JPS6226370A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To improve injection performance during high speed revolution by using, in addition to a first pressurizing chamber, a second pressurizing chamber and by introducing fuel pressurized in the second pressurizing chamber during the stroke of pressurized feed of fuel in the first pressurizing chamber into a separately formed cylinder chamber. CONSTITUTION:A barrel 6 is of a two-stepped shape consisting of a smaller diameter section 61 and a greater diameter section 62. A first pressurizing chamber 9 is formed by the smaller diameter section 61 and a plunger 7 tip. A second pressurizing chamber 10 is formed by the greater diameter section 62 and the tip of the base section of the plunger 7. While the first pressurizing chamber 9 is in pressure-feed stroke, fuel oil in the second pressurizing chamber 10 is pressurized and stored in a cylinder chamber 141. During the suction stroke of the first pressurizing chamber 9, pressurized fuel in the cylinder chamber 141 is introduced into the first pressurizing chamber 9, while fuel in a pump chamber 4 is introduced into the second pressurizing chamber 10. As a result, adequate fuel can be introduced into pressurizing chambers even when the plunger is driven at high revolutions.

Description

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

(Prior Art) A fuel injection pump is configured to suck fuel in a pump chamber into a pressurizing chamber while a suction groove provided in a plunger communicates with a suction hole provided in a barrel. For this reason, when the rotational speed of the plunger increases, the period during which the suction groove and the suction hole communicate with each other, that is, the suction period, becomes insufficient, resulting in an insufficient suction amount, which has a negative effect on injection performance.

To this end, it is possible to raise the set pressure of the feed pump to increase the fuel pressure in the pump chamber and to draw all the fuel into the pressurizing chamber in a short period of time, but due to the structure of current feed pumps, this measure is not effective. You can't expect good results.

(Object of the Invention) The present invention has been made in view of the above, and an object of the present invention is to provide a fuel injection pump that can sufficiently introduce fuel into a pressurizing chamber even when the plunger is driven to rotate at high speed.

(Summary of the Invention) A step consisting of a small diameter portion and a large diameter portion following the small diameter portion, and a stage that rotates and reciprocates in accordance with the rotational speed of the engine output shaft, is installed in a sealing hole at one end in which the end of the small diameter portion is sealed. In addition to a first pressurizing chamber formed by the tip of the small diameter portion of the plunger and the end face of the one end sealing hole, a plunger with an attached shape is fitted in a fluid-tight manner. A second pressurizing chamber is provided between the piston and the piston, which is fluid-tightly inserted into the hollow hole, and one end surface of the hollow hole and the piston. A spring is provided on the other end surface of the hollow hole, and during the process of pressurizing and distributing fuel in the first pressurizing chamber, the fuel pressurized in the second pressurizing chamber is transferred to the hollow hole. into a cylinder chamber formed by the other end surface of the cylinder and the piston, pressurizes the cylinder chamber and introduces the fuel into the first pressurization chamber during a fuel suction stroke into the first pressurization chamber. The fuel pump is configured to introduce fuel in the pump chamber into the second pressurizing chamber.

In order to keep this in mind, the pressurized fuel that has been pressurized by the plunger in the second pressurization chamber and stored in the cylinder chamber is introduced into the first pressurization chamber. Since the pressure of the pressurized fuel can be maintained regardless of the fuel pressure in the pump chamber, the first pressurized chamber is sufficiently filled in a short period of time even if the rotational speed of the plunger increases.

(Example of the invention) The present invention will be explained below with reference to Examples.

FIG. 1 is a sectional view showing the configuration of an embodiment of the present invention.

Fuel oil in the fuel tank is fed into a pump chamber 4 in a bonder housing 3 by a feed pump 2 driven by an engine via a drive shaft l. A regulating pulp 5 is provided between the suction side and the discharge side of the feed pump 2, and the regulating pulp 5 controls the pump chamber 4.
The fuel oil pressure inside the engine is made to respond to the engine output shaft rotational speed.

A barrel 6 attached to the pump housing 3 is fitted with a plunger 7 for pumping and distributing purposes.

The barrel 6 is formed into a two-stage shape consisting of a small inner diameter section 61 and a large inner diameter section 62 . Similarly, the plunger 7 is formed in a two-stage shape, consisting of a small diameter portion 71 on the tip side and a large diameter portion 72 on the base side. Here, the small inner diameter portion 61 of the barrel 6
and the small diameter portion 71 of the plunger 7 are the same as in the case of a conventional fuel injection pump. 8 is revealed.

This is a bolt that seals the tip of the bolt 6. A first pressurizing chamber 9 is formed between the small diameter portion 61 of the barrel 6 and the tip of the plunger 7, and a second pressurizing chamber 9 is formed between the large diameter portion 62 of the barrel 6 and the base tip of the plunger 7. A pressurized chamber 10 is formed.

