JPS62276261A - Fuel injecting pump - Google Patents

Abstract

PURPOSE:To have reduction of combustion noise in low-speed operating range and holding of the combustion characteristic in the high-speed operating range simultaneously by forming a throttle flowout passage at a plunger. CONSTITUTION:At the periphery of the top of a plunger 3, a throttle flowout passage 13 is formed which is in communication with a lead 11 and allows the fuel to flow out in throttle state in the condition in communication with a barrel port 10. In low-speed operation, fuel flowout is made smoothly through said throttle flowout passage 13, so that two-staged injection consisting of a fore stage and after stage is obtained, i.e. a fore injection to be made till the barrel port 10 being put in communication with the flowout passage 13 and a main injection to be made from said communication being shut off till the barrel port 10 to be put in communication with said lead 11. In high-speed operation, on the other hand, fuel flowout via throttle flowout passage 13 is suppressed, which reduces drop of the fuel pressure while the barrel port 10 is in communication with the throttle flowout passage 13, to lead to accomplishment of single-staged injection free of interruption of the injection.

Description

[Detailed description of the invention] 3. Detailed description of the invention (Industrial application field) The present invention relates to a fuel injection pump.

(Prior art) In general, in diesel engines, during low-speed operation, the ignition delay period of fuel spray is longer than during high-speed operation. Therefore, during low-speed operation, combustion occurs rapidly after ignition, and the pressure in the cylinder increases. There is a problem in that the combustion rate increases, which causes large combustion noise.

In order to suppress such combustion noise, considering the cause of its occurrence, it is necessary to suppress the rate of pressure rise in the cylinder due to combustion.
In other words, it is effective to cause the mixture to burn slowly in the cylinder, and to achieve this, for example, the method disclosed in Japanese Utility Model Application Publication No. 59-30555 is proposed.
Types employing a staged injection method are known.

By the way, the two-stage injection mechanism in this known fuel injection pump includes a preliminary injection group that communicates with the oil suction side between the top surface of the plunger and a diagonal groove-shaped control group (reed) formed on the outer peripheral surface of the plunger. is provided, and during the compression stroke of the plunger, a small hole provided in the barrel is first closed at a portion of the plunger closer to the top surface than the above-mentioned preliminary injection group, thereby performing pre-injection, and then the above-mentioned small hole is closed in the above-mentioned preliminary injection group. Fuel injection is interrupted by communicating with
After that, the small hole is again blocked between the preliminary injection group and the control group to perform main injection, and then the small hole overlaps with the control group to complete the fuel injection. is,
This realizes two-stage injection. In this case, in the fuel injection pump of this known example, since the pre-injection group and the control group have a deep groove shape (in other words, the passage area of the pre-injection group is wide), it is difficult to move the plunger. Accordingly, when the small hole overlaps with the preliminary injection group, fuel is always discharged from the preliminary injection group regardless of the operating speed of the plunger, and a two-stage injection is performed.

However, when two-stage injection is performed even in the high-speed operating range of the engine, the injection time becomes longer than the injection period in the case of single-stage injection, which deteriorates the fuel injection rate characteristics. A problem arises in that good combustion cannot be obtained.

(Objective of the Invention) The present invention is intended to solve the problems pointed out in the above-mentioned section of the prior art, and is designed to simultaneously reduce combustion noise in low-speed operating ranges and maintain combustion characteristics in high-speed operating ranges. The object of the present invention is to provide a fuel injection pump that has the following characteristics.

