JPS63302171A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To improve combustion performance, by a method wherein, during low load running of an engine, injection in two-stage of fuel is effected, the generation of noise is reduced during low speed running and failure in ignition is prevented from occurring during high speed running, and an injection timing is advanced or delayed according to the number of revolutions of an engine. CONSTITUTION:With a plunger 1 reciprocated within a barrel 2, fuel is sucked and forcibly fed in a pressurizing chamber 3 formed in the top surface of the plunger 1. By regulation of a relative rotation amount between the plunger 1 and the barrel 2, an amount of injected fuel is controlled. In this pump, during low load running in which a relative rotation amount is low, a subport 5 is positioned facing a third reed 8, injection in two-stage of fuel is effected, and a delay in ignition of fuel is shortened. During middle and high load running in which a relative rotation amount is high, the subport is not positioned facing the third reed, and injection in one-stage of fuel is effected. When the number of revolutions of an engine is further increased, the subport 5 is moved toward the side, where a relative rotation amount is low, of a second reed 7, and an injection timing of fuel is advanced.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a fuel injection pump.

(Prior Art) In general, diesel engines have problems with combustion noise at low speeds and low loads and countermeasures against misfires at high speeds and low loads.

By the way, these problems are caused by the ignition delay characteristics of the injected fuel, but it is extremely difficult to solve these problems with conventional injection systems that match combustion performance at high speeds and high loads. It is.

(Purpose of the Invention) The present invention aims to solve the problems pointed out in the above-mentioned prior art section, and aims to reduce noise at low speeds by always performing two-stage injection when the engine is under low load, regardless of the rotational speed. This system aims to prevent misfires at high speeds, maintains conventional output performance with single-stage injection at medium and high loads, and advances the injection timing as the engine speed increases and retards the injection timing as the load increases. The purpose of this is to improve combustion performance by squaring.

(Means for Achieving the Object) As a means for achieving the above object, the present invention includes a plunger fitted into a barrel so as to be relatively slidable and relatively rotatable, and the plunger is reciprocated within the barrel. The fuel is sucked into a pressurized chamber formed on the top surface of the plunger and is fed under pressure, and the amount of fuel injection is controlled by adjusting the amount of relative rotation between the plunger and the barrel. In the injection pump, the plunger has a vertical groove on its outer peripheral surface that extends in the stroke direction on the outer peripheral surface and communicates with the top surface of the plunger, and an inclined surface facing the side opposite to the top surface of the plunger, and one end thereof a first lead communicating with the vertical groove; a second lead having an inclined surface facing the top surface of the plunger and having one end communicating with the vertical groove; and a second lead communicating with the top surface of the plunger at a position closer to the top surface of the plunger than the first lead. a stepped portion formed of a plane facing the surface side and extending parallel to the circumferential direction of the plunger; and a stepped portion located on the side opposite to the top surface of the plunger from the second lead, and one end of which extends continuously to the vertical groove, and is connected to the second lead. A third lead formed of an inclined slit extending in the same direction as the second lead and having a length shorter in the circumferential direction of the plunger than the second lead.
The barrel has a reed on its inner peripheral surface,
A main port that can selectively correspond to the first lead and the stepped portion of the plunger in the direction of the plunger rotor, and a main port that can correspond to the second lead and the third lead in the direction of the plunger stroke. In addition, in the circumferential direction of the plunger, a sub-port is provided which can accommodate the third lead only in a range where the amount of relative rotation between the plunger and the barrel is small.

(Function) In the present invention, by the above means, (1) Under low load when the amount of relative rotation between the plunger and the barrel is small, two-stage injection of fuel is realized from where the sub port corresponds to the third lead. , the ignition delay of the injected fuel is shortened. (2) Under medium and high loads, where there is a large amount of relative rotation between the plunger and the barrel, one-stage fuel injection is achieved because the sub port and the third lead do not correspond. (3) When the engine speed increases, the sub port moves to the side where the relative rotation amount between the plunger and the barrel decreases with respect to the second lead, the fuel injection timing is advanced, and the engine load is reduced. When rising, the sub port moves to the side where the amount of relative rotation increases with respect to the second lead, and the fuel injection timing is retarded.

