JPH05149151A - Distribution type fuel injection pump - Google Patents

Abstract

PURPOSE:To provide a distribution type fuel injection pump wherein rapid delay characteristics to a microchange in an injection amount can be provided and a novel LST standard can be satisfied. CONSTITUTION:A plurality of orifices 51 and 52 axially spaced away from each other are arranged to the governor sleeve 33 of a centrifugal governor 50 and annular grooves 53 and 54 are formed in the inner surface of the governor sleeve. A plurality of annular grooves 55 and 56 communicated to the annular grooves 53 and 54 through movement of the governor sleeve 33 and guiding fuel to a fuel escape passage 57 are formed in a governor shaft 39. Through movement of the governor sleeve, a plurality of the annular groove 53 and 54 are simultaneously communicated to a plurality of annular grooves 55 and 56, respectively, of the govornor shaft 39 through movement of the governor sleeve and the area of an escape route can be increased, whereby fuel in a housing can be allowed to rapidly escape to the low pressure side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distribution type fuel injection pump for distributing and supplying fuel to each cylinder of an internal combustion engine, and relates to a structure of a load sensing timer.

[0002]

BACKGROUND ART Generally di - For diesel engines, but can reduce the emissions of the NO _x Delaying injection timing, emissions output performance and NO _x are in opposite relationship with respect to the fuel injection timing If the fuel injection timing is delayed in order to reduce the NO _x emission amount, the output will decrease.

However, the reduction of NO _x emission is strongly demanded as a social demand, and therefore, in order to reduce the NO _x emission without lowering the output under high load, injection like under light load is performed. An injection timing control device that delays the injection timing only when the amount is small compared to when the injection amount is large,
That is, a load sensing timer (LST) has been developed.

A load sensing timer of this type is disclosed in Japanese Utility Model Publication No. 59-36675. That is, the load sensing timer shown in this publication forms an orifice in the governor sleeve of the centrifugal governor that responds to the rotation of the engine, and forms a fuel escape passage leading to the low pressure portion in the governor shaft that guides this governor sleeve. However, when the orifice communicates with the fuel escape passage of the governor shaft by the operation of the governor sleeve, the fuel in the housing is allowed to escape from the fuel escape passage to the low pressure portion, thereby lowering the fuel pressure in the housing. The timer piston is actuated to the retard side, and as a result, the cam roller rolling on the face cam is moved to control the injection timing.

By the way, in the load sensing timer described in the above publication, an annular groove continuous with the orifice is formed on the inner surface of the governor sleeve in order to obtain a rapid retarding characteristic with respect to a minute change in the injection amount. The movement of the governor sleeve causes the orifice to communicate with the fuel escape passage of the governor shaft through the annular groove. As a result, even if the governor sleeve has a small displacement, that is, a small change in the injection amount, a large area for the fuel escape passage is secured, the fuel pressure in the housing is quickly reduced, and the timer piston is quickly activated. It is designed to operate on the retard side.

[0006]

However, in recent years, exhaust gas regulations for diesel engine vehicles have tended to become more stringent, and there is a movement to establish a new LST standard. However, with the structure of the load sensing timer described in the above publication, it has become difficult to satisfy the new LST standard.

That is, the conventional load sensing timer described above has the characteristics as shown by the chain double-dashed line in FIG. 4, but the new LST standard shows the beginning and end of the effect as indicated by the broken line rectangle in the figure. Therefore, the conventional load sensing timer has a problem that the new LST standard cannot be cleared.

The present invention has been made in view of such circumstances, and an object of the present invention is to obtain a more rapid retardation characteristic with respect to a change in the injection amount which is much smaller than that of the conventional one, and to provide a novel The present invention aims to provide a distributed fuel injection pump that can satisfy various LST standards.

[0009]

In order to achieve the above object, the present invention provides a governor sleeve with a plurality of orifices axially separated from each other and an annular groove continuous with these orifices on the inner surface of the governor sleeve. Is provided with a plurality of ring grooves that are electrically connected to these annular grooves by the movement of the governor sleeve and guide the fuel to the fuel escape passages.

