JPH08232794A - Distribution type fuel injection pump - Google Patents

Abstract

PURPOSE: To enable an engine to quickly stop after stopping fuel supply thereto as well as to increase a fuel sucking quantity into a pressure chamber. CONSTITUTION: Two fuel sucking holes 32 for communicating a communicating part 21 formed on the outer wall part of a plunger barrel 20 with a barrel inside hole 20a are formed in both end positions in an angular range of the communicating part 21 and always communicating with each other through the communicating part 21. Each fuel sucking hole 32 comprises a sucking port 33 and a sucking slit 34 and a volume reducing member 30 is received in each sucking port 33. Each fuel through hole 31 formed in the volume reducing member 30 continues to the communication part 21 and the sucking slit 34. Since the fuel is sucked into a pressure chamber from two fuel sucking holes 32, the fuel sucking quantity is increased. Furthermore, since the volume of the sucking port 33 is reduced by means of the volume reducing member 30 and the fuel quantity sucked into the pressure chamber becomes small after a fuel sucking-in passage is blocked, the engine stops quickly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed fuel injection pump for an internal combustion engine (hereinafter referred to as "engine").

[0002]

2. Description of the Related Art A conventional distributed fuel injection pump for a diesel engine, which pumps and distributes fuel by reciprocating and rotating movements of a plunger, is provided with a fuel suction hole in a plunger barrel that slidably supports the plunger. It is common to draw fuel from the pump chamber into the pressure chamber through a hole. The fuel suction hole includes a suction port formed on the outer peripheral side of the plunger barrel and a suction slit formed on the inner peripheral side of the plunger barrel and having a smaller flow passage cross-sectional area than the suction port. For example, in a distributed fuel injection pump that supplies fuel to each cylinder of a multi-cylinder engine such as a 6-cylinder engine, it is necessary to suck the fuel 6 times in one revolution of the plunger, so the pressure is increased in each fuel intake stroke. It is required to reliably inhale the required amount of fuel into the chamber. Therefore, it is considered that a plurality of fuel suction holes are formed and the fuel suction holes are communicated with the outer wall portion of the plunger barrel to increase the fuel suction amount from the pump chamber to the pressure chamber.

However, when a plurality of fuel intake holes are formed, the sum of the volumes of the intake ports becomes large. Therefore, even if the fuel intake passage is cut off on the pump chamber side of the fuel intake hole to stop the engine, the fuel intake passage will be connected to the intake port. The filled fuel may be pumped and supplied to the injector, and the engine may not stop immediately. In order to solve such a problem, in the fuel injection pump disclosed in Japanese Utility Model Laid-Open No. 1-80663, the suction port has a vertical length of 2 mm.
By making the ellipse about twice as long and making the suction slit along the suction port longer, the cross-sectional area of the fuel flow passage is increased and the amount of fuel suctioned into the pressure chamber is increased while suppressing the increase in volume of the suction port. . The structure of such a fuel injection pump is illustrated in FIG.

As shown in FIG. 6A, the plunger 1
01 is supported by the plunger barrel 100 so as to be rotatable and reciprocally movable in the axial direction, and the fuel suction groove 102 corresponding to the number of cylinders of the engine is formed in the outer wall portion. Fuel suction hole 1 formed in plunger barrel 100
03 is the suction port 103a and the suction slit 103
It consists of b. As shown in FIG. 6B, the suction port 1
The cross-sectional shape of 03a is an elliptical shape, and the suction slit 10
3b is formed in a square hole shape along the longitudinal direction of the suction port 103a. For this reason, the suction port 103a is different from the circular suction port that can form the suction slit 103b.
Since the volume of the engine can be reduced, the stopping performance of the engine can be improved. In addition, the suction slit 103
Since the opening area of b increases, the amount of fuel filled in the pressure chamber increases.

