JP2516082Y2 - Fuel rate control type fuel injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a fuel injection rate control type fuel injection pump in which a pre-stroke adjusting mechanism is incorporated in a row type injection pump.

[Prior Art] The well-known in-line injection pump used in many diesel engines forms a spill port directly on the plunger barrel, so that the plunger closes the spill port and starts pumping fuel. The prestroke cannot be changed.

For this reason, in recent years, the plunger for pumping the fuel in the barrel of the row-type injection pump has been improved, and a control sleeve for varying the prestroke in cooperation with the plunger has been slidably fitted into the plunger. A fuel injection rate control type fuel injection pump (such as "fuel injection device for internal combustion engine" (Japanese Utility Model Publication No. 61-110884)) has been proposed.

The construction and operation of this type of fuel injection rate control type fuel injection pump will be described below.

As shown in FIG. 7, a cylindrical barrel 3 is formed in the upper part of the pump housing 1 to partition and form the fuel pressure chamber 2. The barrel 3 has a barrel 3 for pumping the fuel in the pressure chamber 2. The plunger 4 is slidably fitted.
The plunger 4 has an outer peripheral surface 5 as shown in FIG.
After being once opened radially inward from, the connecting path 6 is formed that is bent in the axial direction at the axial position of the plunger 4 and opens at one end surface (end surface on the barrel 3 side) of the plunger 4.
The radial opening of the communication path 6 serves as a fuel intake port 7, and the opening on the end surface on the side of the balles 3 serves as a fuel supply port 8. A lead 9 is formed on the outer peripheral surface of the plunger 4 starting from the suction port 7 side, and the lead 9 and the suction port 7 are formed by a notch groove 10 formed along the axial direction of the plunger 4. It is in communication. The lead 9 of the plunger 4 has a rectangular cross section and is formed along the lead direction of the screw.
It is about 1/4 of the circumference of. On the other hand, the control sleeve 11 is formed in a cylindrical shape slidably fitted on the outer peripheral surface of the plunger 4. The entire length of the control sleeve 11 is longer than the length from the lower end position of the suction port 7 to the barrel side end of the lead 9. The spill port 12 for fuel is provided in the control sleeve 11 at a position spaced from the terminal end position of the lead 9 to the barrel 3 side at a position where the lower end side of the control sleeve 11 completely closes the intake port 7. Is formed.

According to this structure, the fuel sucked from the suction port 7 opened at the bottom dead center of the plunger 4 is supplied into the parel 3 through the communication path 6, and the plunger 4
The pressure stroke of the plunger 4 is started when the suction pressure reaches the position where the suction port 7 is closed by the control sleeve 11. When the lifting of the plunger 4 progresses to the position where the end of the lead 9 and the spill port 12 sign, the fuel is discharged from the spill port 12 and the pressure feeding period of the fuel ends.

Therefore, in order to change the prestroke of the plunger 4 for starting the pressure feeding of the fuel, the control sleeve 11 is moved relative to the plunger 4 and the suction port 7 is moved.
Adjust the closing time of.

Therefore, as shown in FIG. 7, the control sleeve is
A hole or groove-shaped engaging portion 13 is formed on the outer peripheral surface of 11, and a pin 15 integral with the control rod 14 is engaged with the engaging portion 13 and the control rod 14 is rotated to position the control sleeve 11. I am trying to adjust. The control rod 14 is configured to be controlled by an actuator electrically controlled by a controller (not shown).
Various kinds of actuators such as rotary solenoids, stepping motors, hydraulic pumps can be used.
For example, the actuator may be a U-shaped rotary solenoid 16 surrounding the control rod 14 as shown in FIG.
In the case of the above construction, the return spring 31 is provided by hooking it on the control rod 14 and the rotary solenoid 16.

As a result, the control rod 14 is rotated until the rotary solenoid 16 is balanced with the urging force of the return spring 31, and the control sleeve 11 can be adjusted to the rotational position. Therefore, it is possible to change the prestroke of the plunger 4 by uniquely determining the original position of the control sleeve 11 with respect to the bottom dead center of the plunger 4 and determining the rotation angle of the rotary solenoid 15.