[0010]

According to the structure of the present invention, the annular groove provided at a distance in the axial direction by the movement of the governor sleeve communicates with the plurality of ring grooves formed on the governor shaft at the same time, thereby reducing the area of the escape path. Since the amount of fuel can be increased, the fuel in the housing can quickly escape to the low pressure side through the fuel escape passage. For this reason, the fuel pressure in the housing is promptly reduced to promptly actuate the timer piston to the retard side, and as a result, the cam roller rolling on the face cam is moved to control the injection timing, and thus the minute injection is performed. It is possible to obtain a rapid retardation characteristic with respect to a change in quantity.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings.

FIG. 3 shows the whole of the distribution type fuel injection pump. In FIG. 3, 1 is a drive shaft. The drive shaft 1 is driven by a diesel engine, and rotates a rotary feed pump 3 mounted in a pump housing 2. The feed pump 3 sucks up fuel from a fuel tank 4, and a pressure regulating valve. This fuel is pressure-controlled by 5 and then supplied to the low-pressure fuel chamber 6 in the pump housing 2.

A plunger 8 is connected to the drive shaft 1 via a coupling 7, and the plunger 8 is integrally provided with a face cam 9. Above coupling 7
Transmits the rotation of the drive shaft 1 to the plunger 8 and allows the plunger 8 to move freely in the axial direction.

The face cam 9 is provided with a cam profile 9a having a plurality of ridges corresponding to the number of cylinders of the engine in the circumferential direction on the surface opposite to the surface to which the plunger 8 is connected. The cam roller 10 is in rolling contact with 9a. By the cam roller 10 rollingly contacting the cam profile 9a, the face cam 9 and the plunger 8 reciprocate a plurality of times during one rotation, that is, a plurality of reciprocating movements depending on the number of cylinders of the engine.

The cam profile 9a is set to have a shape such that an optimum fuel injection pressure and injection timing can be obtained in order to match the desired engine performance.

During the intake stroke of the plunger 8, when one of the intake grooves 11 formed on the peripheral surface of the distal end of the plunger 8 communicates with the intake port 12, the fuel in the low pressure fuel chamber 6 is introduced through the introduction passage 13 into the plunger 8. Is sucked into the pressure pump chamber 14 formed at the tip of the.

During the compression stroke of the plunger 8, the fuel in the pumping pump chamber 14 is pressurized, and the pressurized fuel is supplied to the plunger 8.
Is extruded into the vertical hole 15 formed inside. At this time, since the plunger 8 is rotating, when the supply port 16 opened on the circumferential surface communicates with one of the plurality of discharge ports 17, the fuel flows from the injection passage 18 through the delivery valve 19 and the fuel. It is supplied to the injection valve 20.

A spill ring 21 is slidably fitted in the plunger 8, and the spill ring 21 opens and closes a spill port 22 formed in the plunger 8.
The spill port 22 communicates with the vertical hole 15.

The fuel injection valve 2 passes through the injection passage 18 from the vertical hole 15 through the supply port 16 and the discharge port 17.
When the spill port 22 opens the spill ring 21 while the fuel is being pumped to 0, the fuel in the vertical hole 15 is released from the spill port 22 to the low pressure fuel chamber 6. Therefore, the fuel supply to the fuel injection valve 20 is stopped. Therefore,
The spill ring 21 controls the fuel injection amount.

The spill ring 21 is connected to a control lever 23 and a tension lever 24 via a joint 46. These control levers 23
The tension lever 24 is rotatably attached to the guide lever 26 via the pin 25.

The guide lever 26 is rotatably attached to the pump housing 2 by another pin 27, and the guide lever 26 is urged to rotate in one direction by a pressing spring 28. The upper end contacts a full load stopper 29 for adjusting the maximum injection amount.

The control lever 23 and the tension lever 24 are urged in a direction in which they are separated from each other by a start spring 30 and an idle spring 31 provided therebetween. Also, the tension lever 2
A protrusion 32 is formed on the control lever 4. When the protrusion 32 hits the control lever 23, the control lever 23 and the tension lever 24 rotate integrally with the pin 25 as a fulcrum.

