JPS6123836A - Fuel injection controller - Google Patents

Abstract

PURPOSE:To aim at an increment of pressure-feed power in a fuel injection pump, by controlling a valve, installed in a bypass passage of a fuel injection nozzle, and a regulator lever of the fuel injection pump according to engine speed and load. CONSTITUTION:A valve 21, installed in a bypass passage 18 of a fuel injection nozzle 12, is connected to a linear solenoid 23 via a rod 22, and the upper end of a fuel quantity regulator lever 5 of a fuel injection pump 2 is made contact with a linear solenoid 7. According to engine speed and load, both these solenoids 23 and 27 are driven, controlling the valve 21 and the lever 5. With this constitution, even in times of low speed and low load, the fuel injection pump 2 is operatable for its full load operation so that pressure-feed power in the fuel injection pump 2 is well improved, thus fuel atomization is improvable.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fuel injection control device used in an internal combustion engine such as a diesel engine.

Conventional technology Conventionally, a fuel injection device pumps fuel from an injection pump and injects the fuel into an engine cylinder using an injection nozzle.
As a measure to atomize the injected fuel at low rotation speeds and low loads, a fuel injection control device using an injection nozzle with a throttle mechanism that has a variable injection nozzle cross-sectional area has been proposed. In addition, in the sense of controlling the pressure of the fuel injection valve, it is
No. 1375 fuel injection valve and the like have been proposed.

Problems to be Solved by the Invention However, in the injection nozzle with a throttle mechanism, the structure of the injection device, that is, the method of metering and pressure-feeding fuel with an injection pump and injecting it from the injection nozzle, naturally depends on the rotation speed and load. This causes the injection pressure of the fuel injected from the injection nozzle to change significantly, limiting the range in which the throttle mechanism can effectively act. There were disadvantages in that the pressure did not increase sufficiently, the outflow speed of the spray decreased, and a large amount of exhaust HC was generated due to insufficient atomization of the injected fuel. In addition, the fuel injection valve of Utility Model Application Publication No. 58-81375 is
The purpose of this method is to prevent the injection pressure from rising too high, but it does not solve the problem of the present invention, which is that the injection pressure drops too much.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, the object of the present invention is to
An object of the present invention is to provide a fuel injection control device that can sufficiently atomize injected fuel, suppress HC emissions, and obtain stable combustion even under low loads.

Means for Solving the Problems A fuel injection control device of the present invention that meets this objective includes an injection pump that delivers fuel at high pressure, a needle tip conical portion, and an inner circumferential conical portion of a nozzle body that abuts the conical portion. A fuel injection nozzle having a bypass passage communicating with the outside when the needle is raised is formed on a seat portion formed by the fuel injection nozzle, and a flow control valve communicating with the bypass passage of the fuel injection nozzle. , rotational speed detection means, and in the case of the injection pump, a flow control valve that communicates the delivery fuel flow rate adjustment means and the flow rate detection means with the bypass passage of the fuel injection nozzle, the flow rate control valve adjustment means. and a flow rate detection means, and a microcomputer controls the flow rate of the injection pump and the flow rate control valve according to the engine speed and load condition.

Operation In a device configured as described above, even when the engine speed is low and the load is low, the fuel injection pump is operated at full load and the amount of fuel escaping through the bypass passage is controlled to maintain high-pressure fuel. The pressure of the fuel injection pump can be sufficiently increased regardless of the rotation speed and load, and the atomization of the injected fuel is improved, making it possible to reduce exhaust HC.

EXAMPLES Below, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an electronically controlled fuel injection system according to the present invention, in which 1 is a fuel tank and 2 is an electronically controlled fuel injection pump that sucks fuel from the fuel tank 1 through a pipe 28 and pumps it under high pressure. Built into the fuel injection pump 2 are a plunger 3 that pumps fuel under high pressure, and a spill ring 4 that adjusts the amount of fuel pumped by the plunger. This spill ring 4 uses a fulcrum 6 as a fulcrum, and a lever 5 moves the plunger 3
Translate on the axis of The upper end of the lever 5 is in contact with a linear solenoid 7, and the amount of movement of the spill ring 4 is determined by the movement of the linear solenoid 7. 8 more
The amount of movement is detected by the spill position sensor.

The detected signal is transmitted to the microcomputer 25 via a signal line 35. Further, a gear 9 is attached coaxially with the plunger 3, and a rotation speed sensor 10 detects the rotation speed. The signal of the rotation speed sensor 10 is transmitted through the signal line 34
The information is transmitted to the microcomputer 25 by the following.

A discharge port 11 of the fuel injection pump 2 is connected to a fuel injection nozzle 12 via a vibrator 29.

