GB2127095A - Turbocharged i.c. engine with additional charge air supply - Google Patents

Abstract

Compressed air is supplied upstream and downstream of the compressor 5 by opening solenoid valves 22, 23 in air supply lines 10, 10' in response to an increased load on the electricity generator 20. A solenoid actuator 32 may also move the fuel injection pump rack (34), Fig. 3 (not shown), to increase the fuel supply faster than the governor response. A valve 42 at the compressor inlet may close in response to the pressure rise resulting from the compressed air supply. The compressed air supply reduces load induced engine speed fluctuations. <IMAGE>

Description

SPECIFICATION Internal combustion engine with supercharger The present invention relates to an internal combustion engine with a supercharger and, more particularly, to those engines with a supercharger which quickly increases the air intake as soon as the engine load suddenly increases to prevent the engine revolution speed from falling.

Generally, the difference between the air intakes for no-load operation and maximum load operation with the engine equipped with a supercharger is greater than that with the naturally aspirated engine.

And the engine with a supercharger shows a delay in supplying air due to a slow reaction of the supercharger. The resultant incomplete combustion causes a momentary drop in the engine revolution speed or in the worst case the engine speed may not be restored to the required level and more exhaust smoke is generated, which will pollute air.

Especially, for the engines for generators, an excess fall in the engine revolution speed will cause the voltage to drop out of the automatic voltage regulation range or operated protective relays.

The object of this invention is to provide an internal combustion engine with a supercharger which can quickly increase the air intake when the load has abruptly increased, thereby preventing the engine revolution speed from falling.

Another object of this invention is to prevent thrust and surge that would adversely affect the supercharger blower when increasing the air intake.

Still another object of this invention is to provide an internal combustion engine with a supercharger that can prevent the discharge of smoke when the load has suddenly increased.

The internal combustion engine of this invention having a supercharger consists of: a main air supply means for injecting air under high pressure, connected to the intake manifold; a secondary air supply means for injecting air under high pressure, connected to the front of the supercharger blower; and solenoid valves, provided in respective pipes connecting to the main and secondary air supply means, for automatically opening and closing the pipes according to a load variation.

With this invention, the automatic open/close operation of solenoid valves depending on a load variation of the internal combustion engine ensures quick supply of high pressure air from the main air supply means into the intake manifold without delay and at the same time makes up for the instantaneous air deficiency by the high pressure air delivered from the secondary air supply means provided in front of the supercharger blower. The additional supply of high pressure air results in an increase in exhaust gases which in turn produces a sharp increase in the supercharger revolution. The higher revolution speed of the supercharger rapidly increases the intake of external air thereby preventing an air supply lag due to load variation.Thus, the drop in engine revolution speed during load variation can be prevented insuring higher reliability of the internal combustion engine as a generating unit.

In addition, simuitaneous supply of high pressure to the intake manifold and to the front of the supercharger prevents the surge resulting from a sharp increase in the back pressure of the blower.

This invention also prevents the thrust on the blower caused when the entire amount of air required is blown under pressure to the front of the blower.

Furthermore, this invention can completely prevent the discharge of smoke when the load on the engine suddenly increases.

Other features and advantages of this invention will become apparent in the following description with reference to the attached drawings.

Figure 1 is a schematic plan view, partially cut away, of the internal combustion engine with a supercharger embodying this invention; Figure 2 is a side view, partially cut away, of another embodiment of this invention; Figure 3 is a side view, partially cut away, of a forced driving equipment; Figure 4 is a diagram showing the relationship between the engine revolution, the rack displacement and the boost pressure with respect to time; Figure 5 is a plan view, partially cut away, of a further embodiment of this invention having a supercharger; Figure 6 is a plan view, partially cut away, of a still further embodiment of this invention having a supercharger; and Figure 7is a diagram showing the performance of the internal combustion engine of this invention.

As mentioned above, Figure 1 is a plan view, partially cut away, of the internal combustion engine with a supercharger of a first embodiment of this invention. As shown, the exhaust gas discharged into the exhaust manifold 2 passes through an exhaust pipe 17 and to the exhaust turbine 4 of the supercharger 3 which is driven by the exhaust gas. A blower 5 is rigidly connected to the turbine 4through a shaft 11 so that it turns with the exhaust turbine 4.

As it turns, the blower 5 forces the air in the blower case 14 out through an intake pipe 15 and the intake manifold 6 into the combustion chamber (not shown) of the engine 1. An air cooler 16 is provided in the intake pipe 15 to cool the high pressure air passing through the intake pipe 15.

The crank shaft of the engine 1 is coupled with the rotating shaft of a generator 20 through a joint 18 so that the generator produces electricity while the engine 20 is running. The electricity produced is supplied to the load 24. According to a load variation, a controller 21 controls the operation of solenoid valves 22 and 23.

