JPS62197651A - Fuel injection timing control device of engine with pressure wave supercharger - Google Patents

Abstract

PURPOSE:To obtain required supercharge effect and output performance in a specified range of medium revolution and medium load where adequate supercharge effect is difficult to obtain by means of a pressure wave supercharger by controlling fuel injection timing to be retarded so that exhaust gas temperature is raised. CONSTITUTION:A bypass passage 50 is arranged to connect a pump chamber 20a of a fuel injection pump 20 with a return passage 29, with a solenoid valve 51 and an orifice 52 interposed in the bypass passage. When an engine operating range is discriminated to be in a specified operating range other than a high revolution, high load range and low revolution, low load range at a controller for inputting an engine revolution signal (b) and a load signal (c), the solenoid valve 51 is actuated to open. This makes fuel in the pump chamber 20a flow via the bypass passage 50 to the return passage 29 to lower the fuel pressure in the pump chamber 20a and, as a result, to retard fuel injection timing by a specified amount to raise exhaust gas temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection timing control device for an engine, and particularly to a fuel injection timing control device for a diesel engine equipped with a pressure wave supercharger and a fuel injection pump.

(Prior Art) As a type of supercharger installed in automobile engines, especially diesel engines,
As shown in Publication No. 428, there is a so-called pressure wave supercharger that obtains a supercharging effect by compressing intake air using pressure waves generated based on the pressure of exhaust gas. be. As shown in FIG. 6, this pressure wave supercharger A includes a cylindrical casing 8 and a plurality of blades C1...C1 rotatably held within the casing B.
An air cleaner (
(not shown), and an intake/discharge passage 02 leading to the combustion chamber via an intake valve E is connected to the intake/discharge port B2. The exhaust gas introduction port 81' formed on the end face has an exhaust gas introduction passage G1 led from the combustion chamber through the exhaust valve F, and the exhaust gas discharge port B2' has an exhaust gas discharge passage leading to the atmosphere through a muffler or the like. The communication passages G2 are connected to each other. A plurality of Groove-shaped passages H...H are formed, and when the rotor C is rotationally driven at a predetermined speed in synchronization with the rotation of the crankshaft I, the groove-shaped passages H are formed.
...:H at a predetermined time, each of the above-mentioned inlets and discharge ports B1,
B2.81', 82' are opened respectively, and the passage H...
・It is configured to create a flow of intake and exhaust air inside H.

Here, the operation of this pressure wave supercharging 11A will be explained based on FIG. 7, which shows the rotor C expanded for convenience. That is, assuming that the groove-shaped passage H... day moves downward (on the drawing) as the rotor C rotates, the right end of the uppermost groove-shaped passage H filled with intake air is the exhaust inlet B1. ' At the time when the passage H is opened, high-pressure exhaust gas flows into the shaded part (a) of the passage H and collides with the intake air at atmospheric pressure, thereby generating a pressure wave, that is, a compression wave of the intake air. do.

Then, this compression wave propagates to the left and causes a flow of intake air in the passage section (b) shown by the dotted line in the same figure, but in this case, as the groove-shaped passage H moves downward, the exhaust air The amount of gas flowing in increases and the passage portion where the intake air flow occurs gradually expands. Further, the passage H is moved downward and its left end is opened to the intake discharge port B2 formed slightly below the position facing the exhaust gas introduction port B1', so that the intake air is compressed. The air is compressed by the action of waves and is discharged into the intake/discharge passage D2 and supplied to the combustion chamber. In this way, while the groove-like passage H is open to both the exhaust gas inlet 81' and the air intake/discharge port B2, the above-described operation continues. Note that when the groove-like passage H moves downward from this state and only its right end is opened and closed by the end face of the casing B, an exhaust stationary part is generated in the portion shown by dotted hatching in the passage H. The intake air is still being discharged due to the expansion of the exhaust gas, and when the groove-shaped passage H moves further downward and both ends of the passage H are closed, the intake air is moved to the exhaust stationary part shown by the dotted line. In addition, an intake stationary portion is created on the left side.

