JPH11343944A - Fuel injection pump for internal conbustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection pump for an engine in which the diameter of a plunger can be increased without enlarging a constitution. SOLUTION: In this pump, a holder part 21 in the form of a flange is formed integrally with a cylindrical barrel part 22 to form an element barrel 20, so that the diameter of a plunger can be relatively increased without enlarging a constitution or decreasing the thickness of the barrel part 22. Accordingly, the pressure supply efficiency of fuel is improved to inject the fuel under high pressure and the atomization of injection fuel is urged to improve the emission of exhaust air. Since a slip-off preventing pin is inserted into a pump housing 11 below the element barrel 20, a step part for supporting an upper sheet 41 may not be formed in an inner hole 11b. Thus, since the form of the inner hole 11b of the pump housing 11 can be made simple, the pump housing 11 can be easily worked and the number of manufacture steps can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a fuel injection pump disclosed in Japanese Utility Model Publication No. Sho 61-28050 is known as a fuel injection pump used for a diesel engine of an agricultural machine or a construction industrial machine, for example.

[0003]

In such a fuel injection pump for an engine, high pressure injection of fuel is known as one of means for improving exhaust emission in order to reduce soot emission due to unburned fuel. Therefore, atomization of injected fuel by high-pressure injection of fuel is one of the important factors for improving exhaust emission.

In order to inject fuel at a high pressure, for example, it is necessary to increase the diameter of the plunger of the pumping mechanism to improve the fuel transfer rate. However, Shoko 61-2
In the fuel injection pump disclosed in Japanese Patent No. 8050, when the diameter of the plunger is increased while the physique is kept constant, the thickness of the element barrel becomes thin, and the element barrel is cracked or broken during heat treatment at the time of manufacturing. The barrel may be distorted. In addition, when distortion occurs in the element barrel, the movement of the injection amount adjusting member of the fuel injection pump is deteriorated, and there is a problem that responsiveness to the engine side governor is deteriorated and the plunger is fixed. Furthermore, when the diameter of the plunger is increased while the thickness of the element barrel is kept constant, the pitch between the cylinders of the fuel injection pump needs to be increased, so that the physical size increases and the parts are shared. There was a problem that could not be done.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a fuel injection pump for an engine capable of increasing the diameter of a plunger without increasing the physical size. And

Another object of the present invention is to provide a fuel injection pump for an engine which can reduce the number of assembling steps and the number of manufacturing steps.

[0007]

According to the fuel injection pump for an engine of the present invention, the element barrel is fixed to the cylindrical barrel portion provided in the pump housing by the fixing member. And a flange-shaped holder portion, and a liquid-tight seal member holds the space between the pump housing and the barrel portion.
Therefore, by integrating the barrel portion and the holder portion, the plunger diameter can be made relatively large without increasing the physical size or reducing the thickness of the barrel portion. Therefore, the fuel pumping efficiency can be improved to enable high-pressure injection of the fuel, and the atomization of the injected fuel can be promoted to improve the exhaust emission. Furthermore, by making the wall thickness of the barrel relatively thick, it is possible to prevent the occurrence of cracks and distortion in the barrel during heat treatment during element barrel manufacturing, to deteriorate the movement of the injection amount adjustment mechanism of the fuel injection pump, and to improve the engine side. Deterioration of responsiveness to the governor and sticking of the plunger can be prevented. Furthermore, by making the physique relatively small, a mounting space can be easily secured, and components can be shared.

According to the fuel injection pump for an engine of the present invention, the movement restricting means is provided in the pump housing below the element barrel.
Can be restricted from moving in the element barrel direction. For this reason, since there is no need to form a step for supporting the first sheet in the inner hole of the pump housing below the element barrel, the shape of the inner hole of the pump housing can be simplified. Therefore, the processing of the pump housing is facilitated, and the number of manufacturing steps can be reduced.

According to the fuel injection pump for an engine according to the third, fifth or sixth aspect of the present invention, the tappet roller is rotated by the rotation of the cam of the cam shaft which is rotated in synchronization with the drive shaft of the engine. The tappet body which reciprocates in the pump housing by the rotation of the roller has a cutout penetrating at the lower end. For this reason, a pin can be fitted into the lower part of the pump housing, and a tappet can be assembled from the upper part of the pump housing so that the upper end of the notch is locked to this pin. Therefore, all the members can be assembled from the upper part of the pump housing, so that the assembly is easy and the number of assembling steps can be reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a fuel injection pump for a separate camshaft type (PFR type) engine.
3 to FIG.