By the way, in the fuel injection rate control type fuel injection pump configured to adjust the prestroke of the plunger 4 by the plunger 4 and the control sleeve 11 as described above,
It is necessary to give sufficient consideration to the mutual contact between the fitting surfaces of the plunger 4 and the control sleeve 11 and the viscosity of the fuel between the fitting surfaces. That is, in the fuel injection rate control type fuel injection pump, the input of vibration of the engine as external force (disturbance force) and vibration input from the road surface acts on the rotation center of the rotary solenoid 16 and the control rod 14. , The vibration input is the pin 15 and the engaging portion 13 of the control sleeve 11 as a radius, and a rotation moment is generated with the load as the vibration input, and this rotation moment is applied to the control sleeve 11 as friction, so that it is accurate and stable. It was difficult to adjust the target prestroke position of the plunger 4. Therefore, as shown in FIG. 9, the control rod 14 has an arm 17 at a position symmetrical with the pin 15 on the axis.
To attach the counterweight 18 to the arm 17 and a tubular member 19 is integrally attached to the tip of the arm 17 as shown in FIG. 10, and the tubular member 19 is attached to the tubular member 19. Proposals for fitting a relatively sliding guide 20 have attempted to cancel the rotational moment.

[Problems to be Solved by the Invention] However, as shown in FIGS. 9 and 10, the plunger 4 and the sleeve 11 are configured to cancel the rotational moment.
However, the target prestroke control was not sufficient due to the friction still acting.

That is, the lead 9 of the plunger 4, the spill port 12 of the control sleeve 11, and the force generated by the high-speed fuel flow associated with the supply and discharge of fuel at both end surfaces of the control sleeve 11, and the control sleeve as the plunger 4 slides.
This is because a force dragging 11 is generated, and these forces make it difficult to perform accurate and stable target prestroke adjustment.

Of these external forces, the former is a small force determined by the number of revolutions and the amount of oil fed, so the latter has the greatest effect on the target prestroke.

The latter is caused by the local hydraulic deformation of the plunger 4 and the control sleeve 11 during the oil feeding process (pressurizing process) of the plunger 4. That is, as shown in FIG. 11, because the high pressure of the fuel acts on the lead 9, the diameter of the control sleeve 11 on the end face side from the start point and the end point of the lead 9 is reduced to be smaller than the diameter of the control sleeve 11 on the lead 9 side. The sliding surfaces of the sleeve 11 and the plunger 4 come into contact with each other with a large sliding resistance, which causes a so-called "hugging" phenomenon of the control sleeve 11 with respect to the plunger 4. As a result, in the course of the relative movement of the plunger 4 and the control sleeve 11, relative vibrational friction is applied to each other.

As a result, accurate and stable target prestroke adjustment becomes difficult. In addition, "hugging" causes oil film breakage on the sliding surface (poor lubrication), metal contact, and seizure and sticking. As a result, the fuel injection timing fluctuates, and various performances such as in-cylinder (explosion) pressure of the engine change. The fluctuation of the prestroke affects the injection amount due to the cycle of the vibration, and also causes the fluctuation of the engine output and the engine torque.

In order to solve the above-mentioned problems, it is conceivable to improve the absolute capacity of the actuator or attach a dashpot to the counterweight, but this is not preferable from the viewpoint of cost and layout.

[Means for Solving the Problems] The present invention is intended to solve the above problems, and a plunger having a lead and a notch groove corresponding to the oil feeding range is formed on the outer peripheral surface, and is slidable on the plunger. And a control sleeve in which a spill port for discharging the fuel to the outside in conformity with the lead is fitted, in an oil rate control type fuel injection pump, at least one of the plunger and the control sleeve. A relief part is formed at a position spaced apart from the lead and the notch groove and corresponding to both ends of the control sleeve to avoid contact with the inner peripheral surfaces of both ends of the control sleeve. .

