a diesel engine or the like and can suppress the generation of erosion caused by a jet of fuel discharged from a plunger barrel into a supply / discharge fuel chamber.

  A fuel injection pump used for a diesel engine or the like includes a cylindrical plunger barrel having a supply / discharge port formed therethrough, a plunger that is disposed in the plunger barrel and defines a plunger chamber together with the plunger barrel, and a plunger barrel. The fuel from the supply / discharge fuel chamber to the plunger barrel is opened and closed by opening and closing the supply / discharge port with a lead formed on the peripheral surface of the plunger by reciprocating movement of the plunger. While supplying and discharging the fuel from the plunger barrel to the supply / exhaust fuel chamber, the fuel is discharged from the plunger chamber to the engine body.

  In such a fuel injection pump, when the plunger discharges fuel from the plunger barrel to the supply / exhaust fuel chamber, cavitation occurs in the fuel injected into the supply / discharge fuel chamber through the supply / discharge port, and this cavitation is generated by the supply / discharge port. This causes a cavitation erosion in the wall portion of the supply / discharge port.

  Therefore, for the purpose of suppressing the occurrence of cavitation erosion to the supply / discharge port, a deflector is provided in the supply / discharge port, and a high-speed fuel flow discharged from the plunger barrel to the supply / discharge fuel chamber is made to collide with the deflector. Techniques for suppressing the occurrence of cavitation erosion in a supply / discharge port or the like are disclosed (see, for example, Patent Documents 1 and 2).

JP 2000-179428 A JP 2008-115791 A

  However, even if the techniques described in Patent Documents 1 and 2 are used, the fuel injection pump such as a diesel engine has severe use conditions, and it is necessary to periodically replace the installed deflector. There is a strong technical demand for more efficient control and thus maintenance costs.

  Thus, as a result of earnest research on the technology for suppressing the collision of cavitation against the supply / exhaust port using the deflector, the inventors have made the gradant angle formed on the plunger appropriately correspond to the shape of the deflector. It has been found that the cavitation can be efficiently collided with the deflector and the collision of the cavitation with the wall of the supply / discharge port can be greatly reduced.

  The present invention has been made in consideration of such circumstances, and in a fuel injection pump such as a diesel engine, the erosion caused by cavitation generated in the fuel discharged from the plunger barrel into the supply / discharge fuel chamber is efficiently performed. It is an object of the present invention to provide a fuel injection pump that can be suppressed.

In order to achieve the above object, the present invention proposes the following means.
The invention according to claim 1 is a cylindrical plunger barrel having a supply / exhaust port formed therethrough, a plunger disposed in the plunger barrel and defining a plunger chamber together with the plunger barrel, and the plunger barrel A supply / exhaust fuel chamber for storing fuel supplied / exhausted between, and by opening / closing the supply / exhaust port by a lead formed on the peripheral surface of the plunger by reciprocation of the plunger, A fuel injection pump for supplying fuel to the plunger barrel from the plunger barrel and discharging fuel from the plunger barrel to the supply / exhaust fuel chamber, and for discharging fuel from the plunger chamber, A solid deflector extending to the plunger side is arranged, and the plunger is grabbed from the lead to the plunger chamber side. Emissions is formed, the Guradan is characterized in that the inclined portion of the following Guradan angle 45 ° in the cross section including the central axis of the plunger is formed.

  According to the fuel injection pump according to the present invention, the gradation angle of the inclined portion formed in the gradane is reduced to 45 ° or less to make the jet flow upward, and by making the deflector solid, the cavitation erosion is caused on the deflector. Can be generated. In addition, since the deflector is solid and the portion where the jet collides is thick, the deflector can be used for a long period of time.

  The invention according to claim 2 is the fuel injection pump according to claim 1, wherein the deflector is configured to be rotatable by the fuel discharged through the supply / discharge port.

  According to the fuel injection pump according to the present invention, the deflector is rotatable, and the jet flow is prevented from colliding with a specific portion in the circumferential direction of the deflector. As a result, erosion occurs uniformly in the circumferential direction of the deflector, and the deflector can be used for a long period of time, so that maintenance costs can be reduced.

