JPH1037828A - Fuel injection pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an injection time for fuel (the timing for starting forced feeding) to be mechanically adjusted in a fuel injection pump in response to a rotating speed of an engine and its load. SOLUTION: An outer circumference of a plunger 4 for use in forcedly feeding fuel is provided with an injection time adjustment sleeve 11 having a slant suction lead hole 12 rotated in response to a rotating speed of an engine to open or close a fuel suction port 5 of the plunger 4 and to adjust a fuel forced feeding start time. In addition, the outer circumference of the plunger 4 is provided with an injection amount adjustment sleeve 17 having a slant overflow lead hole 18 rotated in response to a load of the engine to open or close a fuel overflow port 6 of the plunger 4 and to adjust a forced feeding completion time. Stoppers 24, 25 opposed to be enabled to abut to each other are formed between the axial opposing surfaces of both sleeves 11, 17 while a predetermined clearance S being left in the rotating direction. When the injection amount adjustment sleeve 17 is rotated in such a direction as one to make fast a forced feeding completion time, a rotating amount of the injection time adjustment sleeve 11 in such a direction of making fast the forced feeding start time can be restricted in response to the rotating amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection pump for pressurizing and supplying fuel to an internal combustion engine such as a diesel engine, and more particularly to a fuel injection pump having the same number of plungers as the number of engine cylinders, which are arranged in series. The present invention relates to a row type fuel injection pump.

[0002]

2. Description of the Related Art A conventional line type fuel injection pump has a plunger as a fuel pressurizing mechanism which moves up and down in a cylinder by rotation of a cam, and pressurizes fuel flowing into a pump chamber from a fuel chamber in a suction process. The pumping is performed to the fuel injection nozzle, and the pumping is completed when the notch hole provided in the plunger communicates with the fuel chamber. In addition, it has a governor for adjusting the injection amount, and a plunger pumping stroke (a stroke from the start of fuel pumping to the end of pumping during the plunger ascent stroke) via a control rack that operates according to the movement of the accelerator pedal and the engine speed. ) Is changed to adjust the injection amount. In addition, a centrifugal timer is provided to adjust the injection timing by giving a phase difference in the rotation direction between the drive shaft on the engine side and the driven shaft on the injection pump side according to the amount of weight movement according to the rotation speed of the engine. ing.

[0003]

However, in the above-described conventional fuel injection pump which mechanically adjusts the injection amount and the injection timing, the injection amount is adjusted according to the engine load, and the injection timing is adjusted according to the engine load. In this method, the injection timing cannot be adjusted in accordance with the engine load. That is, when the engine speed is constant, the injection timing is kept constant.

[0004] In a diesel engine, it is desirable to adjust the fuel injection timing in accordance with not only the engine speed but also the load from the viewpoint of improving fuel efficiency, noise, NOx, and smoke.
In general, it is known that the earlier the fuel injection timing, the quicker the combustion, the temperature inside the cylinder becomes high and the pressure becomes high, and the noise and NOx deteriorate. Therefore, when the load is light, it is more advantageous to delay the injection timing than when the load is high, which is advantageous in reducing NOx and noise. Therefore, it is preferable to adjust the injection timing according to the load. Although the electronic control unit can control the adjustment of the injection timing according to the rotational speed and load of the engine based on such a concept, there is a problem in that the electronic control is expensive.

The present invention has been made in view of the above circumstances, and has as its object to provide a fuel injection pump capable of mechanically adjusting the fuel injection timing according to the engine speed and the engine load. And

[0006]

Means for Solving the Problems In order to solve the above problems, the present invention is configured as follows. That is, the invention according to claim 1 is a fuel injection pump, which comprises a plunger for pumping fuel by reciprocating in a cylinder;
An injection timing adjusting sleeve that is rotatably fitted to the plunger and that rotates in accordance with the rotation speed of the engine to adjust the timing of starting fuel pressure feeding; And an injection amount adjusting sleeve that adjusts the fuel pumping end time by rotating according to the injection timing. When the injection amount adjusting sleeve is rotated in a direction to advance the pumping end timing, the injection timing adjusts according to the rotation amount. And a rotation restricting means for restricting a rotation amount of the adjustment sleeve in a direction to advance the pressure feeding start timing.

