JPH02188666A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To correct a variation in a fuel injection quantity by providing mutually engaging portions on a control sleeve side and a casing side and rotating the control sleeve in a circumferential direction by a defined angle accompanying the movement thereof in the axial direction. CONSTITUTION:As the coil of a rotary solenoid 26 is electrified, a rotor 27 is rotated. Thereupon, a control sleeve 21 is moved in the axial direction via the pin 25 of a control rod 24. Also, a plunger 14 is lifted up and the stroke up to where its suction port 29 is closed is varied. In this case, the pin 33 on a casing side is engaged with the inclined groove 32 of the control sleeve 21 side. Accompanying the movement of the control sleeve 21, the control sleeve 21 is relatively rotated in the circumferential direction of the plunger 14 by a defined angle corresponding to the inclined angle of the inclined groove 32. Thereby, fuel injection quantity accompanying the variation in pre-stroke is corrected.

Description

[Detailed description of the invention]

[Industrial Field of Application] "Summary of the Invention 1. A control sleeve for changing the pre-stroke of a fuel injection pump is provided in which the anti-rotation groove formed in the control sleeve is inclined, and this control is used to change the pre-stroke. When the sleeve is moved in the axial direction of the plunger, the control sleeve is rotated by a predetermined angle by the pin on the casing side and the inclined groove of the control sleeve, thereby eliminating changes in the fuel injection amount due to changes in the prestroke. It was designed to reduce the number of times.

[Conventional technology]

In a diesel engine, fuel is pressurized by a fuel injection pump, and the pressurized fuel is supplied to a fuel injection nozzle through an injection pipe, and the nozzle injects the fuel into a cylinder. Then, the fuel spray is ignited and combusted by the heat of the intake air compressed by the piston, thereby generating power. A fuel injection pump for pressurizing fuel has a plunger that is pushed up by a cam, thereby pressurizing the fuel introduced from the spill boat and pumping it out. In the casing of such a fuel injection pump, as shown in "Automotive Technology" Vol. The provision of a control sleeve makes it possible to change the prestroke of the fuel injection pump. Since the control sleeve is provided with a spill boat, moving the control sleeve downward causes the spill boat to close earlier and shorten the prestroke. On the other hand, when the control sleeve is moved upward, the timing at which the spill boat is closed by the plunger is delayed, and the prestroke becomes larger.

[Problems to be solved by the invention]

If the pre-stroke of the plunger is changed by moving the control sleeve in the axial direction, the fuel pressure at the start of pumping will be changed. Further, pressure waves are generated within the fuel injection system constituted by the fuel injection pump, the injection t14m, and the fuel injection nozzle, and pressure fluctuations due to the pressure waves change in accordance with the prestroke. Due to this influence, the fifth
As shown by the dotted line in the figure, the fuel injection amount changes depending on the prestroke of the fuel injection pump. Conventional fuel injection pumps have not taken any measures against changes in fuel injection amount due to changes in prestroke. The present invention has been made in view of such problems, and an object of the present invention is to provide a fuel injection pump having a mechanism for correcting the change in fuel injection amount when the prestroke is changed. That is.