[Operation] In the oil feeding process of the plunger, since the high pressure of the fuel acts on the reed, the diameter of the control sleeve on the end face side, that is, on both ends from the start and end points of the reed is smaller than the diameter of the control sleeve on the reed side, that is, the central part Although it will be reduced in size, if at least one of the plunger and the control sleeve is formed with an escape portion for avoiding contact with the inner peripheral surfaces of both ends of the control sleeve,
There is no contact between the both ends of the reduced diameter and the plunger,
The so-called "hugging" of the control sleeve with respect to the plunger, in which the sliding surfaces of the control sleeve and the plunger contact each other with a large sliding resistance, does not occur. When the lifting of the plunger progresses to the lead end, that is, the position where the lift side end and the spill port sign, the fuel is discharged from the spill port and the fuel pumping period ends. As a result, accurate and stable target prestroke adjustment becomes possible, and the oil film on the sliding surface and metal contact due to "hugging" can be prevented. In particular, the escape portion is located at a distance from the lead and the notch groove and therefore does not communicate with them. Also, the escape part is
Since the control sleeve is formed at positions corresponding to both ends of the control sleeve, no contact occurs during the pressure feeding period of the plunger.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 5, the pump housing 1 is integrally mounted on the upper portion thereof with a bale 3 for partitioning and forming a cylindrical pressure chamber 2, and on the upper portion of the pump housing 1, the pressure chamber is formed. A well-known equal pressure valve 21 which functions as a discharge valve by being connected to the valve 2 is provided. That is, the equal pressure valve 21 is configured such that the plunger 4 is in the pressure feeding chamber 2 in the oil feeding process (pressurizing process).
When the fuel pressure in the cylinder rises above a predetermined level, the fuel is opened and the fuel in the pressure chamber 2 is injected into the cylinder (not shown) via an injection pipe (not shown).
It is configured to be able to send oil to. Further, in the pump housing 1, a cylindrical plunger 4 which is slidably fitted in the barrel 3 and pressurizes the fuel in the pressure chamber 2 is housed. The plunger 4 is reciprocally moved by a roller tappet 22 which is reciprocally housed in the lower portion of the pump housing 1. On the other hand, a cam shaft 23 for reciprocating the roller tappet 22 to drive the plunger 4 is rotatably supported at the lower part of the pump housing 1. Rotational support of the cam shaft 23 is provided by a bearing 24 integrally incorporated in the lower portion of the pump housing 1. On the cam shaft 23 side of the pump housing 1 that accommodates the plunger 4 in a reciprocating manner, a spring accommodating chamber 25 that is radially expanded outward in a cylindrical shape is defined. In the spring accommodating chamber 25, one end abuts on a spring retainer 26 seated on the upper part of the accommodating chamber 25, and the other end abuts on a spring retainer 27 integrally formed on the cam shaft 23 side of the plunger 4. A contacting return spring 28 is housed. On the other hand, in the upper part of the pump housing 1, an oil storage chamber 29 is formed so as to surround the shaft portion of the plunger 4 along the circumferential direction and introduce the fuel. An oil passage 30 communicates with the oil reservoir 29, and fuel such as light oil stored in a fuel tank (not shown) is continuously fed into the oil reservoir 29 via the oil passage 30. I am trying to supply it to.

Next, a configuration for adjusting the prestroke of the plunger 4 will be described.

As shown in FIGS. 5 and 6, the plunger 4 is temporarily opened radially inward from the outer peripheral surface thereof, and is then bent in the axial direction at the axial position of the plunger 4 so as to be bent in the axial direction.
Is formed on one end surface (end surface on the side of the balless 3) of the. The radial opening of the communication path 6 serves as a fuel intake port 7, and the opening on the end surface on the side of the balles 3 serves as a fuel supply port 8. A lead 9 is formed on the outer peripheral surface of the plunger 4 starting from the suction port 7 side, and a notch groove 10 formed along the axial direction of the plunger 4 communicates the lead 9 with the suction port 7. Let The lead 9 of the plunger 4 has a rectangular cross section and is formed along the direction of the lead 9 of the screw, and the length of the lead 9 is about 1/4 of the circumference of the plunger 4. On the other hand, the control sleeve 11 is formed in a cylindrical shape slidably fitted on the outer peripheral surface 5 of the plunger 4. The entire length of the control sleeve 11 is longer than the length from the position of the suction port 7 to the end of the lead 9 on the barrel side. The spill port 12 for fuel is provided in the control sleeve 11 at a position spaced from the terminal end position of the lead 9 to the barrel 3 side at a position where the lower end side of the control sleeve 11 completely closes the intake port 7. Is formed. According to this structure, the fuel sucked from the suction port 7 opened at the bottom dead center of the plunger 4 is supplied into the barrel 3 through the connecting path 6, and the lift of the plunger 4 is changed to the suction port. Plunger 4 when 7 is closed with control sleeve 11.
The pressurization process of is started. When the lifting of the plunger 4 progresses to the position where the end of the lead 9 and the spill port 12 sign, the fuel is discharged from the spill port 12 and the pressure feeding period of the fuel ends. A hole or groove-like engaging portion 13 is formed on the outer peripheral surface 5 of the control sleeve 11, and the engaging rod 13 has a control rod.
The control pin 14 is rotated by engaging an integral pin 15 with the control rod 14 to adjust the position of the control sleeve 11, that is, the prestroke with respect to the plunger 4. The control rod 14 is configured to be controlled by an actuator electrically controlled by a controller (not shown). As the actuator, various ones such as a rotary solenoid, a stepping motor, and a hydraulic pump can be used. For example, when the actuator is constituted by the U-shaped rotary solenoid 16 surrounding the control rod 14 as described in FIG. 14 and rotary solenoid 16 with return spring
Multiply by 31 and set up.