According to the first aspect of the present invention, the injection timing adjusting sleeve rotates around the plunger according to the rotational speed of the engine to adjust the timing of starting the fuel pressure feed. That is, the injection timing adjustment corresponding to the rotation speed is performed. In addition, the injection amount adjusting sleeve rotates around the plunger according to the level of the engine load, and adjusts the end time of the fuel pressure feeding. That is, the injection amount adjustment corresponding to the load is performed.

On the other hand, when the injection amount adjusting sleeve is rotated in a direction to advance the pumping end time in accordance with the engine load, the rotation restricting means presses the injection timing adjusting sleeve in accordance with the rotation amount of the injection amount adjusting sleeve. The pumping start timing is adjusted by limiting the amount of rotation in the direction in which the start timing is advanced. That is, the injection timing is adjusted according to the level of the engine load.

According to a second aspect of the present invention, there is provided the fuel injection pump according to the first aspect, wherein the fuel pumping start timing can be adjusted also by the axial displacement of the injection amount adjusting sleeve.
Lifting means for maintaining a constant amount of fuel pumped by the plunger by displacing the injection amount adjusting sleeve in the axial direction in accordance with the rotation of the injection timing adjusting sleeve is provided. And

Therefore, according to the second aspect of the present invention, when the pumping start timing is adjusted by the rotation of the injection timing adjusting sleeve, the lifting / lowering means moves the injection amount adjusting sleeve to the shaft corresponding to the rotation amount of the injection timing adjusting sleeve. By displacing in the direction, the pumping end time is adjusted according to the pumping start time. For example, when the pumping start time is adjusted to be earlier, the pumping end time is adjusted to be later. This allows
The pumping amount is kept constant.

According to a third aspect of the present invention, in the fuel injection pump according to the first or second aspect, the rotation restricting means is provided on the injection timing adjusting sleeve and hastens the timing of starting pressure feeding of the injection timing adjusting sleeve. A stopper portion provided on the injection amount adjusting sleeve and having a rotation direction for advancing the end of pressure feeding of the injection amount adjusting sleeve and having a contact surface as a contact surface; The contact surfaces are opposed to each other with a predetermined gap therebetween, and the gap is narrowed when the injection amount adjusting sleeve is rotated in a direction to advance the end timing of the pressure feeding.

Therefore, according to the third aspect of the invention, when the injection amount adjusting sleeve is rotated according to the engine load, the gap between the contact surfaces of the two stopper portions changes, and the injection timing adjusting sleeve is accordingly changed. Is restricted, whereby the timing for starting the pressure feeding is adjusted.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The vicinity of one pump chamber of a row type fuel injection pump according to an embodiment of the present invention will be specifically described below with reference to the drawings. In an actual fuel injection pump, mechanisms constituted by a pump chamber, a plunger, and the like described below are arranged in series along the cam shaft by the number of cylinders of the engine. 1 is an explanatory view showing a main part of the fuel injection pump, FIG. 2 is an exploded perspective view of the same, FIG. 3 is a longitudinal sectional view of the fuel injection pump, and FIG. However,
In FIG. 4, the pump housing is omitted. In the drawing, reference numeral 1 denotes a vertically long pump housing, and a cylindrical cylinder 3 is fixed to an upper inner side thereof to form a pump chamber 2.

The head of a cylindrical plunger 4 is slidably and non-rotatably fitted into the pump chamber 2, and the plunger 4 is connected to a flange 4a provided on the lower side and a pump 4a. A spring 8 interposed between the housing 1 and the housing 1 urges the spring 8 downward, and a lower end portion thereof is pressed by a cam 10 of a cam shaft 9 that is linked to a crank shaft (not shown). The cam 10 is rotated once by two rotations of the crankshaft to move the plunger 4 up and down.