This fuel injection pump 10 is provided with a drive side camshaft, a timer for adjusting the fuel injection timing, and a governor as a speed governor on the engine side. The injection pump itself has four pumping mechanisms. It has a four-cylinder configuration provided in series.

As shown in FIG. 1, the pump housing 11
Inside the plunger 15 and the element barrel 2
0, a pumping mechanism for sucking and pumping fuel,
Control rack 37 and control sleeve 38
And an injection amount adjusting mechanism for adjusting the injection amount of the fuel.

In the pump housing 11, an inner hole 11a having a large diameter is formed at an upper portion, and an inner hole 11b having a slightly smaller diameter than the inner hole 11a is formed at a lower portion. Further, a fuel chamber 36 is formed in the pump housing 11, and the fuel chamber 36 communicates with a fuel pipe (not shown) fixed by the holo screw 34 via a fuel supply passage 35 in the pump housing 11. The inner wall of the fuel chamber 36 is provided with a spill receiver 43 made of a hard material for receiving an overflow generated at the end of the fuel injection of the fuel injection pump 10 and attenuating the impact force of the high-pressure fuel.

The element barrel 20 comprises a flange-shaped holder portion 21 and a cylindrical barrel portion 22. For each cylinder, in this case, for each of the four cylinders, a seal member is provided in the inner holes 11a and 11b of the pump housing 11. Of 0
Liquid-tightly and rotatably fitted through rings 51 and 52. The element barrel 20 includes the holder 2
1 is fixed to the upper part of the pump housing 11 by a bolt 50 as a fixing member and is attached to the pump housing 11. The barrel portion 22 slidably holds the plunger 15 in the inner peripheral surface 23. A port 26 communicating with the fuel chamber 36 is formed in the barrel section 22, and the port 26 draws fuel from the fuel chamber 36,
A suction / discharge hole for discharging fuel to the fuel chamber 36 is formed. In the barrel portion 22, a plunger chamber 24 is formed by an upper end surface 25 of the plunger 15, an inner peripheral surface 23 of the barrel portion 22, and a lower end surface 14a of a delivery valve 14 described later.

A valve holder 12 is fitted into an inner hole 22a formed in the upper part of the plunger chamber 24 of the barrel portion 22, and the valve holder 12 is closed by contact with the barrel portion 22, thereby closing the barrel. A delivery valve 14 that opens when separated from the portion 22 and a valve spring 13 that urges the delivery valve 14 in the valve closing direction are provided on the side opposite to the plunger of the delivery valve 14.
The valve holder 12 has an outlet 12a communicating with the fuel injection nozzle via a fuel injection pipe (not shown).

The foot portion 17 of the plunger 15 is in contact with a lower sheet 42 to be described later.
6 is fitted with a control sleeve 38 described later. Leads 28 are formed obliquely in the axial direction from below the upper end surface 25 of the plunger 15.

The tappet 30 presses against a cam of a cam shaft which is rotated in synchronization with a drive shaft of an engine (not shown), and a tappet roller 32 which is rotated by the rotation of the cam, and a pump which is rotated by the rotation of the tappet roller 32. Housing 11
And a tappet body 31 that reciprocates in the inner hole 11b. As shown in FIG. 3, the tappet body 31 has a notch 33 penetrating through a lower end 31 a of the tappet body 31. As shown in FIG. 1, a pin 60 is fitted into the lower part of the pump housing 11, and the pin 60 is locked to the upper end 33 a of the notch 33, whereby the lowermost position of the tappet 30 is positioned.

As shown in FIG. 2, the element barrel 20
A retaining pin 70 is press-fitted in the lower part of the upper sheet, and an upper end of an upper sheet 41 as a first sheet is in contact with a lower end of the retaining pin 70. The lower sheet 42 serving as the second sheet has one end in contact with the foot 17 of the plunger 15 and the other end in contact with the tappet 30, and restricts the plunger 15 from being released upward in FIG. ing. Between the upper sheet 41 and the lower sheet 42, one end is in contact with the upper sheet 41, and the other end is connected to the lower sheet 42.
Coil spring 40 as urging means for contacting
Is provided. The compression coil spring 40 urges the tappet 30 and the lower sheet 42 in a direction opposite to the element barrel. Thereby, the tappet 30, the lower seat 42, and the plunger 15 move up and down integrally by the rotation of the cam. Here, the retaining pin 70 constitutes a movement restricting means capable of restricting the movement of the upper sheet 41 in the element barrel 20 direction.

