JPH06307308A - Multiple fuel supply device - Google Patents

Abstract

PURPOSE:To suppress generation of smoke by reducing any pressure reduction in a pressure chamber at the time of lowering a plunger. CONSTITUTION:A pressure control means 96 is composed by a check ball and a spring which energizes it to the side of a fuel chamber 32 in a communication passage between a pressure chamber 36 and the fuel chamber 32. When the pressure in the pressure chamber 36 is decreased at the time of lowering a plunger 24, the spring is compressed so that the pressure chamber 36 and the fuel chamber 32 may be communicated mutually, and thereby decrease in the pressure in the presure chamber 36 is suppressed. Therefore, the operation period of a constant remaining pressure valve 46 can be reduced, and any decrease in the pressure downstream from the constant remaining pressure valve 46 to a discharge port 54 of auxiliary fuel is made small, and then an excessive quantity of the next auxiliary fuel discharge quantity becomes small, and thereby smoke can be rarely generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection system for a multi-cylinder internal combustion engine. The present invention relates to a dual fuel supply device for a diesel engine used.

[0002]

2. Description of the Related Art In a multiple fuel supply system using alcohol or the like as a main fuel and light oil or the like as an auxiliary fuel, it is known that it is preferable to inject alcohol and light oil in layers without mixing them. . That is, a device for injecting a small amount of light oil first to provide a fire seed and then injecting alcohol as a main fuel is disclosed in, for example, JP-A-63-1705.
No. 54 publication. This device comprises an in-line fuel injection pump for pumping the main fuel, a pump for pumping the sub fuel, and a fuel injection nozzle for injecting the main and sub fuels. Then, in order to supply the main and sub fuels in the above-mentioned layered manner, the introduction of the sub fuel into one fuel injection nozzle is operated by the pressure of the main fuel being pumped to the main fuel introduction passage of another fuel injection nozzle. It is designed to be carried out by a pump. Therefore, the sub fuel is introduced into a certain fuel injection nozzle prior to the injection timing of the fuel injection nozzle, and the valve opens when the pressure of the main fuel when the main fuel is pumped to the fuel injection nozzle reaches a predetermined pressure. The main and sub fuels are injected in layers. The sub fuel is introduced at a pressure that does not reach the valve opening pressure of the fuel injection nozzle. Here, the fuel injection nozzle has a main fuel introduction passage that communicates with the row-type fuel injection pump and a sub fuel introduction passage that communicates with the pump, and each of them is communicated with the tip of the fuel injection nozzle. Main and sub fuels can be injected simultaneously by pressure.

The row fuel injection pump has a conventionally well-known structure, and has a plunger barrel having a pressure chamber communicating with the main fuel introducing passage, and a main body capable of communicating with the pressure chamber opened on the side surface of the plunger barrel. The fuel intake / exhaust passage, the plunger that reciprocates in the plunger barrel to open / close the main fuel intake / exhaust passage, the lead portion for adjusting the main fuel injection amount formed in the plunger, and the pressure chamber and the main fuel introduction passage are connected. The delivery valve is provided in the middle of the path, and the delivery valve opens the path by the pressure of the pressure chamber when the main fuel is pressure-fed. In the fuel intake stroke, the upper end of the plunger opens the main fuel intake / exhaust passage to suck the main fuel into the pressure chamber, and in the fuel pressure stroke, the upper end of the plunger closes the main fuel intake / exhaust passage and the plunger still rises to generate pressure. When the pressure in the chamber rises to a predetermined value, the delivery valve opens and the main fuel is pumped. And
When the reed portion meets the main fuel intake / exhaust passage, the main fuel in the pressure chamber escapes to the main fuel intake / exhaust passage via the reed portion, and the pressure chamber becomes a low pressure equal to that of the main fuel intake / exhaust passage, and the fuel pumping ends.