On the other hand, when the groove-like passage H moves further downward with the rotation of the rotor C and only its right end opens into the exhaust outlet 82', the outlet 82' communicates with the atmosphere. Due to this, the exhaust gas expands in the passage section (c) shown with diagonal lines in the same figure and flows out into the exhaust discharge passage G2, but at this time, as the exhaust gas expands, a pressure wave in a negative pressure state is generated. In other words, an expansion wave is generated and this expansion wave propagates toward the left, causing a flow of intake air within the passage portion (d) shown by the dotted line in the figure. Since the left end of the groove-like passage H is opened to the intake air introduction port B1, the expansion wave of the negative pressure causes the intake air introduction passage D to be opened as shown by the symbol (E) in the same figure.
As intake air is drawn in from 1 and exhaust gas is pushed out accordingly, as the groove-like passage H moves downward, the intake air inflow gradually increases, and the exhaust gas gradually decreases until finally The waste is discharged. In addition, if only the left end of the groove-shaped passage opening is chained lN-1, the passage H
When an intake stationary portion shown by dotted lines is generated in a part of the passage H and both ends of the passage H are closed, all intake air is in a stationary state.

The pressure wave supercharging 11A, which performs supercharging of intake air and scavenging of exhaust gas in addition to this based on the above-described operation, is performed when the pressure or temperature of the exhaust gas introduced from the exhaust gas introduction passage G1 is a predetermined value. Or if the value is within a specified range,
Desired pressure waves are generated in the groove-like passages H...H, and this pressure wave can provide good supercharging capacity, so for example, the supercharging capacity of a turbo supercharger can be improved. is mainly dependent on the exhaust gas flow m, compared to the type in which the speed is mainly dependent on the exhaust gas flow m, in the low rotation region IIi! It has the advantage that a good supercharging effect can be obtained in the above cases.

(Problems to be Solved by the Invention) By the way, the above-mentioned pressure wave supercharger generates a desired pressure wave ( The arrangement of the suction, exhaust inlet, and discharge port, or the length and cross-sectional area of the grooved passage are set so that the maximum supercharging capacity is obtained by generating compression waves. In the load region during rotation, etc., due to the relatively low exhaust gas temperature, the desired pressure waves are no longer generated and sufficient supercharging capacity cannot be obtained, resulting in poor acceleration performance or engine failure in such regions. The response deteriorates, making it difficult to ensure good driving performance. In addition, in this medium-speed, medium-load region, etc., not only the desired pressure wave, that is, compression wave, for supercharging the intake air cannot be obtained as described above, but also the exhaust gas shown in the shaded area (C) in FIG. When the exhaust gas is discharged, a sufficient expansion wave is not generated to properly discharge the exhaust gas, and therefore, it is necessary to ensure that the exhaust gas is discharged between the time when the groove-like passage H is opened to the exhaust discharge port 82' and the time when it is closed. It becomes impossible to discharge, and a large amount of exhaust gas remains in the passageway 1 when it is closed. Then, when the groove-shaped passage H is opened to the intake outlet B2, this remaining large amount of exhaust gas is discharged from the outlet B2 together with the intake air and is supplied (refluxed) to the combustion chamber. A problem arises in that the exhaust gas distal flow rate in the medium rotation and medium load region becomes larger than necessary and the combustion condition deteriorates.

The present invention addresses the above-mentioned problems in engines, especially diesel engines, when equipped with a pressure wave supercharger. By focusing on the characteristics of the fuel injection pump and adding a predetermined configuration or means to the fuel injection pump that controls the injection timing, the fuel injection pump can maintain the desired supercharging effect and output performance in high rotation and high load regions, etc. In particular, we aim to improve acceleration performance or engine response in the mid-rpm load range, that is, the operating range where it is difficult to obtain sufficient supercharging effect due to relatively low exhaust gas temperature, and improve the exhaust gas recirculation amount. To prevent unnecessary increase in the amount of fuel and the deterioration of flammability caused by this,
The purpose is to ensure good driving performance over a wide driving range.