(Means for Achieving the Object) As a means for achieving the above object, the present invention makes it possible to pressurize and force-feed fuel by reciprocating a plunger within a barrel. A diagonal groove-like lead is formed on the outer circumferential surface that communicates with the top surface of the plunger.
By appropriately rotating the plunger and barrel relative to each other and adjusting the communication timing between the lead and the barrel port formed in the barrel, Mffi of the fuel injection amount can be adjusted.
In the fuel injection pump, a portion of the outer circumferential surface of the top of the plunger, which is located between the top surface of the plunger and the lead in the axial direction of the plunger, communicates with the lead and extends in the circumferential direction of the plunger. In the state of communication with the above-mentioned barrel port, the 猷i! A throttle outflow passage is formed that acts to cause the flow to flow out, and as the plunger reciprocates, the barrel port is moved between the top surface of the plunger and the throttle outflow passage. The upper outer circumferential surface located between the throttle outlet passage and the lower outer circumferential surface located between the throttle outlet passage and the barrel port can be respectively closed. The size is set to allow smooth flow of fuel during low speed operation, while suppressing fuel flow during high speed operation more than during low speed operation.

(Function) In the present invention, by the above means, when the polymerization communication between the barrel port and the throttle outlet passage is performed during low speed operation of the engine, that is, in the operating region where the plunger speed is low, the viscosity and inertia of the fuel are reduced. has little effect on its flow, and the fuel easily flows out to the barrel port side through the throttle outflow passage.On the other hand, the above-mentioned polymerization communication occurs when the engine is operating at high speed, that is, in an operating region where the plunger speed is high. In this case, the viscosity and inertia of the fuel will have a large effect on its flow, and the outflow of the fuel to the barrel port side will be suppressed.

Therefore, when the engine is running at low speed, pre-injection is performed between the point where fuel flows out smoothly through the throttle outflow passage and the point where the barrel port communicates with the throttle outflow passage, and the pre-injection between the barrel port and the throttle. After communication with the outflow passage is cut off and before the barrel port communicates with the reed, two-stage injection is realized, consisting of two stages of injection before and after the main injection. During high-speed operation, the outflow of fuel through the throttle outflow passage is suppressed, so one-stage injection is realized with less pressure drop in fuel pressure under the state of communication between the barrel port and the throttle outflow passage, and without interruption of injection. That will happen.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. 1 to 6.

(First Embodiment) FIG. 1 shows a fuel injection pump for an internal combustion engine according to a first embodiment of the present invention, in which reference numeral 1 denotes a pump body with an integrated mounting flange, and 2 This is a barrel fitted and fixed inside the pump body 1, and a horizontally long rectangular barrel port 10 extending in the circumferential direction is formed on one side of the barrel 2. Further, a plunger insertion hole 18 is formed in the axial center of the barrel 2 so as to communicate with the barrel port 10. Inside this plunger insertion hole 18,
A plunger 3 is fitted so as to be relatively rotatable and slidable, and the plunger 3 is reciprocated in the axial direction by the spring force of the plunger spring 5 and the cam action of a fuel cam (not shown). The fuel sucked into a pressurizing chamber 16 formed on the top surface 3b is pressurized, and the fuel is delivered to an injector (not shown) provided in each cylinder of an engine (not shown) via a delivery valve 6. It has become.

Further, in FIG. 1, reference numeral 7 denotes a plunger rotating wheel that is attached to the plunger 3 so as to be able to engage with it in the circumferential direction, and the plunger 3 is engaged with the plunger rotating wheel 7 by a metering operator 8. By appropriately pushing and pulling the rack gear 9, it is caused to rotate relative to each other within the barrel 2, thereby performing a predetermined metering action. That is, as shown in FIGS. 2 and 3, on the outer circumferential surface 3c of the head 3a of the plunger 3, a diagonal groove-like glue 11 is provided at an appropriate distance from the top surface 3c over approximately half the circumference. It is formed. Further, this lead 2 is communicated with the top surface 3b of the plunger 3 via a communication i1*12 extending in the plunger axial direction. Therefore, by rotating the plunger 3 relative to the barrel 2, the lead l of the plunger 3 is increased! By changing the relative communication timing between the barrel port 10 of the barrel 2 and the barrel port 10, and adjusting the closing period of the barrel port 10, the fuel injection amount is adjusted. Although the Ifi1 mechanism consisting of a combination of such a barrel port 10 and a lead 11 for superimposed communication with the barrel port 10 is conventionally known, this is not limited to this in this embodiment. By applying this, it has the ability to change the injection form. That is, in this embodiment, as shown in FIGS. 2 and 3, the plunger is attached to a portion of the outer circumferential surface 3c of the head 3a of the plunger 3 and located between the lead 11 and the top surface 3b of the plunger. A recess 'flt14' having a minute depth extending in a direction parallel to the plunger top surface 3b at an appropriate distance from the top surface 3b is formed over approximately the same range as the formation range of the lead 11, and this recess groove 14 and this The inner circumferential surface 18a of the plunger fitting hole 18 of the barrel 2, which faces the inner circumferential surface 18a of the plunger fitting hole 18 of the barrel 2, constitutes a throttle outflow passage portion 13 extending in the circumferential direction of the plunger.