Further, in this dual fuel supply system, a pressure feeder is provided in consideration of both ignitability and prevention of smoke generation. This pump is applied to the piston unlike the conventional one in which the displacement of the piston of the pump that pumps the sub fuel to the sub fuel introduction passage is always constant, regardless of the pressure of the main fuel when pumping the main fuel. Due to the difference between the main fuel pressure during the pressure-feeding to the main fuel introduction passage and the residual pressure of the sub-fuel in the sub-fuel introduction passage on the side of the sub-fuel outlet of the pump, the amount of movement of the piston changes and The amount of pumped sub fuel changes. Therefore, when the total injection amount is large, that is, when the main fuel pressure at the time of main fuel pressure feeding is high, the movement amount of the piston for feeding the sub fuel increases, and the sub fuel feeding amount increases. On the other hand, when the total injection amount is small, that is, when the pressure during the main fuel pressure feeding is low, the movement amount of the piston for feeding the sub fuel decreases, and the sub fuel feeding amount decreases. Therefore, the supply of auxiliary fuel does not become excessive or insufficient.

However, when fuel injection is completed and the delivery valve is closed, the residual pressure in the main fuel introducing passage on the fuel injection nozzle side of the delivery valve is high, and as described above, the main fuel introducing passage and the sub fuel introducing passage are separated from each other. Since it is communicated at the tip of the fuel injection nozzle, the residual pressure in the auxiliary fuel introduction passage also increases,
It may be difficult to introduce the auxiliary fuel from the pressure feeder to the fuel injection nozzle. To solve this problem,
It is conceivable to use a constant residual pressure valve provided in the delivery valve for suppressing the increase in residual pressure in the dual fuel supply system as disclosed in Japanese Patent No. 184864. This constant residual pressure valve does not operate when the main fuel is being pumped, but opens when the main fuel is not being pumped, so that the pressure difference between the upstream side (pressure chamber side) and the downstream side (main fuel introduction passage side) of the constant residual pressure valve is almost It should be kept constant. The pumping of the main fuel ends when the main fuel in the pressure chamber flows into the main fuel intake / exhaust passage via the lead portion described above.
Therefore, the pressure in the pressure chamber immediately after the completion of the main fuel pressure feeding is reduced to the pressure in the main fuel intake / exhaust passage and is maintained at a pressure almost equal to the pressure in the main fuel intake / exhaust passage, and the pressure in the main fuel intake / exhaust passage is always constant. Since the residual pressure valve maintains the pressure difference between the upstream side and the downstream side thereof substantially constant, the pressure in the main fuel introduction passage downstream of the constant residual pressure valve is kept low and substantially constant when the main fuel is not pressure-fed. Therefore, the sub fuel is smoothly introduced into the fuel injection nozzle without being hindered by the residual pressure in the main fuel introduction passage and the sub fuel introduction passage.

[0006]

However, even in the above-described multiple fuel supply system, under the operating condition of low rotation and low load such as idle operation, after the constant residual pressure valve is opened and pressure is adjusted during non-pressurization of the main fuel, The plunger that reciprocates to pump the main fuel in the row fuel injection pump begins to descend, and the main fuel intake / exhaust passage is disconnected from the lead portion. At this time, the pressure chamber is in a hermetically sealed state, and the pressure of the pressure chamber is lowered by lowering the plunger. Therefore, the constant residual pressure valve is opened again to regulate the pressure, and the pressure in the main fuel introduction passage downstream of the constant residual pressure valve is reduced. Since the main fuel introduction passage is connected to the sub fuel delivery port via the sub fuel introduction passage, the pressure of the passage up to this point decreases. If the above operating conditions do not change, the same pressure as the main fuel pressure during the previous main fuel pressure feed will be applied to the piston of the pressure feeder during the main fuel pressure feed this time. Since the difference between the pressure of the main fuel and the pressure on the side of the sub fuel outlet when the main fuel is pressure-fed is increased, the movement amount of the piston is increased and the pressure amount of the sub-fuel is excessive this time. Under the operating condition of low rotation and low load, the total injection amount is small, and the sub fuel delivered to the fuel injection nozzle may exceed the total injection amount. Therefore, the sub fuel delivered from the pressure feeder is injected by one fuel injection. There are things I can't do. If this operating condition is continued, the auxiliary fuel that cannot be consumed by the injection will be accumulated, and if acceleration or racing is performed in this state, a large amount of the auxiliary fuel will be injected, which may cause smoke.