(Means for Solving the Problems) The present invention is configured as shown below to achieve the above object.

That is, in a diesel engine having a pressure wave supercharger and a fuel injection pump, fuel is injected by the fuel injection pump when the operating region is in a predetermined region excluding the low rotation and low load region and the high rotation and high load region. A control means is provided to retard the timing. Specifically, this control means:
When the operating range is determined based on the output values etc. from the engine rotation speed detection means and the engine load detection means, and this judgment result indicates that the operating range is within the above-mentioned predetermined operating range, for example, as described in the following embodiments, the fuel By lowering the fuel pressure within the injection pump, it operates to retard the fuel injection timing from the normal injection timing in that area.

(Function) According to the above configuration, it is difficult to obtain a sufficient supercharging effect by a pressure wave supercharger because the exhaust gas temperature does not reach a predetermined temperature. In a predetermined operating region, the fuel injection timing is retarded compared to the normal injection timing in that region, resulting in so-called afterburning, and this afterburning increases the exhaust gas temperature. The desired supercharging effect by the charger is ensured, and engine response etc. are effectively improved. In addition, in such areas, conventionally, the exhaust gas temperature does not reach a predetermined temperature, which impairs the scavenging efficiency of the exhaust gas by the supercharger, and as a result, the exhaust gas recirculation r decreases. Although the temperature had been increased needlessly, such a problem can be effectively eliminated by raising the exhaust gas temperature as described above.

In addition, in the high-speed, high-load range and the low-speed, low-load ffi range, the fuel injection timing is not retarded, so the excessive rise in exhaust gas temperature in the high-speed, high-load range and the resulting exhaust system The required supercharging effect and engine output in this area can be obtained without causing various adverse effects, and
This will prevent deterioration of the combustion state in the low rotation and low load range, as well as the occurrence of misfires.

(Example) Embodiments of the present invention will be described below based on the drawings.

First, the pressure wave supercharger, which is one of the components of the present invention, will be explained. As shown in FIG. The rotor 3 is fitted and held. The rotor 3 has a plurality of groove-like passages 4...4 formed by an inner circumferential wall 3a, an outer circumferential wall 3b, and a large number of blades 3C...3C partitioning the two circumferential walls 3a, 3b at equal intervals. The rotor 3 is configured to be rotationally driven by transmitting the rotation of a crankshaft (not shown) to the rotor shaft 5 via a belt or the like, but in this case, the rotor 3 is rotationally driven at twice the speed of the crankshaft. Ru.

The pressure wave supercharger 1 also includes an intake air introduction lower for introducing intake air guided from an air cleaner (not shown) into the rotor 3 (groove passage 4) via an intake air introduction passage 6, and a rotor. 3 through the intake/discharge passage 8 (this passage 8
A shutter valve 9 for bypassing the supercharging 111 at the time of startup, and a one-way valve 10a provided in the bypass passage 10 and opened by intake negative pressure are provided on the downstream side of the engine.)
an intake/discharge port 11 for supplying the combustion seedlings through the combustion chamber; an exhaust gas introduction port 13 for guiding the exhaust gas discharged from the combustion chamber into the rotor 3 via the exhaust gas introduction passage 12; Exhaust discharge ports 15 for discharging exhaust gas to the atmosphere through exhaust discharge passages 14 are disposed at predetermined positions, each having a predetermined frontage area. Incidentally, lubricating oil is supplied to the vicinity of the bearing portion of the rotor shaft 5 from an oil inflow hole 16, and the oil that has lubricated each part of the bearing is discharged through an oil outflow hole 17. .

Next, the fuel injection pump, which is the main component of the present invention, will be explained based on FIG.