When the fuel injection pump 10 is mounted on the engine, the control rack 37 is connected to and controlled by a governor (not shown) on the engine side. Control sleeve 3
8 is rotatable by receiving the driving force of the control rack 37 and is fitted to the two surface portions 16 of the plunger 15. The injection amount is adjusted by rotating the control sleeve 38 by the control rack 37 and changing the pressure feeding stroke of the plunger 15. For example, in FIG. 1, when the control rack 37 is moved to the front or the back of the drawing, the plunger 15 rotates through the two-faced portion 16 that moves integrally with the control sleeve 38 that meshes with the control rack 37, and the port 26 and the lead 28 are connected. A pumping stroke is obtained before the communication, and a fuel amount corresponding to the pumping stroke is pumped. Therefore, the injection amount is adjusted by transmitting the rotational motion to the plunger 15. A control rack pin 39 connected to the governor is provided on the left side of the pump housing 11 shown in FIG.

Next, the procedure for assembling the fuel injection pump 10 configured as described above will be described.

(1) A pin 6 is provided at the lower part of the pump housing 11.
0, and the tappet 30 having the tappet roller 32 incorporated in the tappet body 31 from the upper part of the pump housing 11 so that the upper end 33a of the notch 33 of the tappet body 31 is engaged with the pin 60. 11 into the inner hole 11b.

(2) The lower seat 42, the compression coil spring 40, and the upper seat 41 are inserted into the inner hole 11b of the pump housing 11 in the above order from the upper part of the pump housing 11, and the lower end of the lower seat 42 contacts the upper end of the tappet 30. Contact

(3) The retaining pin 70 is pressed into the pump housing 11 while pressing the upper sheet 41 downward against the urging force of the compression coil spring 40, and the upper end of the upper sheet 41 is fitted to the lower end of the retaining pin 70. The upper sheet 41 is restricted from moving upward.

(4) The plunger 15 is inserted into the barrel portion 22 of the element barrel 20 in which the O-rings 51 and 52 are fitted.
Insert the control sleeve 38 into the plunger 15
Of the pump housing 11 with the foot 17 of the plunger 15 down.
2. Insert the control sleeve 38 and the plunger 15 into the inner holes 11a and 11b of the pump housing 11, insert the control sleeve 38 and the plunger 15 into the upper seat 41 and the compression coil spring 40, and connect the foot 17 to the upper end of the lower seat 42. Contact. At this time, the O-ring 52 is rubbed on the inner wall of the pump housing 11 by forming the large-diameter inner hole 11a in the upper part of the pump housing 11 and forming the inner hole 11b having a slightly smaller diameter than the inner hole 11a in the lower part. Damage can be prevented.

(5) Holder section 22 of element barrel 20
Is fixed to the upper part of the pump housing 11 by bolts 50.

(6) The valve holder 12 incorporating the delivery valve 14 and the valve spring 13 is inserted into the inner hole 22a of the element barrel 20, and finally, the control rack 37 and the control rack pin 39 are mounted on the pump housing 11. Thus, the assembly of the fuel injection pump 10 is completed. Then, the fuel injection start timing and the fuel injection amount are adjusted.

As described above, the lower end 3 of the tappet body 31
Since the notch 33 penetrating through 1a is formed in the tappet main body 31, all members can be assembled from the upper part of the pump housing 11. Therefore, assembling becomes easy, and the number of assembling steps can be reduced.

Next, the operation of the fuel injection pump 10 assembled according to the above procedures (1) to (6) will be described.

The fuel passes through a fuel pipe fixed by a horo screw 34, passes through a fuel supply passage 35 and a fuel chamber 36.
And plunger chamber 24 is filled with fuel. When the plunger 15 moves upward in FIG. 1 and the upper end face 25 of the plunger blocks the upper end face of the port 26, the plunger chamber 2
The fuel pressure of 4 is increased. When the fuel pressure opposes the spring force of the valve spring 13 and the valve 14 is opened, the pumping of the fuel starts. The pumped fuel is pumped from the outlet 12a of the valve holder 12 through the injection pipe to the injection nozzle, and is injected from the injection nozzle into the fuel chamber of the engine. When the plunger 15 is further raised and the upper end surface of the lead 28 is higher than the lower end surface of the port 26, the fuel in the plunger chamber 24 is discharged to the fuel chamber 36 via the lead 28 and the port 26, and the pumping of the fuel ends. .