Further, one end of this throttle outflow passage section 13 is connected to the communication groove 1.
2 to the top surface 3b of the plunger 3.

The passage cross-sectional area of this throttle outflow passage section 13 is
It is set as follows depending on the relative relationship between the moving speed of the fuel and the viscosity and inertia of the fuel. That is, the throttle outflow passage section 13
In the low-speed operating range of the engine where the moving speed of the planter 3 is slow (i.e., the operating range in which the viscosity and inertia of the fuel have little effect on the flow resistance of the fuel), the cross-sectional area of the passage is:
When the throttle outlet passage 13 and the barrel port 10 communicate with each other, a portion of the pressurized fuel in the pressurizing chamber 16 is smoothly transferred to the fuel chamber 17 ( (see Figure 1).
On the other hand, in a high-speed operating range of the engine where the plunger 3 moves quickly (i.e., an operating range where the flow resistance of fuel increases due to the influence of its viscosity and inertia), the throttle outlet passage 13 and the barrel When the ports 10 and 10 communicate with each other, a portion of the pressurized fuel in the pressurized chamber t6 is throttled and gradually transferred to the fuel chamber 1 through the outflow passage 13 and the barrel port 10.
It is set based on the relative relationship between the moving speed of the plunger 3 and the viscosity and inertia of the fuel so that the fuel can flow out to the 7 side. Therefore, in the low-speed operating range of the engine, a portion of the pressurized fuel in the pressurizing chamber 16 quickly flows out from the barrel port 10 to the fuel chamber 17 side by polymerizing communication with the throttle outlet passage 13 and the barrel port 10. However, the fuel pressure in the pressurizing chamber 16 momentarily drops below the valve opening pressure of the injector, and fuel injection from the injector is interrupted. On the other hand, in the high-speed operating range of the engine, even if the throttle outlet passage section 13 is in polymer communication with the barrel port 10, the pressurized fuel in the pressurizing chamber 16 only gradually flows out to the fuel chamber 17 side. There is almost no drop in the fuel pressure in the pressurizing chamber 16 when the throttle outlet passage section 13 and the barrel port 10 are in polymer communication (despite the polymer connection between the throttle outlet passage section 13 and the barrel port 10, the injector Fuel injection from continues without interruption.

On the other hand, the formation position of the calibration outflow passage section 13 in the plunger axial direction is set according to the relationship with the plunger axial direction dimension (1 (see Fig. 2) of the barrel port 1°. When the upper edge of the barrel port 10 matches the top surface 3b of the plunger 3 as shown by the chain line 10A in FIG. The lower edge position of the barrel port 10 and the lower edge position of the barrel port 10 in a state where there is a plunger stroke corresponding to 10B and the upper edge of the barrel port 10 matches the lower edge of the throttle outlet passage 13 as shown by the chain line 10B.
The plunger stroke corresponding to the dimension S is set to exist between the position of the lower edge of the barrel port 10 in a state where its lower edge overlaps the upper edge of the lead 11 as shown by C. In the following description, for convenience of explanation, among the outer circumferential surfaces of the plunger 3 that are closer to the top surface 3b than the lead 11, the top surface 3b is closer to the throttle outlet passage section 13.
The portion located on the side is the upper outer peripheral surface 31. The portion located between the throttle outlet passage portion 13 and the reed 2 is the lower outer circumferential surface 32.
That's what it means. Further, the relative circumferential position of the barrel port IO with respect to the plunger 3 in FIG. 2 corresponds to the rack position of the rack gear 9 when the engine is in idle operation (low speed idle).