As a result, the control rod 14 is rotated until the rotary solenoid 16 is balanced with the urging force of the return spring 31, and the control sleeve 11 can be adjusted to the rotational position. Therefore, it is possible to change the prestroke of the plunger 4 by uniquely determining the original position of the control sleeve 11 with respect to the bottom dead center of the plunger 4 and determining the rotation angle of the rotary solenoid 16. It should be noted that the controller is configured to input engine load, rotation speed, cooling water temperature, fuel oil level, etc. from a sensor, correlate the input with an internal stored value, and perform arithmetic processing to operate the rotary solenoid 16. To be done.

An object of the present invention is to prevent "hugging" between the plunger 4 and the controller sleeve 11 and enable accurate and stable prestroke control.

Therefore, reexamining the mechanism and the place where the “hugging” occurs in the control sleeve 11, as shown by the dotted line in FIG. 11, the control sleeve 11
Is formed in a cylindrical shape thinner than the plunger 4, and therefore expands and deforms with respect to the high pressure of the fuel, but even if the axially intermediate side of the plunger 4 expands due to the high pressure of the fuel, the control sleeve 11 Since it expands more than that, "hugging" on the center side of the plunger 4 does not occur. Considering the vicinity of the lead 9, since the high pressure of the fuel acts on the lead 9,
"Hugging" occurs because the diameter of the control sleeve 11 on the end face side, that is, both end portions from the starting point and the end point is smaller than the diameter of the control sleeve 11 on the lead 9 side, that is, the central portion.

Therefore, a portion where the diameter of the control sleeve 11 on the end face side from the start point and the end point of the lead 9 is smaller than the diameter of the control sleeve 11 on the lead 9 side (reference numeral A in FIG. 11).
Although the pre-stroke control of the plunger 4 can be suitably executed by forming the relief portion that eliminates the “hugging” in (), the relief portion and the lead 9 are communicated with each other and the lead 9 of the lead 9 is substantially connected. If the volume is increased, the function of the plunger 4 for pumping fuel (pressure of fuel and amount of fuel to be fed) will be hindered, so it is necessary to consider this point. That is, the escape portion cannot be formed at the position of the lead 9.

Therefore, in the embodiment, as shown in the development view of the control sleeve 11 in FIG. 3, a relief is formed in a portion outside the envelope 33 of the prestroke adjustment range (a portion indicated by diagonal lines).

Specifically, as shown in FIG. 1, the fitting surface 33, which is the inner peripheral surface of the barrel side end of the control sleeve 11, is continuous from the barrel side edge of the spill port 12 to the barrel side edge of the control sleeve 11. And a relief portion 34 having a width substantially equal to the diameter of the spill port 12 is formed. As shown in FIG. 2, the relief portion 34 is formed as an arcuate recess with respect to the fitting surface 33.

On the other hand, as shown in the development view of FIG. 3, even if an attempt is made to form the relief portion 34 on the cam side end portion of the control sleeve 11, since most of the portion overlaps with the inside of the envelope 32 of the lead 9, In the portion, the escape portion 35 is formed in the plunger 4 without forming the escape portion 34.

That is, as shown in FIG. 4, the relief portion 35 is formed in the adjustment range of the control sleeve 11 (from the idle position to the full position).

Specifically, with respect to an imaginary lead position on the outer peripheral surface of the plunger 4, the lead 9 and the notch groove 10 are avoided from that position to a position on the cam side, and a circumferential interval is provided so as not to communicate with them. To form the escape portion 35. Further, in correspondence with the relief portion 34 formed around the spill port 12, a relief portion 36 having a projected area of a substantially parallelogram along the virtual line of the lead 9 at a position closer to the barrel 3 than the virtual line of the lead 9 is provided. To form. These relief portions 35, 36 are formed such that the length along the plunger longitudinal direction is slightly longer than the stroke (movement) length of the plunger 4 in the oil feeding stroke, and both end portions of the control sleeve 11 during the oil feeding stroke. It is always located at and is approaching. The escape portions 35 and 36 are also formed in an arc shape recessed from the outer peripheral surface 5.