[Means for solving the problem 1] The present invention provides a control sleeve that is slidably fitted to the plunger, forms a spill boat in the control sleeve, and moves the control sleeve in the axial direction by a moving means. In the fuel injection pump, an engaged portion is provided on the outer peripheral surface of the control sleeve or on the casing side, and the casing side or the control sleeve is provided with an engaged portion that engages with the engaged portion. An engaging portion for mating is provided. 1. Accordingly, when the control sleeve is moved in the axial direction by the moving means in order to change the pre-stroke, the control sleeve is rotated by a predetermined angle by the inclined engaged portion and the engaging portion. This rotation changes the effective stroke of the plunger, thereby correcting changes in fuel injection amount due to changes in prestroke. Embodiment] FIG. 3 shows the overall structure of a fuel injection pump according to an embodiment of the present invention, in which a camshaft 11 is provided at the bottom of a casing 10. A cam 12 is attached to the cam 12. The cam 12 presses the plunger 14 upward via the tappet 13. Note that the 7-lunger 14 is pressed downward by a compression coil spring 15. A rotary sleeve 16 is attached to the plugger 14, and a pinion 17 of the rotary sleeve 16 is attached to the plugger 14.
A control rack 18 is engaged with the control rack 18. A control sleeve 21 is disposed within the casing 10 and is slidably fitted to the plunger 14. The control sleeve 21 is provided with a spill boat 22 as shown in FIG.
is provided. The lateral groove 23 is adapted to be engaged with a pin 25 installed on the outer peripheral surface of the control head 24. Further, a rotary solenoid 26 has a circle 27 fixed to the end of the control rod 24. The rotor 27 is pulled by a tension coil spring 28. A suction boat 29 is attached to the outer peripheral surface of the plunger 1ν14 that is slidable relative to the control sleeve 21.
and an inclined groove 30 are formed. Furthermore, both the suction boat 29 and the inclined groove 30 are communicated with a central hole 31 that is open at the top. On the other hand, as shown in FIG. 1, an obliquely inclined groove 32 is formed on the outer peripheral side of the control sleeve 21, and is adapted to be engaged with a fixed pin 33 on the casing side. Further, as shown in FIGS. 2 and 3, an auxiliary casing 34 is provided above the control sleeve 21, and the inside of this casing 34 constitutes a pressure chamber 35. A pre-bell valve 36 is attached to the upper part of the pressure chamber 35. In the above configuration, the cam 12 provided on the camshaft 11 is connected to the plunger 1 via the tappet 13.
When you push up on 4, fuel is pumped out. This operation will be explained with reference to FIGS. 4A-D. As shown in FIG. 4A, when the lift of the plunger 14 is low, even if the plunger 14 lifts, the fuel in the pressure chamber 35 escapes through the suction boat 29, so the fuel pressure in the pressure chamber 35 does not increase. The plunger 14 is further pushed up by the cam 12,
The suction boat 29 of this plunger 14 is shown in Fig. 4B.
When the control sleeve 21 is closed as shown in FIG. 2, the pressure in the pressure chamber 35 begins to rise, and the fuel injection pump starts pumping fuel. While both the suction boat 29 and the inclined groove 30 of the plunger 14 are closed by the control sleeve 21, the plunger 14
While the fuel injection pump is lifted as shown in FIG. 4C, the fuel injection pump continues to pump fuel. When the inclined groove 30 provided in the plunger 14 communicates with the spill boat 22 of the control sleeve 21 as shown in the fourth figure, the high pressure fuel in the pressure chamber 35 passes through the center hole 31 of the plunger 14 and the inclined groove 30. The fuel will be discharged from the spill boat 22, the pressure of the fuel in the pressure chamber 35 will drop rapidly, and the fuel injection pump will stop pumping the fuel. In this way, the fuel injection pump intermittently pumps fuel once every rotation of the cam 12. The control rack 18 controls the fuel injection amount according to the engine load. When the control rack 18 is moved perpendicular to the page in FIG.
This movement of the rack 18 is transmitted to the plunger 14 via the pinion 17 and the 0-tally sleeve 16, and the plunger 14 rotates relatively within the control sleeve 21. Although the axial position of the spill boat 22 does not change even when the plunger 14 rotates, the plunger 14 is rotated by the control rack 18 in order to change the position of the inclined groove 30 that aligns with the spill boat 22 of the control sleeve 21. As a result, the effective stroke of the plunger 14 changes. In this way, the fuel injection pump injects the fuel at one time tA
The amount is adjusted. Next, the operation of changing the prestroke of this fuel injection pump will be explained with reference to FIG. Rotary solenoid 26
The rotor 27 is rotated by energizing the coil. This rotation of the rotor 27 is transmitted to the control sleeve 21 via the pin 25 of the control rod 24, and the control sleeve 21 is moved in the axial direction. Therefore, the stroke of the plunger 14 until the plunger 14 rises and the suction boat 29 is closed as shown in FIG. 4B is changed, thereby changing the pre-stroke of the fuel injection pump. Become. Furthermore, in this fuel injection pump, when the pre-stroke is changed by moving the control sleeve 21 in the axial direction of the plunger 14, the bin 33 on the casing 10 side moves into the inclined groove of the control sleeve 21 as shown in FIG. Because it is engaged with 32,
Depending on the inclination angle of the inclined groove 32, a predetermined angle control sleeve 21 is rotated relative to the circumferential direction of the plunger 14. Therefore, even if the plunger 14 is not rotated, the spill port 22 of the control sleeve 21
The position of the engagement groove 30 of the plunger 14 that is aligned with this changes, thereby making it possible to adjust the amount of fuel to be injected. Generally, when the pre-stroke of the plunger 14 of the fuel injection pump is changed by the rotary solenoid 26 shown in FIG. 2, the pressure in the pressure chamber 35 at the time when fuel starts to be pumped changes. Furthermore, the fuel injection amount changes as shown by the dotted line in FIG. 5 in accordance with the prestroke due to pressure waves within the fuel injection system. Changes in the fuel injection r due to changes in the bristle angle are absorbed by adjusting the rotation of the control sleeve 21 using the inclination 11132, thereby correcting the change in the fuel injection amount when the prestroke is changed. It becomes possible to do so. This makes it possible to make the change in the fuel injection amount very small with respect to the prestroke, as shown by the solid line in FIG. 5, or to make it almost constant. The angle of inclination of the inclined groove 32 with respect to the axial direction may correspond to the change in the injection DA loss according to the prestroke accompanying the movement of the control sleeve 21, and may be within the range of 0.5 to 10 degrees. In practical terms, it is preferable to set the above-mentioned inclined groove to a value within the range of 2 to 3 degrees. K Effect of the Invention 1 As described above, the present invention provides an engaged portion that slopes on the outer peripheral surface of the control sleeve or the casing side, and an engaging portion that engages with the engaged portion on the casing side or the control sleeve side. It was designed to provide a. Therefore, when the control sleeve is moved in the axial direction to change the pre-stroke, the control sleeve is rotated by a predetermined angle in the circumferential direction by the inclined engaged portion and the engaging portion, and this rotation This makes it possible to correct changes in fuel injection amount due to changes in prestroke.・Con1 to Roll Sleeve・Spill Bow 1・・Horizontal Groove・Roll Rod to Con1・Bin・Rotary Solenoid・Slope Groove・Engagement Bin

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a main part showing a structure for correcting the injection amount of a fuel injection pump according to an embodiment of the present invention, FIG. 2 is a perspective view of a main part showing a structure for changing a prestroke, Third
The figure is a longitudinal sectional view showing the overall structure of the fuel injection pump.
The figure is an enlarged sectional view of the main part of the same pressure feeding operation, and FIG. 5 is a graph showing the change in the fuel injection amount with respect to the pre-stroke. The names of the main parts in the drawings are as follows. 14... Plunger

Claims (1)

[Claims] 1. A fuel injection pump comprising a control sleeve slidably fitted to a plunger, a spill port formed in the control sleeve, and a prestroke being changed by moving the control sleeve in the axial direction by a moving means. In this method, an inclined engaged portion is provided on the outer peripheral surface of the control sleeve or on the casing side, and an engaging portion that engages with the engaged portion is provided on the casing side or the control sleeve. and fuel injection pump.