JPH0210288Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distribution type fuel injection pump for internal combustion engines.

Conventionally, the outer diameter of a plunger, which performs reciprocating and rotational movement to suction and pressure feed and distribute fuel, is divided into two stages: a small diameter part at the tip and a large diameter part connected to this, to form two pressure chambers. JP-A-57-65857 discloses a distribution type fuel injection pump in which the injection rate is made variable by pumping fuel from one or both of the above.

This involves inserting and fixing a barrel into which the small diameter portion of the plunger is slidably fitted into the back (tip) of a sliding hole formed in the pump housing and into which the large diameter portion of the plunger is slidably fitted. Because of this structure, the centering of the sliding hole and the barrel, the centering of the large diameter part of the plunger and the sliding hole and small diameter part and the barrel, and the centering of the large diameter part and the small diameter part of the plunger can be performed accurately. Otherwise, the plunger will not operate smoothly, and therefore high precision is required in machining and assembly, resulting in low mass productivity.

The present invention was developed in view of the above circumstances, and aims to improve mass productivity by reducing machining and assembly precision.To achieve this purpose, the invention uses reciprocating and rotational movements to pump and distribute fuel. The outer diameter of the plunger that performs this is divided into two stages, a small diameter part at the tip and a large diameter part connected to this, to form two pressure chambers, and the fuel is force-fed from either or both of these pressure chambers to the nozzle. In the distribution type fuel injection pump, a sub plunger barrel in which a small diameter portion of the plunger is slidably fitted is loosely fitted inside the tip side of the main plunger barrel into which the large diameter portion of the plunger is slidably fitted. , there is provided a distribution type fuel injection pump characterized in that the sub-plunger barrel is attached to the main plunger barrel by a screw member so as to be non-rotatable and non-movable in the axial direction.

An embodiment of the present invention will be described below with reference to the drawings. Figure 1 shows the main parts of the distributed fuel injection pump of the present invention, in which a main plunger barrel 4 is fitted and fixed into a fitting hole 3 provided in the center of a wall 2 at one end (right end in the figure) of a pump housing 1. A plunger 6 is slidably fitted into the sliding hole 5 of the main plunger barrel 4. The plunger 6 is caused to reciprocate and rotate by a driving means (not shown) to suck in, pressure feed and distribute fuel, and its outer diameter is divided into a small diameter part 7 at the tip (right end in the figure) and a large diameter part connected to the small diameter part 7. It has a two-stage configuration with section 8.
The large diameter portion 8 is fitted into the sliding hole 5 of the main plunger barrel 4. The small diameter portion 7 of the plunger 6 is slidably fitted into a sliding hole 10 of a sub-plunger barrel 9 provided inside the sliding hole 5 of the main plunger barrel 4 on the distal end side. The sub-plunger barrel 9 is made of a short-axis cylindrical member having a flange 11 on the outer periphery of one end (right end in the figure), and is inserted into the sliding hole 5 of the main plunger barrel 4 from its distal opening. The collar 11 abuts and engages with an annular step 12 provided at the periphery of the opening on the distal end side of the sliding hole 5 of the main plunger barrel 4 . In this state, the sub plunger barrel 9 is loosely fitted into the sliding hole 5 of the main plunger barrel 4. As shown in FIGS. 1 and 2, the sub-plunger barrel 9 is attached to the main plunger barrel 4 by a threaded member 13 such as a screw so that it cannot rotate or move in the axial direction. A protrusion 1 is provided on the outer end surface (right end surface in FIG. 1) of one end wall 2 of the pump housing 1 so as to communicate with the fitting hole 3 of the main plunger barrel 4.
A closing member 15 is screwed onto the main plunger barrel 4, and a high-pressure sealing annular edge 16 protruding from the inner end surface of the closing member 15 is in close contact with the end surface of the main plunger barrel 4.

A first pressure chamber 17 is provided between the distal end surface of the small diameter portion 7 of the plunger 6 and the inner end surface of the closing member 15.
However, second pressure chambers 20 are defined between the boundary step portion 18 between the small diameter portion 7 and the large diameter portion 8 and the other end surface 19 of the sub-plunger barrel 9, respectively.