  A third aspect of the present invention is the fuel injection pump according to the first or second aspect, wherein the plunger is provided in a recess side region formed on the opposite side of the plunger chamber via the lead. Pressure loss generating means for generating pressure loss in the fuel flowing through the exhaust port is provided.

According to the fuel injection pump according to the present invention, the pressure of the fuel discharged to the exhaust port tends to be largely controlled by the opening degree (port opening degree) of the supply / exhaust port. By providing pressure loss generating means in the fuel tank and generating pressure loss in the fuel discharged to the supply / exhaust port, it is possible to suppress jet flow and static pressure drop at the supply / discharge port portion. Even if the differential pressure is large, the occurrence of cavitation can be suppressed.
Further, by generating a pressure loss at a port other than the supply / discharge port, the sensitivity to the port opening decreases, and fine adjustment is possible.

  A fourth aspect of the present invention is the fuel injection pump according to the third aspect, wherein the pressure loss generating means has a convex portion formed in the concave side region.

  According to the fuel injection pump according to the present invention, the pressure loss generating means has the convex portion formed in the concave side region, so that pressure loss can be generated with a simple configuration, and cavitation is generated. It can be suppressed efficiently.

  According to the fuel injection pump according to the present invention, it is possible to suppress the occurrence of cavitation erosion to the supply / discharge port by colliding the cavitation generated in the fuel discharged from the supply / discharge port with the deflector, and consequently the maintenance cost. Can be reduced. Further, the reliability of the fuel injection pump can be improved.

It is a figure explaining the outline of the fuel injection pump which concerns on the 1st Embodiment of this invention. It is a figure explaining the Gradan angle of the fuel injection pump concerning a 1st embodiment. It is a conceptual diagram explaining the effect | action of the deflector which concerns on 1st Example. It is a figure explaining the fuel injection pump which concerns on the 2nd Embodiment of this invention. It is a conceptual diagram explaining the effect | action of the deflector which concerns on 2nd Example. It is a figure which shows the modification of the deflector which concerns on 2nd Example.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 is a diagram showing an outline of a fuel injection pump (jerk type fuel injection pump) for a diesel engine according to a first embodiment of the present invention. Reference numeral 1 denotes a fuel injection pump.

  As shown in FIG. 1, the fuel injection pump 1 includes a plunger barrel 2, a plunger 3 disposed in the plunger barrel 2, and a supply / discharge fuel chamber 4 that stores fuel supplied and discharged between the plunger barrel 2. And the pump case 5 and the deflector 40. The plunger barrel 2, the plunger 3, the supply / exhaust fuel chamber 4, and the deflector 40 are disposed in the pump case 5.

  The plunger barrel 2 is formed in a cylindrical shape, and a tapered supply / discharge port 11 whose outer peripheral side is enlarged is formed on the peripheral wall portion, for example, so that the plunger 3 reciprocates in the axial direction inside the plunger barrel 2. It has become.

  As shown in FIG. 1, the plunger 3 has a substantially cylindrical shape, and a lead 31 is formed on the peripheral surface thereof. The concave portion side region 32 disposed on the opposite side of the plunger chamber via the lead 31, and the lead 31 And a convex portion side region 33 formed on the plunger chamber side, and the concave portion side region 32 and the convex portion side region 33 are connected by a lead 31.

  As shown in FIG. 2, the plunger 3 is formed with a gradan (step) on the side of the plunger chamber 21 with respect to the lead 31, an inclined portion 34 is formed on the gradan, and the inclined portion 34 has a central axis of the plunger 3. In the cross section including the crossing angle of the plunger 3 with the reciprocating direction, the so-called Gradane angle α is set to 45 ° or less. As a result, cavitation erosion to the wall portion of the supply / discharge port 11 is suppressed by causing the cavitation to collide with the deflector 40. The arrow F shown in FIG. 2 indicates the reciprocating direction (plunger traveling direction) of the plunger 3, and the upper side in FIG. 2 indicates the front side in the plunger traveling direction, and the lower side indicates the rear side in the plunger traveling direction.

  The plunger 3 together with the plunger barrel 2 defines a plunger chamber 21 at the upper portion of the plunger barrel 2 and reciprocates while sliding in the plunger barrel 2 by a tappet and a tappet spring (not shown).

