JPH032700Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a distribution type fuel injection pump for an internal combustion engine, and more particularly to a distribution type fuel injection pump equipped with a servo timer.

(Technical background of the invention and its problems) A distribution type fuel injection pump that injects fuel to a diesel engine has a configuration as shown in FIG. 1, for example, and is installed through the rear part of the pump housing 1. A feed pump 3 consisting of a vane pump is attached to the drive shaft 2 connected to the output shaft of an engine (not shown).
A rotor 4 is fitted therein. The fuel pumped up by the pump 5 is passed through the filter 6 to the rotor 4.
Fuel is supplied through a passage 7 formed in the pump housing 1 and pressurized by vanes (not shown) engaged with the rotor 4, that is, fuel at a pressure related to the engine speed is supplied to the housing of the feed pump 3. The pump chamber 11 in the pump housing 1 is supplied through a through hole 10 formed in a cover member 9 which also serves as a part of the pump housing 1 .

A flange 13 in which a plurality of pawls 12 are formed is integrally provided at the right end of the drive shaft 2, and the pawls 12 are formed in a plurality of notch grooves 1 formed in the middle plate 14.
5, the intermediate plate 14 is further formed with a plurality of other cutout grooves 16 (only one is shown), in which a plurality of pawls 19 of a cam disk 18 fixed to the plunger 17 are formed. (Only one 9 shown) is engaged.

With this configuration, the relative position of the cam disk 18 and therefore the plunger 17 with respect to the drive shaft 2 is always constant in the rotational direction, that is, in the circumferential direction, but is made to be displaced in the axial direction.

Furthermore, a plurality of rollers 2 are provided on the outer periphery of the intermediate plate 14.
0 (only one is shown) and is allowed to rotate through a limited angle.A roller holder 21 is provided concentrically with the drive shaft 2.
Cam surface 22 having ridges corresponding to the number of engine cylinders
is formed, and the cam disk 18 is connected to the roller 20 of the roller holder 21 by a spring (not shown).
Since the cam surface 22 is pressed against the cam surface 22, as the drive shaft 2 rotates, the cam disk 18, and therefore the plunger 17, simultaneously rotate for fuel distribution and reciprocate for sucking and pumping fuel, as is known in the art. They are supposed to do it.

A servo timer 23 is arranged below the roller holder 21. The servo timer 23 has a casing 24 in which a hydraulically responsive piston 25 is slidably disposed. This piston 25 and the roller holder 21
are connected by a connecting lever 27 via a ball 26. The left side of the piston 25 is the low pressure chamber 2
8. The right side is the high pressure chamber 29, and the low pressure chamber 28
A hole 30 is formed in the axial direction of the piston 25 from the side, and a small diameter hole 31 is further formed in the deep part of this hole 30. The piston 25 has this hole 31.
A passage 32 communicating between the peripheral surface of the hole 31 and the high pressure chamber 29 is formed, and a servo is slidably fitted into the hole 31 and biased by a coil spring 33 to close the passage 32 at all times. A valve 34 is provided. This servo valve 34 has a communication hole 35.
is formed, and when the communication hole 35 matches the passage 32, the low pressure chamber 28 and the high pressure chamber 29 communicate with each other. Moreover, the low pressure chamber 28 is
It communicates with the passage 7 via a passage 36 formed in the pump housing 1 .

A mechanical governor 40 is provided above the cam disk 18 and includes a flyweight 39 attached to a governor sleeve 38 at the tip of a governor shaft 37.
The tip of the plunger 17 is in pressure contact with a start lever 41 connected to a plunger barrel 17' mounted on the plunger 17.

Further, the passage 7 is connected to a regulating valve 44 via passages 42 and 43.

In the distribution type fuel injection pump equipped with the servo timer 23 described above, the amount of fuel returned from the servo timer 23 to the feed pump 3 via the passage 36 and the passage 7 is larger than that of conventional pumps.
Therefore, a large amount of dust such as metal powder in the pump chamber 11 returns to the regulating valve 44, causing dust clogging. Furthermore, the filter for the valve section of the servo timer previously filed by the present applicant (Utility Application No. 153809/1983) has a small passage area, so the filter is easily clogged, which adversely affects the timer performance.