The fuel injection nozzle 12 that injects the fuel pressure-fed from the injection pump 2 is made up of a nozzle body 13 and a needle 14. A nozzle hole 16 is opened at the tip of the nozzle 12, and the tip of the needle 14 and the nozzle body 13 come into contact. The sheet portion 15 formed by the contact is normally urged downward in the figure by a spring (not shown) to maintain the seal.

Fuel is supplied to the fuel supply passage 17 via the communication passage 19, but when the needle 14 rises, the needle 1
It also communicates with a fuel bypass passage 18 that opens at the axial center of No. 4, and the communication passage 20 is also filled with fuel.

To explain the detailed structure of the nozzle tip with reference to FIG. 2, the nozzle body 13 at the tip of the fuel injection nozzle 12 has a needle 1.
4 is inserted and abuts against the conical end portion 40 thereof,
The nozzle body 13 is also formed with an inner circumferential conical portion 41, and a seat portion 1 that blocks fuel from the nozzle 16 and the fuel supply passage 17.
5 is formed. A fuel bypass passage 18 passes through the center of the needle 14 parallel to the axis, and its end opens into a communication passage 39 . The communication portion 39 opens toward the seat portion 15, and when the needle 14 is tightly closed to the seat portion 15, it does not communicate with either the fuel supply passage 17 or the injection port 16, but the needle 14 Go up and seat part 1
5 is opened, the communication passage 39 communicates with the fuel supply passage 17 and the injection port 16, and also with the bypass passage 18.

FIG. 2(b) shows the structure of the nozzle tip according to another embodiment. In this embodiment, a fuel bypass passage 18 is formed in the nozzle body 13. 39 is a communication path, 39a
, 39b are blind plugs for forming passages.

As shown in FIG.
0 and led to the bypass valve 21 by a pipe 30. The bypass valve 21 is a flow rate control type valve that can vary the cross-sectional area of the flow path. The fuel bypassed by the bypass valve 21 is returned to the fuel tank 1 through a pipe 31.

In addition, the bypass valve 21 includes a rod 22 connected to a linear solenoid 23 whose absorption force can be freely changed by changing the current value.
connected by.

A rod position sensor 24 serves to transmit the amount of change in the bypass valve 21 to the microcomputer 25 via a signal line 36. .

Reference numeral 26 denotes an accelerator pedal whose movement is transmitted to the accelerator opening sensor 27 via a wire 32, converted into an electrical signal, and transmitted to the microcomputer 25 via a signal line 33.

The output signal of the microcomputer 25 is transmitted through the signal line 37.
38 to the linear solenoid 7 of the fuel injection pump 2 and the linear solenoid 23 of the bypass valve 21, respectively, to control their respective flow rates.

The action will be explained below.

Fuel is 1. After being supplied from the fuel tank 1 to the fuel injection pump 2 through the pipe 28 and compressed at high pressure by the plunger 3,
It is supplied from the discharge port 11 to the injection nozzle 12 through a pipe 29. When the communication passage 19 and the fuel supply passage 17 are filled with fuel, the pressure applied to the needle 14 increases and the needle 14 rises against the spring, the seat portion 15 is opened and fuel is injected from the nozzle 16. . At the same time, high-pressure fuel is also supplied to the fuel bypass passage 18, introduced into the bypass valve 21 through the pipe 30 via the communication passage 20, and returned to the fuel tank 1 through the pipe 31 after flow rate adjustment.

The microcomputer 25 includes an accelerator opening sensor 2.
7, an output signal from the rotation speed sensor 0 attached to the injection pump 2, an output signal from the spill position sensor 8 directly connected to the linear solenoid 7 that also moves the spill ring 4 of the injection pump 2, and a bypass valve 21. The output signals from the rod position sensor 24 are directly connected to the driving linear solenoid 23 and are taken in through signal lines 33, 34, 35, and 36, respectively, and the spill ring 4 is controlled according to the control contents stored in the microcomputer 25 in advance.
A control signal is outputted via signal lines 37 and 38 so as to independently drive the near solenoid 7 that drives the bypass valve 21 and the near solenoid 23 that drives the bypass valve 21, respectively.

Specifically, as shown in FIG. 6, when the microcomputer circuit starts (step 100), the rotation speed Ne of the rotation speed sensor 10 attached to the injection pump 2 is read (step 101). If the engine is stopped for some reason, the rotational speed Ne is determined (step 102) and the process returns to step 101.