In the above embodiment of the present invention, the element barrel 20 is formed by integrating the flange-shaped holder 21 and the cylindrical barrel 22 to increase the physical size and the thickness of the barrel 22. The plunger diameter can be made relatively large without reducing the thickness of the plunger. Therefore, the fuel pumping efficiency can be improved to enable high-pressure injection of the fuel, and the atomization of the injected fuel can be promoted to improve the exhaust emission. Furthermore, by making the thickness of the barrel portion 22 relatively large, the occurrence of cracks and distortion of the barrel portion 22 during heat treatment during the manufacture of the element barrel 20 is prevented, and the movement of the injection amount adjusting mechanism of the fuel injection pump 10 is reduced. Deterioration, responsiveness with the engine side governor, and sticking of the plunger 15 can be prevented. Furthermore, by making the physique relatively small, a mounting space can be easily secured, and components can be shared.

In the embodiment of the present invention, the retaining pin 70 is pressed into the pump housing 11 below the element barrel 20, and the upper end of the upper sheet 41 is in contact with the lower end of the retaining pin 70. It is not necessary to form a step for supporting the upper sheet 41 in the inner hole 11b of the pump housing 11. Therefore, since the shape of the inner hole 11b of the pump housing 11 can be made simple, processing of the pump housing 11 becomes easy,
The number of manufacturing steps can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an engine fuel injection pump according to one embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a view showing a tappet body according to one embodiment of the present invention, and is a view as seen in the direction of arrow III in FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 fuel injection pump 11 pump housing 12 valve holder 14 delivery valve 15 plunger 20 element barrel 21 holder part 22 barrel part 24 plunger chamber 26 port 28 lead 30 tappet 31 tappet body 32 tappet roller 33 cutout part 36 fuel chamber 37 control rack 38 Control sleeve 40 Compression coil spring (biasing means) 41 Upper sheet (first sheet) 42 Lower sheet (second sheet) 43 Spill receiver 50 Bolt (fixing member) 51, 52 O-ring (seal member) 70 Retaining pin (Movement control means)

Claims (6)

[Claims] A pump housing; a tubular barrel provided in the pump housing;
An element barrel having a flange-shaped holder fixed to the pump housing; a plunger slidably held in the barrel; a fixing member fixing the holder to the pump housing; and the pump housing. A sealing member for maintaining a liquid-tight relationship between the tappet roller and the barrel portion, a tappet roller rotated by rotation of a cam of a cam shaft rotated in synchronization with a drive shaft of the internal combustion engine, and a rotation of the tappet roller And a tappet having a tappet body that reciprocates in the pump housing. 2. A first sheet provided in the pump housing below the element barrel, a second sheet having one end contacting the plunger and the other end contacting the tappet, and one end contacting the tappet. A biasing means for abutting against the first sheet, the other end abutting against the second sheet, and biasing the tappet and the second sheet in a direction opposite to the element barrel; The fuel injection pump for an internal combustion engine according to claim 1, further comprising: movement restricting means capable of restricting movement in a direction. 3. The fuel injection pump for an internal combustion engine according to claim 1, wherein the tappet body has a cutout portion penetrating at a lower end. 4. A pump housing, an element barrel provided in the pump housing, a plunger slidably held in the element barrel, and a cam shaft rotated in synchronization with a drive shaft of the internal combustion engine. A tappet roller having a tappet roller rotated by rotation of a cam, a tappet having a tappet body reciprocating in the pump housing by rotation of the tappet roller, and a first sheet provided in the pump housing below the element barrel A second sheet having one end in contact with the plunger and the other end in contact with the tappet; and one end in contact with the first sheet, the other end in contact with the second sheet, and the tappet and Urging means for urging the second sheet in a direction opposite to the element barrel; Internal combustion engine fuel injection pump, characterized in that and a movement regulating means capable regulating the movement in the Ntobareru direction. 5. The fuel injection pump for an internal combustion engine according to claim 4, wherein the tappet body has a cutout portion penetrating at a lower end. 6. A pump housing, an element barrel provided in the pump housing, a plunger slidably held in the element barrel, and a cam shaft rotated in synchronization with a drive shaft of the internal combustion engine. A tappet roller having a tappet roller that rotates by rotation of a cam, and a tappet having a tappet body that reciprocates in the pump housing by rotation of the tappet roller, wherein the tappet body has a cutout penetrating at a lower end. A fuel injection pump for an internal combustion engine, comprising: