JPH0458045A - Fuel injection device - Google Patents

Abstract

PURPOSE:To reduce noise, to prevent excessive fuel injection, improve exhaust gas and to miniaturize a fuel injection device by delivering always a pilot signal for pilot injection from a controller to a solenoid valve prior to a main drive signal for main injection from a fuel injection valve. CONSTITUTION:A controller 19 delivers a pilot signal for pilot injection to a solenoid valve 16 prior to a main drive signal for main fuel injection from a fuel injection valve 14. Thus, the solenoid valve 16 controlled by the controller 17 can carry out the pilot injection prior to the main injection, and accordingly a rise of the pressure in a pipe can be prevented during transient operation so that noise from an engine and NOx can be reduced. Further, the adjustment to the fuel feed rate and the adjustment to the injection timing in association therewith can be made so that the fuel feed rate and the injection timing can be set in optimum conditions in accordance with an engine revolutional speed range and a load range, thereby it is possible to reduce noise during idle operation and to enhance the output power in a low speed but high load range. Meanwhile, during high revolutional speed but low load operation, injection is made at a low injection rate so as to prevent excessive fuel injection in order to enhance the fuel injection system and the durability of the engine, thereby it is possible to reduce vibration and noise caused by revolution of the engine.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a device for injecting fuel pressurized by a fuel injection pump of an internal combustion engine into a combustion chamber, and particularly to a device for injecting fuel pressurized by a distribution type injection pump into a combustion chamber. Regarding an injection device.

(Prior Art) Internal combustion engines, particularly diesel engines, inject fuel into high-temperature, high-pressure air in a combustion chamber to perform compression ignition to obtain a predetermined output.

In such a diesel engine, the fuel is pressurized by a fuel injection pump driven by a portion of the engine's driving force, and this fuel is guided through an injection pipe to a fuel injection valve. Fuel is sprayed into the combustion chamber.

The fuel injection pumps used here are frequently strip type fuel injection pumps and distribution type fuel injection pumps.

The peel-type fuel injection pump is equipped with plungers equal to the number of cylinders in the internal combustion engine, and each plunger is driven by an opposing cam to pressurize the fuel. On the other hand, a distribution type fuel injection pump pressurizes fuel by reciprocating a single plunger, and also distributes fuel to multiple cylinders by rotating the plunger.

In this way, compared to side-type fuel injection pumps, distribution-type fuel injection pumps have a relatively smaller number of parts and are easier to downsize, so they are widely used.

By the way, as an example of this distribution type fuel injection pump is shown in FIG. 6, rotational force is transmitted from the engine side to a plunger 2 that slides and rotates within a pump sleeve 1, and a face cam 3 that is integrally connected to the plunger 2 rotates inside the pump sleeve 1. The plunger 2 is configured to slide and operate the pump when the roller 4 comes into rolling contact with the pump.

Here, the pivot member 5 of the roller 4 uses a hydraulic timer to advance or retard the lift operation timing of the face cam.
This mechanism adjusts the oil supply timing of the pump. On the other hand, a spill ring 6 operated by an accelerator link system equipped with a governor (not shown) is fitted into the plunger 2, and the amount of oil sent is adjusted according to the position at which this ring opens the spill port 7. It is configured.

(Problems to be Solved by the Invention) In the case of the fuel injection pump of such a fuel injection device, the fuel supplied to the combustion chamber generates noise, NO, etc. due to the ignition delay ta and the subsequent sudden explosion combustion Br. Leher tends to increase rapidly, which is becoming a problem.

An object of the present invention is to provide a fuel injection device equipped with a distribution type fuel injection pump that can reduce noise generation.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention has one end coupled to a rotating shaft driven by an internal combustion engine so as to rotate integrally therewith, and a roller attached to a roller on the base side of an injection pump. A plunger is integrally connected with a contacting face cam, and a plunger hole is formed into which the other end of the plunger is slidably and rotatably inserted, and fuel pressurized in a pressure feeding chamber in the plunger hole is transferred to multiple cylinders. a pump sleeve formed with a plurality of distribution passages leading to each of the fuel injection valves; a normally open solenoid valve that closes the gap between the pressure chamber and the spill port in a timely manner;
The controller includes a controller that receives engine rotation speed information, load information, and crank angle information of the internal combustion engine from a rotation speed sensor, a load sensor, and a crank angle sensor, and outputs a motion signal to the solenoid valve.

The controller is characterized in that the controller always outputs a pilot signal for pilot injection to the electromagnetic valve prior to a main drive signal for main injection of the fuel injection valve.

(Function) Since the controller always outputs the pilot signal prior to the main drive signal, the fuel injection valve can always perform pilot injection prior to main injection.

(Embodiment) The fuel injection device shown in FIG. 1 is attached to a fuel supply system 10 of a multi-cylinder diesel engine.

A fuel supply system 10 of this diesel engine supplies fuel from a fuel tank 11 to a distribution type fuel injection pump (hereinafter simply referred to as an injection pump) 2 via a filter (not shown),
The fuel injection valve 14 is configured to supply fuel pressurized by the pump to a fuel injection valve 14 via an injection pipe 13.

