JPS58106135A - Fuel supply device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To both improve an output of an engine and reduce its noise without causing the worsening of exhaust emission, by providing a solenoid valve, which controls pressure of fuel supplied to a high pressure chamber of an injection pump, and a fuel supply pressure control circuit. CONSTITUTION:An outlet 109 of a pressurizing pump 108 and an overflow pipe 112 reaching a fuel tank 103 are connected through a pipe 114 equipped with a solenoid valve 113. Opening of this solenoid valve 113 is controlled by a fuel supply pressure control circuit 115 to variably control supply pressure of fuel to a high pressure chamber of a fuel injection pump 101. In this way, exhaust emission and noise of an engine can be improved while improving its fuel consumption and output.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system for an internal combustion engine equipped with a fuel injection pump, such as a diesel engine.

It is well known that in diesel engines, the fuel injection amount is variably controlled depending on the engine speed and load. For example, a distribution type fuel injection pump is used to control the amount of fuel injection. (daily car■,
Published in April 1982.

``Service Bulletin No. 418 Datsun Blue Pardon'' This distribution type fuel injection pump Fi is configured as shown in Figure 1.
Fuel is sucked from an inlet 1 of the pump body by a feed pump 3 driven by a drive shaft 2 connected to an engine output shaft. The fuel discharged from the feed pump 3 is supplied to the pump chamber 5 in the pump/X Ujifugu 31 with the supply pressure controlled by the pressure regulating valve 4 . The fuel in the pump chamber S lubricates each operating part and is simultaneously sent to the plunger pump 6 through the suction boat 12.

The plunger 7 of this pump 6 is fixed to an eccentric disk 8 connected to the drive shaft 2, and is driven by the drive shaft 2 through a slide joint 2at in synchronization with the rotation of the engine. has the same number of 7-eighth cams 9 as the number of engine cylinders, and this face cam 9 is set to low? By contacting the row 211 supported by the ring 10, the face cam 9 reciprocates by a predetermined cam lift each time it crosses over the roller 111. Therefore, the plunger T makes a reciprocating motion while rotating, and by this reciprocating motion, the fuel sucked into the bipressure chamber 6a from the suction boat 12 is forced to be sent from the distribution boat 13 through the delivery valve 14t to an injection nozzle (not shown). . Incidentally, the fuel injection timing can be freely adjusted by rotating the roller ring 10 with a timer piston 29 to which pressure from the pump chamber 5 is supplied, and by changing the relative position between the face cam 9 and the roller 11. Ru.

On the other hand, the amount of fuel to be injected is determined by the position of the control sleeve 16 that covers the cut-off boat 15 formed on the plunger T. For example, cant off boat 15
When the opening of the plunger 1 passes over the right end of the control sleeve 16 by moving the plunger 1 to the right, the fuel that was being pumped from the bipressure chamber 6a to the distribution boat 13 is released to the pump chamber 5 through the cut-off boat 15. As a result, the pumping of fuel is completed. Therefore, if the control sleeve is moved relative to the right in the figure with respect to the plunger T, the fuel injection end time will be delayed and the injection amount will be increased, and if it is moved to the left, the injection end time will be delayed. It becomes faster and the injection amount decreases.

The control sleeve 16 is supported by a link lever device 19 that communicates with an accelerator pedal (not shown), and is displaced according to the amount of depression of the accelerator pedal. At the same time, a governor mechanism 18 driven by the drive shaft 2
The mechanism 18 corrects and controls the link lever device 1g to increase or decrease the fuel injection amount to maintain the engine speed corresponding to the accelerator opening. The link lever device 19 includes a collector lever 21, a tension lever 22. It is composed of a start lever 23 and a start spring 24.

Here, the collector lever 21 is rotatably supported by the pump housing 31 about the fulcrum B, is pressed against the load adjustment screw 26 by the compression spring 25 and remains stationary, and the tension lever 22
The start lever 23 is pivotally connected to the collector lever 21 at a fulcrum A, and the tension lever 22 includes a control lever 2. which is linked to an accelerator pedal (not shown).
00 The tension of a tension spring 28 whose biasing force changes depending on the rotation position is applied, and the tension (biasing force) of this spring is transmitted to the start lever 23 via the start spring 24, and the start lever 23 is connected to a governor mechanism, which will be described later. 18 governor sleeve 111f. The control sleeve 16t is connected to the start lever 23 via a ball joint 18g.