(Example) Below, Figure 1 to Figure 1! A preferred embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIGS. 1 and 2 show the main parts of a fuel injection pump according to a first embodiment of the present invention, and in each figure, l is a plunger, and 2 is a barrel. It is.

The plunger I has, on its top surface 1a side, a second lead 7 composed of a circumferential seam of a semicircular inclined surface that slopes downward toward the plunger axis, and an annular shelf surface continuous to the second lead 7. A step portion 14 is formed. Further, at a position corresponding to the outermost edge of the second lead 7 on the side circumferential surface 1b of the plunger 1, the second lead is placed on the side circumferential surface 1b.
A vertical groove 11 extending from the lead 7 in the plunger axial direction
is formed. Further, the vertical groove 1 is formed on the side peripheral surface 1b of the plunger 1 at a position below the second lead 7.
A diagonal groove 12 is formed which communicates with the lead 1 and is inclined along the direction in which the second lead 7 is inclined. The upper edge of this oblique groove 12 serves as a first lead 6.

Further, on the outer circumferential surface Ib of the plunger l and at a position intermediate between the second lead 7 and the first lead 6, there is provided a groove that is connected to the vertical groove 11 and is inclined in the same direction as the first lead 6 and the second lead 7. A third lead 8 consisting of an extending slit is partially formed.

A large-diameter main port 4 and a small-diameter sub-port 5 are formed on the inner circumferential surface 2a of the barrel 2 so as to be appropriately spaced apart in the circumferential direction and the vertical direction.

The relative relationship between each lead 6.7.8 of this plunger 1 and each port 4.5 of the barrel 2 is schematically shown in FIG. That is, the main port 4 (indicated by reference numerals 4A and 4B in FIG. 3) is connected to the first lead 6 and The relative position with respect to the plunger l is set so as to correspond to the stepped portion 14.

On the other hand, the sub port 5 (numerals 5A and 5B in Fig. 3)
) is applicable to the 2nd lead 7 and 3rd lead 8 in the entire speed range from low speed to high speed and only at low loads, and the 3rd lead is applicable at medium and high loads. The relative position with respect to the plunger l is set so that it does not correspond to the second lead 8 but only corresponds to the second lead 7.

Furthermore, this main port 4, sub port 5 and each lead 6.7
．． 8, the main port 4 and the sub port 5 are both set at a position corresponding to low speed and low load in the circumferential direction of the plunger (low speed idle position), and the sub port 5A is set as shown in Fig. 3. The distance in the stroke direction between the main port 4A and the second lead 7 when the main port 4A is at the position just before the third lead 8, and the distance in the stroke direction between the main port 4A and the stepped portion 14 are both dimension S. , is said to be.

This dimension Sl becomes a primary stroke for pre-injecting fuel.

Further, the stroke direction interval S between the sub port 5B and the third lead 8 when the main port 4B is at the position just before the first lead 6 corresponds to a secondary stroke for main injection of fuel.

In a fuel injection pump in which the relative relationship between each port 4.5 and each lead 6, 7, 8 is set in this way, the sub port 5 can overlap with the third lead 8 only under low load. , two-stage injection is performed only at low loads, and there is no injection interruption effect by the third lead 8 at medium and high loads, so the injection amount is regulated by the communication timing between the first lead 6 and the main port 4. A normal one-stage injection is realized (see FIG. 4).

Further, the fuel injection timing is controlled as follows.

That is, at low speeds and low loads, when the load increases from low to medium or high loads (i.e., when both the main port 4 and the sub port 5 move relative to the plunger l in the right direction in the drawing) , the second lift 7 slopes downward toward the high load side, whereas the stepped portion! 4 is parallel to the circumferential direction of the plunger, the injection timing is defined by the second lead 7 and is sequentially retarded (see Fig. 4, aI>bl
> e+, at > ba > ct, as > bs).

On the other hand, when the rotational speed increases from the low speed side to the high speed side, contrary to the above, the main port 4 and the sub port 5 are connected to the plunger l.
The injection timing is determined by the second lead 7, and is sequentially advanced as the speed increases (see Fig. 4, al<al<83, bt<b
e<ba, a, <c,).