The plunger 4 is provided with a fuel inlet 5 and a fuel overflow 6 which are open on the outer peripheral surface and are provided at predetermined intervals in the axial direction in the radial direction, and are provided in the fuel inlet 5 and the fuel overflow 6. Fuel passages 7 that communicate with each other and communicate with the pump chamber 2 are formed in the axial direction. On the outer periphery of the body portion of the plunger 4, fuel injection start timing, that is, an injection timing adjusting sleeve 11 for adjusting the injection timing,
That is, the injection amount adjusting sleeve 1 for adjusting the injection amount (compression feed amount).
7 are rotatably fitted.

The injection timing adjusting sleeve 11 has a suction lead hole 1 having a predetermined length formed by being cut off obliquely in the circumferential direction.
The suction lead hole 12 is always in communication with a fuel chamber 13 provided in the pump housing 1. Therefore, in the lowered position of the plunger 4, the fuel inlet 5
While the fuel chamber 1 communicates with the suction lead hole 12.
When the fuel in the pump 3 is sucked into the pump chamber 2 and then the plunger 4 is lifted and the fuel suction port 5 is disengaged from the suction lead hole 12 and closed, the pumping is started. Since the suction lead hole 12 is provided obliquely, the timing at which the fuel suction port 5 closes when the plunger 4 is raised, that is, the pressure feeding start time, is adjusted by rotating the injection timing adjustment sleeve 11.

As means for rotating the injection timing adjusting sleeve 11, the outer periphery of the injection timing adjusting sleeve 11
As shown in FIG.
The pinion gear 14 is provided with a rack drive unit 16.
With the timing rack 15 which is moved forward and backward. The rack driving unit 16 moves the timing rack 1 according to the movement of the fly weight corresponding to the rotation speed of the engine.
5 to go back and forth. The rack drive unit employs a general centrifugal-type timer structure, for example, as shown in FIG. 2 of Japanese Utility Model Application Laid-Open No. 52-80371, and further detailed description is omitted.

Therefore, when the engine is rotating at a high speed, the rack drive unit 16 rotates the injection timing adjusting sleeve 11 via the timing rack 15 in the direction R shown in FIG. The suction lead hole 12 is turned in the illustrated L direction, which is the downward inclination direction. That is, during high-speed rotation, the pressure feeding start timing is adjusted to be advanced, and at low-speed rotation, it is adjusted to be delayed.

On the other hand, the injection amount adjusting sleeve 17 is disposed above the injection timing adjusting sleeve 11. The injection amount adjusting sleeve 17 has an overflow lead hole 1 inclined in a direction opposite to the suction lead hole 12 of the injection timing adjusting sleeve 11.
The overflow lead hole 18 is always in communication with the fuel chamber 13 provided in the pump housing 1. Therefore, when the fuel overflow port 6 communicates with the overflow lead hole 18 when the plunger 4 is raised, the fuel pressure in the pump chamber 2 decreases and the pumping ends. Since the overflow lead hole 18 is provided obliquely, by rotating the injection amount adjusting sleeve 17, the timing at which the fuel overflow port 6 communicates with the overflow lead hole 18 is changed, whereby the fuel injection amount is reduced. Adjusted.

As a means for rotating the injection amount adjusting sleeve 17, a pinion gear 19 is provided on the outer periphery of the injection amount adjusting sleeve 17, similar to the injection timing adjusting sleeve 11 over a predetermined range, but with a wider tooth width. The pinion gear 19 is operated according to the movement of an accelerator pedal (not shown) or the rotation speed of the engine, that is, meshes with a control rack 20 which is operated according to the engine load. The driving force for moving the control rack 20 forward and backward with respect to the timing rack 15 is set to be always larger.

Therefore, when the load of the engine is high, the injection amount adjusting sleeve 17 is rotated through the control rack 20 in the direction R shown in FIG. By rotating the hole 18 in the illustrated L direction, which is the upward inclination direction of the hole 18, the timing at which the fuel overflow 6 communicates with the overflow lead hole 18 is changed.
In other words, when the load is high, the pumping end time is delayed
When the load is light, it is adjusted to the quicker side.