Here, the number of fuel injection valves 14 is equal to the number of cylinders in the engine, and each fuel injection valve 14 is connected to an injection pump I2 via an injection pipe 13. Note that the injection pipe 13 and the fuel injection valve 1 are shown here.
Only one 4 was shown.

Here, reference numeral 15 indicates a drain path.

The fuel injection device is composed of a distribution type fuel injection pump 12, a controller 17 that drives a normally open electromagnetic valve 16 of the pump, and a load sensor 18, a crank angle sensor 19, and a rotation sensor 41 connected to this controller. There is.

A needle valve (not shown) is disposed in the fuel injection valve 14, and the needle valve receives fuel from the injection pump 12 that is pumped through the injection pipe 3, and changes the injection pressure Pf in the injection pipe.
A needle valve (not shown) is lifted R in response to a change in the injection pressure Pf, and fuel is injected in a predetermined injection amount pattern as shown in FIG. 2, for example.

The injection pump 12 includes a rotating shaft 21 that is pivotally supported by a casing 2o as a base, a feed pump 22 attached to the rotating shaft 21, and a pump sleeve 23 that is a part of the base.
, a plunger 26 coupled to the rotating shaft 21 via a joint 24 and slidably and rotatably fitted into the plunger hole 25 of the pump sleeve 23, and the casing 2.
Four rollers 27 supported on the 0 side, a face cam 28 in rolling contact with these rollers 27, and a pressure feeding chamber 29 forming a part of the plunger hole 25 within the pump sleeve 23.
and a normally open solenoid valve 16 that closes the gap between the drain passage 15 and the spill port 30 communicating with the drain passage 15 in a timely manner.

Here, the face cam 28 is formed with four lift parts r, and when these parts face the four rollers 27, the face cam 28 and the plunger 26 are lifted in the pump operation direction P, and the plunger 26 is moved as shown in FIG. The lift amount Rp of 26 is configured to change.

Note that the joint 24 is configured to connect the rotating shaft 21 and one end of the plunger 26 so that they can be relatively moved toward and away from each other, and so that they can be integrally moved.

The plunger 26 is provided with a central passage 32 communicating with the pumping chamber 29 at the other end, and is configured such that the distribution groove 33 at one end faces the four distribution passages 34 of the pump sleeve 23 in sequence, and is always connected to the pumping chamber 29. The opposing suction grooves 35 are configured to face the suction passage 36 of the pump sleeve 23 .

Here, the suction passage 36 is connected to the foot pump 22 via a cam chamber 37. The reference numeral 18 indicates an overflow orifice provided in the drain passage 15, the reference numeral 39 indicates a return spring of the plunger 26, and the reference numeral 40 indicates a delivery valve.

The solenoid valve 16 is normally open and is switched to the closed position as shown in FIG. 1 upon receiving a drive signal.

The controller 17 includes a control circuit 171. memory circuit 172,
It is composed of an input/output circuit 173, drive circuits 174 and 175, a power supply circuit (not shown), and the like.

The input/output circuit 173 in the controller 17 is configured to receive detection signals from the load sensor 18, the crank angle sensor 19, the rotation speed sensor 41 that outputs engine rotation speed information, and the like. The memory circuit 172 is shown in FIG. 5(a), (
The injection control program shown in b) and the oil feed rate (
Calculation map of Δq/Δt) and injection timing T, or injection amount (on time of solenoid valve 1, (= 1°) in Fig. 4).

1+t. 2) calculation maps of values corresponding to 2) are respectively set and stored.

In particular, when controlling the drive of the solenoid valve 31, the controller 17
At each injection timing T, prior to main injection, the solenoid valve 16 for pilot injection is closed twice, and four timers are set.

That is, the main injection on timer is set in the main injection valve closing process, the main injection off timer is set in the main injection valve opening process, and furthermore, at each injection timing T, prior to main injection, the pilot valve is set. The pilot on timer is set in the closing process, and the pilot off timer is set in the pilot valve opening process.

Here, the oil feed rate (Δq/Δt) and injection timing T shown in FIG.
The calculation map is set to obtain the following characteristics.

Here, at low rotation and high load, a high oil feed rate (Δq/Δ
t), and accordingly, the injection timing T is retarded, thereby making it possible to increase output through high-pressure injection.

On the other hand, the oil feed rate (△q/Δt) at high revolutions is relatively reduced, and the injection timing T is accordingly advanced to prevent excessive injection, improve durability, reduce particulate matter, and reduce HC. We aim to reduce the

Furthermore, the engine is retarded in the idle range, and high oil feed rate (Δq/Δt)
The aim is to stabilize idle rotation and reduce idle noise.

On the other hand, in the calculation map of the injection amount q shown in Fig. 4, the injection amount q (a value corresponding to the ON time t of the solenoid valve) increases as the load increases, regardless of the engine rotation. It is set.

The control circuit 171 calculates the control amount according to the injection control program in the memory circuit 172, and controls the solenoid valve 16 in its drive circuit 1.
74, and is configured to perform pressure regulation control of the injection pressure Pf.