The intake manifold 6 is provided with a main air injection nozzle 13, one example of the main air supply means, which communicates with an air tank 7 through a pipe 12. The air tank 7 is charged with air by compressor 8. In front of the blower 5 is located a secondary air injection nozzle 9, one example of the secondary air supply means, which communicates with the air tank 7 through a pipe 10. Solenoid valves 22 and 23 are provided in the pipes 10 and 12 respectively. These solenoid valves are controlled by the controller 21 which is programmed so that upon detecting a sharp load variation it opens the solenoid valves 22 and 23 for a predetermined period of time.

When the amount of air jetted from the secondary air injection nozzle 9 is too small, surging will occur on the blower 5, so that the amount of air supplied from the secondary injection nozzle 9 is set at 30 to 50 percent or more of the total amount of air injected. This adjustment is made by changing the ratio of the nozzle areas of the main and secondary air injection nozzles.

Next, the operation of the internal combustion engine as shown in Figure 1 will be explained in the following. As mentioned above, as the internal engine starts, the generator 20 begins generation, and the yenerated power is supplied to the load 24 through cable 19. If any change in the load 24 occurs, it is immediately detected by the controller 21 which then opens the solenoid valves 22 and 23 for a predetermined duration of time according to the program. With the solenoid valves 22 and 23 open, the high pressure air stored in the air tank 7 is allowed to flow through the pipe 12 and the main air injection nozzle 13 into the intake manifold 6, from which it is further supplied into the combustion chamber of the engine. At the same time, the high pressure air also passes through the pipe 10 and out from the secondary air injection nozzle 9.The high pressure air jetted from the nozzle 9 increase the pressure in front of the blower and accelerates it as the air passes through the blower. The high pressure air is then carried through the intake pipe 15 into the intake manifold 6 where it combines with the high pressure air supplied from the nozzle 13 before being supplied into the combustion chamber.

This supply of high pressure air eliminates a momentary air deficiency at the time of load variation thus preventing fall of revolution speed of the engine 1. Further, the occurrence of surging resulting from a sudden rise in back pressure of the blower 5 can be prevented because the high pressure air is supplied simultaneously to the intake manifold 6 and the front of the supercharger blower 5. Moreover, the above construction also protects the blower from the thrust that would result in when high pressure air is blown against the blower 5. This construction also prevents the discharge of smoke that would be produced as a result of incomplete combustion due to insufficient air.

Figure 2 shows a second embodiment of this invention where structural members like those shown in Figure 1 carry like reference numbers. The second embodiment is constructed in such a way that when the load varies It increases both the supply of air and the amount of fuel to be injected so as to prevent a drop in the engine revolution speed.

The increase of fuel to be injected is achieved as follows. As shown in Figure 2, a solenoid equipment 32 mounted to the fuel injection pump 30 is controlled by the controller 21 so that it is operated upon the occurence of load variation to increase the amount of injection fuel. The detail of the solenoid equipment 32 is shown in Figure 3. An iron core 33 is screwed into the right end of a rack 34 of the fuel injection pump 30 and, almost concentric with the iron core 33, a cylindrical solenoid holder 37 is secured to the outer frame of the fuel injection pump 30. Mounted on the outer side of the solenoid holder 37 is a coil 16 which is contained in a cover 39. The end of the solenoid holder 37 is closed by a plug 38.

A bleeder passage 35 opens at one end to the front end of the iron core 33 and at the other end to the side of the rack 34 to enable smooth movement of the rack 34. The fuel injection pump 30 has a governor 31 on the left side with a governor handle 29 attached to the left side of the governor 31.

The pipe 10 is branched at a point downstream of the solenoid valve 22 to form a branch pipe 10' which is provided with a main air injection nozzle 13 at the front end and a check valve 27 upstream of the nozzle 13. With this construction, the controller 21 opens the solenoid equipment 32 and the solenoid valve 22 simultaneously, allowing high pressure air to be jetted from the main and secondary air injection nozzles 13 and 9 into the internal combustion engine 1.

As can be seen from the foregoing, the second embodiment can prevent the revolution speed of engine from falling at the time of load variation more positively than the first embodiment can do because the second embodiment increases the amount of fuel injected as well as the air supply.

Acomparison is made between the second embodiment and an example where the rack of the fuel injection pump is operated by the governor alone.

As shown in Figure 4, with the latter case where the rack of the fuel injection pump is activated by the governor alone, the revolution speed of the engine suddenly decreases as indicated by the dashed line because of delay in the rack response and the supply of pressurized air. On the contrary, with the second embodiment the rack response is quick and the supply of pressurized air quickly increases as indicated by the solid line, therefore the drop in the engine revolution speed is small.

