JPH041465A - Fuel injection pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection pump for a plunger pressure-feeding diesel engine.

[Conventional technology]

A conventional fuel injection pump will be explained with reference to FIGS. 9 to 12. FIG. 9 shows an external view and a sectional view of the Shark type injection pump. In the figure, the camshaft that causes the plunger to reciprocate is installed on the engine body side, and the injection pump itself does not have a camshaft internally, but is a normal cam-resist that is installed by incorporating it into the engine body through the same flange surface. This is an example of a Shark type injection pump called (PFR type).

1 is a pump body, 2 is a plunger barrel, and 3 is a plunger. The plunger barrel 2 is provided with an oil supply/discharge lower, and the plunger 3 is provided with a plunger main lead 8. As shown in the figure, during the period when the upper end of the plunger 3 opens the oil supply/discharge lower, fuel flows into the plunger barrel 2 and is supplied, and the pressure feeding of fuel starts from the time the oil supply/discharge port is closed. and eventually the plunger main lead 8
When the fuel pump reaches the position where it opens to the fuel supply/drainage port, the fuel pumping ends.

A holder 12 divided into two is attached to the upper part of the fuel injection pump, and within the holder, a delivery valve 9 is provided with a valve seat 10 and a valve spring 11, which are engaged with an injection pipe after the injection pump. The delivery valve set controls the compressed fuel mode in the combined injection tube up to the nozzle.

Furthermore, in order to improve the cutoff of fuel injection from the nozzle after the so-called end of injection, which occurs approximately at the same time as the oil supply/discharge lower comes into contact with the plunger word 8, it has the effect of rapidly reducing the pressure inside the injection pipe.

Reference numeral 13 is a follower screw for connecting fuel system piping, and reference numeral 14 is an air vent screw for venting air within the fuel system.

Further, the fuel pumping amount control rack pin 4A, which is press-fitted or brazed into the fuel pumping amount control rack 4, can slide within the range indicated by the arrow P in FIG. When the fuel pumping amount control rack pin 4A is slid, the binion sleeve 5 is rotated. As a result, in order to rotate the plunger +3, the lower part of the plunger 3 has a flat part 3.
A is provided, and the flat portion is engaged with two pawls 5A provided at the lower end of the pinion sleeve 5 shown in FIG. That is, the plunger 3 rotates as shown in the figure in response to the movement of the rack pin 4A, and the position of the plunger main lead 8 relative to the oil supply/drainage lower is changed, thereby controlling the amount of fuel pumped. There is.

Regarding the rack position in FIG. 9, Ro is the rightmost end of the rack bin in the right direction, R1 is the pumping start point, and R
The period between 0 and R1 is a zero pumping amount section. R1□ is the maximum pumping amount position during load operation, and R5 is a position where the pumping amount is particularly increased, which is set only when the engine is started. A notch is provided in the head of the plunger 3 so that by setting the rack bin 4A to R5, the optimum fuel pumping amount for starting and the optimum static injection timing ΔT can be obtained. Also, after the engine starts, the movable range of rack bin 4A is R0 to Rwa.
A stopper, etc. (not shown) is provided to restrict the amount of pumped fuel during load operation to an amount corresponding to the R and □ positions by restricting the amount of fuel to the position R and □, thereby preventing excessive fuel from being delivered and generating black smoke. are doing. Reference numeral 6 denotes a pin that engages with a groove provided on the outer surface of the plunger barrel 2, and is used to position the plunger barrel 2.

Fig. 10 shows the relative relationship between the main lead 8 of the plunger 3 and the oil supply/discharge diameter φd in an exploded view of the plunger 3, and Fig. 11 shows the position of each rack bin 4A, the fuel pumping amount Q, and the static This is a diagrammatic representation of the injection timing (S r T). In FIG. 10, reference numeral 5A indicates a claw provided at the tip of the lower part of the binion sleeve 5. A flat part 3A of the lower part of the plunger is fitted between the claws 5A, and as the plunger rotates toward the rack bin 4, the plunger rotates to indicate the relative positional relationship between the lower oil supply/drainage position and the plunger main lead 8. The head of the plunger 30 is a flat surface, and the flat surface of the head is R3 from the upper edge of the oil supply/drainage lower when the plunger 3 is at the bottom dead center.
It is assembled by positioning it downwards. Next, when the plunger 3 is raised from the bottom dead center by a height P by the drive cam, the oil supply and drainage lower is closed by the outer peripheral wall of the plunger 3,
Pumping begins. This P is called a pre-stroke, and the period from when the plunge +3 further rises until the oil supply/discharge lower reaches the upper part of the main lead 8 is the effective stroke for pumping fuel.