[0005]

[Problems to be Solved by the Invention] However, the actual Kaihei 1-8
In the fuel injection pump disclosed in Japanese Patent No. 0663,
Since the length of the suction slit is limited due to the regulation of the body size of the plunger, it is not possible to expect a large increase in the fuel suction amount.
The present invention has been made to solve such a problem, and provides a distributed fuel injection pump that increases the amount of fuel sucked into a pressure chamber and stops the engine promptly after stopping the fuel supply. The purpose is to

[0006]

A distribution type fuel injection pump according to claim 1 of the present invention for achieving the above object, is a distribution type which pumps and distributes fuel in a pressure chamber by reciprocating movement and rotational movement of a plunger. A fuel injection pump, comprising a plurality of suction grooves formed at equal intervals in the circumferential direction of the outer wall portion for sucking fuel into the pressure chamber, and a plunger having a distribution port for distributing the fuel in the pressure chamber, A guide hole for accommodating the plunger so that the plunger can reciprocate and rotate.
A plurality of fuel suction holes, which communicate with the guide hole and are formed in the circumferential direction for sucking fuel from the pump chamber to the suction groove, and a communication portion which communicates the plurality of fuel suction holes with each other at the outer wall portion. And a volume reducing member housed in the fuel suction hole and having a suction through hole capable of sucking fuel from the pump chamber into the suction groove, the fuel suction hole communicating with the communication portion. An outer suction hole for accommodating the volume reducing member, and an inner suction hole which is formed so as to communicate with the guide hole radially inward from the outer suction hole and has a smaller flow passage cross-sectional area than the outer suction hole. The suction hole is communicated with the inner suction hole.

A distribution type fuel injection pump according to a second aspect of the present invention is the distribution type fuel injection pump according to the first aspect, characterized in that the suction through hole has a larger sectional shape than the inner suction hole. To do. A distribution-type fuel injection pump according to a third aspect of the present invention is the distribution-type fuel injection pump according to the first or second aspect, wherein the suction through-hole and the inner suction hole are in the shape of an elongated hole. It is characterized by being.

[0008]

According to the distribution type fuel injection pump of the first aspect of the present invention, a plurality of fuel suction holes each having an outer suction hole and an inner suction hole having a flow passage cross-sectional area smaller than that of the outer suction hole are provided. Since the plunger barrel is formed, a large amount of fuel can be simultaneously sucked into the pressure chamber from the plurality of fuel suction holes through the suction groove formed in the outer wall portion of the plunger. Further, by accommodating the volume reducing member in the outer suction hole,
Since the amount of fuel filled in the outer suction hole is reduced, the engine stops immediately when the fuel suction passage on the pump chamber side of the fuel suction hole is shut off for the purpose of stopping the engine.

According to the distribution type fuel injection pump of the second aspect of the present invention, since the cross-sectional shape of the suction through hole is larger than that of the inner suction hole, even if a processing error occurs in the inner suction hole or the suction through hole. Fuel can be satisfactorily sucked into the pressure chamber through the inner suction hole and the suction passage. According to the distribution type fuel injection pump of the third aspect of the present invention, by making the cross-sectional shapes of the flow passages of the suction through hole and the inner suction hole of the volume reducing member the same shape as the elongated holes extending in the axial direction, the respective inner suction ports are formed. The amount of fuel sucked into the pressure chamber through the hole can be increased.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 shows an embodiment in which the present invention is applied to a fuel injection pump for a 6-cylinder engine. A drive shaft 3 is rotatably supported in a housing 2 of the fuel injection pump 1. A face cam 4 is connected to the drive shaft 3 and rotates together with the drive shaft 3. The face cam 4 has a large number of cams 5 that cooperate with rollers (not shown). When the cams 5 ride on the rollers, they reciprocate in the axial direction. The vane-type feed pump 6 is driven by the drive shaft 3 to supply low-pressure fuel to the pump chamber 7
Supply to. The number of cams 5, that is, the number of strokes per rotation corresponds to the number of cylinders of an engine (not shown).