The control lever 23 is a centrifugal governor 5.
It is adapted to be pushed by the governor sleeve 33 of 0.
The governor sleeve 33 is slidably covered on the governor shaft 39, and therefore is guided by the governor shaft 39 so as to be movable in the axial direction. The governor sleeve 33 generates thrust by the operation of the flyweight 34. Be done. The flyweight 34 is rotated integrally with the driven gear 35 to generate a centrifugal force, and the centrifugal force gives a thrust to the governor sleeve 33. The driven gear 3
Reference numeral 5 meshes with a drive gear 36 attached to the drive shaft 1.

Therefore, the rotation of the engine is transmitted from the drive shaft 1 to the flyweight 34 of the centrifugal governor 50 through the drive gear 36 and the driven gear 35, and the centrifugal force generated by the flyweight 34 applies a thrust to the governor sleeve 33. give. For this reason, the control lever 23 is pushed according to the number of rotations of the engine. Therefore, the control lever 23 rotates about the pin 25, which moves the spill ring 21 in the axial direction and changes the fuel injection amount. regulate.

A load sensing timer (LST) described later is formed between the governor sleeve 33 and the governor shaft 39 of the centrifugal governor 50.

On the other hand, the upper end of the tension lever 24 is connected to one end of a control spring 37, and the other end of the control spring 37 is an operating lever 38.
Is linked to. The operating lever 38 is operated by an accelerator pedal (not shown) not shown. When the operation lever 38 is rotated by the accelerator pedal, the tension lever 24 is moved through the control spring 37.
Is rotated about the pin 25, so that the spill ring 21 is moved in the axial direction. Therefore, the fuel injection amount can be controlled also by the accelerator operation amount.

The cam roller 10 with which the face cam 9 is in rolling contact is supported by a roller ring 40, and this roller ring 40 is connected to a timer piston 42 via a rod 41. The timer piston 42 is housed in the timer pressure chamber 43, and the fuel pressure in the low pressure fuel chamber 6 is introduced into the timer pressure chamber 43.

When the fuel pressure in the timer pressure chamber 43 is changed according to the pressure in the low pressure fuel chamber 6, the timer piston 42 is displaced in the axial direction, and this displacement causes the roller ring 40 to rotate in the circumferential direction via the rod 41. To move. Therefore, since the cam roller 10 is displaced in the circumferential direction relative to the face cam 9, the timing at which the mountain portion of the face cam 9 rides on the cam roller 10 changes, and the injection timing is controlled by this.

The timer-piston 42 and the timer pressure chamber 43 are actually provided in a direction perpendicular to the plane of the drawing, but for convenience of drawing, they are shown as illustrated.

Next, the load sensing timer (LST) formed between the governor sleeve 33 and the governor shaft 39 of the centrifugal governor 50 will be described.

The governor sleeve 33 is formed with a plurality of orifices 51 and 52 which are axially separated from each other. A plurality of these orifices 51 and 52 are formed in the circumferential direction at positions separated from each other in the axial direction. In the present embodiment, two orifices 51 are provided in each of the two positions separated from each other in the axial direction.
A total of four orifices 51, 51, 52, 52 are formed. Further, annular grooves 53 and 54 are formed on the inner surface of the governor sleeve 33 so as to be separated from each other in the axial direction.
The respective annular grooves 53, 54 are in communication with the respective orifices 51, 51 and 52, 52 which are spaced apart in the circumferential direction.

In contrast to such a governor sleeve 33, the governor shaft 39 is formed with ring grooves 55 and 56 axially separated from each other. The separation distance between the ring grooves 55 and 56 that are separated in the axial direction is set to be equal to the separation distance in the axial direction of the annular grooves 53 and 54 formed on the inner surface of the governor sleeve 33.

A fuel escape passage 57 is formed in the inside of the governor shaft 39 along the axial direction, and the fuel escape passage 57 is formed with the through holes 58, 5 respectively.
9 to the ring grooves 55 and 56.