As shown in the figure, the fuel injection pump 20 includes a drive shaft 21 that is rotatably driven by a crankshaft (not shown) via a belt or the like, and a drive shaft 21 that is driven by the drive shaft 21 to suck fuel from a fuel tank and pump the injection pump. 2
A vane-type feed pump 22 (for convenience, this pump 2 is shown at the left end in the drawing) that discharges into the pump chamber 20a of
2), a cam disk 24 connected to the drive shaft 21 via a joint 23 that allows movement only in the axial direction, and the cam disk 24.
The plunger 26 is fixed to the cylinder 25 and has a plunger 26 whose tip end is held reciprocatingly within the cylinder 25.

The feed pump 22 sucks the fuel led from the fuel tank into the fuel suction passage 27 through the suction port 22a, and adjusts the discharge pressure or discharge amount according to the rotational speed of the drive shaft 21 (engine rotational speed). Although the fuel is discharged into the pump chamber 20a of the fuel injection pump 20 through the discharge port 22b, if the discharge pressure of the fuel increases excessively, the excess fuel is discharged through the regulating valve 28. The fuel flows out into the return passage 29 and is again supplied to the fuel suction passage 27.

The cam disk 24 has the same number of cam ridges as the number of cylinders on its cam surface, and is in contact with the peripheral surface of a roller 31 supported by a roller holder 30 that can rotate by a predetermined angle. The plunger 26 is configured to reciprocate at a predetermined period by rotating the disk 24 while moving the roller 31 at a predetermined position. The plunger 26 has slits 26a, . Fuel flows into the cylinder 25 through the cylinder 26a, and this inflowing fuel is compressed by the forward movement of the plunger 26 and passes through the internal passage 26b formed in the plunger 1226 to the delivery valve. 32, the valve 32 is opened, and the fuel is supplied into the combustion chamber through an injection vibrator and a fuel injection nozzle (not shown).

In this case, the engine rotational speed, that is, the rotational speed of the drive shaft 210 increases, and thereby the discharge capacity of the feed pump 22 is increased, and the injection pump 210 increases.
When the fuel pressure in the pump chamber 20a increases, a piston 34 (
In the drawings, for convenience, a chamber 33 and a piston 34 are shown.
90". Therefore, in reality, the piston 3
4 moves back and forth in the chamber 33 in a direction perpendicular to the drive shaft 21), but as the roller holder 30 moves backward against the spring force of the spring 35, the roller holder 30 moves in a predetermined direction via the pin 36. be rotated. As the roller holder 30 rotates, the relative position between the roller 31 and the cam disk 24 changes! By shifting the IQ ratio to a predetermined state, the reciprocating timing of the plunger 26, that is, the fuel injection timing is advanced. Conversely, if the engine speed decreases,
Since the fuel pressure in the pump chamber 20a also decreases and the piston 34 moves forward, the fuel injection timing is retarded.

On the other hand, a lever shaft 37 is rotatably attached to the upper part of the fuel injection pump 20 and has a lever 37a linked to an accelerator pedal fixed to the upper end and an eccentric shaft 37b at the lower end. room 2
At a predetermined portion of 0a, there is a control member whose upper end is connected to the eccentric shaft 37b via a tension coil spring 38, and which is swung via a support shaft 39 in response to depression of the accelerator pedal, that is, rotation of the lever shaft 37. A lever 40 is provided. The control lever 40 is composed of a tension lever 40a and a start lever 40b, and when the engine is started, the start lever 40b is separated from the tension lever 40a by the spring force of the start spring 40c as shown in the figure. However, after the start is completed, the upper end of the start lever 401) comes into contact with the tension lever 40a, and both levers 40a, 40
b is configured to swing integrally. The lower end of the control lever 40 is connected to a cylindrical member 41 that is fitted into the plunger 26 and is movable in the axial direction. By moving the plunger 26, the effective stroke of the plunger 26, that is, the fuel injection amount changes.