When the engine is rotating and the rotational speed Ne is read, the accelerator opening θa of the accelerator opening sensor 27 is then read (step 103). As shown in Figure 3, the relationship between the engine speed and the injection pressure of the injection nozzle in a general fuel injection system varies greatly depending on the engine speed and injection amount. As shown in , there were regions where the minimum pressure level required to achieve atomization of the fuel spray was not reached and sufficient atomization was not achieved. Therefore, the present invention adjusts the fuel injection pump 2 in this region so that the injection amount is equal to or higher than the minimum pressure level for atomization, and after securing the pressure, adjusts the fuel amount to the fuel injection pump 2. This is done using a nozzle 12'' and a bypass valve 21. Returning to FIG. 6 again to explain the control contents, step 101, step 1
When the engine speed Ne and the accelerator opening θa are inputted in step 03, the diagram of the engine speed and injection pump discharge force (Ne - Qp
In step 104), the injection pump discharge force Qp corresponding to IjSJe and Qa is read out from FIG. Next, the spill ring 4 of the fuel injection pump 2 is multiplied by the coefficient α to the value of Qp.
The value is converted into a spill position Sp which is the amount of change in (step 105). Furthermore, the actual spill position Sp' is read from the spill position sensor 8 of the fuel injection pump 2 (step 106), the final spill position movement amount (Sp) is calculated (step 107), and output (step 108), and the fuel injection The amount of fuel supplied from the pump 2 to the fuel injection nozzle 12 is controlled within the shaded range shown in FIG. On the other hand, the bypass valve 21 is activated at the same time as step 104 (a diagram UNe-Qb of engine speed and bypass valve discharge amount shown in FIG. 5).
The bypass valve discharge amount Qb corresponding to Ne and θa is read from (step 109). As is well known, the discharge amount at this time has an inverse relationship to the pump discharge amount shown in FIG. It has become. Next, the value of Qb is converted into a Rondo position value of the bypass valve (step 110), and in step 111, the actual rod position is read from the sensor 24.

Furthermore, the final Rondo movement amount (Lb) is calculated (step 112), and (LB) is outputted to the linear solenoid 23 (step 113). In this way, the bypass valve 21
The linear solenoid 23 moves the arrow 4 around the shaft 42.
3 to control the flow rate of fuel between pipe 30 and pipe 31. Steps 104 to 108 above
The operations up to and including steps 109 to 113 are performed in the same manner, and after outputting (Sp) and (LB) respectively, the process returns to step 114, and the process returns to the start of step 100.

Effects of the Invention According to the present invention, a bypass passage is provided in the fuel injection nozzle, a bypass valve is provided in the bypass passage, and the bypass valve and the fuel injection pump are controlled by a microcomputer. By supplying high-pressure fuel even under low load, the pressure of the injection pump can be sufficiently increased regardless of the load, and by improving the atomization of the injected fuel, it is possible to reduce exhaust HC. This effect can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an overall system diagram showing an embodiment of the present invention, Fig. 2 (a) and (b) are respectively enlarged sectional views of the tip of the injection nozzle, and Fig. 3 is a diagram showing the relationship between engine speed and injection pressure. Figure 4 is a diagram showing the relationship between engine speed and injection pump discharge output, Figure 5 is a diagram showing the relationship between engine speed and bypass valve discharge amount, and Figure 6 is a flowchart showing the control of each linear solenoid according to the present invention. . 1... Fuel tank 2... Injection pump 3... Plunger 4... Spill ring 5... Lever 6... Fulcrum 7... Linear sononoid 8... Spill position sensor 9... Gear 10... Rotation speed sensor 11... Discharge port 12. ... Fuel injection nozzle 13 ... Nozzle body 14 ... Needle 15 ... Seat part 16 ... Nozzle 17 ... Fuel Supply passage 18...Fuel bypass passage 19.20...Communication passage 21...Bypass valve 22...Rod 23...Linear sononoid 24...Rod position sensor 25...Microcomputer 26...
・Accelerator pedal 27...Accelerator opening sensor 28.29.30,31...Pipe 32...
...Wire 33.34.35. 36.37.38... Signal line 39... Communication path 40... Tip 41... Conical part 42... Shaft 43... ...Arrow Figure 1 Figure 2 (A)

Claims (1)

[Claims] (1) An injection pump that delivers fuel at high pressure, and a bypass passage that communicates with the outside when the needle rises on a seat portion formed by a conical tip end of the needle and an inner conical portion of the nozzle body that abuts the conical portion. and a flow rate control valve communicating with a bypass passage of the fuel injection nozzle. In the case of a flow rate control valve that communicates a flow rate adjustment means and a flow rate detection means with a bypass passage of a fuel injection nozzle, the flow rate control valve is provided with an adjustment means and a flow rate detection means for the flow rate control valve, respectively, and the flow rate is controlled according to the engine speed and load condition. A fuel injection control device characterized in that the flow rate adjustment of the injection pump and the flow rate adjustment of the flow rate control valve are performed by a microcomputer.