 Next, the operation of this embodiment will be described.

As shown in FIG. 5, when the cam shaft 23 is rotationally driven, the plunger 4 is reciprocated by the roller tappet 22.
At the bottom dead center of the plunger 4, the intake port 7 on the outer peripheral surface of the shaft of the plunger 4 is opened, and fuel is supplied from the intake port 7 into the barrel 3. The lifting of the plunger 4 causes the suction port 7 on the outer peripheral surface 5 to move to the control sleeve 11
When the operation proceeds to the position closed by, the oil feeding process of the plunger 4 is started. In the oil feeding process, since the end surface on the barrel 3 side is supported by high pressure, the plunger 4 is compressed by the thrusting force of the cam at this time, and as a result, the plunger 4 is elastically deformed into a barrel shape. On the other hand, since the central portion of the control sleeve 11 has a large expansion, "hugging" does not occur. But,
Since the high pressure of the fuel acts on the lead 9, the diameter of the control sleeve 11 on the end face side from the start point and the end point of the lead 9 becomes smaller than the diameter of the control sleeve 11 on the lead 9 side. As shown in FIG. 4, a fitting surface (sliding surface) between the sleeve 11 and the plunger 4
In addition, since the relief portions 34, 35, 36 for maintaining a predetermined clearance are formed between the deformed portions of the sliding surface during the hydraulic deformation, the sliding surfaces of the control sleeve 11 and the plunger 4 slide with respect to each other. Like contacting with resistance,
"Hugging" does not occur. In particular, during the oil feeding process, the relief portions 35, 36 formed on the plunger 4 constantly come in contact with both ends of the control sleeve 11, so that "hugging" can be always prevented. As a result, "hugging"
As a result, an abnormal friction load is not applied to the control sleeve 11, and accurate and stable target prestroke adjustment can be performed. Therefore, the fuel injection timing becomes accurate, and various performances (engine output, engine torque, etc.) such as in-cylinder (explosion) pressure of the engine (not shown) become stable. In addition, the oil film on the sliding surface and the metal contact due to "hugging" are prevented, abnormal wear between the two is prevented, and its durability and reliability are improved.

When the lifting of the plunger 4 advances to a position where the end (end) of the lead 9 on the barrel 3 side and the spill port 12 sign, fuel is discharged from the spill port 12 and the fuel pumping engine is terminated.

The relief portions 34, 35, 36 may be provided on the plunger 4 and the control sleeve 11 by processing, or may be formed simultaneously as a material.

[Effect of the Invention] According to the present invention, the following excellent effects are exhibited.

(1) It is possible to eliminate the contact between the plunger and both ends of the control sleeve, prevent "hugging" at all times during the fuel pressure feeding period, and perform accurate and stable prestroke control of the plunger.

(2) It can be manufactured at low cost.

[Brief description of drawings]

1 is a development view showing an embodiment of the present invention, FIG. 2 is a plan view showing an embodiment of the present invention, FIG. 3 is a development view showing an embodiment of the present invention, and FIG. FIG. 5 is a development view showing an escape portion formed in the plunger, FIG. 5 is a cross-sectional view of an oil-feed rate control type injection pump according to the present invention, FIG. 6 is a perspective view of a combination state of a plunger and a control sleeve, and FIG. Is a cross-sectional view of an oil-feed rate control type injection pump as a conventional example, FIG. 8 is a perspective view showing an example of a prestroke adjusting device, and FIGS. 9 and 10 show a mechanism for suppressing friction of a control sleeve. A sectional view and FIG. 11 are explanatory views showing the control sleeve in a state of being deformed by fuel pressure or the like. In the figure, 3 is a barrel, 4 is a plunger, 6 is a connecting path, 9 is a lead, 10 is a notch groove, 11 is a sleeve, 12 is a spill port, and 34, 35 and 36 are relief portions.

Claims (1)

(57) [Scope of utility model registration request] 1. A plunger having a lead and a notch groove corresponding to an oil feeding range formed on an outer peripheral surface, and a plunger slidably fitted to the plunger and discharging the fuel to the outside in conformity with the lead. In a fuel injection rate control type fuel injection pump having a control sleeve in which a spill port is formed,
At least one of the plunger and the control sleeve is in contact with the inner peripheral surfaces of both ends of the control sleeve at positions corresponding to both ends of the control sleeve with a space between the lead and the notch groove. An oil feed rate control type fuel injection pump, characterized in that an escape portion for avoiding is formed.