JPH0617653B2 - Fuel injection control device - Google Patents

Description

The present invention relates to a fuel injection control device used in an internal combustion engine such as a diesel engine.

[Prior Art] Conventionally, in a fuel injection device that pumps fuel from an injection pump and injects the fuel into an engine cylinder with an injection nozzle,
A fuel injection control device using an injection nozzle with a throttle engine having a variable injection port cross-sectional area has been proposed as a measure against atomization of injected fuel at low rotation speed and low load. Also, in the sense that the pressure of the fuel injection valve is controlled
No. 1375 fuel injection valve and the like have been proposed.

[Problems to be Solved by the Invention] However, in the injection nozzle with the throttle engine, in the configuration of the injection device, that is, in the method of injecting fuel from the injection nozzle by metering and pressure-feeding the fuel with the injection pump, the number of revolutions is naturally increased. The load changes the injection pressure of the fuel injected from the injection nozzle significantly, limiting the range in which the throttle mechanism works effectively. Especially, at the time of extremely low rotation and low load, the fuel compressed by the injection pump is sent. However, there is a drawback that a large amount of exhausted HC is generated due to insufficient increase in the pressure of No. 3, the decrease in the outflow rate of the spray, and insufficient atomization of the injected fuel. In addition, the fuel injection valve of Jiukai Sho 58-81375 is
The purpose of the present invention is to prevent the injection pressure from rising too high, and it has not solved the problem of the present invention in which the pressure is too low.

The object of the present invention is to achieve extremely low engine speed and low load.
It is an object of the present invention to provide a fuel injection control device capable of sufficiently atomizing the injected fuel, suppressing the discharge of HC, and obtaining stable combustion.

[Means for Solving the Problems] A fuel injection control device of the present invention that achieves this object includes the following device. That is, a fuel tank, a fuel injection pump having an inlet and an outlet, the inlet being connected to the fuel tank and delivering fuel at high pressure from the outlet, and a needle tip cone connected to the outlet of the fuel injection pump. And a seat formed by an inner peripheral conical part of the nozzle body that abuts on the conical part and the seat is opened to the seat when the needle rises and bypasses the fuel injection pump to the fuel tank. A fuel injection nozzle having a bypass passage communicating with the fuel injection nozzle, a flow control valve provided on a passage communicating the bypass passage of the fuel injection nozzle with the fuel tank, a load detecting means of the engine, the engine or the fuel. An injection pump rotation speed detecting means, a delivery fuel flow rate adjusting means and a flow rate detecting means provided in the fuel injection pump, and the flow provided in the flow rate control valve. A quantity control valve adjusting means and a flow rate detecting means; a delivery fuel flow rate adjusting means and a flow rate detecting means of the fuel injection pump; and a microcomputer electrically connected to the flow rate control valve adjusting means and the flow rate detecting means. The flow control of the fuel injection pump and the flow control of the flow control valve are performed by the microcomputer according to the load condition of the engine and the rotation speed of the engine or the fuel injection pump.

[Operation] In the above-described device of the present invention, the high-pressure fuel is controlled by operating the fuel injection pump at full load and controlling the amount of fuel escaping through the bypass passage even at low engine speed and low load. The pressure-feeding pressure of the fuel injection pump that delivers the fuel can be sufficiently increased regardless of the number of rotations and the load, and atomization of the injected fuel is improved,
It is possible to reduce the exhausted HC.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an electronically controlled fuel injection device according to the present invention. Reference numeral 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 sends it under high pressure. In the fuel injection pump 2, a plunger 3 for pressure-feeding fuel and a spill ring 4 for adjusting the amount of fuel pressure-fed by the plunger are incorporated. This spill ring 4 is a lever 5 with a fulcrum 6 as a fulcrum, and a plunger 3
Translate on the axis of. The upper end of the lever 5 is in contact with the linear solenoid 7, and the movement amount of the spill ring 4 is determined by the movement of the linear solenoid 7. 8 more
The spill position sensor detects the amount of movement.
The detected signal is transmitted to the microcomputer 25 by the signal line 35. Further, a gear 9 is mounted coaxially with the plunger 3, and a rotation speed sensor 10 detects the rotation speed. The signal of the rotation speed sensor 10 is the signal line 34.
Is transmitted to the microcomputer 25. The discharge port 11 of the fuel injection pump 2 is connected to the fuel injection nozzle 12 via a pipe 29.