Therefore, an object of the present invention is to prevent the pressure drop in the main fuel introduction passage due to the opening of the constant residual pressure valve by reducing the pressure drop in the pressure chamber when the plunger is lowered.

[0008]

A dual fuel supply system according to the present invention comprises a column fuel injection pump for pumping a main fuel, a pump for pumping a sub fuel, and a main fuel introducing passage for introducing a main fuel. And a plurality of fuel injection nozzles each having an auxiliary fuel introduction passage for introducing an auxiliary fuel, and the main fuel introduction passage and the auxiliary fuel introduction passage are in communication with each other. A plunger barrel having a pressure chamber that communicates with the fuel introduction passage, a main fuel intake / exhaust passage that is opened in a side surface of the plunger barrel and can communicate with the pressure chamber, and a plunger that reciprocates in the plunger barrel to open / close the main fuel intake / exhaust passage. And a lead portion for adjusting the main fuel injection amount formed on the plunger and a path connecting the pressure chamber and the main fuel introduction passage, and the path is opened by the pressure of the pressure chamber when the main fuel is pressure-fed. deli And a constant residual pressure valve provided in parallel with the delivery valve and opened by the residual pressure in the main fuel introducing passage when the main fuel is not being pressure-fed, wherein the pump is the main fuel introducing passage of a certain fuel injection nozzle. Is operated by the differential pressure between the pressure of the main fuel being pumped to the secondary fuel and the residual pressure of the secondary fuel in the secondary fuel introduction passage of another fuel injection nozzle, and the secondary fuel is pumped to the secondary fuel introduction passage. In the dual fuel supply apparatus described above, when the pressure of the pressure chamber becomes equal to or lower than a predetermined pressure while the main fuel is not being pressure-fed, the pressure of the pressure chamber and the main fuel intake / exhaust passage are communicated with the column fuel injection pump. A pressure control means is provided.

[0009]

According to the above means, the plunger reciprocating in the plunger barrel in the row type fuel injection pump opens the main fuel intake / exhaust passage opened in the plunger barrel before rising, so that the main fuel is introduced from the main fuel intake / exhaust passage to the pressure chamber. Is supplied.
While the plunger is rising, the pressure in the pressure chamber rises because the main fuel intake / exhaust passage opened in the plunger barrel is closed, and the delivery valve provided in the middle of the route connecting the pressure chamber and the main fuel introduction passage opens the route. , Is pumped to the main fuel introduction passage of the fuel injection nozzle where the main fuel is present. The pressure transmitter is operated by the differential pressure between the pressure of the main fuel being pumped to the main fuel introduction passage of the certain fuel injection nozzle and the residual pressure of the sub fuel introduction passage of another fuel injection nozzle, and the auxiliary fuel introduction is performed. A sub fuel amount corresponding to the differential pressure is pumped to the passage. The sub fuel is previously introduced into the sub fuel introduction passage of a certain fuel injection nozzle by the above procedure, and the valve is opened at the pressure of the main fuel to inject the main fuel and the sub fuel. When the plunger further rises, the lead part for adjusting the main fuel injection amount formed on the plunger meets the main fuel intake / exhaust passage, and the main fuel in the pressure chamber leaks to the main fuel intake / exhaust passage through the lead part, causing the pressure in the pressure chamber to rise. Lowers, the delivery valve closes, and the pumping of the main fuel ends. Then, the constant residual pressure valve is opened by the residual pressure in the main fuel introducing passage, the main fuel is leaked from the main fuel introducing passage to the pressure chamber, and the residual pressure in the main fuel introducing passage is reduced to close the valve.