Further, there is provided an elevating means for keeping the pumping amount constant by displacing the injection amount adjusting sleeve 17 in the vertical direction, that is, in the axial direction in association with the rotation of the injection timing adjusting sleeve 11. As shown in FIGS. 2 and 3, the elevating means includes an injection timing adjusting sleeve 11 and an injection amount adjusting sleeve 1.
The main component is the roller 21 interposed between the roller 21 and the roller 8.

The shaft of the roller 21 is vertically movably mounted along a vertically extending guide groove 22 formed in the pump housing 1. And roller 2
The upper end surface of the injection timing adjusting sleeve 11 abutting on the slope 1 has the same slope 1 as the suction lead hole 12 over a predetermined range.
1a, the lower end surface of the injection amount adjusting sleeve 18 abutting on the roller 21 has a horizontal surface 1a over a predetermined range.
7a. The injection amount adjusting sleeve 17
Is constantly pressed downward by a spring 23 interposed between the upper end surface and the lower end surface of the cylinder 3.

Therefore, when the injection timing adjusting sleeve 11 is rotated around the plunger 4 and the pressure feeding start timing is adjusted, the injection amount adjustment sleeve 17 is moved by the roller 21 which comes into contact with the slope 11a. Is moved up or down by an amount corresponding to the adjustment amount, so that the pumping stroke is kept constant. That is, the injection amount is kept constant.

Further, between the injection timing adjusting sleeve 11 and the injection timing adjusting sleeve 17, when the injection timing adjusting sleeve 17 is adjusted in a direction to advance the pumping end timing (the L direction in the drawing), A rotation restricting means is provided for adjusting the rotation start timing by restricting the rotation in the direction (R direction in the drawing) to advance the rotation start timing. As shown in FIG. 1, the rotation restricting means is formed so as to be abuttable by providing a staggered notch at one position in the circumferential direction on the surface facing the injection timing adjusting sleeve 11 and the injection amount adjusting sleeve 17. It is constituted by the opposed stopper portions 24 and 25 which are formed.

Stopper 2 of injection timing adjusting sleeve 11
Reference numeral 4 denotes a contact surface in which the rotation direction of the injection timing adjusting sleeve advances the timing of starting the pressure feeding, and the stopper portion 25 of the injection amount adjusting sleeve 17 contacts the rotation direction of speeding the timing of terminating the pressure feeding of the injection amount adjusting sleeve. The two contact surfaces are opposed to each other with a predetermined gap S in the circumferential direction. The opposed gap S is a direction in which the injection amount adjusting sleeve 17 hastens the end of the pressure feeding (a direction in which the injection amount is reduced). ), The gap is narrowed, and the gap S is narrowed, so that the amount of rotation of the injection timing adjusting sleeve 11 in the direction to advance the pressure feeding start timing is limited.

The fuel injection pump according to the present embodiment is configured as described above, and its operation and effect will be described below. FIG. 7 is an explanatory view showing the fuel pumping operation of the fuel injection pump. In the (A) suction stroke in which the plunger 4 is located at the lower end, the fuel inlet 5 is connected to the injection timing adjusting sleeve 11.
The fuel in the fuel chamber 13 is sucked into the pump chamber 2 through the fuel passage 7. At this time, the fuel overflow port 6 is located below the overflow lead hole 18 of the injection amount adjusting sleeve 17 and is closed.

When the plunger 4 is lifted and the fuel suction port 5 is disengaged from the suction lead hole 12 and is closed, as shown in FIG. 3B, the pumping of the fuel in the pump chamber 2 to the fuel injection nozzle by the plunger 4 starts. When the fuel outlet 6 is communicated with the overflow lead hole 18 as shown in FIG.
The pressure in the pump chamber 2 decreases, and the pumping ends.

FIG. 8 is a diagram for explaining the adjustment of the timing of starting the pressure feeding.
(A) shows a high-speed rotation, and (B) shows a low-speed rotation. At the time of high-speed rotation, the injection timing adjusting sleeve 11 is rotated in the R direction via the timing rack 15, the position where the fuel suction port 5 is disconnected from the suction lead hole 12 is displaced downward, and the pressure feeding start timing is advanced. Can be At the time of low-speed rotation, the injection timing adjusting sleeve 11 is rotated in the L direction, the position where the fuel suction port 5 is not connected to the suction lead hole 12 is displaced upward, and the pressure feeding start timing is delayed. That is, the injection timing is adjusted.