The plunger 10 includes a plunger barrel 20.
It is housed in the barrel inner hole 20a, which is a guide hole of the, and rotates with the face cam 4 and reciprocates in the axial direction. The plunger barrel 20 is fixed to the head 8, and the closing member 9 screwed to the head 8 is in contact with the end of the plunger barrel 20. The pressure chamber 11 formed on the closing member 9 side of the plunger 10 can be adjusted in volume by a stopper 29 screwed to the closing member 9. The plunger 10 is formed with a bag hole 13 communicating with the pressure chamber and a lateral hole 16 communicating with the bag hole 13 and the pump chamber 7. Side hole 1
6 cooperates with a staggerable spill ring 17 on the plunger 10. The spill ring 17 defines the position of the plunger 10 in which the lateral hole 16 and the pump chamber 7 communicate with each other when the plunger 10 moves in the B direction in FIG. When the lateral hole 16 and the pump chamber 7 communicate with each other during the fuel pressure-feeding process, the high-pressure fuel in the pressure chamber 11 overflows into the pump chamber 7, so that the pressure-feeding process ends. By adjusting the position of the spill ring 17, the amount of fuel actually injected can be changed.

Further, on the outer wall of the plunger 10, suction grooves 12 are formed in the end portion on the pressure chamber 11 side at equal intervals of 60 ° in the circumferential direction according to the number of cylinders of the engine, and an angle is formed in the circumferential direction with the suction grooves 12. Distributing port 1 with the same number formed by shifting
4. One pressure equalizing groove 15 is formed which can communicate the distribution passage 24 and the pump chamber 7. In the plunger barrel 20, a fuel suction hole 32 capable of sucking fuel into the suction groove 12,
A distribution passage 24 that can communicate with the distribution port 14 is formed through the side wall of the plunger barrel 20.

The solenoid valve 40 is arranged in the head 8 so as to be able to connect and disconnect the suction passage 23. As shown in the figure, when the ignition switch is turned on, energization to a coil (not shown) is turned on, and when the ignition switch is turned off, energization to the coil is turned off. When the coil is not energized, the valve member 41 is urged in the valve closing direction by the urging force of a compression coil spring (not shown) to close the suction passage 23, and when the coil is energized, the valve member 41 is generated in the coil. The suction passage 23 communicates with the fuel suction hole 32 by being attracted by the magnetic force in the valve opening direction.

The delivery valve 50 is circumferentially attached to the end portion of the head 8 in accordance with the number of cylinders of the engine, and the fuel supplied from the distribution passage 24 through the distribution passage 25 is attached to each cylinder of the engine. Supply to. Plunger 10 and plunger barrel 20
The fuel intake structure will be described in more detail with reference to FIGS. 1, 2 and 3.

As shown in FIGS. 1A and 2, the outer wall portion of the plunger barrel 20 is formed with a communicating portion 21 which is a groove in a predetermined angle range along the outer periphery thereof. Fuel suction hole 3 that communicates the communication part 21 and the barrel inner hole 20a
Two 2 are formed at both ends of the angular range of the communication portion 21,
The communication parts 21 are always in communication with each other. The fuel suction holes 32 are formed at positions that can match circumferentially with a pair of adjacent suction grooves 12 of the suction grooves 12 formed at intervals of 60 ° on the outer peripheral wall of the plunger 10. This is to reduce the angular range of the communication portion 21 as much as possible and reduce the amount of fuel filled in the communication portion 21. Fuel intake hole 3
Reference numeral 2 designates an intake port 33 and an intake port 3 which are outside intake holes.
3 and the suction slit 34 which is an inner suction hole having a smaller flow passage cross-sectional area. The suction port 33 communicates with the communication portion 21, and the suction slit 34 communicates with the barrel inner hole 20a. The suction slit 34 is formed in a rectangular long hole shape as shown in FIG. 1B, and a pair of adjacent suction grooves 12 are formed in the suction groove 12 formed at intervals of 60 ° on the outer peripheral wall of the plunger 10. It is possible to communicate with the suction groove 12.

The volume reducing member 30 is the plunger barrel 20.
It is formed in a cylindrical shape separately from and is inserted into the suction port 33. The volume reducing member 30 is formed with an elongated suction hole 31 having substantially the same shape as the suction slit 34 so as to penetrate in the axial direction. As can be seen by comparing (B) and (C) of FIG. 1, the suction through hole 31 is formed in a sectional shape so as to cover the suction slit 34 and slightly larger than the suction slit 34. This is because even if a processing error occurs in the suction through hole 31 or the suction slit 34, the suction through hole 3
This is for ensuring the communication between 1 and the suction slit 34.
In the present invention, the volume reducing member 30 can also be attached to the plunger barrel 20 by press fitting, caulking or bonding. The reason why the volume reducing member 30 is formed separately from the plunger barrel 20 will be described below.