Next, when the plunger begins to descend, the lead portion is displaced from the main fuel intake / exhaust passage, the pressure chamber and the main fuel intake / exhaust passage are cut off, and the pressure chamber is sealed. Still further, when the plunger is lowered and the pressure in the pressure chamber is reduced to a predetermined pressure or less, the pressure control means communicates the pressure chamber with the main fuel intake / exhaust passage to introduce the main fuel into the pressure chamber from the main fuel intake / exhaust passage, Reduce the pressure drop in the pressure chamber. Therefore, unnecessary opening of the constant residual pressure valve due to pressure drop when the plunger is lowered can be suppressed. Therefore, the pressure drop in the sub fuel introduction passage communicating with the main fuel introduction passage is also suppressed to a small level, and the difference between the pressure of the main fuel and the pressure on the side of the sub fuel outlet when pumping the main fuel to operate the pressure feeder is increased. And excessive pumping of the auxiliary fuel due to the expansion of the differential pressure is reduced.

[0011]

1 to 3 relate to a first embodiment of the present invention. FIG. 1 is a block diagram showing a first embodiment of a multiple fuel supply system according to the present invention, and FIG. 2 is a column in the first embodiment. FIG. 3 is a detailed view of the fuel injection pump of FIG. 3, and FIG. 3 is a detailed view of the pump in the first embodiment. This dual fuel supply system includes a column-type fuel injection pump 10 composed of main fuel pumping means 108, 208, 308, 408 of the same number as the number of cylinders, pumps 112, 212, 312, 412 of the same number as the number of cylinders, and the number of cylinders. And the same number of fuel injection nozzles 114, 214, 314, and 414. Further, there is a first fuel tank 16 for storing a main fuel such as alcohol and a second fuel tank 18 for storing a sub fuel such as light oil. An in-tank pump 20 for pumping the main fuel is provided in the first fuel tank 16, and an in-tank pump 22 for pumping the sub fuel is
Is in the second fuel tank 18. In-tank pump 20
Sends the main fuel to the column fuel injection pump 10 via the filter 21, and the in-tank pump 22 sends the sub fuel to the pressure feeders 112, 212, 312, 412 via the filter 23. The excessively supplied main fuel is returned to the first fuel tank 16 through the return passage 6, and the excessively supplied auxiliary fuel is returned through the return passage 7 to the second fuel tank 1
Returned to 8. The pressure regulator 9 in the return passage 7 adjusts the pressure of the sub fuel pumped up from the in-tank pump 22. There is also a pressure regulator in the bolt 11 of the row fuel injection pump 10 to adjust the pressure of the main fuel.

The column fuel injection pump 10 is for pumping the main fuel. As described above, the row fuel injection pump 1
0 is the same number of main fuel pumping means 108, 208, 3 as the number of cylinders.
No. 08, 408, and the main fuel pumping means 308 will be described below. The main fuel pressure feeding means 108, 2
08 and 408 have the same structure. Main fuel pumping means 30
8 is formed in the pump housing 23. Then, the plunger 24 is driven by a cam shaft (not shown) and reciprocates in the plunger barrel 26. The plunger 24 has a cylindrical shape, and the lead portion has an escape hole 28 formed in the center portion of the upper end portion of the plunger 24 in the axial direction.
And a plunger lead 30 provided on the side surface of the plunger 24 and communicating with the relief hole 28. A main fuel intake / exhaust passage is composed of a fuel chamber 32 and a feed hole 34 around the plunger barrel 26.
6 and the fuel chamber 32 are communicated with each other. The pressure chamber 36 is formed by the upper ends of the plunger barrel 26 and the plunger 24, and the pressure chamber 36 and the fuel injection nozzle 31
A delivery valve 38 and a spring 40 for urging the delivery valve 38 toward the pressure chamber 36 are provided in the main fuel pumping passage 35 as a path connecting the main fuel introduction passage 84 of No. 4 and No. 4. A constant residual pressure valve 46 and a spring 48 for urging the constant residual pressure valve 46 toward the main fuel introduction passage 84 are provided in the port 42 penetrating the central portion of the delivery valve 38. The spring force of the spring 48 of the constant residual pressure valve 46 is set lower than the auxiliary fuel pressure feed pressure.