As shown in FIG. 2(a), suction grooves 11 are formed at the tip of the base of the plunger 7 at equal intervals in the circumferential direction according to the number of cylinders of the internal combustion engine. A suction hole 12 is provided through the pump housing 3 and the barrel 6 to guide fuel oil in the pump chamber 4 to the second pressurizing chamber 10 via a suction groove 11. On the other hand, at the tip of the small diameter portion 71 of the plunger 7, as shown in FIG. 2(b), suction grooves 13 are similarly formed at equal intervals in the circumferential direction according to the number of cylinders of the internal combustion engine.

On the other hand, a hole 14 forming a cylinder is formed in the pump housing 3, and a piston 15 is fitted in the hole 14 in an oil-tight manner. Furthermore, one cylinder chamber 141 and a second pressurizing chamber 10 are formed by the hole 14 and the piston 15, passing through the barrel 6 and the pump housing 3.
A communication hole 16 selectively communicates with the suction groove 11 through the suction groove 11.
A communication hole 17 for selectively communicating one cylinder chamber 141 and the first pressurizing chamber 9 via the suction groove 13 is formed. The hole 14 is communicated with the pump chamber 4 through a communication hole 18, and the other cylinder chamber formed by the hole 14 and the piston 15 has a spring 19 that biases the piston 15 toward the one cylinder chamber 141. This is an insert.

Cam disc 20 fixed to the rear end of the base of the plunger 7
and the drive shaft 1 are coupled in the rotational direction via a driving disk (not shown). Further, the cam disk 20 is formed with a cam surface having ridges corresponding to the number of cylinders of the internal combustion engine. This cam surface is brought into pressure contact with a roller 23 of a roller holder 22 held by a timer piston 21 by a plunger spring (not shown).

Therefore, while the plunger 7 rotates for distribution as the drive shaft 1 rotates, the plunger 7 sucks in fuel by the rolling guidance action of the cam surface of the cam disk 20 and the roller 23.
Performs reciprocating motion for pressure feeding.

Now, when the plunger 7 is in the suction stroke moving leftward in FIG. 1, the communication hole 17 communicates with one of the suction grooves 13, and the fuel oil stored in one cylinder chamber 141 during the previous pressure feeding is introduced into the first pressurizing chamber 9, and the first pressurizing chamber 9 is filled. At the same time, the suction hole 12 communicates with one of the suction grooves 11, and the fuel oil in the pump chamber 4 is introduced into the second pressurizing chamber 10, and the fuel oil in the pump chamber 4 fills the second pressurizing chamber 10. be done. At this time, the communication hole 16 is closed by the plunger 7.

Next, when the plunger 7 moves to the rightward in the pressure feeding stroke, the suction groove 13 is closed by the barrel 6, and while the fuel oil in the first pressurizing chamber 9 is pressurized, the axial hole 24, The fuel is fed under pressure to a fuel injection valve provided in each cylinder via a distribution groove 25, a pressure feeding passage 26, and a delivery pulp 27 communicating with the axial hole 24, and is injected. Since the pressure passages 26 are arranged at equal intervals in the circumferential direction according to the number of cylinders of the internal combustion engine, as the plunger 7 rotates and reciprocates, fuel oil can be sequentially pressure-fed to each fuel injection valve in a fixed order. become. At the same time, in the pressure feeding stroke, the fuel oil filled in the second pressurizing chamber 10 is pressurized in the suction stroke, and the communication hole 16 is connected to one of the suction grooves 11.
The fuel oil pressurized in the second pressurizing chamber 10 communicates with the two cylinders and flows into one cylinder chamber 141 through the communication hole 16 by pushing down the piston 15 against the force of the spring 19.
It is stored in the chamber 141. Note that at this time, the communication hole 17 is closed by the plunger 7. In this case, the amount of fuel oil stored in the cylinder chamber 141 is [piston area x piston displacement amount]. Moreover, the pressure of this stored fuel oil is determined by the spring force of the spring 19,
It is in a pressurized state exceeding the pressure of the fuel oil in the pump chamber 4. This pressurized fuel oil in one cylinder chamber 141 will be filled into the first pressurized chamber via the suction groove 13 in the next suction stroke, and this filling period will be short.

Note that in FIG. 2, arrow A indicates the direction of rotation of the plunger 7.