Therefore, when the control sleeve' is rotated via the accelerator pedal to increase the tension of the tension spring 28, the tension lever 22 is rotated in the counterclockwise direction in the figure, and the tension lever 22 is rotated in the counterclockwise direction in the figure. Push the lever 23 and move the control sleeve 16 to the right in the figure centering on the fulcrum Al1 to increase the injection amount.

On the other hand, the governor mechanism 18 is housed in the upper part of the injection pump main body, and the flyweight 18C'i junction 18d is attached to the flyweight holder 18b which is integrated with the gear 18M.
It is mounted so that it can rotate freely around the center. Therefore, when the flyweight holder 18b rotates around the governor shaft 18 due to the 20 rotations of the drive shaft transmitted through the gear 18a, the flyweight 18C also rotates, and the centrifugal force of the rotation causes the center of the contact point 18d'1li7 to rotate. The aperture widens and moves. For example, if the engine speed increases even though the accelerator opening does not change, the governor sleeper 18f, which fits into the governor shaft 7) 186 and engages with the flyweight 18C, is pushed by the flyweight 18C, as shown in the figure. Move forward to the right.

Then, as the governor sleeper 18f moves forward, the start lever 23 rotates in the clockwise direction in the figure around the fulcrum A, causing the control sleeve 16 to move to the left in the figure to reduce the injection amount. , thus lowering the rotational speed of the two engines. When the rotational speed increases in this manner, the engine rotational speed is controlled to a value corresponding to the accelerator opening degree by feedback controlling the control sleeve 160th position IIt. In the figure, 21 is the shaft of the control lever 20.

By the way, the characteristics of feedback control as described above are
This fulcrum A is determined by the position of the fulcrum A, and this fulcrum A is determined by adjusting the load adjustment screw 26 and adjusting the collector lever 21.
By moving the fulcrum Bf: the center of the core, the amount of fuel injection can be positioned as shown in FIG. 2 with respect to the engine speed.

However, in such a conventional device, the collector lever 21
Since the position of the governor sleep 18f is uniquely determined by the load adjustment screw 26, even if the opening degree (fit) of the control lever 20 is constant, the engine speed is low and the position of the governor sleep 18f is at the left limit (maximum). If the engine is close to the reverse position), the start lever 23 will tilt significantly to the left and the position of the control lever 16 will be specified to have the characteristic of injecting the maximum amount of injection. For this reason, for example, when accelerating from a start or accelerating from a low speed, even if the amount of depression of the accelerator pedal is small and the opening degree of the control lever 20 is small, the maximum amount of fuel is injected, increasing the smoke concentration in the exhaust gas and reducing fuel consumption. The problem rarely got worse.

In addition, in the conventional device, plunger 7t-face cam 9
The effective stroke of the plunger T was adjusted by the opening degree of the control lever 20 to control the fuel injection amount. will be determined accordingly.

For this purpose, especially if the engine is a diesel engine,
A frequent problem was that it was difficult to obtain optimal injection characteristics according to engine operating conditions in order to improve fuel efficiency and output while reducing NOx and noise.

The present invention has been made by focusing on the above-mentioned problems of the conventional device, and solves the problems of the above-mentioned conventional device by optimally controlling the pressure of the fuel supplied to the high pressure chamber of the injection pump according to the engine operating condition. The purpose is to solve the problem.

The present invention will be explained in detail below based on an embodiment shown in FIGS. 3 to 5.

W. Figure 3 is a system diagram showing an embodiment of the present invention.
Injection pump 10 configured similarly to the conventional example shown in FIG.
1 fuel population 102, fuel tank 103 and t water separator 1
04, Pretweedon 14 pump 105 and fuel filter 1 (communicated via j6'i. Same, injection pump 10
1 has a built-in feed pump (not shown) as in the conventional case.

A suction port of a pressure pump 108 is connected to the tip of a fuel pipe 107 branched from the downstream side of the fuel filter 106,
The outlet 109 of the pump 10B communicates with the high pressure chamber of the injection pump 101 via a full fuel inlet pipe 110. Incidentally, at the downstream end of this introduction pipe 110, there is a reverse mt of fuel from the bipressure chamber to the pressurizing pump 108.
- layering the blocking delivery valve 111; Then, the outlet 109 of the pressurizing pump 108 and the overflow pipe 112 leading to the fuel tank 103 are connected via a pipe 114 equipped with a solenoid valve 113t, and the opening degree of this solenoid valve 13 is adjusted by a fuel supply pressure control circuit 115. The fuel supply pressure to the high pressure chamber is fully variable controlled.