  As the plunger 3 reciprocates, the supply / discharge port 11 is opened when the concave portion side region 32 overlaps with the supply / discharge port 11, and when the convex portion side region 33 overlaps with the supply / discharge port 11, supply / discharge is performed. The port 11 is closed, and the supply / discharge port 11 is opened and closed to supply fuel from the supply / discharge fuel chamber 4 into the plunger barrel 2 and to discharge fuel from the plunger barrel 2 to the supply / discharge fuel chamber 4. It has come to be.

  Further, when the plunger 3 reciprocates and a valve (not shown) 23 arranged at the upper part of the plunger chamber 21 is opened by the pressure of the fuel, the fuel is discharged to the diesel engine (not shown) through the discharge port 24. It has come to be.

  In addition, a plurality of ribs 35 extending in the circumferential direction of the plunger 3 are formed in the concave portion side region 32 of the plunger 3 in the axial direction of the plunger 3, and the plunger 3 moves toward the plunger chamber 21 and moves to the supply / discharge port. When the fuel is discharged from the supply / discharge port 11 with the valve 11 opened, a pressure loss occurs in the fuel discharged to the supply / discharge port 11.

  As a result, the jet flow and static pressure drop at the supply / discharge port 11 are suppressed, and the occurrence of cavitation can be suppressed even when the differential pressure across the supply / discharge port 11 is large. In addition, by generating a pressure loss on the upstream side of the gradan other than the supply / exhaust port 11, the sensitivity to the port opening degree is lowered and fine adjustment is possible.

The deflector 40 has a solid configuration having a curved surface that expands and has a tapered tip, and is disposed in the supply / exhaust fuel chamber 4 via a fixing member 52 fixed to the pump case 5. The tip is inserted into the supply / discharge port 11.
Further, the deflector 40 is formed such that a gap is formed between the tip of the deflector 40 and the outer peripheral surface of the plunger 3 in the supply / discharge port 11, and a flow path through which fuel flows is formed between the deflector 40 and the supply / discharge port 11. Thus, when the plunger 3 opens the supply / discharge port 11, erosion in the supply / discharge port 11 is suppressed by causing high-pressure fuel ejected to the supply / discharge port 11 to collide with the vicinity of the tip of the deflector 40. It is like that.

  FIG. 3 is a conceptual diagram showing cavitation around the deflector 40. For example, cavitation caused by a jet that has passed through the inclined portion 34 collides with the lower and upper wall portions of the supply / discharge port 11 as shown in FIG. Instead, it collides with the vicinity of the tip of the deflector 40. A symbol C indicates cavitation. Here, the upper side of the supply / discharge port 11 is the upper side in FIG. 3, and as described above, the plunger traveling direction front side, and the lower side is the lower side in FIG. 3, meaning the plunger traveling direction rear side.

  According to the fuel injection pump 1, the plunger gradane angle is reduced to 45 ° or less to make the jet flow upward, and the deflator 40 is made solid so that cavitation erosion is generated near the tip of the deflector 40. it can. Further, since the deflector 40 is solid and the thickness of the portion where the jet collides is thick, the deflector 40 can be used for a long period of time.

Next, a fuel injection pump 1 according to a second embodiment of the present invention will be described with reference to FIGS. The fuel injection pump 1 according to the second embodiment is different from the first embodiment in that a deflector 50 that can be rotated is disposed instead of the deflector 40.
The deflector 50 is supported at the base end side by a rotation support member 55 such as a bearing, and a helical recess 56 for imparting rotation to the tip end of the deflector 50 by colliding with cavitation. It has been configured. As a result, as shown in FIG. 5, when the cavitation C collides with the spiral recess 56, the deflector 50 rotates in the arrow G direction. Others are the same as those in the first embodiment, and thus the same reference numerals are given and the description thereof is omitted.

  According to the fuel injection pump 1 according to the second embodiment, the tip of the deflector 50 is rotatable, and the jet flow is prevented from colliding with a specific portion in the circumferential direction of the deflector 50. As a result, erosion occurs uniformly in the circumferential direction of the deflector 50, and the deflector 50 can be used for a long period of time, so that maintenance costs can be reduced. Moreover, the reliability as the fuel injection pump 1 can be improved.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.
For example, the shape of a deflector shows an example and can be arbitrarily set within the scope of the gist of the invention.

