JPH0426691Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection pump for a diesel engine.

When injecting fuel in a diesel engine, especially in a vehicle diesel engine, first a small amount of preliminary fuel injection, or pilot injection, is performed, and then a large amount of main fuel injection is performed to reduce operating noise. It is a harmful component in exhaust gas.
It is known that fuel efficiency can be improved under the conditions of suppressing the generation of _NOX and suppressing the generation of _NOX below a certain limit. On the other hand, in diesel engines for relatively large vehicles such as trucks, independent pump elements for each cylinder are arranged in a row in a common pump housing as a fuel injection pump, and a transmission device such as a gear train is attached to the engine crankshaft. In-line fuel injection pumps are widely used in which each pump element is driven by a camshaft that is interlocked via a camshaft, and two in-line fuel injection pumps are used to perform the pilot injection and main injection. However, in-line injection pumps are generally expensive, heavy, and occupy a large amount of space, so using two of them would significantly reduce production costs, weight, and space. There is a problem that causes an increase.

This invention was devised in view of the above circumstances.
A plunger inserted into the housing so as to be slidable in the axial direction but not rotated relative to the axis, a discharge valve mounted in the housing and always spring-loaded in the closing direction, and the above-mentioned discharge valve. a pump chamber bounded within the housing by one end surface of the plunger; a fuel chamber defined within the housing surrounding the plunger; a control sleeve fitted outside the plunger within the fuel chamber; An oil passage in the plunger that opens into the pump chamber, a control groove provided on the plunger for communicating or disconnecting the pump chamber and the fuel chamber via the oil passage, and a control that cooperates with the control groove. In the case where the control groove on the plunger and the control hole on the control sleeve are provided with a control hole on the sleeve, a small amount of pilot injection is first performed by relative displacement of the plunger and the control sleeve in the axial direction, and then a main injection is performed. an inclined groove disposed at a relative position such that injection is performed, and in which the control groove is inclined with respect to the axis in order to terminate the main injection by communicating with the control hole; a vertical groove for no-injection provided extending in the control hole, and a first groove extending in the transverse direction with respect to the axis in order to terminate the pilot injection by communicating with the control hole.
and a second lateral groove formed in a direction transverse to the axis to prevent pilot injection by communicating with the control hole during engine idling operation. This article focuses on the characteristic fuel injection pump.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 10 is a housing of a fuel injection pump; 12 is a barrel that is removably fitted into the upper end of the housing and fixed with a bolt; 14
16 is a pump chamber formed in the barrel 12, and 16 is a discharge valve holder 18 screwed to the upper end of the barrel.
a fuel discharge valve 22 housed in the discharge valve holder 18 and preloaded by a spring 20 to close off the pump chamber 14; a discharge passage communicating with a fuel injection nozzle via a fuel injection pipe (not shown);
A plunger 24 is slidably fitted into the housing 10 via the barrel 12, and its upper end face 24a faces the pump chamber 14, and its lower end face 24b faces the cam holder 26 and roller 28.
It is in contact with the cam 30 via. 32 is a camshaft driven by an engine (not shown); 34 is a spring that always presses the cam holder 26 against the cam 30; 36 is a fuel chamber formed surrounding the plunger 24; Fuel is constantly supplied by a feed pump (not shown). 38 is a cylindrical control sleeve fitted on the outer circumference of the plunger 24 in the fuel chamber 36 so that it can freely slide in the axial direction and rotate freely; An arcuate guide groove cut in a plane perpendicular to the axis; 42, an injection timing control shaft whose axis is included in a plane perpendicular to the axis of the plunger 24; 44, an injection timing control shaft protruding from the control shaft 42; An injection timing control arm 48 having a spherical portion 46 at the tip fitted into the guide groove 40 is provided on the outer peripheral surface of the control sleeve 38 on the opposite side from the guide groove 40 over approximately a semicircumference. A gear, 50 is a control rack that meshes with the gear 48, and 52 is a plunger whose one end opens into the pump chamber 14 and whose other end communicates with a control groove 54 cut into the outer peripheral surface of the plunger that contacts the control sleeve 38. The control groove 54 has an inclined groove 54a inclined with respect to the plunger axis and a vertical groove 54b extending in the direction of the plunger axis, and the main injection part has an overall λ (lambda) shape; There is a pilot injection part consisting of a first horizontal groove 54c extending in a direction substantially perpendicular to the axis, and above the groove 54c, a short longitudinal groove in the axial direction and a second horizontal groove extending transversely to the axis.
and an idle portion consisting of a hook-shaped groove 54d including a horizontal groove. 56 is the control sleeve 3
The control groove 54 is bored in the radial direction on the top of the control groove 54.
The control hole 58, which cooperates with the plunger 24, is a hollow tubular plunger guide fitted into the lower end portion of the plunger 24, and the square section of the lower end thereof is fitted into the corresponding square section 24c on the plunger 24. As a result, the plunger 24 can be freely displaced in the axial direction with respect to the barrel 12 and the plunger guide 58, but cannot rotate relative to the plunger guide 58 around the axis. Further, a protrusion 62 provided with an axial engagement groove is provided on the outer peripheral portion of the upper end flange of the plunger guide 58,
On the other hand, an adjustment member 66 having an eccentric pin 64 that fits into the engagement groove is rotatably fitted on the wall surface of the housing 10 facing the protrusion, and a screw of the adjustment member 66 protrudes from the housing. A lock nut 68 is screwed into the portion.