The plunger barrel 20 is made of a material having a high hardness in order to support the plunger 10 in a rotatable and reciprocating manner. To directly form a rectangular oblong suction hole in the plunger barrel 20, it is necessary to perform electric discharge machining or long-time cutting, so that the machining cost is significantly increased. When the volume reducing member 30 is formed separately from the plunger barrel 20, the material of the volume reducing member 30 does not require the hardness as high as the material forming the plunger barrel 20, so that before the volume reducing member 30 is assembled to the plunger barrel 20. Further, the suction through hole 31 can be easily processed by cutting, molding, sintering, or the like.

Next, the operation of the fuel injection pump 1 will be described. The ignition switch is in the ON state, and the suction passage 23 and the communication portion 21 communicate with each other. (1) Intake stroke When the plunger 10 moves in the direction A of FIG. 5 and the positions of the suction slit 34 and the suction groove 12 coincide with each other as shown in FIG. 1 (A), the pump chamber 7, the suction passage 23, Fuel is sucked into the pressure chamber 11 through the suction groove 12. At this time,
Since the two suction slits 34 communicate with the respective two suction grooves 12 and the fuel is sucked into the pressure chamber 11, a large amount of fuel can be sucked into the pressure chamber 11.

(2) Pressure-feeding stroke When the plunger 10 is rotated more than in FIG. 1A, the suction slit 34 is closed by the outer wall of the plunger 10.
When the cam 5 of the face cam 4 rides on the roller, the plunger 10 moves in the direction B of FIG. 5, and the fuel in the pressure chamber 11 is pressurized. When the plunger 10 further rotates, the distribution port 14 communicates with one distribution passage 24. Then, when the fuel pressure in the pressure chamber 11 becomes equal to or higher than a predetermined pressure, one of the delivery valves 50 opens, and the delivery valve 50 passes from the delivery valve 50 to the injector via the pressure chamber 11, the bag hole 13, the distribution port 14, the distribution passage 24, and the distribution passage 25. Fuel is supplied.

(3) Process of ending pressure feeding When the plunger 10 further moves in the direction B in FIG. 5, the opening of the lateral hole 16 is disengaged from the spill ring 17 and the lateral hole 16 and the pump chamber 7 communicate with each other. Then, the high-pressure fuel in the pressure chamber 11 overflows into the pump chamber 7 and the fuel pressure in the pressure chamber 11 decreases, so that the delivery valve 50 closes and the pressure feeding process ends. When the plunger 10 further rotates, the distribution passage 24 and the pump chamber 7 communicate with each other through the pressure equalizing groove 15, so that the distribution passages 24 and 25 formed on the fuel upstream side of the delivery valve 50 become equal to the fuel pressure in the pump chamber 7. . Then, the plunger 10 starts moving again in the direction A of FIG. 5, and shifts to the suction stroke (1).

Above, (1) suction stroke, (2) pressure stroke, (3)
By repeating the pressure feeding end process, the fuel can be satisfactorily supplied to the injector attached to each cylinder of the engine. When the ignition switch is turned off, the coil of the solenoid valve 40 is de-energized so that the valve member 41 is urged in the valve closing direction by the urging force of the compression coil spring to close the suction passage 23. Inhalation port 33
The volume reduction member 30 accommodated in the suction port 3
Since the volume of 3 is reduced by the volume of the substantial portion of the volume reducing member 30, the amount of fuel filled from the closed position of the intake passage 23 by the valve member 41 to the intake slit 34 is small. Therefore, after the suction passage 23 is closed, the amount of fuel sucked into the pressure chamber 11 is also reduced, so that the engine stops quickly.

A modification of the volume reducing member of this embodiment is shown in FIG. The suction through hole 61 has a circular cross section and is formed through the volume reducing member 60 in the axial direction. The plunger side of the suction passage hole 61 has a diameter larger than that of the communication portion side in order to cover the cross-sectional area of the long-hole-shaped suction slit. Intake hole 61
Since the cross-sectional shape of (1) is circular, the volume is larger than that of the above-mentioned embodiment, but the processing of the suction through hole is further facilitated.