In this conventional fuel injection pump, in order to obtain the optimum fuel pumping amount Q and the optimum pumping timing at the time of starting, a start lead 8A is provided as shown in FIG. In order to improve starting performance by retarding the angle, a starting lead 8B is provided by cutting out the upper part of the plunger 3. Therefore, by setting the position of the rank pin 4A to R3 at startup, the static injection timing becomes Ps + Pc from the top dead center position of the engine, and the sections R, -R, □ are kept constant at P. They are different. Main lead 8 and start lead 8
A is cut to a depth that communicates with the central fuel return hole φD of the plunger 3, and the combustion inside the plunger barrel 2 is through the fuel passage hole φD.

It will be returned to the oil supply and drainage lower through 8 and 8A. In the developed view of the outer surface of the plunger on the right side of Fig. 10, the stroke indicated by the diagonal line indicated by the two-dot chain line corresponds to the stroke of each rack bin 4.
This is the effective stroke at the holding position of A.

Fig. 11 shows the above explanation, where the horizontal axis shows the fuel pumping amount control rack bin position, and the vertical axis shows the pumping timing, that is, the static injection timing 5IT (Static 1n).
injection timing), and the fuel pumping amount Q is shown in the lower half. Rank bin position to starting position R3
By holding the static injection timing SIT at ΔT8 before the engine compression top dead center (TDC), the fuel pumping amount Q becomes Q. RIIIX ” SIT in RI section is TD
ΔT before C is always kept constant, and at Rsaw, Q=Q, . . ., and at point R1, Q=O, and the engine is stopped by holding the rack bin 4A in this section.

At maximum load operation, rack bin 4A is Rs m
Therefore, the maximum fuel amount Q11 is supplied, and the static injection timing is always maintained and fixed at a constant ΔT.

That is, even if an overload is applied and the rotational speed of the engine decreases, 5IT=ΔT, Q=Q, . . . will be operated at - constant.

FIG. 12 shows an example in which, in addition to the above-mentioned starting retard lead 8B, a retard lead 8C is provided on the top surface of the plunger 30, which changes the static injection timing together with the position of the rack bin 4A (along with changes in the amount of fuel pumped). In R8 to R8, the static injection start is constant at 5IT-ΔT, in Rt it is retarded to 8T, and further in R1 it becomes ΔT. That is, the fuel pumping amount and static injection timing at each holding point are R, respectively, Qms* at 8 points: ΔT, and Q3 at R3 point.
:ΔT, R, at point Q2 :ΔT2. At R1 point, Q-
〇: ΔTI At Rs point, Qs: ΔT.

[Problem to be solved by the invention]

By the way, in the conventional device, the fuel control rack bin 4A
When operating at a fixed position, that is, R111aX position or R
When operating at any position of RI, the static injection timing SIT is uniquely determined by the static injection timing SIT in which the oil supply and drainage port of the plunger barrel 2 is blocked by the upper end surface of the plunger 3 or the retard lead 8C. In other words, the static injection timing is uniquely determined by the amount of fuel pumped, regardless of the rotational speed of the engine.

It is well known that normally in a diesel engine, fine atomized fuel is injected into air compressed to high temperature and high pressure, and this becomes high temperature and self-ignites to cause explosive combustion.

A predetermined absolute time T is required for the atomized fuel particles to rise in temperature and self-ignite, resulting in explosive combustion, regardless of the rotational speed of the engine. Generally, in order to operate a diesel engine with the highest combustion efficiency, the best ignition timing for the atomized fuel injected into the combustion chamber is just before top dead center. To obtain this, if the most suitable static injection timing for a set engine speed of a certain engine is, for example, 3.00 rpm, is set to ΔT = 23° before top dead center (BTC), then this engine will run under full load. The static injection timing on the performance curve is operated at a constant ΔT-23° over the entire rotation range. As a result, the rated point N R (=300Orpm)
However, at a rotation speed below the rated rotation speed, the static injection starts too early and is operated.

That is, in the conventional example, since fuel injection is performed at the static injection timing that is set regardless of the engine rotational speed, the injection timing is too early in the range below the rated point rotational speed. As a means to avoid this, a method is generally used to incorporate a mechanical timer that uses the centrifugal force of a centrifugal weight into the camshaft drive gear of the fuel injection pump, but mechanical timers are expensive and large. is often difficult to employ.

An object of the present invention is to solve the problems of the conventional device, and to provide the fuel injection pump itself with a pre-stroke (a stroke from the bottom dead center until the circumferential wall of the plunger closes the fuel inlet) in response to the rotational speed of the engine. By providing a variable function, the static injection timing can be varied to provide a fuel injection pump that can always obtain the optimum injection timing depending on the rotational speed.