The fuel injection nozzle 12 for injecting the fuel pumped from the injection pump 2 is composed of a nozzle body 13 and a needle 14. An injection hole 16 is opened at the tip of the fuel injection nozzle 12, and the tip of the needle 14 and the nozzle body 13 come into contact with each other. By the seat portion 15 formed by the contact, the needle 14 is normally urged downward in the drawing by a spring (not shown), and the sealing is maintained. The fuel is supplied to the fuel supply passage 17 through the communication passage 19. When the needle 14 rises, the fuel is also communicated with the fuel bypass passage 18 that opens in the axial center of the needle 14, and the communication passage 20 is also filled with the fuel. Be done.

The detailed structure of the nozzle tip will be described with reference to FIG. 2. The needle 1 is attached to the nozzle body 13 at the tip of the fuel injection nozzle 12.
4 is inserted and touches the tip conical portion 40,
An inner peripheral conical portion 41 is also formed in the nozzle body 13, and the seat portion 1 that shuts off the fuel in the injection port 16 and the fuel supply passage 17 is formed.
5 is formed. A fuel bypass passage 18 passes through the center of the needle 14 in parallel with the axis, and its end opens into a communication passage 39. The communication passage 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 Seat part 1
When 5 is opened, the communication passage 39 communicates with the fuel supply passage 17 and the injection port 16, and also communicates with the bypass passage 18.

FIG. 2B shows the structure of the nozzle tip according to another aspect. In this aspect, the fuel bypass passage 18 is formed in the nozzle body 13. 39 is a communication passage, 39a,
39b is a blind plug for forming a passage.

As shown in FIG. 1, the fuel bypass passage 18 of the fuel injection nozzle 12 having the above-described nozzle structure is connected to the communication passage 20 and guided to the bypass valve 21 by the pipe 30. The bypass valve 21 is composed of a flow rate control valve capable of varying the flow passage cross-sectional area. The fuel bypassed by the bypass valve 21 is returned to the fuel tank 1 through the pipe 31. Further, the bypass valve 21 is connected by a rod 22 to a linear solenoid 23 whose absorption force can be freely changed by changing the current value. Reference numeral 24 denotes a rod position sensor, which serves to transmit the amount of change of the bypass valve 21 to the microcomputer 25 via the signal line 36.

Reference numeral 26 denotes an accelerator pedal, the movement of which is transmitted to the accelerator opening sensor 27 by a wire 32 and is transmitted to the microcomputer 25 by a signal line 33 after being converted into an electric signal.

The output signal of the microcomputer 25 is the signal line 37,
They are sent to the linear solenoid 7 of the fuel injection pump 2 and the linear solenoid 23 of the bypass valve 21 via 38 to control the respective flow rates.

The operation will be described below.

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

The microcomputer 25 includes an accelerator opening sensor 2
7, an output signal from a rotation speed sensor 10 attached to the injection pump 2, an output signal from a spill position sensor 8 directly connected to a linear solenoid 7 for moving the spill ring 4 of the injection pump 2, and a bypass valve 21. The output signals of the rod position sensor 24, which are directly connected to the driving linear solenoid 23, are taken in through the signal lines 33, 34, 35 and 36, respectively, and the spill ring 4 is supplied in accordance with the control contents stored in the microcomputer 25 in advance.
A control signal is output via the signal lines 37 and 38 so that the linear solenoid 7 that drives the control valve and the linear solenoid 23 that drives the bypass valve 21 are driven independently of each other.

Specifically, when the circuit of the microcomputer is started as shown in FIG. 6 (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 number of revolutions Ne is determined (step 102), and the process returns to step 101.