However, this fuel injection pump 20 has a pump chamber 2Oa.
A guide shaft 42 that protrudes inward, and a sleeve 43 that is fitted and held on the shaft 42 and whose tip abuts the negative side of the control lever 40 (start lever 40b) are provided. The sleeve 43 is configured to swing back and forth in accordance with changes in the amount of depression of the accelerator pedal. In this case, the rotation of the drive shaft 21 is controlled by the first and second gears 44.4.
5 to the flyweight holder 46', and the flyweight 4646, which is opened outward by the action of the centrifugal force generated at this time,
By biasing or moving the forward (rightward in the drawing), the amount of accelerator pedal depression, that is, the engine load, and
The rotational speed of the drive shaft 21, ie, the rotational speed of the engine, is kept in good balance. Furthermore, the guide shaft 42 is formed with an internal passage 428 that is open at one end and communicates with the return passage 29 at the other end, and the sleeve 43 has a through hole 43a at a predetermined portion thereof. It is formed. Then, the sleeve 43 is moved back and forth by moving the control lever 40 in accordance with the amount of depression of the accelerator pedal and the 1lrfl movement of the flyweights 46.46. The chamber 20a is communicated with or cut off through the through hole 43a, and the fuel pressure in the pump chamber 20a changes with such operation, causing the piston 34 in the chamber 33 to move back and forth. The fuel injection timing is retarded or advanced.

In addition to the above configuration, this fuel injection pump 20) is provided with a bypass passage 50 whose one end opens into the pump chamber 20a and whose other end communicates with the two return passages. is provided with a solenoid pulse 51 for opening and closing the passage 50, and an orifice 52 for making the fuel passing through the passage 50 a set flow m.

The solenoid valve 51 is connected to the controller 5.
The controller 53 detects the engine rotation speed. [Based on the rotation speed signal from the engine rotation sensor 54 and the load signal C from the load sensor 55 that detects the engine load, it is determined whether the engine operating range is within a predetermined range, and When the determination result indicates that the valve 51 is in a predetermined range, a control signal a for opening the valve 51 is output.

Next, the operation of the above embodiment will be explained.

First, to briefly explain the operation of the pressure wave supercharger 1 based on FIG. 1, as the rotor 3 rotates, a specific groove-like passage 4
is connected to the intake/discharge passage 8 via the intake/discharge port 11 at its left end, and connected to the exhaust gas inlet 1 at its right end.
When connected to the exhaust introduction passage 12 via 3,
High-pressure exhaust gas discharged from the combustion chamber into the exhaust introduction passage 12 flows into the groove-shaped passage 4 through the exhaust introduction port 13 and collides with the atmospheric pressure air intake filling the passage 4. At the same time, a compression wave of the intake air is generated. Further, from this state, the exhaust gas moves the intake air to the left and the compression wave propagates leftward, so that the intake air in the groove-shaped passage 4 is compressed and the intake air is moved to the left side. 11 to the combustion chamber via the intake/discharge passage 8, thereby obtaining a supercharging effect by the supercharging I11 and increasing the intake air filling efficiency. Then, when the exhaust gas reaches near the left end of the groove-shaped passage 4 after discharging substantially the entire amount of intake air, the passage 4 is closed and the high-pressure exhaust gas remains within the passage 4.

Further, as the rotor 3 further rotates, the specific groove-like passage 4 is communicated with the intake air introduction passage 6 via the intake introduction lower at its left end, and is exhausted via the exhaust discharge port 15 at its right end. When connected to the discharge passage 14, the exhaust gas in the groove-shaped passage 4 expands and is discharged to the exhaust discharge passage 14, but at this time an expansion wave in a negative pressure state is generated and the leftward This expansion wave causes intake air to be blown from the intake air introduction passage 6 and moves the exhaust gas to the right, thereby pushing the exhaust gas into the discharge passage 14, improving exhaust efficiency or scavenging. This will improve efficiency. Then, when the exhaust gas is reliably discharged into the discharge passage 14, the groove passage 4 is closed. The detailed operation of this supercharger 1 is explained in the seventh section.
Since this has already been explained based on the figures, the explanation will be omitted here.