The pumps 112, 212, 312, 412 are for pumping the auxiliary fuel.
2 is taken up and its configuration is explained. Incidentally, the pressure feeder 212,
312 and 412 also have the same configuration. The pump 112 has an inlet 52 and an outlet 54 for the auxiliary fuel. A pump chamber 74 is formed between the inlet 52 and the outlet 54. Sub fuel is supplied from the second fuel tank 18 to the inlet 52. The piston 56 in the pump 112 is capable of reciprocating in a cylinder 58, and a first spring 60 for urging the piston 56 toward the main fuel pumping passage 35 is provided at the left end portion of the piston 56 in the figure. Piston 5
An orifice 53 is provided on the rear side of the right end portion of FIG. 6, that is, on the side facing the main fuel pumping passage 35 in order to prevent a sudden pressure increase. The first spring 60 is a cap-shaped protrusion 61 of the auxiliary piston 62 having a protrusion 61 provided therein.
The auxiliary piston 62 is fitted to the outer peripheral portion, is urged by the second spring 64 so as to come into contact with the stopper 68, and the through hole 67 is provided. The pump chamber 74 is connected to the piston 56 side and the stopper 66 by the auxiliary piston 62.
Since it is divided into two parts, the through hole 67 connects the two. There is a gap a between the piston 56 and the auxiliary piston 62, and a gap b between the auxiliary piston 62 and the stopper 66. The spring force of the first spring 60 is weaker than the spring force of the second spring 64. A check valve 70 that allows only the introduction of the sub fuel at a valve opening pressure lower than the pressure of the sub fuel sent from the second fuel tank 18 is disposed downstream of the introduction port 52, and the sub fuel is provided upstream of the delivery port 54. A check valve 72 having a higher opening pressure than the check valve 70 is arranged.

Fuel injection nozzles 114, 214, 314,
Reference numeral 414 is for injecting the main fuel and the sub fuel, and the fuel injection nozzle 314 will be described below. The fuel injection nozzles 114, 214 and 414 have the same structure. The fuel injection nozzle 314 includes a nozzle main body 78 having an injection port 76 at its tip and a needle 80 inserted in the nozzle main body 78. Although the upper portion of the fuel injection nozzle 314 is omitted in FIG. 1, a spring for urging the needle 80 toward the valve seat 82 is arranged in the upper portion, and the valve opening pressure thereof is higher than that of the delivery valve 38. It is set high.

A main fuel introducing passage 84 for introducing the main fuel is formed around the needle 80, and can communicate with the injection port 76 when the needle 80 is opened. The main fuel introduction passage 84 is connected to the main fuel pressure feeding passage 35. An auxiliary fuel introduction passage 86 for introducing an auxiliary fuel is formed at the center of the needle 80.
Is communicated with the main fuel introduction passage 84 near the lower end of the. The sub fuel introduction passage 86 is connected to the delivery port 54 of the pump 112. The check valve 90 is a check valve that prevents the reverse flow of fuel during fuel injection, and is set to a valve opening pressure lower than that of the check valve 72. The needle 80 has a pressure receiving portion 92 that receives the pressure of the main fuel.

According to the present invention, in the multiple fuel supply system constructed as described above, the communication passage 94 for communicating the pressure chamber 36 and the fuel chamber 32 with the pump housing 23 is provided.
Is provided, and the pressure control means 96 is provided in the communication passage 94. The pressure control means 96 is composed of a check ball 98 and a spring 100 that biases the check ball 98 toward the fuel chamber 32. The spring force of the spring 100 that biases the check ball 98 is set to be weaker than the spring force of the spring 48 that biases the constant residual pressure valve 46. When the pressure difference between the pressure in the pressure chamber 36 and the pressure in the fuel chamber 32 exceeds the spring force of the spring 100, the check ball 9
8 compresses and compresses the spring 100 so that the pressure chamber 36 and the fuel chamber 32 are communicated with each other, and the pressure difference between the pressure chamber 36 and the fuel chamber 32 is maintained at a substantially constant pressure difference determined by the spring force of the spring 100. There is.