FIG. 3 schematically shows the suction groove, communication hole, and piston displacement in the suction and pressure strokes in correspondence to the rotation angle of the cam disk of the cam 20. In FIG. 3, (a) shows the fuel oil passage area (hereinafter simply referred to as passage area) on the plunger side of the pressure feeding passage 26, (b) shows the passage area of the communication hole 17, and (C) shows the passage area of the piston 15. (d) shows the passage area of the communication hole 16, (e) shows the passage area of the suction hole 12, and (f) shows the cam lift. The horizontal axis is the cam disk rotation angle. In FIG. 3, T1 indicates the start of the suction stroke, and T2 indicates the start of the pumping stroke.

The control sleeve 28 inserted into the proximal side of the plunger 7 has a cut-off port 29 communicating with the axial hole 24.
When the cut-off boat 29 comes off the end face of the control sleeve 28 and opens into the pump chamber 4 as the plunger 7 reciprocates and opens and closes, the injection in one stroke ends.

In addition, in one embodiment of the present invention described above, the suction hole 1
2 is provided as an example, but by providing a plurality of them as shown by the broken line in FIG. 2(a) and increasing the passage area of the suction hole 12, the fuel oil pressure in the pump chamber 4 can be reduced. Also, the second pressurizing chamber 10 can be filled with fuel oil more reliably even if the rotational speed of the plunger 7 is higher.

``Furthermore, filling the first pressurizing chamber 9 with fuel oil can be done by filling according to the embodiment of the present invention described above, or by directly filling the first pressurizing chamber 9 with the fuel oil in the pump chamber 4. It is also possible to use it in combination with conventional filling, and in this case, inhalation can be performed more reliably.

(Effects of the Invention) As explained above, according to the present invention, a second pressurizing chamber is provided in addition to the first pressurizing chamber, and the fuel filled in the second pressurizing chamber is fed during the pressure feeding and distribution process. The fuel is pressurized by the plunger and stored in the cylinder chamber, and during the suction stroke, the pressurized fuel stored in the cylinder chamber is introduced into the first pressurization chamber and is filled into the first pressurization chamber. Further, the pressurized fuel stored in the cylinder chamber can be set to a high pressure regardless of the fuel pressure in the pump chamber. Therefore, even if the rotational speed of the plunger increases, the first pressurizing chamber is filled with fuel in a short time, and the conventional drawbacks are solved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an embodiment of the present invention. FIGS. 2(a) and 2(b) are a sectional view taken along the line 1-1 of FIG. 1 and a cross-sectional view of the seal portion. FIG. 3 is a diagram for explaining the operation of one embodiment of the present invention. 6... Barrel, 61... Small inner diameter part, 62... Large inner diameter part, 7... Plunger, 71... Small diameter part, 7
2... Large diameter part, 9... First pressurizing chamber, 10... Second pressurizing chamber, 11 and 13... Suction groove, 12... Suction hole, 14... Hole, 14,... One cylinder chamber, 16 and 17... Communication hole, 15... Piston,
19...Spring. Patent applicant: Diesel Kiki Co., Ltd. Agent Patent attorney: Nobuo Sunako Figure 1 Figure 2 (a)

Claims (3)

[Claims] (1) In a fuel injection pump, the pump is composed of a small diameter part and a large diameter part following the small diameter part, and is fluid-tightly fitted into a sealing hole at one end of which the end of the small diameter part is sealed, and the rotation speed of the engine output shaft. a stepped plunger that rotates and reciprocates as the cylinder moves; a piston that is fluid-tightly fitted in a hollow hole that forms a cylinder; and a piston that is inserted between one end surface of the hollow hole and the piston; A spring that biases the piston toward the other end surface of the hollow hole, and a first pressurized chamber formed between the sealed end surface of the one end sealed hole and the tip of the plunger, and the fuel filled in the first pressurized chamber is fed under pressure. During the distribution stroke, the fuel pressurized in a second pressurizing chamber formed between the step end surface of the one end sealing hole and the step end surface of the plunger is transferred to the other end surface of the hollow hole and the piston. and a first introducing means for introducing pressurized fuel in the cylinder chamber into the first pressurizing chamber during a fuel suction stroke into the first pressurizing chamber. and second introducing means for introducing fuel in the pump chamber into the second pressurizing chamber. (2) The second introducing means is provided in number corresponding to the number of engine cylinders on the tip side of the large diameter part of the plunger, and is connected to a first suction groove that communicates with the second pressurizing chamber, and a first suction groove that communicates with the second pressurizing chamber. A suction hole that selectively guides the fuel in the pump chamber through the first suction groove, and a second suction hole that is provided in number corresponding to the number of engine cylinders on the tip side of the small diameter portion of the plunger and communicates with the first pressurizing chamber. Claim 1, further comprising a suction groove and a first communication hole that communicates one of the second suction grooves with the cylinder chamber as the plunger rotates. fuel injection pump. (3) The first introduction means is a second communication hole that communicates one of the first suction grooves with the cylinder chamber as the plunger rotates. fuel injection pump.