Although not shown in detail, the fuel escape passage 57 is connected to the fuel tank 4 via the pressure adjusting valve 5 shown in FIG.

The operation of the embodiment having such a structure will be described.

When the engine load is increased, the operation lever 38 shown in FIG. 3 is rotated by the accelerator pedal, and the tension lever 24 is moved through the control spring 37.
When is rotated counterclockwise, the spill ring 21 moves axially to the right in the figure, so that the fuel injection amount can be increased.

In this case, the governor sleeve 33 of the centrifugal force governor 50 is regulated by the control lever 23 and is shown in FIG.
(A), the annular grooves 53, 54 formed on the inner surface of the governor sleeve 33 are located on the left side of the drawing, and therefore the ring grooves 55, 5 formed on the outer surface of the governor shaft 39.
Not connected to 6.

For this reason, the fuel pressure in the low-pressure fuel chamber 6 in the pump housing 2 is kept relatively high, so that the timer piston 42 is pushed by the fuel pressure in the timer pressure chamber 43 and the peak portion of the face cam 9 is formed. The pressing timing of the cam roller 10 is controlled and the injection timing is set to the advance side.

As is apparent from FIG. 4, this state is the same as that of the above-mentioned Japanese Utility Model Publication No. 59-36675.

When the rotation of the operating lever 38 by the accelerator pedal is released in order to reduce the load on the engine, the tension lever 24 is rotated clockwise by the action of the control spring 37, so that the spill ring 21 moves to the left side in the drawing. Since it moves, the fuel injection amount is reduced.

At this time, the governor sleeve 33 of the centrifugal governor 50 is released from the regulation of the control lever 23. Therefore, the flyweight 34 of the centrifugal force governor 50 rotated by the rotation of the drive shaft 1 via the drive gear 36 and the driven gear 35 causes the governor sleeve 33 to move.
Moves to the right as shown in FIG.

Therefore, the annular grooves 53 and 54 formed on the inner surface of the governor sleeve 33 are electrically connected to the ring grooves 55 and 56 formed on the outer surface of the governor shaft 39. Therefore, the fuel in the low-pressure fuel chamber 6 in the pump housing 2 is guided from the orifices 51, 51, 52, 52 to the ring grooves 55, 56 via the annular grooves 53, 54, and escapes through the conduction holes 58, 59. It flows into the passage 57 and escapes to the fuel tank 4 via the pressure regulating valve 5 shown in FIG.

That is, the fuel in the low-pressure fuel chamber 6 is released to the fuel tank 4, so that the fuel pressure in the low-pressure fuel chamber 6 decreases, and the fuel pressure in the timer pressure chamber 43 also decreases, so that the timer piston 42 operates. The injection timing is controlled to the retard side by correcting the pressing timing of the mountain portion of the face cam 9 and the cam roller 10.

That is, when the engine load is reduced to reduce the fuel injection amount, the load sensing timer (LST) formed between the governor sleeve 33 and the governor shaft 39 of the centrifugal governor 50 acts to operate the low pressure fuel chamber. The fuel of No. 6 is released to the fuel tank 4, the timer piston 42 is operated, and the injection timing is controlled to the retard side, so that the emission amount of NO _x can be regulated.

In this embodiment, the governor sleeve 33 has a plurality of orifices 51, 5 spaced apart in the axial direction.
1, 52, 52 are provided, and a plurality of axially spaced annular grooves 53, 54 communicating with the respective orifices 51, 51 and 52, 52 are formed on the inner surface, while the governor shaft 39 is provided with an axial direction. Ring grooves 55, 5 separated from each other
6 is formed, when the governor sleeve 33 moves to the right side as shown in FIG. 2B, all the orifices 51, 51, 52, 5 formed in the governor sleeve 33 are formed.
2 conducts to the ring grooves 55 and 56 through the annular grooves 53 and 54, and communicates with the fuel escape passage 57.

That is, the operation of the governor sleeve 33 allows the fuel in the low-pressure fuel chamber 6 to quickly escape to the fuel tank 4 side. In other words, as shown in FIG. Since the area of the escape passage for escape to the tank 4 side increases, the escape amount of fuel also increases, and therefore the fuel pressure in the low-pressure fuel chamber 6 is promptly reduced.