Next, the basic operation of the fuel injection pump 20 shown in FIG.
The conventional fuel injection timing control operation) will be explained as follows.

That is, in a low load region where the tension of the tension coil spring 38 connecting the lever shaft 37 and the control lever 40 is weak due to a small depression amount of the accelerator pedal, the flyweights 46...46 are affected by the centrifugal force. As the sleeve 43 is held at the forward end position by being pushed outward by the action, the through hole 43a and the opening at the tip of the internal passage 42a match, and the fuel in the pump chamber 2Oa flows into the return passage. 29, the fuel pressure within the pump chamber 2Oa is maintained in a reduced state.

When the fuel pressure decreases like this, the pump chamber 20a
The piston 34 provided below is moved forward by the spring force of the spring 35, and the cam disc 24 and roller 31
Since the relative position of the plunger t26 is in a state where the reciprocating timing of the plunger t26 is delayed, the fuel injection timing is indicated by the symbol () in FIG.
It is held in a retarded state as shown by X). Also,
When the accelerator pedal is gradually depressed from such a state and shifts to a medium load region, etc., the control lever 40 is swung counterclockwise by the spring force of the tension coil spring 38 to move the sleeve 43 backward. Therefore, the through hole 4
3a and the tip opening in the internal passage 42a gradually narrows, and the fuel pressure in the pump chamber 20a gradually increases, and as a result, the piston 34
Since the engine is also gradually moved backward, the fuel injection timing is gradually advanced as shown by the symbol (Y) in FIG. When the accelerator pedal is further depressed and the high load region is reached, the sleeve 43 is also moved back further and the internal passage 42a is closed, so that the fuel injection timing is indicated by the symbol (Z) in FIG. ), the engine is maintained in an advanced state to ensure the desired engine output.

However, according to such fuel injection timing control, the third
As shown by the symbol (Y) in the figure, the desired supercharging effect cannot be obtained by the pressure wave supercharging vs1 in the medium load region or medium rotation medium load region where the injection timing is gradually advanced. occurs.

In other words, the pressure wave supercharger 1 operates in a high load region or a high rotation high load region where the fuel injection timing is advanced as shown by the symbol (Z) in FIG. In areas where the pressure or exhaust gas temperature is extremely high,
Suction and exhaust introduction lowers, 13
and arrangement of intake and exhaust outlets 11.15 and groove-like passages 4...
・Since the length etc. of 4 are set, the desired pressure wave is not generated in the medium rotation and medium load region as mentioned above due to the relatively low exhaust gas temperature, and therefore sufficient supercharging is not achieved. The ability cannot be increased by 1q.

Now, considering the exhaust gas temperature mentioned above, in this engine, that is, a diesel engine, so-called afterburning occurs by retarding the fuel injection timing from the normal timing, and this afterburning causes the exhaust gas temperature to increase. It has the characteristic that it increases. Therefore, in this engine, focusing on the above characteristics, in order to improve the supercharging ability of the pressure wave supercharger 1 in the medium rotation and medium load region, etc.
The controller 53 performs the following operations.