(Purpose of the invention) An object of the present invention is to provide a distribution type fuel injection pump which eliminates the drawbacks of the conventional pump described above and can sufficiently remove dust in the fuel returning from the low pressure chamber of the servo timer to the feed pump.

(Summary of the invention) In order to achieve the above purpose, in this invention,
In a distribution type fuel injection pump equipped with a servo valve timer, a high pressure chamber and a low pressure chamber are formed on both sides of a timer piston, and the high pressure chamber and the low pressure chamber are communicated with each other by movement of a spring-biased servo valve. The present invention provides a distribution type fuel injection pump in which a filter is provided in a passage communicating with a feed pump.

(Embodiments of the invention) The invention will be described below with reference to embodiments shown in the drawings. In addition, the same reference numerals are attached to the same components in the drawings and the explanation thereof will be omitted.

FIG. 2 shows a first embodiment of the present invention, showing a fuel tank (not shown) and passages 7, 36,
A step 46 is formed at the lower end of the straight hole 45 that communicates the holes 42 and 43, and below the step 46, the straight hole 45 communicates with the passage 36. A cylindrical mesh filter 47, for example, is mounted in the straight hole 45, and the outer diameter of the middle portion of the filter 47 is smaller than the inner diameter of the straight hole 45. The outer diameter of the upper and lower ends of the filter 47 is approximately equal to the inner diameter of the straight hole 45, and reinforcing caps 48 and 48 are attached to the upper and lower ends of the filter 47, respectively. and,
A base 48 at the lower end of the filter 47 is seated on the stepped portion 46, and a threaded joint 4 is provided in the straight hole 45 to prevent upward movement of the filter 47.
9 is screwed on. This threaded joint 49 is connected to a fuel tank (not shown).

According to this configuration, the filter 47 having a large surface area reliably removes dust mixed in the fuel returned from the low pressure chamber 28 of the servo timer 23 to the feed pump 3, thereby preventing the regulating valve from clogging. There is no fear,
In addition, there is no possibility that the timer characteristics will be adversely affected.

According to the embodiment described above, the filter can be easily attached and detached, and the passage area of the filter 41 can be increased.

FIG. 3 shows another embodiment of the present invention, in which a filter 47A is disposed only between the areas of the straight hole 45 communicating with the passage 7 and the passage 36, respectively. The filter 47A has a cylindrical shape with a bottom and has a slightly smaller diameter below the middle portion, and a cap 48 is attached to the upper end of the filter 47A. Further, a compression coil spring 50 is stretched between the upper end of the filter 47A and the threaded joint 49, and the filter 47A is positioned within the lower end of the straight hole 45.

Even with this configuration, the filter 47A with a large surface area is disposed between the passage 36 from the low pressure chamber 28 of the servo timer 23 and the passage 7 to the feed pump 3, so that metal powder etc. mixed in the fuel can be removed. garbage will be reliably removed. Also in this embodiment, the filter 47A can be easily attached and detached.

(Effects of the invention) As explained above, in the distribution type fuel injection pump according to the invention, since the filter is provided in the passage communicating with the low pressure chamber of the servo timer and the feed pump, it is possible to increase the surface area of the filter. This has the practical effect of being able to reliably remove dust from the fuel.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a general distribution type fuel injection pump, and FIGS. 2 and 3 are schematic longitudinal sectional views of main parts showing an embodiment of the distribution type fuel injection pump according to the present invention, respectively. . 1...Pump housing, 2...Drive shaft, 3...
...Feed pump, 17...Plunger, 18...
...Cam disc, 23...Servo timer, 25...
...Piston, 28...Low pressure chamber, 29...High pressure chamber,
34...Servo valve, 39...Fly weight, 40...Mechanical governor, 45...Straight hole,
47, 47A... Filter, 48... Base, 49
...Threaded joint, 50...Coil spring.

Claims (1)

[Scope of utility model registration request] In a distribution type fuel injection pump equipped with a servo valve timer, a high pressure chamber and a low pressure chamber are formed on both sides of a timer piston, and the high pressure chamber and the low pressure chamber are communicated with each other by movement of a spring-biased servo valve. A distribution type fuel injection pump characterized in that a filter is provided in a passage communicating with a feed pump.