As a result, the timing of controlling the injection timing to the retard side can be made sensitive as the fuel injection amount decreases, and as shown by the solid line in FIG. It becomes possible to meet the newly set LST standard.

In the above embodiment, the governor sleeve 3
3, the orifices 51, 51, 52, 52 are formed at two positions axially separated, the annular grooves 53, 54 are provided at two positions axially separated, and the ring grooves 55, 56 of the governor shaft 39 are provided. Also, although it is formed at two locations separated from each other in the axial direction, it may be formed at three or more locations along the axial direction.

[0049]

As described above, according to the present invention, the plurality of annular grooves, which are axially separated by the movement of the governor sleeve, communicate with the plurality of ring grooves formed in the governor shaft at the same time. Since the area of the escape path can be increased, the fuel in the housing can be quickly escaped to the low pressure side through the fuel escape passage. For this reason, the fuel pressure in the housing is rapidly reduced to promptly actuate the timer piston to the retard side, and as a result, the injection timing is controlled, so that a rapid retard characteristic is obtained for a minute change in the injection amount. be able to. Therefore, it becomes possible to satisfy the new LST standard, which is a severe condition.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a load sensing timer set in a centrifugal governor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a detailed structure of the load sensing timer of the embodiment, in which (A) is a state before the operation and (B) is a state after the operation.

FIG. 3 is a diagram showing an overall structure of a distribution type fuel injection pump of the embodiment.

FIG. 4 is a characteristic diagram showing a relationship between a fuel injection amount and a timer advance angle.

FIG. 5 is a characteristic diagram showing a relationship between a fuel injection amount and an escape passage area.

[Explanation of symbols]

1 ... Drive shaft, 2 ... Housing, 4 ... Fuel tank, 6 ... Low-pressure fuel chamber, 8 ... Plunger, 9 ... Face cam, 10 ...
Cam roller, 14 ... Pressure pump chamber, 20 ... Fuel injection nozzle, 21 ... Spill ring, 22 ... Spill port, 23 ...
Control lever, 24 ... Tension lever, 50 ...
Centrifugal force governor, 33 ... Governor sleeve, 34 ... Fly weight, 39 ... Governor shaft, 42 ... Timer piston, 43 ... Timer pressure chamber, 51, 52 ... Orifice, 5
3, 54 ... Annular groove, 55, 56 ... Ring groove, 57 ... Fuel escape passage, 58, 59 ... Conducting hole.

Claims (1)

[Claims] 1. A plunger reciprocates a plurality of times during one revolution of the engine by a cam roller rotated by the engine and a face cam rollingly contacting the cam roller, and the reciprocating motion of the plunger pressurizes the fuel in the pumping pump chamber. While injecting fuel into each cylinder of the engine, fuel is pumped into the housing of the injection pump by the feed pump, the timer piston is activated by receiving the fuel pressure in this housing, and the cam roller is moved by the timer piston to inject the fuel. The spill ring slidably attached to the plunger is opened to open the spill port to control the fuel injection amount, and the spill ring is a governor of the centrifugal governor that responds to the rotation of the engine. The sleeve is activated by the While forming the orifice in the
The governor shaft that guides the governor sleeve has a fuel escape passage communicating with the low pressure portion.When the above-mentioned orifice communicates with the fuel escape passage of the governor shaft due to the operation of the governor sleeve, the fuel in the housing passes through this fuel escape passage. Then, the fuel pressure in the housing is reduced, the fuel pressure in the housing is reduced, and the timer piston is activated.As a result, in the distribution type fuel injection pump that controls the injection timing, the governor sleeve is separated from the axial direction. A plurality of orifices and annular grooves connected to these orifices are provided on the inner surface of the governor sleeve, and the governor shaft is provided with a plurality of ring grooves for conducting the respective annular grooves by the movement of the governor sleeve to guide the fuel to the fuel escape passage. A distributed fuel injection pump characterized by being provided.