That is, the controller 53 determines whether the engine operating range is the high-speed high-load range I or the high-speed high-load range I shown by the shaded area in FIG. 4, based on the engine speed indicated by the engine speed signal S and the load indicated by the load signal C. When it is determined that the system is in a predetermined operating range (medium speed, medium load range, etc.) within the region ■ excluding the low rotation and low load region shown by the dotted hatched area, the A control signal a for opening the solenoid valve 51 is output. By such an operation, the bypass passage 50 is opened, and the fuel in the pump chamber 20a is transferred to the passage 5.
0 to the return passage 29, the fuel pressure inside the pump W2Oa decreases, and as a result, the fuel injection timing changes as shown by the symbol <Y' in FIG. 3, that is, the dotted line. The injection timing is delayed by a predetermined period from the normal or conventional injection timing (indicated by the symbol (Y) in the figure) in the region. By retarding the injection timing in this way, combustion occurs, and as shown by the symbol (W') or dotted line in Fig. 5, the exhaust gas temperature becomes the normal temperature in this region (Fig. (indicated by the solid line (W)), a desired pressure wave (compression wave) is generated in the groove-shaped passage 4 of the pressure wave supercharger 1, and a sufficient supercharging effect is obtained. It will be done. This improves acceleration performance or engine response in this region, that is, in the medium rotation and medium load region, and makes it possible to ensure good running conditions.

Furthermore, as the exhaust gas temperature rises in the medium rotation and medium load region as described above, a desired expansion wave (negative pressure state) is generated even when the exhaust gas is discharged from the pressure wave supercharger 1. Therefore, the exhaust gas is discharged well and the scavenging efficiency is improved, thereby avoiding the problem that the amount of exhaust gas recirculation 1 is increased needlessly.

Furthermore, by excluding the high rotation, high load area and the low rotation, low load area from the area where the fuel injection timing is retarded,
Excessive rise in exhaust gas temperature and associated heat damage to the exhaust system are prevented when the retardation control is performed in a high-speed, high-load region, and the retardation control is performed in a low-speed, low-load region. This will prevent the deterioration of combustion conditions and even the occurrence of misfires in the event of combustion.

In the above embodiment, the control signal a outputted from the controller 53 to the solenoid valve 51 is an ON or OFF signal that only indicates the delay in opening or closing. By using a as a signal to linearly control the opening amount of the valve 51, the fuel injection timing is gradually retarded or advanced as shown by the chain line in FIG. As shown by the chain line in FIG. 5, it may be configured to gradually increase or decrease.

(Effects of the Invention) As described above, according to the fuel control device for an engine with a pressure wave supercharger according to the present invention, due to the relatively low exhaust gas temperature, sufficient supercharging effect by the supercharger can be achieved. In predetermined regions such as the mid-rpm and mid-load region, where it was difficult to obtain the desired acceleration performance, the fuel injection timing was retarded to raise the exhaust gas temperature to the desired temperature, thereby improving acceleration performance in this region. In addition, the engine response, etc. is improved, and in addition, the exhaust gas recirculation m is reduced, and the required supercharging effect is maintained as before without causing heat damage to the exhaust system in high rotation and high load regions. In addition, misfires and the like are prevented in the low rotation and low load range, and good running performance is ensured over a wide operating range.

[Brief explanation of drawings]

Figures 1 to 5 show embodiments of the present invention. Figure 1 is a sectional view showing a pressure wave supercharger and its passage structure, Figure 2 is a sectional view of a fuel injection pump, and Figure 3 is a load FIG. 4 is a schematic explanatory diagram showing a control region, and FIG. 5 is a graph showing characteristics of exhaust gas temperature with respect to load. Further, FIG. 6 is a schematic perspective view showing the pressure wave supercharger and its installation state, and FIG. 7 is a developed view of the rotor in the pressure wave supercharger to show the operation of the pressure wave supercharger. 1... Pressure wave supercharger, 20... Fuel injection pump, 5
0... Bypass passage, 51... Solenoid pulp,
53...controller.

Claims (1)

[Claims] (1) Equipped with a pressure wave supercharger and a fuel injection pump,
In an engine configured to control fuel injection timing by the fuel injection pump according to an operating range,
An engine equipped with a pressure wave supercharger, characterized in that the engine is equipped with a control means for retarding the fuel injection timing when the operating range is in a predetermined range excluding the low-speed, low-load range and the high-speed, high-load range. Fuel injection timing control device.