At this time, with the rotation of the injection timing adjusting sleeve 11, the roller 21 moves up or down along the slope 11a of the injection timing adjusting sleeve 11, and the injection amount adjusting sleeve 1
In order to raise or lower the nozzle 7, the injection amount adjusting sleeve 17
If the position in the rotation direction is the same, the same pumping stroke,
That is, a constant injection amount can be obtained.

When the engine is under a high load, the injection amount adjusting sleeve 17 is rotated in the R direction shown in the figure via the control rack 20, and the communication timing of the fuel overflow port 6 with the overflow lead hole 18 is delayed. Increase. During·
When the load is light, the injection amount adjusting sleeve 17 is rotated in the L direction in the figure, the communication timing of the fuel outlet 6 with the overflow lead hole 18 is advanced, and the injection amount is reduced.

When the injection amount is adjusted by the injection amount adjusting sleeve 17, the injection timing is also adjusted at the same time. That is, when the engine is under a high load, the injection amount adjusting sleeve 17 is rotated in the illustrated R direction, which is the injection amount increasing side, as shown in FIG. Away from the stopper part 24 of
The gap S between the contact surfaces of the stopper portions 24 and 25 widens. On the other hand, at the time of medium / light load, the injection amount adjusting sleeve 17 is rotated in the illustrated L direction, and the gap S is narrowed as shown in FIG.

That is, as the engine load becomes smaller, the gap S between the contact surfaces of the stopper portions 24 and 25 becomes narrower, thereby restricting the rotation of the injection timing adjusting sleeve 11 in the direction to advance the pressure feeding start timing. For this reason, as shown in FIG. 10, the pumping start timing is adjusted according to the load, that is, the pumping start timing is adjusted to be later as the load becomes smaller. Also, for example, when the engine load shifts from a state where the load is large to a state where the load is large at the time of high speed rotation of the engine, the injection timing adjusting sleeve 11 is rotated in the L direction by the contact of the stopper portions 24 and 25, The pumping start time is delayed.

FIGS. 11A and 11B are injection amount characteristic diagrams, in which FIG. 11A shows a case using a conventional fuel injection pump, and FIG. 11B shows a case using the fuel injection pump according to the present embodiment.
Conventionally, the injection amount is only adjusted according to the level of the load, and the compression start timing is the same regardless of the level of the load. However, in this embodiment, the injection amount is adjusted according to the level of the load. Is adjusted, and the smaller the load is, the more the injection timing is adjusted. When the pressure feed start time is delayed at light load, rises in the in-cylinder pressure and the temperature are suppressed, so that NOx and noise can be reduced. Further, at light load, even if the pumping start time is delayed, the fuel is completely burned, and the smoke is not deteriorated.

In this embodiment, the roller 21 is shown on one side. However, the roller 21 may be arranged symmetrically on both sides with respect to the center line to stabilize the movement. Further, the rotation restricting means for adjusting the injection start timing to the side where the pressure feed start timing is delayed at the same time as the injection amount adjustment by the injection amount adjustment ring 17 is not limited to the above-described notch structure of the stopper portions 24 and 25, but the injection timing adjustment sleeve 11. It may be a projection that is provided so as to be able to abut both the rotation direction and the injection amount adjusting sleeve 17.

Although the roller 21 is used as the elevating means in this embodiment, a slide piece 41 having a shape as shown in FIGS. 12 and 13 may be used. When such a slide piece 41 is used, the contact between the injection timing adjustment sleeve 11, the elevating means (slide piece 41), and the injection amount adjustment sleeve 17 is a surface contact, so that the durability of the contact portion is improved.

In addition to this embodiment, as shown in FIG. 14, the upper part of the fuel chamber 13 and the pump chamber 2 is allowed to flow only from the fuel chamber 13 to the pump chamber 2.
The connection may be made in the fuel supply passage 42 via a directional valve. By connecting the fuel chamber 13 and the pump chamber 2,
After the completion of the fuel feeding, the resistance acting on the plunger 4 when the plunger 4 is lowered by the spring 8 is reduced, and the followability of the plunger 4 to the cam 10 is improved.

