JPH048862A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To improve following performance of a plunger to a motion of a control rack so as to stabilize an injection amount by providing an elastic body attached at a plunger small diameter part for pressing a driving face to a recess groove on an inner circumferential wall surface in a control sleeve. CONSTITUTION:In assembling a pump element 5, an elastic body 30 is inserted from a plunger lower end 9e while opening bent parts 31a and 31b, and an inner circumferential wall surface 31c of an elastic body main body 31 is attached to a plunger small diameter part 9d. Next, a plunger 9 to which the elastic body 30 is attached is inserted to an inner circumferential wall surface 8a of a cylinder 8. Then, a back part 32c of a curved part 32a presses a control sleeve inner circumferential wall surface 22a, and the inner circumferential wall surface 31c presses the plunger small diameter part 9d. And a driving face 9b is pressed to a groove end 22d of recess grooves 22b and 22c of a control sleeve 22, and a relative motion of the plunger 9 against the control sleeve 22 in the rotation direction is blocked.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an in-line fuel injection pump for diesel carrots, and more particularly to a fuel injection pump that stabilizes the amount of fuel injected.

(Prior art) The plunger that controls the injection amount of a conventional size-type fuel injection pump is reciprocated in the cylinder by a cam via a tappet, sucks fuel from the fuel chamber, pressurizes it, and then passes it to the delivery valve at the top of the cylinder. Open it and force feed it from the injection nozzle. Here, the fuel injection amount is adjusted by rotating a control sleeve fitted to the driving face of the plunger using a control rack, and changing the pumping stroke of the plunger.

When the rotational movement of the control rack is transmitted to the plunger via the control sleeve, the plunger moves slightly due to play between the control sleeve and the plunger, making the injection amount unstable. For example, US Pat. No. 4,793,316 is known in order to solve the instability.

(Problem to be Solved by the Invention) However, in the prior art disclosed in U.S. Pat. It is not possible to design a symmetrical shape. Therefore, it is necessary to manufacture the fitting part between the driving face and the control sleeve into a special shape, and since the existing plunger, driving face, control sleeve, etc. cannot be used as they are, there is a problem that the manufacturing cost is high.

The present invention has been made to solve these problems, and an object of the present invention is to provide a fuel injection pump that improves the ability of a plunger to follow the movement of a control rack and stabilizes the injection amount.

(Means for Solving the Problems) To achieve this, the fuel injection pump of the present invention includes a cylinder having a feed hole, and a notch with an oblique angle that can be slid back and forth within the cylinder and can face the feed hole. A plunger having a groove, a high pressure chamber communicating with the notch groove and facing the top surface of the plunger, a control sleeve rotatably guided around the cylinder outer periphery to adjust the injection amount, and a control sleeve formed in the small diameter portion of the plunger. and a driving face that is axially movably fitted into a concave groove on the inner circumferential wall surface of the control sleeve, the fuel injection pump being attached to the small diameter portion of the plunger and having a driving face that fits into the concave groove on the inner circumferential wall surface of the control sleeve. The driving face is characterized in that an elastic body is provided in the groove to press the driving face.

(Function) According to the fuel injection pump of the present invention, since the elastic body is provided that urges the driving face in one direction against the concave groove on the inner circumferential wall of the control sleeve, the connection between the control sleeve and the plunger via the driving face is Since backlash in the rotational direction is eliminated, the fuel injection amount adjustment position of the control sleeve can be accurately transmitted to the plunger via the driving face. This eliminates minute rotations around the axis of the plunger during the fuel pumping process, eliminating instability in the injection amount.

(Example) Embodiments of the present invention will be described below based on the drawings.

1 to 4 show a first embodiment of a square fuel injection pump to which the present invention is applied to a diesel engine.

A camshaft 2 that interlocks with the diesel engine is provided in the pump body l of the fuel injection pump shown in FIG. roller 3 and tappet 4 depending on the cam shape of this cam portion 2a.
Several cylinders of pump elements 5 are provided which move the plunger 9 up and down through the cylinders.