In the fuel injection pump Z equipped with the plunger 3 having the throttle outflow passage 13 configured as described above, two-stage injection is realized in the low-speed operating range of the engine as described below, whereas in the high-speed operating range of the ennon In the operating range, one-stage injection is realized. That is, in the low-speed operating range of the engine, the barrel 2 moves upward as the plunger 3 moves upward.
The barrel port 10 of the plunger 3 is connected to the upper outer circumferential surface 31 of the plunger 3.
Injection (pre-injection) is started from the time when the barrel port 10 and the throttle outlet passage 13 are overlapped and communicated with each other, and the injection is continued for a period of stroke s1.
At the time when the barrel port 1o is in superimposed communication with the throttle outflow passage section 13, fuel injection is temporarily interrupted. Further, as the plunger 3 moves upward, fuel injection (main injection) is started again from the point at which the barrel port 10 is closed by the lower outer peripheral surface 32 of the plunger 3, and the barrel port 10 is in superimposed communication with the portion 11 of the plunger 3. The main injection is continued until (realization of two-stage injection, see Figure 6 (a)).

Therefore, in the low-speed operating range of this engine, compared to the case of single-stage injection, the fuel injection rate is low and combustion becomes slow, the rate of pressure rise in the cylinder decreases, and combustion noise is effectively reduced. will be done.

On the other hand, in the high-speed operating range of the engine, the viscosity and inertia of the fuel cause the barrel port lO
Even when the throttle outflow passage section 13 is in polymer communication, the fuel pressure within the pressurizing chamber 16 of the fuel injection pump Z hardly decreases. Therefore, in this operating range, the throttle outflow passage 13 does not substantially function, and from the time the barrel port 10 of the barrel 2 is closed by the upper outer circumferential surface 31 of the plunger 3, the barrel port 10 is in superimposed communication with the lead 2. Until then, fuel injection is performed continuously without interruption (realization of one-stage injection, see FIG. 6(c)).

Therefore, in this operating range, the fuel injection rate is maintained at a high level, so that good combustion is achieved.

In addition, in the medium speed operating range of the engine, Fig. 6 (b)
As shown in Fig. 2, fuel injection characteristics intermediate between the low-speed operation region and the high-speed operation region are obtained.

(Second Embodiment) FIG. 5 shows a plunger head 3a of a fuel injection pump Z according to a second embodiment of the present invention.

This fuel injection pump Z has all the same features as the first one described above except that an inclined upper lead 34 is provided on the top surface 3b of the plunger 3.
It has the same structure as the fuel injection pump Z of the embodiment.

As described above, when the upper lead 34 is provided, the barrel port 10 is in the "idle operating state" corresponding to the rack position immediately after the load is removed during medium/high-speed idling (that is, the rack position immediately after the load is removed in the loaded operating state). Low speed idle (dashed line 10A) as shown by chain line 10D in Figure 4
Since the fuel injection start timing is delayed compared to low-speed idling, the rate of pressure increase in the cylinder pressure is lower than when the injection start timing is at the rack position as in the first embodiment. It is lowered more than when it is set constant regardless of how it is, and the effect of reducing combustion noise is further improved.

Note that each member in FIG. 4 is given a reference numeral corresponding to each member in FIG. 2, and a description thereof will be omitted.