[0038]

As described in detail above, according to the present invention,
It is possible to provide an inexpensive fuel injection pump capable of mechanically adjusting the fuel injection timing according to the engine speed and the engine load, which is advantageous in reducing NOx and noise.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a main part of a fuel injection pump according to the present embodiment.

FIG. 2 is an exploded perspective view of the same.

FIG. 3 is a longitudinal sectional view of the fuel injection pump.

FIG. 4 is a view as viewed in the direction of arrow A in FIG. 3, showing the pump housing omitted.

FIG. 5 is an explanatory diagram of an operation structure of a sleeve.

FIGS. 6A and 6B are explanatory views of a rotation restricting means of the injection timing adjusting sleeve, wherein FIG. 6A is a side view and FIG. 6B is a plan view.

FIGS. 7A and 7B are explanatory diagrams of the operation of the fuel injection pump, in which FIG. 7A shows a state when fuel is sucked, FIG. 7B shows a state when fuel pumping is started, and FIG.

FIG. 8 is a diagram illustrating the operation of adjusting the fuel pumping start timing;
(A) shows a high-speed rotation, and (B) shows a low-speed rotation.

9A and 9B are explanatory diagrams of the operation of adjusting the pressure feeding start timing by the load, wherein FIG. 9A shows a high load, and FIG. 9B shows a medium / light load.

FIG. 10 is a graph showing a pumping start timing characteristic.

FIGS. 11A and 11B are graphs showing injection amount characteristics, in which FIG. 11A shows a conventional example and FIG. 11B shows a case of the present embodiment.

FIG. 12 is an explanatory diagram showing another embodiment.

FIG. 13 is a perspective view showing a slide piece as an elevating means according to another embodiment.

FIG. 14 is a sectional view showing still another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pump housing 2 ... Pump chamber 3 ... Cylinder 4 ... Plunger 5 ... Fuel inlet 6 ... Fuel overflow 7 ... Fuel passage 11 ... Injection timing adjustment sleeve 12 ... Intake lead hole 17 ... Injection amount adjustment sleeve 18 ... Overflow lead hole 21: Lift roller 11a: Inclined surface 17a: Horizontal surface

Claims (3)

[Claims] 1. A plunger for pumping fuel by reciprocating in a cylinder, rotatably fitted to the plunger, and adjusting the start of fuel pumping by rotating according to the rotation speed of the engine. An injection amount adjusting sleeve, which is rotatably fitted to the plunger and adjusts the fuel feeding end timing by turning according to the engine load, and the injection amount adjusting sleeve which stops the pressure feeding. A fuel injection pump comprising: a rotation restricting means for restricting an amount of rotation of the injection timing adjusting sleeve in a direction in which the pressure feeding start timing is advanced in accordance with the amount of rotation when rotated in a direction to advance the timing. 2. The fuel injection start timing can be adjusted also by the axial displacement of the injection amount adjustment sleeve, and the injection amount adjustment sleeve is pivoted in accordance with the rotation of the injection timing adjustment sleeve when the injection time adjustment sleeve is rotated. 2. The fuel injection pump according to claim 1, further comprising a lifting means for displacing the plunger in a direction so as to maintain a constant amount of fuel being pumped by the plunger. 3. The injection amount adjusting sleeve, wherein the rotation restricting means is provided on the injection timing adjusting sleeve, and the stopper portion has a contacting surface in a rotation direction for advancing the pressure feeding start timing of the injection timing adjusting sleeve. And a stopper portion having a rotation direction for advancing the end of pressure feeding of the injection amount adjusting sleeve as a contact surface, and both contact surfaces are opposed to each other with a predetermined gap therebetween, and the gap is the injection amount. The fuel injection pump according to claim 1, wherein the adjustment sleeve is narrowed when the adjustment sleeve is rotated in a direction to advance the end of the pressure feeding.