Therefore, according to the fuel injection pump of this embodiment, two-stage injection consisting of pre-injection and main injection is performed throughout the entire speed range at low load, and the ignition delay h of the injected fuel (than in the case of single-stage injection) is performed. As a result, in the low speed range, combustion noise is reduced (low noise), and in the high speed range, combustion performance is improved by reducing noise and preventing misfires at the same time.

On the other hand, during medium and high loads, single-stage injection is used, which promotes combustion and achieves high engine output.

Also, due to the polymerization between the sub port 5 and the second lead 7,
When the engine speed increases, the injection timing is automatically advanced, and when the load increases, the injection timing is automatically retarded.

(Second Embodiment) FIGS. 5 to 7 show essential parts of a fuel injection pump according to a second embodiment of the present invention. This fuel injection pump basically has three leads formed on the plunger 1, a first lead 6, a second lead 7, and a third lead 8, as in the first embodiment, and the barrel 2 has three leads. Two ports, a port 4 and a sub-port 5, are formed, and their relative relationship is somewhat similar to that of the first embodiment. That is, the first lead 6 and the stepped portion 14 are formed on the same side surface of the plunger 1 and are spaced apart in the vertical direction, and the main port 4 is provided on the barrel 2 side to accommodate them. The second lead 7 and the third lead 8 are formed on the side surface opposite to the first lead 6, and the sub-port corresponding to the second lead 7 and the third lead 8 is substantially the same as the second lead 7 and the third lead 8. 5 is also provided on the opposite side to the main port 4. Also, each of these leads 6.7.8 and each port 4.
The relative relationship with 5 is set as shown in FIG.

Of course, this embodiment also provides the same effects as those of the first embodiment.

(Third Embodiment) FIGS. 9 to 11 show main parts of a fuel injection pump according to a third embodiment of the present invention.

This embodiment is basically similar to the eleventh and second embodiments described above, in that the predetermined action and effect is obtained by the combination of the three leads 6.7.8 and the two ports 4.5. However, in this embodiment, the first lead 6 and the second lead 7 are not provided at separate positions as in each of the above embodiments, but are provided at the upper edge of a single diagonal groove 12. The lower edge portions are used as a first lead 6 and a second lead 7, respectively, and a third lead 8 is formed below the second lead 7.

This embodiment has the advantage that the structure of the plunger I is simpler than those of the above embodiments.

(Effects of the Invention) The fuel injection pump of the present invention has a plunger formed on the top surface of the plunger by fitting the plunger into the barrel so as to be relatively slidable and relatively rotatable, and reciprocating the plunger within the barrel. In a fuel injection pump that sucks fuel into a pressurizing chamber and feeds it under pressure, the injection amount of fuel is controlled by adjusting the amount of relative rotation between the plunger and the barrel. a first lead on the outer circumferential surface that extends in the stroke direction and communicates with the top surface of the plunger; and a first lead that is formed of an inclined surface facing away from the top surface of the plunger and has one end that communicates with the vertical groove; a second lead configured with an inclined surface facing the top surface of the plunger and one end of which communicates with the longitudinal groove; and a second lead facing the top surface of the plunger at a position closer to the top surface of the plunger than the first lead and parallel to the circumferential direction of the plunger. a stepped portion formed of a flat surface extending in the direction of the second lead; and a stepped portion located on the side opposite to the top surface of the plunger from the second lead, and one end of which extends back to the vertical groove and is inclined in the same direction as the inclination direction of the second lead. and a third lead formed of an inclined slit that extends and has a shorter length in the circumferential direction of the plunger than the second lead, while the barrel has the first lead of the plunger on its inner circumferential surface in the plunger stroke direction. A main port that can selectively correspond to the lead and the stepped portion; a main port that can selectively correspond to the second lead and the third lead in the plunger stroke direction; The present invention is characterized in that a sub-port is provided which can accommodate the third lead only in a range where the amount of relative rotation is small.