When the plunger 6 is in the suction stroke in which it moves to the left in FIG. The air is sucked into the first pressure chamber 17 through the suction grooves 24 (see FIG. 4), which are equally spaced and provided in the same number as the number of cylinders.
5 to the second pressure chamber 20 through suction grooves 26 (see FIG. 3), which are equally spaced in the circumferential direction on the outer periphery of the large diameter portion 8 and provided in the same number as the number of cylinders.

Further, when the plunger 6 enters the pressure feeding stroke in which it moves to the right side in FIG. 1, the one suction port 23
and the suction groove 24 are blocked, and the first pressure chamber 1
7 is compressed, and the other suction port 25 and the suction groove 26 are shut off to form the second pressure chamber 2.
0 fuel is compressed.

The fuel in the first pressure chamber 17 is then passed from a through hole 27 bored along the axis of the plunger 6 through a distribution groove 28 to a discharge passage 29 (equally distributed in the circumferential direction, the same number as the number of cylinders is provided). ), and is injected into the cylinder from a fuel injection nozzle via a delivery valve (not shown). In this way, fuel is injected into each cylinder in a predetermined order as the plunger 6 reciprocates and rotates.

On the other hand, one end 30a of a first communication passage 30 is open to the second pressure chamber 20, and the other end 30b of the first communication passage 30 communicates with one end 31a of a second communication passage 31. The other end 31 of the second communication path 31
b is a relief passage 32 via a switching valve 34 which will be described later.
One end 32a and one end 33a of the third communication path 33
selectively communicate with.

The other end 31b of the second communicating passage 31 opens into the valve chamber 35 of the switching valve 34 and is connected to the relief passage 3.
One end 32a of 2 opens into the valve chamber 35 of the switching valve 34, and the other end 32b opens into the annular groove 3 provided on the outer periphery of the main plunger barrel 4 so as to communicate with the suction port 25.
It opens at 6. One end 33a of the third communicating path 33 opens into the valve chamber 35 of the switching valve 34, and the other end 33b communicates with one end 37a of the fourth communicating path 37. The other end 37b of the fourth communication path 37 is connected to the annular groove 3 provided on the outer periphery of the large diameter portion 8 of the plunger 6.
8, and the annular groove 38 communicates with the through hole 27 of the plunger 6 via a communicating hole 38a.

The switching valve 34 has a valve body 39 and an electromagnetic solenoid 40 that drives the valve body 39. The valve body 39 is housed in the valve chamber 35 so as to be movable in a direction perpendicular to the axis of the plunger 6 (vertical direction in FIG. 1). The valve body 39 has an annular groove 41 with a predetermined axial length on its outer peripheral surface, and a through hole 42 along the axis.
and a communication hole 43 that communicates orthogonally with the through hole 42 on the tip side (upper end side in FIG. 1). The valve body 39 is urged upward by a spring 44. The solenoid 40 switches and moves the valve body 39 downward against the biasing force of a spring 44 by being energized and excited, and is electrically connected to a control unit (not shown). Engine rotational speed, fuel injection amount, fuel temperature, engine cooling water temperature, lubricating oil temperature, injection timing, etc. are input to this control unit, and the switching valve 34 is controlled by taking into consideration all engine operating conditions. It is becoming possible to do so.

When the engine is in a low-speed, low-load operating state such as when idling, the solenoid 40 is energized and energized, so that the valve body 39 of the switching valve 34 changes from the state shown in FIG. The other end 31b of the second communication passage 31 and the one end 32 of the relief passage 32 move downward against the biasing force.
a, and the other end 31b of the second communication path 31
and one end 33a of the third communication path 33 are cut off.

In this state, during the pressure stroke, the fuel in the second pressure chamber 20 flows from the first communication passage 30, the second communication passage 31, and the relief passage 32 through the annular groove 36 on the outer periphery of the main plunger barrel 4 to the suction port. 2
It leaks to the second side and is not supplied to the third communication path 33 side. Therefore, as described above, only the fuel in the first pressure chamber 17 is fed under pressure to the nozzle, resulting in a decrease in the fuel injection rate.