Here, the operation of the fuel injection device will be explained along with the injection control program shown in FIGS. 5(a) and 5(b).

When a main switch (not shown) of the engine is turned on, the controller 17 starts operating the main routine.

First, the current engine speed N, load L, and crank angle θ
, injection timing T, etc., and store them in a predetermined area.

Then, the target injection timing T and oil feed rate (Δq/Δt) according to the engine speed N and load are calculated according to the calculation map of the injection timing T and oil feed rate (Δq/Δt,) shown in Fig. 3. is calculated based on the calculated value, stored in a predetermined area, and returns to step a1.

On the other hand, a control routine (not shown) sequentially counts the crank angle signal θ by interrupt processing.

Furthermore, an electromagnetic valve drive routine is entered by the interruption of the reference signal θ0 for each cylinder, and step b1 is reached.

Here, when the pilot signal is on for pilot injection according to the target injection timing T (see areas t and 1 in Figure 2), tpl
and off-time tp2 are calculated and set in the pilot-on counter and pilot-off counter in sequence.

Furthermore, step b2 is reached. Here, the main injection signal ON time t1 of the main injection (refer to t, 2 area in Figure 2) corresponding to the target injection timing T is calculated, set in the main injection on counter, and further When the main injection signal is turned off according to T, t2 is calculated and set in the main injection off counter, and the process returns.

Through this process, the pilot injection is performed for a predetermined time period (t...1
) Fuel is supplied from the injection pump to the fuel injection valve 14, and when the valve opening pressure ρa is exceeded in the opposite valve, the injection valve is lifted.
Pilot injection is performed, followed by main injection for a predetermined time (
t=, 2) Fuel is supplied from the injection pump to the fuel injection valve 14, and when the valve opening pressure of the opposing valve exceeds pa, the injection valve lifts and main injection is performed.

Incidentally, as the injection timing T advances, the operating characteristics change to those shown by the broken line in FIG. 2.

In this way, in this fuel injection system, the solenoid valve 16 operated by the controller can perform pilot injection prior to main injection, so it is possible to prevent an excessive increase in cylinder pressure, reduce engine noise, and reduce NoX. I can figure it out. Moreover, the oil feed rate (Δq/Δt) is adjusted (from the ta position to the tb position in Fig. 5).
Since the injection timing T can be adjusted accordingly (at a position where the oil feeding rate is small), the oil feeding rate (Δq/Δt) and the injection timing T can be set to the optimum state according to the engine rotation range and load range. Therefore, it is possible to reduce noise during idling and improve output at low speeds and high loads.

On the other hand, at high rotations and low loads, injection is performed at a low injection rate (Δq/Δ) to prevent excessive injection, improve the durability of the injection system and engine, and reduce vibration and noise caused by engine rotation. be able to.

Furthermore, this fuel injection device can eliminate a spill ring operated by an accelerator link system equipped with a governor and a hydraulic timer for adjusting injection timing, making it easy to downsize the device.

Furthermore, the oil feed rate (Δq
/Δ1) - The injection timing T can be adjusted appropriately, and the responsiveness during these controls is improved.

(Effects of the Invention) As described above, the present invention is capable of suppressing and preventing an excessive rise in combustion pressure in the combustion chamber, since the normally open solenoid valve operated by the controller can perform pilot injection in conjunction with main injection. In addition, the oil feed rate and injection timing can be freely set to the optimum conditions within the engine rotation range and load range, and from this point of view, it is possible to reduce engine noise and reduce over-injection. prevention, improve exhaust gas emissions, and easily downsize the device.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of a fuel injection device as an embodiment of the present invention, Fig. 2 is an operational characteristic diagram of each part during control performed by the same device, and Figs. Figure 5 (a) and (b) are flowcharts of the control program for the same device, and Figure 6 is a cross-section of the main parts of a conventional injection pump. It is a diagram. 1...Diesel engine, 12...Injection pump,
14...Fuel injection valve, 16...Solenoid valve, 17...
Controller, 18...Load sensor, 19...Crank angle sensor. 20...Casing, 21...Rotating shaft, 23...
Pump sleeve, 25...Plunger hole, 26...
Plunger, 27... Roller, 28... Face cam, 29... Pressure feeding chamber, 30... Spill port. 34... Distribution passage, 41... Rotation sensor. Agent Kabayamadai

Claims (1)

[Claims] A plunger whose one end is integrally connected to a rotating shaft driven by an internal combustion engine so as to rotate integrally with it and a face cam that makes rolling contact with a roller on the base side of the injection pump, and the other end of the plunger slides. and a pump sleeve formed with a rotatably fitted plunger hole and a plurality of distribution passages for guiding fuel pressurized in a pressure-feeding chamber in the plunger hole to each fuel injection valve of a plurality of cylinders; A normally open solenoid valve that closes the space between the chamber and the spill port in a timely manner; and a controller that outputs a drive signal to the valve, wherein the controller always outputs a pilot signal for pilot injection to the electromagnetic valve prior to a main drive signal for main injection of the fuel injection valve. .