JP2516080Y2 - Fuel injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a fuel injection pump, and more particularly to a fuel injection pump capable of reliably shutting off the fuel fed to a cylinder.

[Prior Art] Generally, in a fuel injection pump used in a diesel engine or the like, fuel is supplied to all cylinders during high-load operation of the engine, while fuel supplied to a predetermined cylinder is shut off during low-load operation. It is necessary to operate the engine with reduced cylinders.

By the way, conventionally, there is known one in which a plunger surface of a fuel injection pump is cut out and the plunger is rotated by a rack and pinion mechanism to adjust the cutout position to cut off the fuel supply to the cylinder. ing.

However, in the case of simply making a notch on the plunger surface and rotating the plunger to reduce the cylinder operation of the engine, especially when adopted in a fuel injection pump with a large number of plungers, the rotation of each plunger is in phase. It becomes difficult to adjust with.

Therefore, conventionally, a so-called fuel cutoff device that cuts off or changes the flow path of the fuel has been generally attached to the injection pipe that connects the fuel injection pump and the nozzle.

[Problems to be Solved by the Invention] However, when the fuel cutoff device is attached to the injection pipe to cut off the fuel as described above, the fuel pressure in the injection pipe becomes high, so the fuel should be cut off completely. There was a problem that I could not do it.

In addition, as an injection pump having a function of shutting off fuel, there is Japanese Utility Model Laid-Open No. Sho 62-188548. However, this Japanese Utility Model No. 62-188548 is designed to open and close the barrel port with a ball valve so that the supply of fuel to the plunger chamber can be shut off. If the seat is not properly seated, fuel may be supplied and injected into the plunger chamber, and it may not be possible to completely cut off the fuel supply. Further, since the plunger chamber has a negative pressure when the plunger descends, fuel may be supplied and injected into the plunger chamber through the clearance between the plunger and the plunger barrel, and it may not be possible to completely cut off fuel supply. .

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel injection pump capable of reliably shutting off the fuel fed to the cylinder.

[Means for Solving the Problems] The present invention relates to a plunger barrel that defines a pressure chamber for pumping fuel, a suction port that is housed in the plunger barrel so as to be movable up and down, and one end of which opens to the pressure chamber, and A plunger having a groove formed on the other end of the suction port and a plunger slidably fitted to the plunger to perform prestroke control by vertical movement thereof, and communicate with the oil reservoir chamber and the groove outside thereof. A sleeve having a spill port and the plunger barrel are formed to communicate the pressure chamber and the oil reservoir chamber, and when the sleeve is set to have a small prestroke, the plunger has the groove and the spill port. When it is in a position where it does not communicate, the fuel in the pressure chamber is returned to the oil reservoir chamber and the plunger is raised. The fuel discharge port is closed by the plunger when the groove and the spill port communicate with each other.

[Operation] When the pre-stroke is set small by lowering the sleeve, and when the plunger is in a position where the groove and the spill port do not communicate with each other in the process of ascending the plunger, the fuel discharge port opens to open the pressure chamber and the oil reservoir chamber. The fuel in the pressure chamber is returned to the oil reservoir through communication. When the plunger moves up to the position where the groove and spill port communicate with each other as the plunger rises, the fuel discharge port is blocked by the plunger and fuel does not move through it, but now the fuel is in the suction port, groove and spill port. Since the oil sequentially passes through the ports and flows into the oil reservoir, the fuel in the pressure chamber is not pressurized. Therefore, the fuel is not pressure-fed regardless of the rise of the plunger, so that the oil supply can be interrupted and the cut-off cylinder operation can be surely executed.

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

As shown in FIG. 2, the fuel injection pump according to the embodiment has a cam 2 rotatably supported by a pump housing 1 via a bearing 3. And on the cam 2,
Plunger 5 is placed via roller tappet 4 at predetermined intervals. An upper end portion and an intermediate portion of the plunger 5 are vertically movably guided by a plunger barrel 6 and an inner sleeve 7, which are concentrically fixed to the pump housing 1. Also, the plunger 5
The cam 2 is urged downward by the compression coil spring 8.
It is possible to move up and down with a predetermined stroke while interlocking with the rotation of. A pressure chamber 10 is defined by the top surface of the plunger 5 and the inner peripheral surface of the plunger barrel 6. An equal pressure valve 9 as a discharge valve is attached to the upper part of the plunger barrel 6 so as to face the pressure chamber 10. When the fuel pressure in the pressure chamber 10 reaches a predetermined value or more, the equal pressure valve 9 opens and the pressure chamber 10 The fuel inside can be sent to the cylinder through an injection pipe (not shown).