  Further, in the above-described embodiment, the plurality of ribs 35 of the plunger 3 are formed in the recess side region 32 via the lead 31 of the plunger 3 as pressure loss generating means for causing pressure loss in the fuel flowing through the supply / discharge port 11. However, the direction in which the ribs extend may be the direction intersecting with the circumferential direction of the plunger, or the ribs 35 may be cut or the pressure loss generating means may be constituted by a plurality of pins. . Moreover, it is good also as a structure which does not provide a pressure loss generating means in the plunger 3. FIG.

Moreover, in the said embodiment, although the jet flow collided with the spiral recessed part 56 formed in the surrounding surface of the deflector 50, and the case where a deflector rotated was demonstrated, FIG. 6 (A)-FIG. The configuration exemplified in E) may be used. 6A to 6E are configured to be supported by a rotation support member 55 such as a bearing.
A deflector 60 shown in FIG. 6A is configured to have a plurality of dimples 61 on the surface, and fuel passing around the deflector 60 acts on the dimples 61 to rotate the deflector 60.
Further, the deflector 70 shown in FIG. 6B is configured to rotate by injecting fuel taken from suction (not shown) through a spill hole 71 opened in a direction offset from the rotation shaft.
The deflector 80 shown in FIG. 6C includes radial grooves 81 that extend in the axial direction along the surface of the deflector 80 with the rotation axis as the center, and the fuel acts on the radial grooves 81 to rotate. ing.
Further, the deflector 85 shown in FIG. 6D includes radial fins 86 centering on the rotation axis and extending in the axial direction along the surface of the deflector 85, and the fuel is configured to rotate by acting on the radial fins 86. ing.
Further, the deflector 90 shown in FIG. 6 (E) includes a spiral fin 91 that spirally extends along the surface of the deflector 90 with the rotation axis as the center, and the fuel acts on the spiral fin 91 to rotate. ing.
In addition, other known configurations may be used. 6B is a cross-sectional view taken along the line XX in the left view, and right views in FIGS. 6C to 6E are views of the deflectors 80, 85, 90 viewed from the front end side in the axial direction. It is.

  According to the present invention, the occurrence of cavitation erosion in the supply / exhaust port or the like can be suppressed by causing the cavitation to collide with the deflector.

α Gradan angle 2 Plunger barrel 3 Plunger 4 Supply / exhaust fuel chamber 11 Supply / exhaust port 21 Plunger chamber 31 Lead 32 Recess side area 33 Protrusion side area 34 Inclined part 35 Rib (convex shape part)
40, 50, 60, 70, 80, 85, 90 Deflector

Claims (4)

A cylindrical plunger barrel formed by penetrating the supply / discharge port;
A plunger disposed within the plunger barrel and defining a plunger chamber with the plunger barrel;
A supply / exhaust fuel chamber for storing fuel supplied / exhausted with the plunger barrel,
Fuel supply from the supply / discharge fuel chamber to the plunger barrel, and supply / discharge fuel chamber from the plunger barrel by opening / closing the supply / discharge port by a lead formed on the plunger peripheral surface by reciprocation of the plunger A fuel injection pump for discharging fuel to the plunger chamber and discharging fuel from the plunger chamber,
A solid deflector extending toward the plunger side is disposed in the supply / discharge port,
In the plunger, a gradan is formed on the plunger chamber side from the lead, and an inclined portion having a gradan angle of 45 ° or less is formed in the cross section including the central axis of the plunger. Fuel injection pump. The fuel injection pump according to claim 1,
The fuel injection pump, wherein the deflector is configured to be rotatable by fuel discharged through the supply / discharge port. The fuel injection pump according to claim 1 or 2,
The plunger includes a pressure loss generating means for generating a pressure loss in the fuel flowing through the supply / exhaust port in a recess side region formed on the opposite side of the plunger chamber via the lead. . The fuel injection pump according to claim 3,
The fuel injection pump characterized in that the pressure loss generating means has a convex portion formed in the concave side region.

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