The pump element 5 is composed of a cylinder 8 fixed to the pump body I and a plunger 9 that reciprocates up and down within the cylinder 8. It is slidable in the axial direction and rotatable in the circumferential direction.

A high pressure chamber 0 is formed in the cylinder 8 facing the upper end of the plunger 9, and a delivery valve 12 is provided in this high pressure chamber 10.
is connected. When the pressure in the high pressure chamber 10 exceeds a predetermined value, the delivery valve 12 overcomes the biasing force of the spring 14 and pushes the valve 13 upward to forcefully deliver fuel from the valve holder 16.

A notched groove 18 formed by adding an oblique angle to the outer periphery of the plunger 9 can face a feed hole 19 formed in the cylinder 8, and by rotating the plunger 9, the notched groove 18 and the feed hole 19 can be faced. The timing at which the holes 19 overlap changes, that is, the fuel pumping distance changes to adjust the fuel pumping amount. The state shown in FIG. 2 shows the state in which the plunger 9 is at the top dead center, that is, at the uppermost position. Second
When the plunger 9 descends from the position shown in the figure, the fuel chamber 2
4 is sucked into the high pressure chamber 10 through the feed hole 19.

When the roller 3 rides on the cam portion 2a due to the rotation of the camshaft 2, the plunger 9 rises, and after the outer circumferential surface of the plunger closes the feed hole 19, the plunger 9 rises and begins to pump fuel. Thereafter, the fuel in the high pressure chamber 10 is pressurized as the Blunger 9 rises, and when the fuel pressure overcomes the set pressure of the spring 14, the valve 13 is opened and fuel is pumped from the valve holder 16.

Next, the injection amount adjustment mechanism, as shown in FIG. 1, mainly consists of a control rack 20 and a control sleeve 22 to which rotational force is transmitted via teeth 23 that mesh with the control rack 20.

The control sleeve 22 is the cylinder small diameter outer peripheral wall 8b.
As shown in FIG. 3, recesses fi 22b and 22c, which will be described later, are formed in the inner peripheral wall surface 22a of the control sleeve 22.

On the other hand, the driving face 9b formed on the small diameter portion 9a of the plunger 9 is formed in the shape of a flange that projects radially outward from the plunger body between the plunger small diameter portions 9a and 9d, as shown in FIG. The maximum diameter outer wall surface 9c of this flange-shaped driving face 9b corresponds to the groove 2 formed in the inner peripheral wall surface 22a of the control sleeve 22.
2b.

22c so as to be slidable in the axial direction.

An elastic body 30 is elastically fitted to the small diameter portion 9d of the plunger below the driving face 9b. The elastic body 30 is made of a spring material and has a shape as shown in FIG.
1 and a tongue body 32 protruding from the upper end. Elastic body body 3
1 has a pair of bent parts 3 extending from the upper end to the lower end on both edges.
1a.

31b is formed. Inner peripheral wall surface 3 of elastic body main body 31
1c comes into close contact with the plunger small diameter portion 9d due to its elastic force.

The tongue body 32 is curved in an R shape, and as shown in FIG.
The back portion 32c of the control sleeve 2a is the inner peripheral wall surface 22 of the control sleeve.
a, and as shown in FIG. 3, the tip 32b is in contact with the flat surface 9f of the driving face 9b, and the back portion 32c of the tongue body 32 pushes the inner peripheral wall surface 22a of the control sleeve to the left side in FIG. The inner wall surface 31c presses the small diameter portion 9d of the plunger to the right in FIG.

As a result, the driving face 9b of the plunger 9
is positioned in contact with the groove end 22d of the concave groove 22b22c of the control sleeve 22. In addition, the tongue body 32
The pointed end 32b does not need to be in contact with the flat surface of the driving face 9b.