Also, when the engine is operating at high speed and high load,
The energization to the solenoid 40 is cut off, and the valve body 39 is moved upward by the biasing force of the spring 44 to the state shown in FIG. One end 32a is blocked, and the other end 31b of the second communication path 31 and one end 33a of the third communication path 33 are connected to the annular groove 41 of the valve body 39.
communicated via.

In this state, during the pressure feeding stroke, the fuel in the second pressure chamber 20 is transferred to the first communication passage 30, the second communication passage 31, the annular groove 41 of the valve body 39, the third communication passage 33, and the fourth communication passage. The fuel flows into the through hole 27 of the plunger 6 through the passage 37, the annular groove 38 of the plunger 6, and the communication hole 38a, merges with the pressurized fuel from the first pressure chamber 17, and is sent from the distribution groove 28 to the discharge passage 29. be done. Therefore, since fuel is simultaneously fed to the nozzle from the first pressure chamber 17 and the second pressure chamber 20, the fuel injection rate increases by the amount of fuel fed from the second pressure chamber 20.

A control sleeve 45 is slidably inserted into the outer periphery of the base of the plunger 6 located on the pump chamber 21 side, and a cut-off port 46 bored in the base so as to communicate with the through hole 27 controls the plunger 6. When the sleeve 45 comes off the inner circumferential surface and opens into the pump chamber 21, the fuel leaks into the pump chamber 21, so the fuel delivery to the discharge passage 29 side is stopped and injection ends. Therefore, by adjusting the position of the control sleeve 45, the injection end timing can be changed and the injection amount can be controlled.A lever 47 of a drive mechanism (not shown) is engaged with this control sleeve 45, and this lever If the control sleeve 45 is moved to the right in the figure by 47, the injection amount will increase, and if it is moved to the left, the injection amount will be decreased. Further, numeral 48 in FIG. 1 is a fuel cut solenoid valve provided in the suction passage 22.

As mentioned above, the distribution type fuel injection pump of the present invention has the same fuel injection action as the conventional one, but
In particular, the sub-plunger barrel 9, into which the small-diameter portion 7 of the plunger 6 fits, is loosely fitted inside the tip side of the main plunger barrel 4, into which the large-diameter portion 8 of the plunger 6 fits,
Since the sub-plunger barrel 9 is attached to the main plunger barrel 4 by the screw member 13 so as to be non-rotatable and non-movable in the axial direction, it is easy to center the main plunger barrel 4 and the sub-plunger barrel 9. Even if the centers of the small diameter part 7 and the large diameter part 8 of 6 are slightly misaligned, this misalignment can be absorbed, which eases processing and assembly precision, increases mass production, and allows for smooth cost reduction. It is.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a vertical sectional view of the main part of a distribution type fuel injection pump, and FIG.
Figure 3 is a vertical cross-sectional view taken along the - line in Figure 1, Figure 4 is a vertical cross-sectional view taken along the - line in Figure 1, and Figure 4 is a vertical cross-sectional view taken along the - line in Figure 1.
It is a longitudinal cross-sectional view along a line. 4... Main plunger barrel, 6... Plunger, 7... Small diameter part of plunger, 8... Large diameter part of plunger, 9... Sub-plunger barrel, 13...
...screw member, 17...first pressure chamber, 20...second pressure chamber.

Claims (1)

[Scope of utility model registration request] The outer diameter of the plunger, which performs reciprocating and rotational movement to suction and pressure feed and distribute fuel, is made into two stages with a small diameter part at the tip and a large diameter part connected to this, forming two pressure chambers. In a distribution type fuel injection pump configured to forcefully feed fuel to a nozzle from either one or both, the small diameter portion of the plunger is located inside the tip side of the main plunger barrel into which the large diameter portion of the plunger is slidably fitted. A distribution type fuel, characterized in that a sub-plunger barrel that is slidably fitted is loosely fitted, and the sub-plunger barrel is attached to the main plunger barrel by a screw member so as to be non-rotatable and non-moveable in the axial direction. injection pump.