In the above device, each member of the fuel pump is
When in the position shown in the figure, the control hole 56 and the control groove 54 do not communicate with each other, and the lower end of the control groove 54 protrudes below the lower end surface of the control sleeve 38 and opens into the fuel chamber 36, so the pump chamber 14 and the fuel chamber 36 are in communication. From this state, when the camshaft 32 is rotated by the engine and the plunger 24 is pushed upward by the cam 30 via the roller 28, the vertical groove 5 extending in the axial direction of the control groove 54 is
The lower end of 4b is closed by the control sleeve 38, and the control groove, namely the inclined groove 54a and the control hole 56.
Since the communication between the pump chamber 14 and the fuel chamber 36 is cut off, the communication between the pump chamber 14 and the fuel chamber 36 is cut off. FIG. 4 shows the relative position of the control sleeve 38 with respect to the plunger 24. In the above-mentioned position, the control hole 56 is at position A and the longitudinal groove 54b extending in the axial direction of the control groove is in the control sleeve. It is just closed by the lower edge 38' of 38. Therefore, the fuel in the pump chamber 14 is pressurized by the rise of the plunger 24, and when the pressure exceeds a set value, the discharge valve 16 is opened and the fuel is supplied from the discharge passage 22 to the injection nozzle of the engine. A pilot injection is performed. Then, the plunger 24 further rises, and at a position where the first lateral groove 54c of the control groove 54 crosses the control hole 56 (position B in FIG. 4), the pump chamber 14 and the fuel chamber 36 are connected via the oil passage 52. Because of this, the pilot injection is completed, and then the first lateral groove 54c
Fuel injection is not performed while the control hole 56 and the control hole 56 are communicating with each other. Subsequently, when the plunger 24 further rises and reaches position C in FIG. 4 and the control hole 56 is closed, the fuel in the pump chamber 14 is pressurized again, the discharge valve 16 is opened, and main injection is started. Ru. As the plunger 24 rises, the inclined groove 54a of the control groove 54
When the pump chamber 14 communicates with the control hole 56 at position D in FIG.
The main injection ends.
In the diagram of FIG. 5, Ip between AB indicates pilot injection, and Im between CD indicates main injection. Then, by rotating the control shaft 42 around its axis and displacing the control sleeve 38 in the axial direction of the plunger 24 via the control arm 44, The timings of the pilot injection Ip and the main injection Im are adjusted as shown in FIG.
4, and by changing the relative position between the inclined groove 54a of the control groove 54 and the control hole 56, the fuel injection amount, that is, CD in FIG.
The length in the horizontal axis direction will be increased or decreased. Of course, it is clear that the injection amount of the pilot injection as well as the main injection can be adjusted by giving the first lateral groove 54c an appropriate inclination. (The control rack 50 and the control shaft 42 are connected to an engine control device (not shown), such as an accelerator pedal,
It is driven manually by a governor, timer, etc., or by an appropriate actuator. ) Furthermore, the axial component of the hook-shaped groove 54d in the control groove 54, that is, the short longitudinal groove and the axial portion 54 of the main injection part.
b are non-injection notch grooves, and the lateral component of the hook-shaped groove 54d, that is, the short second lateral groove 54d' is:
This constitutes a fuel escape path to prevent pilot injection from occurring when the engine is idling. Furthermore, in the above-mentioned injection pump, when adjusting the injection amounts of the plurality of cylinders, the lock nut 68 may be loosened and the adjustment member 66 may be rotated using a tool such as a screwdriver. Then, due to the cooperation between the eccentric pin 64 and the protrusion 62, the plunger guide 58 moves toward the plunger 2.
4 in a desired direction around the axis of the plunger, the relative position of the plunger with respect to the control sleeve 38 is changed, in other words, the relative position of the control hole 56 with respect to the control groove 54 is changed, so that each Fine adjustments are made to the injection amount of the cylinder's injection pump.