[Means to solve the problem]

This is a shark-type fuel injection pump for diesel engines in which a sliding barrel with fuel supply and drain holes is movable up and down. B. The lower end of the sliding barrel is made into an inclined cam surface, and the barrel is provided with a vertical groove that engages with a rotation stopper press-fitted into the pump body, and the inclined cam surface is used to facilitate movement of the pre-stroke control rack. It is characterized in that it comes into contact with a protrusion provided on the upper end surface of a pinion gear that rotates in response.

[For production]

As configured as described above, when the pre-stroke rack 20 is slid, the pinion gear 21 rotates, and the rotation of the pinion gear brings the protrusion on the upper end surface of the pinion gear into contact with the sliding barrel having the inclined cam surface. When activated, the sliding barrel moves only in the vertical direction, making the pre-stroke variable and making it possible to adjust the injection timing.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 8.

In the figure, 1 is the pump body, 2 is the plunger barrel,
3 is a plunger, 4 is a fuel pumping amount control rack,
5 is a binion sleeve, 6 is a bottle, 8 is a plunger main lead, 9 is a delivery valve, 10 is a valve seat,
11 is a valve spring, 12 is a holder, 13 is a follower screw, and 14 is an air vent screw, which are the same parts as in the conventional example.

As shown in Fig. 1 (1)), there are a pre-stroke control rack 20 and rack bins 2OA installed independently of the rack 4 that controls the amount of pumped fuel.
3. Slide freely as shown by arrow Q. By sliding the rack bin 20A, the nion 21 rotates, and according to the rotation, a cylindrical sliding barrel 22 installed above can be moved up and down. That is, the sliding barrel 22 has a guide groove 6A cut in the vertical direction on its outer surface, and engages with a bottle (fixed to the pump body) 6 inserted into the groove, so that only vertical movement is possible. Further, the sliding barrel is always urged downward by a pressing spring 27 provided at its upper portion.

FIG. 2 explains the mechanism in which the sliding barrel 22 moves up and down by the rotation of the binion 21. The upper surface of the binion 21 is provided with a protrusion 21A with a smooth top, while the lower end of the sliding barrel 22 is provided with a protrusion 21A having a smooth top. is provided with an inclined cam 22A.

As shown in Figure 2-2, the rack bin 2OA is
When sliding in the (low speed) direction, the pinion 21 rotates to the left as shown in the figure, and the sliding valve 22 moves to δ as shown in the figure, (second
Figure 4). This is arbitrary rotation from J
By adding the initial pre-stroke P and the pre-stroke increase δ due to the rise of the sliding valve 22, the pre-stroke after the rack pin 21A slides becomes P, +63.

Figure 3 is an explanatory diagram of the situation in which the amount of fuel pumped is controlled.
Its contents are as described in the conventional example.

However, Figures 2 and 3 are examples in which the sliding barrel 22 has a fuel filler port and an oil drain port separately drilled at approximately symmetrical positions, with the hole on the left side in the figure being the fuel filler port and the hole on the right side being the oil drain port. The hole diameter is φ
It is displayed as DIN + φD, □. Also plunger 3
A deep hole φD, which serves as a fuel passage, is drilled in the axis of the cylinder.

Figure 4 is a model of the exploded view of the plunger 3, fuel filler port, and oil drain port shown in Figures 2 and 3, and Figure 5 shows the fuel pumping amount and static injection with respect to the engine rotation speed in the example shown in Figure 4. This is a graphical representation of the timing. In FIG. 4, the outer surface of the plunger is filled with oil 23. Main lead 8. Start leads 8A are provided, and the depth of each lead is such that it communicates with a fuel conduit φD provided at the plunger shaft core.

When the rack pin 4A is held at the maximum injection amount position, the oil filler port φDIN + oil drain port φD oat position is R in Fig. 4,
Display in □. Protrusion 21 on the top of the binion when flattening
The position A is NI1 in FIG. 1, and the sliding barrel 22 is indicated by a solid line. What is indicated by PSI in the figure is the pre-stroke, which is the upward stroke from the bottom dead center of the plunger 30 until it closes the fuel filler port, and when the plunger moves up from the bottom dead center by PSI, the fuel filler port is blocked.
At this point, pressure feeding of fuel is started. As the plunger 3 further rises, the oil drain hole φD o a
At the point in time when t contacts the main lead 8, the pressure feeding by the plunger 3 is stopped. As mentioned above, since PSI is a pre-stroke, Ha in the figure is an effective fuel pumping stroke.