Therefore, according to the fuel injection pump of the present invention, (1)
Under low load, when the amount of relative rotation between the plunger and the barrel is small, two-stage injection of fuel is realized from where the sub port corresponds to the third lead, and the ignition delay of the injected fuel is shortened. (2) Plunger Under medium to high loads, where there is a large amount of relative rotation between the auxiliary port and the barrel, one-stage fuel injection is achieved because the sub-port and the third lead do not correspond. (3) When the engine speed increases, the second-stage injection The auxiliary port moves to the side where the amount of relative rotation between the plunger and the barrel decreases with respect to the reed, and the fuel injection timing is advanced, and when the engine load increases, the auxiliary port moves to the side where the relative rotation amount between the plunger and the barrel decreases. As a result, the fuel injection timing is retarded by moving to the side where the amount of movement increases, and combustion performance is improved.

[Brief explanation of drawings]

FIG. 1 is a plan view of essential parts of a fuel injection pump according to a first embodiment of the present invention, FIG. 2 is a partial cross-sectional view taken along the line nn in FIG. 1,
Figure 3 is a developed view showing the relative relationship between each lead and port of the fuel injection pump shown in Figure 1, Figure 4 is an injection rate pattern diagram of the fuel injection pump shown in Figure 1, and Figure 5 is A plan view of essential parts of a fuel injection pump according to a second embodiment of the present invention, FIG. 6 is a partial cross-sectional view taken along the line Vl-Vl in FIG. 5, and FIG. 7 is a partial cross-sectional view taken along 8 is a developed view showing the relative relationship between each lead and each port of the fuel injection pump shown in FIG. 5, and FIG. 9 is a fuel injection pump according to a third embodiment of the present invention. Fig. 10 is a partial cross-sectional view taken along the line x-X in Fig. 9, and Fig. 11 is an expanded view showing the relative relationship between each lead and each port of the fuel injection pump shown in Fig. 9. It is a diagram. l... Plunger 2... e Barrel 3... Pressurized chamber 4... Main port 5... Sub port 6... First lead 7. ...Second lead 8...φ・Third lead 11...Vertical groove 12...Oblique groove 14...Step low (1 load 1 load C''1 load +-- 1 At medium speed 1 --- Volume appropriate time sub port 1 - Port 18 moving barrel movement range Fig. 4 J port Sub port movement range Movement range AQ - Fig. 11

Claims (1)

[Claims] 1. Formed on the plunger top surface (1a) by fitting the plunger (1) into the barrel (2) so as to allow relative sliding and relative rotation, and reciprocating the plunger (1) within the barrel (2). The plunger (1) sucks fuel into the pressurized chamber (3) and feeds it under pressure.
) and a barrel (2) to control the amount of fuel injection, the plunger (1) has an outer circumferential surface (1b) on its outer circumferential surface (1b). 1b) Consists of a vertical groove (11) extending in the stroke direction on the top and communicating with the plunger top surface (1a), and an inclined surface facing the side opposite to the plunger top surface (1a), one end of which is connected to the vertical groove (11). a first lead (6) communicating with the plunger; a second lead (7) comprising an inclined surface facing the top surface of the plunger and having one end communicating with the vertical groove (11); and the first lead (6). a step portion (14) formed of a plane facing the top surface of the plunger at a position closer to the top surface (1a) of the plunger and extending parallel to the circumferential direction of the plunger;
It is located on the side opposite to the plunger top surface (1a) from the lead (7), and one end thereof runs back to the vertical groove (11) and extends in an inclined direction in the same direction as the inclined direction of the second lead (7). and a third lead (8) comprising an inclined slit having a length shorter in the circumferential direction of the plunger than the second lead (7).
The barrel (2) has an inner circumferential surface (2a
) above, the first lead (6) of the plunger (1) and the stepped portion (14) in the plunger stroke direction.
The main port (4) can selectively correspond to the second lead (7) and the third lead (8) in the plunger stroke direction, and can correspond to the plunger in the plunger circumferential direction. (1) and an auxiliary port (5) that is compatible with the third lead (8) only within a small range of relative rotation with the barrel (2). pump.