On the other hand, in the pump housing 1, as shown in FIG. 1, an oil reservoir chamber 11 is defined by the plunger barrel 6 and the inner sleeve 7. Then, in the oil sump chamber 11, an oil passage 12 formed along the arrangement direction of the plungers 5 is formed.
Are communicated with each other, and fuel such as light oil stored in a fuel tank (not shown) passes through the oil passage 12 to constantly maintain the oil storage chamber 11
Are supplied within.

As shown in FIG. 1, a vertical groove is formed on the outer peripheral surface of the plunger 5.
A groove composed of 13 and oblique groove 14 is formed. The plunger 5 is formed with a suction port 16 that connects the upper bottom surface of the vertical groove 13 and the pressure chamber 10 to each other.
A substantially tubular sleeve 17 is fitted and guided so as to be vertically movable and slidable. Further, as shown in FIG. 3, the sleeve 17 has a spill port 18 penetratingly formed along its radial direction. Therefore, normally, when the plunger 5 rises in conjunction with the rotation of the cam 2, the process from the time when the vertical groove 13 is closed by the sleeve 17 to the time when the oblique groove 14 opens to the spill port 18 (hereinafter referred to as the pressurizing process). ), The vertical groove
Since the slanted groove 13, the slanted groove 14 and the spill port 18 are closed to each other, the recirculation of the fuel in the pressure chamber 10 is blocked, and the fuel is pressurized and pumped. However, in the case of the illustrated example, as will be described later in detail, pressurization / pressure feeding is not performed under a certain condition.

Further, an engaging groove 19 is formed on the outer peripheral surface of the sleeve 17 along the horizontal direction, and an engaging pin 21 protruding in the radial direction of the control rod 20 is fitted into the engaging groove 19. Have been combined. As shown in FIG. 3, the control rod 20 is arranged along the arrangement direction of the plungers 5, and both ends thereof are rotatably supported by bearings 22 and 23. Then, by controlling the amount of rotation of the control rod 20, the sleeve 17 moves up and down in conjunction with the rotation of the control rod 20, and the start point of the pressure stroke, that is, the prestroke can be adjusted. .

By the way, in this embodiment, as shown in FIG. 3, fuel can be sent to a total of 10 cylinders.
The fuel sent to the five cylinders can be shut off. It is the pumps that are odd-numbered from the left end in FIG. 3 that interrupt the fuel supply.

In this embodiment, as will be described later in detail, when the prestroke is set small by the sleeve 17, the fuel in the pressure chamber 10 escapes to the outside of the pressure chamber 10 during the pressurizing stroke of the plunger 5. A fuel discharge port 24 is formed in the plunger barrel 6 to disable pumping.
The fuel discharge port 24 is formed so as to connect the pressure chamber 10 and the oil reservoir chamber 11, and the opening 25 to the pressure chamber 10 is
By moving the sleeve 17 up and down by a predetermined operation amount, the sleeve 17 is provided above and below the sleeve 17 at positions where the above-mentioned pressurizing stroke occurs. As shown in FIG. 4, when the fuel is pressure-fed by the pressurizing stroke generated above the fuel discharge port 24, that is, in the injectable region, when the pressurizing stroke occurs below the port 24. The fuel in the pressure chamber 10 is returned to the oil reservoir chamber 11 through the port 24 so that the fuel sent to the cylinder can be reliably shut off.

 Next, the operation of this embodiment will be described.

First, when the control rod 20 is rotated, the sleeve 17 is lowered, and the prestroke is set to a small value, the plunger 5 is raised by the rotation of the cam 2, and as shown in FIG. The vertical groove 13 is closed by the sleeve 17 in a state where 24 is opened to the pressure chamber 10.
Then, when the plunger 5 further rises, the inclined groove 14 reaches the spill port 18, but during this time, the open state of the fuel discharge port 24 is maintained. Therefore, in this process, the fuel in the pressure chamber 10 is returned to the oil reservoir chamber 11 through the fuel discharge port 24, and the fuel is not pumped. Then, as shown in FIGS. 5C and 5D, when the plunger 5 is further raised and the fuel discharge port 24 is closed,
Since the vertical groove 13 and the suction port 16 move upward from the upper surface of the sleeve 17 and open to the oil sump chamber 11, the fuel in the pressure chamber 10 is returned to the oil sump chamber 11 through the suction port 16,
Never pump fuel.