Next, overload operation occurs with the fuel pumping amount control rack bin 4A held at the maximum injection amount position R, □, and when the engine speed drops to a desired NL, the rack bin 20A is slid from Nl to NL. The sliding barrel 22 is raised by δ and L by the inclined cam 22A as shown by the dashed line. As a result, the prestroke until the fuel filler port is closed becomes PSI+δ,L, and the static injection timing is retarded. On the other hand, the fuel pumping amount control rough 4 is R
If it is maintained at smX, the fuel pumping amount Ql, 8 can be kept constant and the static injection timing can be varied in accordance with the rotational speed of the engine. Needless to say, the holding position of control rank 4A, which is related to the amount of fuel pumped, is set to R.
The same effect can be obtained at any position from 1 to R+esx, and it becomes possible to independently vary the static injection timing with variations in engine speed, regardless of the set fuel pumping amount.

Furthermore, in order to obtain the optimum static injection timing and fuel pumping amount for starting the engine, it is easy to achieve the objective by holding the rack bins 2OA and 4A at the Ns and R positions, respectively. In the illustrated example of FIG. 4, Ps□ is a pre-stroke when the control rack bin 4A is held at R5, and Hs is an effective stroke. Furthermore, by holding the rack bin 2OA at Ns, the sliding barrel 22 rises by 683 minutes, so the static injection timing at this time is P. +δ5. becomes. To explain the above content again with reference to FIG. 5, regardless of the position of the fuel pumping amount control rack 4A (between R, -R, .
The OA allows the static injection timing to be effectively and independently varied in accordance with the rotational speed of the engine.

FIG. 6 shows a second embodiment in which a single oil intake/drainage port is used as the fuel filler port and oil drain port, as shown in the conventional structure shown in FIG. 9, and the lower end surface of the sliding barrel 22A is tilt cam direction,
Refueling lead 23. Main lead 8. Start lead 8A
The operating effect is the same as described above, except that the positional relationship of the two is different.

〔Effect of the invention〕

Since the present invention is configured as described above, the static injection timing is changed by making the prestroke variable in accordance with the engine rotational speed, and the actual injection timing is set to the actual injection timing that best matches each engine rotational speed. This makes it possible to provide a fuel injection pump that can improve combustion over a wide range of engine speeds.

[Brief explanation of the drawing]

Figures 1 to 8 are related to the present invention, and Figures 1 to 5 are related to the present invention.
An example was shown. Fig. 1(a) is an external view, Fig. 1(a) is a sectional view, Fig. 2 is an explanatory diagram of the mechanism that moves the sliding barrel 22 up and down by rotating the Binioff 210 to change the injection timing, and Fig. 3 is an explanatory diagram for controlling the amount of fuel pumped, Figure 4 is an exploded view of the plunger 3 shown in Figures 2 and 3, and a model representation of the fuel filler port and oil drain port. Figure 5 is the engine rotation speed in the example shown in Figure 4. Figures 6 to 8 show the second embodiment, Figure 6 shows the fuel inlet and oil drain port integrated into the same hole, and Figure 2 corresponds to the same hole. The figures are corresponding diagrams of Figure 4, Figure 8 are corresponding diagrams of Figure 5, Figures 9 to 11 are conventional examples, Figure 9 is the corresponding diagram of Figure 1, Figure 10 is the corresponding diagram of Figure 4, and Figure 11 is the corresponding diagram of Figure 1. The figures correspond to Figure 5 and Figure 12 correspond to Figure 7. 3...Plunger, 8...Lead, 20...Prestroke control rack, 21...Pinion gear, 21A...Protrusion, 22...(Sliding) barrel, 2
2A... Inclined cam surface on the lower end surface, 24... Fuel filler port, 25... Oil drain port, 26... Oil filler and drain port. Figure-1 Figure-2 ・θ0 Figure-1 Figure-2 Figure-1 Figure-2 Figure-2

Claims (1)

[Claims] By reciprocating the plunger, fuel is pumped, and by rotating the plunger, the relative relationship between the fuel filler port and oil drain port drilled in the barrel and the reed provided on the outer surface of the plunger is changed, and the fuel is In devices that control the pumping amount, the barrel with a fuel filler port and oil drain port is movable up and down, and the lower end surface of the barrel is an inclined cam surface, and the inclined cam surface is compatible with the movement of the prestroke control rack. This makes it possible to control the static injection timing by changing the pre-stroke by making the sliding barrel come into contact with a protrusion provided on the upper end surface of the rotating pinion gear, and by vertically displacing the sliding barrel as the pinion gear rotates. An injection pump featuring