When the engine is rotating and the rotation speed Ne is read, next, the accelerator opening θa of the accelerator opening sensor 27 is read.
Is read (step 103). As shown in FIG. 3, the relationship between the engine rotation speed and the injection pressure of the injection nozzle in a general fuel injection device greatly changes depending on the rotation speed and the injection amount. As shown in (3), there was a region where the pressure level that was the minimum required to achieve atomization of the fuel spray was not achieved and atomization was not sufficiently performed. Therefore, in the present invention, the fuel injection pump 2 is adjusted so that the injection amount becomes equal to or higher than the minimum pressure level for atomization in this region, the pressure is secured, and then the fuel amount is adjusted. The nozzle 12 and the bypass valve 21 are used. Referring again to FIG. 6, the control contents will be described. Step 101, step 1
When the rotation speed Ne and the accelerator opening degree θa are input in 03, respectively, the engine rotation speed and the injection pump discharge force (Ne-Qp) shown in FIG. 4 based on the control content described above (Ne-Qp
The injection pump discharge force Qp corresponding to Ne and θa is read from the figure) (step 104). Next, for the value of Qp, the coefficient α
The value is converted to the spill position Sp, which is the change amount of the spill ring 4 of the fuel injection pump 2 by multiplying (step 10).
5). Further, the spill position sensor 8 of the fuel injection pump 2
The actual spill position Sp 'is read from (step 1
06), the final spill position movement amount (Sp) is calculated (step 107), output (step 108), and the fuel supply amount from the fuel injection pump 2 to the fuel injection nozzle 12 falls within the range within the hatched area shown in FIG. 4. Controlled. On the other hand, the bypass valve 21
At the same time as step 104, the engine speed and the bypass valve discharge amount (Ne-Qb diagram) shown in FIG.
The bypass valve discharge amount Qb corresponding to e and θa is read (step 109). The discharge amount at this time is, as is well known,
It has an inverse relationship with the pump discharge amount shown in FIG. 4, and the fuel amount injected from the fuel injection nozzle 12 changes according to the accelerator angle as in the conventional case. Then Q
The value of b is converted into the rod position value of the bypass valve (step 110), and the actual rod position is read from the sensor 24 in step 111. Furthermore, the final rod movement amount (L
b) is calculated (step 112), and (LB) is output to the linear solenoid 23 (step 113). In this way, the bypass valve 21 is rotated around the shaft 42 by the linear solenoid 23 as indicated by an arrow 43 to control the flow rate of fuel between the pipe 30 and the pipe 31. The above steps 104 to 108 and steps 109 to 113 are performed in the same manner, and (Sp), (LB)
When each is output, the process returns again 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, so that the engine speed is low. Even when the load is low and the load is high, the pressure of the injection pump can be sufficiently increased regardless of the load, and the atomization of the injected fuel can be improved to reduce the exhaust HC. The effect of becoming

[Brief description of drawings]

FIG. 1 is an overall system view showing an embodiment of the present invention, FIGS. 2 (a) and 2 (b) are enlarged cross-sectional views of a tip portion of an injection nozzle, respectively, and FIG. 3 is a relationship diagram between engine speed and injection pressure, FIG. 4 is a relationship diagram between engine speed and injection pump discharge force, FIG. 5 is a relationship diagram between engine speed and bypass valve discharge amount, and FIG. 6 is a flow chart showing control of each linear solenoid according to the present invention. . 1 ... Fuel tank 2 ... Fuel injection pump 3 ... Plunger 4 ... Spill ring 5 ... Lever 6 ... Support point 7 ... Linear solenoid 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 ...... Injection port 17 ...... Fuel supply passage 18 ...... Fuel bypass passage 19, 20 ...... Communication passage 21 ...... Bypass valve 22 ... Rod 23 ... Linear solenoid 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 ... Cone 42 ... Shaft 43 ... Arrow

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location F02M 61/18 350 D 9248-3G

Claims (1)

[Claims] 1. A fuel tank, a fuel injection pump having a suction port and a discharge port, the suction port being connected to the fuel tank and delivering fuel at a high pressure from the discharge port, and being connected to the discharge port of the fuel injection pump. A seat formed by a needle tip conical part and an inner peripheral conical part of the nozzle body that abuts the conical part, and an opening in the seat part, and when the needle rises, the seat part bypasses the fuel injection pump and the fuel A fuel injection nozzle having a bypass passage communicating with the tank, a flow control valve provided on a passage communicating the bypass passage of the fuel injection nozzle with the fuel tank, an engine load detection unit, and an engine load detector. Alternatively, the rotation speed detection means of the fuel injection pump, the delivery fuel flow rate adjustment means and flow rate detection means provided in the fuel injection pump, and the flow rate control valve provided A quantity control valve adjusting means and a flow rate detecting means; a delivery fuel flow rate adjusting means and a flow rate detecting means of the fuel injection pump; and a microcomputer electrically connected to the flow rate control valve adjusting means and the flow rate detecting means. The fuel injection is characterized in that the flow rate of the fuel injection pump and the flow rate of the flow control valve are adjusted by the microcomputer according to the load condition of the engine and the rotation speed of the engine or the fuel injection pump. Control device.