Figure 5 illustrates a third embodiment of this invention, which differs from the preceding embodiments in that it is constructed to prevent leakage of high pressure air supplied to the blower 5. Other structural features are almost the same as those of the first embodiment.

An air leak preventor 40 is provided at the front of the case 14 of the blower 5, with its cylindrical body 41 secured to the front surface of the case 14. The cylindrical body 41 has a suction port 43 at the front end where a check valve 42 is installed and supported by a supporting member (not shown). As the pressure in the body 40 becomes higher than the atmospheric pressure the check valve 42 closes the suction port 43.

The pipe 10 is communicated at the front end 9' with the side of the body 41 and the branch pipe 10' is communicated at its front end 13 with the intake manifold 6. The front end 9' of the pipe 10 constitutes one example of the secondary air supply means and the front end 13' of the branch pipe 10' constitutes one example of the main air supply means. The solenoid valves 22 and 23 are provided in the pipe 10 and the branch pipe 10' respectively.

The operation is as follows. When the load 24 varies and the solenoid valves 22 and 23 open, the high pressure air from the container 7 is introduced through the branch pipe 10' into the intake manifold 6 and is also admitted through the pipe 10 into the body 41 of the air leak preventor 40. As the pressure in the body 41 becomes higher than the atmospheric pressure, the check valve 42 blocks the suction port 43 thus preventing the leakage of high pressure air supplied from the container 7. Then as the revolution speed of the exhaust turbine 4 increases with an increase of exhaust gas, the blower turns at a higher speed drawing in a greater amount of air.When the amount of air drawn in by the blower becomes greater than the amount of air supplied through the pipe 10, the pressure in the air leak preventor body 41 goes lower than the atmospheric pressure, opening the check valve 42 allowing the external afr to flow in.

The third embodiment has, in addition to several features of the first and second embodiments, an advantage that the amount of high pressure air supplied from the air tank 7 can be reduced.

Because of the above features, a high pressure air cylinder 7a can be used as an air supply source as shown in Figure 6. Thus, with the fourth embodiment of Figure 6 the air tank 7 and the compressor 8 can be omitted.

In the fourth embodiment, flow meter valves 44 and 45 are provided in the pipes 10 and 10' downstream of the solenoid valves 22 and 23 respectively so that a constant flow of high pressure air is maintained even when the pressure in the high pressure air cylinder 7a varies.

Example With the rating of the generator 20 set at 400 kW/1500 rpm, experiments were conducted for the first embodiment (Figure 1), the second embodiment (Figure 2), the third embodiment (Figure 5) and the conventional internal combustion engine having only a supercharger, to obtain the load application performance, which is shown in Figure 7.

Figure 7 shows that all the three embodiments of the invention have a small instantaneous speed change (%) for the load application factor of 50% or more. In other words they are stable for load variations.

In this experiment the pressure in the air tank 7 used was 6 kg/cm2, the capacity of the air tank 7 and the air cylinder 7a was 0.3 m3 and the injection response was given a delay of zero second.

Claims (9)

1. An internal combustion engine with a supercharger comprising: a main air supply means for injecting high pressure air, provided downstream of the air cooler; a secondary air supply means for injecting high pressure air, installed at the front of the blower; and solenoid valves provided on respective pipes leading to the main and secondary air supply means, the solenoid valves being adapted to automatically open or close according to a load variation of the internal combustion engine.

2. An internal combustion engine with a supercharger as defined in claim 1, wherein the main air supply means is connected to the intake manifold.

3. An internal combustion engine with a supercharger as defined in claim 1, wherein the main and secondary air supply means consist of air injection nozzles.

4. An internal combustion engine with a supercharger as defined in claim 1, wherein the main air supply means consists of an air supply pipe.

5. An internal combustion engine with a supercharger as defined in claim 1, wherein the secondary air supply means includes an air leak prevention device.

6. An internal combustion engine with a supercharger as defined in claim 5 wherein the air leak prevention device consists of a body secured to the case of the blower, an external air suction port formed in the body, a check valve for opening and closing the suction port according to a pressure difference between the inside and the outside of the body, and an air supply pipe communicating with the body.

7. An internal combustion engine with a supercharger as defined in claim 1, wherein a solenoid equipment that activates the rack of the fuel injection pump simultaneous with the solenoid valve operation is provided to the fuel injection pump attached to the internal combustion engine.

8. An internal combustion engine with a supercharger as defined in claim 7, wherein the solenoid equipment consists of an iron core secured to one end of the rack of the fuel injection pump, a solenoid holder disposed concentric with the iron core, and a solenoid coil fixed on the solenoid holder.

9. An internal combustion engine substantially as herein before described with reference to and as shown in the accompanying drawings.