(Effects of the Invention) The present invention makes it possible to pressurize and force-feed fuel by reciprocating the plunger within the barrel, and at the same time, a diagonal groove-like groove is formed on the outer peripheral surface of the head of the plunger, which communicates with the top surface of the plunger. A fuel injection system in which the fuel injection amount is adjusted by forming a reed and adjusting the timing of communication between the reed and a barrel port formed in the barrel by appropriately rotating the plunger and the barrel relative to each other. In the pump,
A portion of the outer peripheral surface of the top of the plunger located between the top surface of the plunger and the lead in the axial direction of the plunger is connected to the lead, extends in the circumferential direction of the plunger, and is in communication with the barrel port. A throttle outflow passage is formed that acts to cause the water to flow out to the barrel port side in a throttled state, and as the plunger reciprocates, the barrel port is positioned between the top surface of the plunger and the throttle outflow passage. is located between the upper outer circumferential surface of the throttle outlet passage and the barrel port, and has a passage cross-sectional area of the throttle outlet passage that allows smooth flow of fuel during low-speed operation of the blur. On the other hand, during high-speed operation, the size is set so that the flow of fuel can be suppressed more than during low-speed operation.

Therefore, according to the fuel injection pump of the present invention, (1) the barrel port communicates with the throttle outflow passage because fuel flows out smoothly through the throttle outflow passage in the low speed operating region of the engine; two stages of injection before and after the main injection, which are performed after the communication between the barrel port and the throttle outflow passage is cut off and before the barrel port communicates with the reed. As a result, combustion is slow and the rate of pressure rise in the cylinder is reduced, which reduces combustion noise accordingly. Since the fuel outflow is suppressed, −1−sρ
Barrel port, μ stirrup outflow Wakufukukan Kinoura, low pressure drop in fuel pressure under city conditions 1 without interruption of fuel injection
Staged injection is realized, and as a result, the fuel injection rate is maintained at a high level and good combustion conditions are obtained, among other effects.

[Brief explanation of drawings]

FIG. 1 is an overall vertical cross-sectional view of a fuel injection pump according to a first embodiment of the present invention, FIG. 2 is an enlarged view of the ■ part in FIG. 1, and FIG. 3 is a view taken along the ■-■ arrow in FIG. 2. , FIG. 4 is an enlarged view of the top of the plunger of the fuel injection pump according to the second embodiment of the present invention, and FIG.
The figure is a view taken along the line ■-■ in FIG. 4, and FIG. 6 is a fuel injection characteristic diagram of the fuel injection pump shown in FIG. 1. l... Pump body 2... Barrel 3... Plunger 4... Plunger rotating wheel 5... Plunger spring 6... Delivery valve 7... ... Plunger rotating wheel 8 ... Metering operator 9 ... Rack gear 10 ... Barrel port 11 ... Lead 12 ... Communication groove 13 ... Throttle outflow passage Part 14... Concave groove 34... Upper lead Figure 1 (A) (B) (C)
Figure 6 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. By reciprocating the plunger (3) within the barrel (2), the fuel can be pressurized and pumped, and the plunger top surface ( A diagonal groove-shaped lead (11) communicating with 3b)
The plunger (3) and the barrel (2) are rotated relative to each other as appropriate so that the lead (11) and the barrel (2) are connected to each other.
) is a fuel injection pump that adjusts the amount of fuel injection by adjusting the communication timing with a barrel port (10) formed in the top outer peripheral surface (3c) of the plunger (3). The barrel port (10) extends in the circumferential direction of the plunger and communicates with the lead (11) in a portion located between the plunger top surface (3b) and the lead (11) in the plunger axial direction.
a throttle outlet passage section (which acts to cause the fuel to flow out to the barrel port (10) side in a throttled state when in communication with the barrel port (10);
13), and as the plunger (3) reciprocates, the barrel port (10) is located between the plunger top surface (3b) and the throttle outflow passage (13). (31), and a lower outer peripheral surface located between the throttle outlet passage (13) and the barrel port (10) (
32) so that they can be respectively occluded, and
The passage cross-sectional area of the throttle outflow passage (13) is set to allow smooth flow of fuel during low-speed operation of the plunger (3), while allowing fuel to flow more smoothly during high-speed operation than during low-speed operation. A fuel injection pump characterized by being set to a size that can be suppressed.