Next, the operation and effect of the first embodiment will be described. The sub fuel in the second fuel tank 18 is sucked into the pump chamber 74 via the in-tank pump 22 and the filter 23 by opening the check valve 70 downstream of the inlet 52 of the pump 112. At this stage, the check valve 72 upstream of the delivery port 54 is closed because it is higher than the valve opening pressure of the check valve 70, and the auxiliary fuel is distributed to the stopper 66 side and the piston 56 side of the pump chamber 74 divided by the auxiliary piston 62. It is filled. The auxiliary fuel is filled in the pump chamber 74 on the piston 56 side through the through hole 67 of the auxiliary piston 62.

Now, when the main fuel is pumped from the main fuel pumping means 108, the pressure of the main fuel is changed to the piston 5 of the pump 112.
6 is on the right end in the figure. Since the spring force of the first spring 60 is weaker than that of the second spring 64, the first spring 60 enters between the piston 56 and the auxiliary piston 62 through the through hole 67 in the direction in which the piston 56 compresses the first spring 60 (left in the figure). Move while pressing the auxiliary fuel. Then pump room 7
As a result, the pressure in the pump chamber 74 rises, the check valve 72 upstream of the delivery port 54 opens, and the auxiliary fuel in the pump chamber 74 enters the auxiliary fuel introduction passage 86 of the fuel injection nozzle 314. It is pressure-fed through the pressure-feeding passage 88. Since the check valve 90 has a lower opening pressure than the check valve 72, the auxiliary fuel is smoothly pumped to the auxiliary fuel introduction passage 86. In addition, the auxiliary fuel is fed by the needle 8 of the fuel injection nozzle 314.
The needle 80 does not open because it is lower than the valve opening pressure of 0, and is higher than the residual pressure in the main fuel introducing passage 84, so the introduced sub fuel is the auxiliary fuel introducing passage 86 and the main fuel introducing passage 8
The main fuel at the tip of the main fuel introducing passage 84 is pushed away from the communicating portion 4 and is filled in the tip of the main fuel introducing passage 84. Therefore, in the main fuel introducing passage 84, there is the sub fuel near the tip portion thereof, that is, near the injection port 76, and the main fuel is upstream thereof. When the pressure of the main fuel pumped from the main fuel pumping means 108 is higher, after the piston 56 moves by a and comes into contact with the protrusion 61 of the auxiliary piston 62,
The second spring 64 is compressed and compressed so that the auxiliary piston 62 is pushed by the piston 56. Then the pump room 74
Since the volume of the secondary fuel is further reduced, the pumping amount of the auxiliary fuel is increased. The maximum movement amount of the auxiliary piston 62 is b.

Next, the main fuel is pumped from the main fuel pumping means 308. The main fuel of the first fuel tank 16 is the in-tank pump 20, the filter 21, the fuel chamber 32,
It is sucked into the pressure chamber 36 through the feed hole 34.
In this fuel intake stroke, since the upper end of the plunger 24 opens the feed hole 34, there is no pressure difference between the pressure chamber 36 and the fuel chamber 32. Therefore, the pressure control means 96
Check ball 98 blocks the communication passage 94. Therefore, when the plunger 24 rises, the main fuel does not escape from the communication passage 94 to the fuel chamber 32 and the pressure chamber 36
The pressure of is also increasing. The pressure in the pressure chamber 36 rises while the plunger 24 is rising and the upper end of the plunger 24 blocks the feed hole 34 and the pressure chamber 36, and the pressure urges the delivery valve 38 to the pressure chamber 36 side. When the urging force of the spring 40 is overcome, the delivery valve 38 rises and opens the passage, and the main fuel in the pressure chamber 36 passes through the main fuel pressure feeding passage 35 and the main fuel introduction passage 8 of the fuel injection nozzle 314.
Pumped to No. 4.

Sub fuel introduction passage 8 of fuel injection nozzle 314
6 and the vicinity of the tip of the main fuel introduction passage 84, that is, the injection port 7
As mentioned above, the auxiliary fuel is filled in the vicinity of 6 in advance. Then, when the pressure of the main fuel pressure-fed from the main fuel pressure-feeding means 308 is applied to the pressure receiving portion 92 and reaches the biasing force of the spring (not shown) that biases the needle 80 toward the valve seat 82, the needle 80 rises to inject fuel. The main fuel and the sub fuel are injected from the injection port 76 of the nozzle 314. At this time, the pressure of the main fuel pumped from the main fuel pumping means 308 is the pressure of the pump 3
12 is operated to introduce the sub fuel into the sub fuel introduction passage of the fuel injection nozzle 414.