The example in which the fuel injection pump of the present invention is applied to a fuel injection pump for supplying fuel to a 6-cylinder engine has been described above. When the present invention is applied to a 6-cylinder engine having a large number of cylinders, in addition to being able to suck the required amount of fuel into the pressure chambers in each suction stroke, the angular spacing of the suction grooves formed on the outer wall of the plunger becomes small, and the fuel suction holes are reduced. Since the volume of the communication portion that communicates with each other is reduced, the engine can be stopped more quickly than when the present invention is applied to an engine with a small number of cylinders.

Further, in the present embodiment and the modified example, only two fuel suction holes are formed at the positions corresponding to the adjacent suction grooves, but in the present invention, the number of cylinders of the engine is increased by expanding the range of the angle of formation of the communicating portion. It is also possible to form the fuel suction holes at even intervals. Further, in the present embodiment and the modified example, the suction port is formed in a circular cross section, and the volume reducing member is formed in a cylindrical shape that can be accommodated in the suction port.However, in the present invention, the suction port is formed in a polygonal cross section and the volume is reduced. By forming the reducing member in the shape of a hollow prism that can be accommodated in the suction port, the volume reducing member can be prevented from rotating without fixing the volume reducing member to the plunger barrel, and the suction through hole and the suction slit can be easily aligned. It is also possible to do so. In the present invention, it is possible to provide the volume reducing member and the plunger barrel with a fitting portion that defines the circumferential position and prevents the rotation of the volume reducing member.

[Brief description of drawings]

FIG. 1A is a sectional view taken along line I-I of FIG. 5 showing an embodiment of a distributed fuel injection pump of the present invention, and FIG. 1B is a sectional view taken along line BB of FIG. , (C) is C- of (A)
It is a C line sectional view.

FIG. 2 is a view on arrow II in FIG. 1 (A).

FIG. 3 is a perspective view showing a volume reducing member of the present embodiment.

FIG. 4 is a perspective view showing a modified example of the volume reducing member.

FIG. 5 is a sectional view showing an embodiment of the distributed fuel injection pump of the present invention.

FIG. 6A is a sectional view of a main part of a conventional distributed fuel injection pump, and FIG. 6B is a view in the direction B of FIG.

[Explanation of symbols]

 1 Fuel Injection Pump 10 Plunger 11 Pressure Chamber 12 Suction Groove 14 Distribution Port 20 Plunger Barrel 20a Guide Hole 21 Communication Portion 30 Volume Reduction Member 31 Suction Through Hole 32 Fuel Suction Hole 33 Suction Port (Outside Suction Hole) 34 Suction Slit (Inside Suction) Hole)

Claims (3)

[Claims] 1. A distribution type fuel injection pump that pumps and distributes fuel in a pressure chamber by reciprocating movement and rotational movement of a plunger, the fuel injection pump being formed at equal intervals in a circumferential direction of an outer wall portion for sucking the fuel into the pressure chamber. A plurality of suction grooves, and a plunger having a distribution port for distributing the fuel in the pressure chamber, a guide hole for accommodating the plunger in a reciprocating and rotationally movable manner, and a guide hole communicating with the guide hole and from the pump chamber. A plurality of fuel suction holes circumferentially formed for sucking fuel into the suction groove, and a plunger barrel having a communication portion that communicates the plurality of fuel suction holes with each other at an outer wall portion; and the fuel suction hole A volume reducing member that is accommodated and has a suction through hole capable of sucking fuel from the pump chamber into the suction groove, the fuel suction hole communicating with the communication portion, An outer suction hole for accommodating a member, and an inner suction hole formed so as to communicate with the guide hole radially inward from the outer suction hole and having a smaller flow passage cross-sectional area than the outer suction hole. A distribution type fuel injection pump characterized in that the suction passage communicates with an inner suction hole. 2. The distributed fuel injection pump according to claim 1, wherein the suction through hole has a larger sectional shape than the inner suction hole. 3. The distribution type fuel injection pump according to claim 1, wherein the suction through hole and the inner suction hole have an elongated hole shape having the same shape.