Next, when the plunger 5 is raised by the rotation of the cam 2 in a state where the control rod 20 is rotated, the sleeve 17 is raised, and the prestroke is set large, when the plunger 5 is raised, as shown in FIGS. ), The vertical groove 13 is closed by the sleeve 17 after the fuel discharge port 24 is closed by the plunger 5. Then, when the plunger 5 further rises, the vertical groove 13, the oblique groove 14, and the fuel discharge port 24 are kept closed by the sleeve 17 and the plunger 5, respectively, and the fuel in the pressure chamber 10 is pumped. Then, as shown in FIG. 6 (d), the slanted groove 14 is a spill port.
When it reaches 18, the fuel in the pressure chamber 10 is returned to the oil reservoir chamber 11 through the inside of the spill port 18, and the pressure feeding of the fuel is completed.

As described above, according to this embodiment, when the pressurizing stroke of the plunger 5 caused by the engagement between the plunger 5 and the sleeve 17 is set to the small prestroke, the fuel pressure feeding by the pressurizing stroke is invalid. Therefore, it is possible to reliably cut off the fuel supply to the cylinder.

In addition, since the fuel discharge port 24 can be easily formed in the plunger barrel 6, the fuel discharge port 24 can have a relatively large diameter and high precision. From this point as well, the shutoff of the fuel can be ensured.

Further, this fuel cutoff is performed only by rotating the control rod 20 and lowering the sleeve 17 to set the prestroke low. Therefore, the fuel injection pump itself is not increased in size and a predetermined amount of fuel is not required. It is possible to easily, reliably and simultaneously shut off the fuel to the cylinders.

It should be noted that in the above-described embodiment, it has been described that the pre-stroke is made variable to switch between the pressure feeding and the shut-off of the fuel. By controlling the rotation of the rod 20, the fuel injection timing and the oil feed rate can be varied, which is extremely effective.

Further, a normal STD type structure is adopted around the plunger 5 of the even-numbered cylinder from the left end of FIG. 3 in which the cylinders cannot be reduced, but instead of this, the fuel discharge port 24 of the above embodiment is removed. A configuration around the plunger 5 may be adopted. In this case, it is possible to simultaneously cut off the fuel and change the oil transfer rate.

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

With an extremely simple structure, the fuel sent to the cylinder can be completely cut off. Then, when the diesel engine or the like is operated at a low load, it is possible to reliably reduce the number of predetermined cylinders, which is advantageous in terms of fuel consumption and the like.

[Brief description of drawings]

FIG. 1 is a sectional view showing an essential part of an embodiment of the present invention, FIG. 2 is a side sectional view showing an entire embodiment of the present invention, and FIG. 3 is a plane sectional view showing the entire embodiment of the present invention. FIG. 4 and FIG. 4 are cam angle-cam lift diagrams showing the operating region of one embodiment of the present invention,
FIG. 5 is an explanatory diagram showing an operation in the case of interrupting the fuel supply of fuel, and FIG. 6 is an explanatory diagram showing an operation in the case of executing the fuel supply of fuel. In the figure, 5 is a plunger, 6 is a plunger barrel, 10 is a pressure chamber, 16 is a suction port, 17 is a sleeve, and 24 is a fuel discharge port.

Claims (1)

(57) [Scope of utility model registration request] 1. A plunger barrel for defining a pressure chamber for pumping fuel, a suction port that is housed in the plunger barrel so as to be movable up and down, and has one end formed at the suction port opening to the pressure chamber and the other end of the suction port. A plunger having a groove, and a sleeve having a spill port that is slidably fitted to the plunger and performs prestroke control by vertical movement of the plunger and that communicates with the outer oil reservoir and the groove. The plunger barrel is formed to communicate with the pressure chamber and the oil reservoir chamber, and when the pre-stroke is set to be small by the sleeve, the plunger is opened when the groove and the spill port are not in communication with each other. Then, the fuel in the pressure chamber is returned to the oil reservoir chamber, and the plunger is raised to communicate the groove and the spill port. Fuel injection pump being characterized in that a fuel discharge port is closed by the plunger when in the position to.