When assembling the pump element 5, the bent portion 31 of the elastic body 30
The elastic body 30 is inserted from the plunger lower end 9e while opening a and 31b, and the inner circumferential wall surface 31c of the elastic body main body 31 is attached to the plunger small diameter portion 9d. Next, the plunger 9 with the elastic body 30 attached thereto is inserted into the inner peripheral wall surface 8a of the cylinder 8. Then, as shown in FIG. 1, the back portion 32C of the curved portion 32a presses the control sleeve inner circumferential wall surface 22a, and the inner circumferential wall surface 31c of the elastic body 31 presses the plunger small diameter portion 9d. As a result, the driving face 9b is pressed against the groove ends 22d of the concave grooves 22b and 22c of the control sleeve 22, preventing relative movement of the plunger 9 in the rotational direction with respect to the control sleeve 22, and only in the axial direction of the plunger 9 with respect to the control sleeve 22. movement is allowed. Therefore, play in the rotational direction between the control sleeve 22 and the plunger 9 is eliminated.

Therefore, when the control sleeve 22 is rotated via the control rack 20, the concave grooves 22b, 22c
The driving face 9b, which fits into the groove end 22d of the control rack 20, accurately rotates by a predetermined angle according to the amount of hypermotion of the control rack 20.

In the first embodiment, the elastic body 30 is made of a thin plate and is fitted to the plunger small diameter portion 9d by spring force, but the elastic body 30 may be fixed to the plunger small diameter portion 9d by adhesive or welding. . Note that the first embodiment can be applied to the current product without any changes.

FIG. 5 shows a second embodiment of the present invention, and shows an elastic body 40 made of a wire. This elastic body 40 is made of one wire rod, and the arcuate parts 41a and 41b are elastically fitted to the plunger small diameter part 9d, and the back part 4 of the tongue body 42
2a presses the control sleeve inner peripheral wall surface 22a. Although the tip 42b of the tongue body 42 comes into contact with the driving face 9b of the plunger 9, it does not have to come into contact with the driving face 9b of the plunger 9 according to the present invention. Here, the back portion 42a is the back portion 32c shown in FIG.
, and the tip 42b corresponds to the tip 32b shown in FIG. Here, the elastic body 40 may be a wire having elastic force as a spring material.

(Effects of the Invention) As explained above, according to the fuel injection pump of the present invention, since an elastic body is added that biases the driving face in one direction against the concave groove on the inner circumferential wall of the control sleeve, the control sleeve and the driving face are This eliminates looseness in the direction of rotation with the plunger through the face.
This has the effect of accurately transmitting the rotational movement of the control sleeve to the plunger via the driving face, thereby reliably stabilizing the fuel injection amount and improving responsiveness.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a cross-sectional view showing the main parts according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a fuel injection pump according to an embodiment of the present invention,
3 is a sectional view taken along line III-III shown in FIG. 1, FIG. 4 is a perspective view showing an elastic body according to an embodiment of the present invention, and FIG. 5 is a perspective view showing an elastic body according to another embodiment of the present invention. It is a diagram. DESCRIPTION OF SYMBOLS 1...Pump body, 8...Cylinder, 9...Plunger, a, 9d...Plunger small diameter part, b...Driving face, 2...Control sleeve. 2a... Control sleeve inner peripheral wall surface, 2b, 22
c... Concave groove, 0.40... Elastic body.

Claims (1)

[Claims] (1) a cylinder having a feed hole; a plunger that is capable of reciprocally sliding into the cylinder and has a notched groove with an oblique angle that can face the feed hole; and a plunger that communicates with the notched groove and is on the top surface of the plunger. High pressure chambers facing each other; a control sleeve rotatably guided on the outer periphery of the cylinder to adjust the injection amount; and a control sleeve formed in the small diameter portion of the plunger and movable in the axial direction in a concave groove on the inner peripheral wall surface of the control sleeve. a driving face that fits into the fuel injection pump, characterized in that an elastic body is attached to the small diameter portion of the plunger and presses the driving face in a concave groove on the inner circumferential wall surface of the control sleeve. and fuel injection pump.