In addition, in the above embodiment, the control sleeve 3
8 is provided with a single control hole 56, which is configured to control both pilot injection and main injection, but as shown in the exploded view on the right side of FIG. Control hole 56 in charge of
A and a control hole 56b in charge of main injection are provided separately and open on the inner circumferential surface of the control sleeve 38 at an angular interval of, for example, 180 degrees, and on the other hand, on the outer circumferential surface of the cooperating plunger 24. , as shown in the developed view on the left side of FIG.
and may be similarly arranged with an angular spacing of, for example, 180 degrees.

As described above, the fuel injection pump according to the present invention includes a plunger inserted into the housing so as to be slidable in the axial direction and not rotate relative to each other around the axis; a discharge valve spring-loaded in a normally closed direction; a pump chamber bounded within the housing by the discharge valve and one end surface of the plunger; a fuel chamber defined within the housing surrounding the plunger; A control sleeve fitted on the outside of the plunger in a room, an oil passage inside the plunger whose one end opens into the pump chamber, and a control sleeve on the plunger for communicating or blocking the pump chamber and the fuel chamber via the oil passage. and a control hole on a control sleeve that cooperates with the control groove, wherein the control groove on the plunger and the control hole on the control sleeve are arranged in the axial direction of the plunger and the control sleeve. The control groove is disposed at a relative position such that a small amount of pilot injection is first performed and then main injection is performed due to the relative displacement of It is characterized by including a groove extending in a direction transverse to the axis, and a groove provided at an angle with respect to the axis in order to terminate the main injection by communicating with the control hole. By making slight structural improvements to the in-line injection pump, it is possible to provide an injection pump capable of two-stage injection consisting of pilot injection and main injection, which is extremely useful in practice.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the entire injection pump showing an embodiment of the present invention, Fig. 2 is a sectional view of the main part taken along the - line in Fig. 1, Fig. 3 is a side view of Fig. 2, Fourth
The figure is an explanatory diagram showing how the control groove on the plunger and the control hole on the control sleeve cooperate, FIG. 5 is a diagram showing the injection timing in the injection pump of FIG. 1, and FIG. 6 is a modification of the present invention. FIG. 6 is an exploded view of a control groove on a plunger and a control hole on a control sleeve in an example. 10...Housing, 36...Fuel chamber, 12...
... Barrel, 38 ... Control sleeve, 14 ... Pump chamber, 50 ... Control rack, 16 ... Discharge valve, 52 ... Oil passage, 24 ... Plunger, 54
...Control groove, 30...Cam, 56...Control hole.

Claims (1)

[Scope of utility model registration request] A plunger inserted into the housing so as to be slidable in the axial direction but not rotated relative to the axis, a discharge valve mounted in the housing and always spring-loaded in the closing direction, and the above-mentioned discharge valve. a pump chamber bounded within the housing by one end surface of the plunger; a fuel chamber defined within the housing surrounding the plunger; a control sleeve fitted outside the plunger within the fuel chamber;
An oil passage in the plunger whose one end opens into the pump chamber, which cooperates with a control groove provided on the plunger and the control groove to communicate or cut off the pump chamber and the fuel chamber through the oil passage. The control groove on the plunger and the control hole on the control sleeve are arranged so that a small amount of pilot injection is first performed by relative displacement of the plunger and the control sleeve in the axial direction. an inclined groove disposed at a position where main injection will later be performed, and inclined with respect to the axis so that the control groove communicates with the control hole to terminate the main injection; a vertical groove for non-injection provided extending in the axial direction; and a first longitudinal groove extending in the transverse direction with respect to the axis for terminating the pilot injection by communicating with the control hole.
and a second lateral groove formed in a direction transverse to the axis to prevent pilot injection by communicating with the control hole during engine idling operation. Features a fuel injection pump.