The fuel supply pressure control circuit 115 includes a fuel pressure (supply pressure) detected via a pressure sensor 1t6fr provided in the fuel introduction pipe 110, a (translation) sensor 117 employed as an intermediate stage for detecting the engine operating state, and Lever opening sensor 118
The output of the engine, that is, each trough of the engine speed and load is supplied as an indicator of the engine operating state, and the fuel introduction pressure te to the high pressure chamber is determined according to the operating state detected by each of these indicators. I try to control it. In the figure, 119.120 is a signal line, 1.21 is an injection nozzle, and 1.
22 is a delivery valve, and 123 is a fuel cut solenoid.

In the above configuration, when the engine is operated, the fuel that has passed through the fuel filter 106 is pumped to the injection pump 101 in the a-in stroke.
From zero population, the water flows into the pump chamber in the same manner as in the conventional art under the pressure action of a feed pump (not shown), and is sucked into the high pressure chamber from the pump chamber via the suction boat. At the same time, the pressure pump 10 is installed in the bipressure chamber.
8, the pressurized fuel is fed into the supply bag, so at least at the end of the suction stroke, the pressure of the high pressure pump 10B becomes equal to the discharge pressure of the pressurizing pump 10B.
When the plunger (not shown) moves to the pressure feeding stroke, the pressure of the valve 122 rises due to the pressurizing action of the plunger and becomes higher than the valve opening pressure of the valve 122, so that the fuel is delivered to each cylinder in a predetermined order. The water is pumped δ to the injection nozzle 121 provided at .

Here, the fuel supply pressure to the high pressure chamber t-
If the pressure is too high, the fuel injection pressure will increase and the injection time will become shorter due to the operation of the governor mechanism. Conversely, if the supply pressure is lowered, the injection pressure will be lower and the injection time will be longer.If the fuel supply pressure to the bipressure chamber is changed, the injection pressure and period will change as shown in Figure 4. .

- side, fuel supply pressure cover to the high-pressure chamber;
'wThe flow rate of fuel leaking from the L magnetic valve 113, that is,
It changes depending on the opening degree of the solenoid valve 113.

That is, as shown in FIG. 5(a), the duty ratio of the signal controlling the solenoid valve 113 is changed, or as shown in FIG. 5(b), the voltage value of the control signal for the solenoid valve 113 is continuously changed. As a result, the flow rate of fuel escaping from the electromagnetic valve 113 changes as shown in (d) of the same figure, so the pressure of fuel supplied to the pressure chamber changes as shown in (C) of the same figure.

Therefore, if the control signal supplied to the solenoid valve 113 is programmed in advance according to each operating state so that the fuel supply pressure is optimized, the fuel supply pressure (injection period) can be optimally controlled according to the engine operating state. Therefore, fuel efficiency and output can be improved without deteriorating exhaust emissions, noise, etc.

In the embodiment, the engine operating state is detected by the rotational speed and the control lever opening (load), but other conditions may also be used as correction factors. Further, although it is not necessarily necessary to provide a pressure sensor, it is also possible to use a signal of the injection period or the pressure of the high pressure chamber as a feedback signal. Furthermore, the pressurizing means and the supply pressure control means are not necessarily limited to the embodiments, and in short, any means may be used as long as they can control the fuel supply pressure to the high pressure chamber according to the engine operating state. As explained above, according to the present invention, the injection characteristics can be optimally controlled by controlling the fuel supply system tIJ to the injection valve according to the operating state of the engine. Therefore, it is possible to improve exhaust emissions and noise while increasing the fuel efficiency and output of one engine. .

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a conventional injection pump, Fig. 2 is a characteristic diagram of the same F fuel pump, and Fig. 3 is a characteristic diagram of fuel supply pressure and relief fuel due to changes in the number of an embodiment of the present invention. Yes, 101... Injection pump, 103... Fuel tank, 108... Pressure bomb, 113... Solenoid valve,
115... Fuel supply pressure control circuit, 116... Pressure sensor, 117... Rotation sensor. 11B・
...Lever opening sensor.

Claims (1)

[Claims] In an internal combustion engine equipped with a fuel injection pump, a pressurizing means for pressurizing fuel, a means for detecting the operating state of the engine, and a means for controlling the injection pump from the pressurizing means according to the operating state of the engine detected through the means. 1. A fuel supply device for an internal combustion engine, comprising: fuel supply pressure control means for controlling the pressure of fuel supplied to a pressure chamber.