When the plunger 24 further rises, the plunger lead 30 provided on the side surface of the plunger 24 encounters the feed hole 34, and the main fuel of the pressure chamber 36 passes from the escape hole 28 of the plunger 24 to the plunger lead 30,
After passing through the feed hole 34 and the fuel chamber 32, the pressure in the pressure chamber 36 decreases, the delivery valve 38 closes, and the pressure feed of the main fuel ends. After the delivery valve 38 is closed, when the residual pressure in the main fuel pumping passage 35 communicating with the main fuel introducing passage 84 downstream of the delivery valve 38 is higher than the pumping pressure of the sub fuel, the constant residual pressure valve 46 is a spring. Four
The pressure chamber 36 and the main fuel pressure feeding passage 35 are communicated with each other by compressing 8 to maintain the pressure difference between the pressure chamber 36 and the main fuel pressure feeding passage 35 at a substantially constant pressure difference determined by the spring force of the spring 48. ing. Since the pressure chamber 36 and the fuel chamber 32 are communicated with each other at the end of the pressure feed of the main fuel, the pressure in the pressure chamber 36 is the same as that of the fuel chamber 32.
Is almost equal to the pressure of.

When the plunger 24 descends after the pressure adjustment by the constant residual pressure valve 46 is completed, the plunger lead 3
0 deviates from the feed hole 34, and finally both of them are cut off. When the plunger 24 descends in this shutoff state, the pressure in the pressure chamber 36 decreases, and the constant residual pressure valve 46 restarts to try to keep the pressure difference upstream and downstream of the constant residual pressure valve 46 constant. . However, the pressure difference between the pressure in the pressure chamber 36 and the pressure in the fuel chamber 32 is
When the spring force of 0 is exceeded, the check ball 98 of the pressure control means 96 compresses and contracts the spring 100 to connect the pressure chamber 36 and the fuel chamber 32, and the main fuel of the fuel chamber 32 is introduced into the pressure chamber 36.

The pressure control means 96 is activated, and the communication passage 9
Since 4 connects the pressure chamber 36 and the fuel chamber 32, the pressure drop of the pressure chamber 36 becomes small when the plunger 24 descends. The constant residual pressure valve 46 is adapted to maintain the pressure difference between the pressure chamber 36 and the main fuel pumping passage 35 downstream of the constant residual pressure valve 46 at a substantially constant pressure difference determined by the spring force of the spring 48. By introducing the main fuel from the fuel chamber 32 to the pressure chamber 36 by 96, the reopening period of the constant residual pressure valve 46 after the pressure adjustment is shortened, and the main fuel pressure feeding passage 35 on the downstream side of the constant residual pressure valve 46, the main fuel Introduction passage 84, sub fuel introduction passage 86, sub fuel pressure passage 8
The pressure drop to the vicinity of the delivery port 54 via 8 becomes small. Therefore, if the same operating condition continues, the amount of movement of the piston 56 of the pump 112 due to the pressure of the main fuel when the main fuel is pumped from the main fuel pumping means 108 next time,
The difference in the moving amount of the piston 56 of the pump 112 at this time is smaller than that in the case where the pressure control means 96 is not provided, and the excessive supply amount of the auxiliary fuel is also small. Therefore, even if the auxiliary fuel that cannot be completely consumed by one injection is supplied, the excessive supply amount is small, and therefore the time until the auxiliary fuel enough to generate smoke is accumulated in the main fuel introduction passage 84 of the fuel injection nozzle 314. Can be long. Therefore, even if acceleration or racing is performed from an operating condition of low rotation and low load such as idle operation, the auxiliary fuel to the extent that smoke is generated is often not accumulated, and smoke is less likely to occur. Further, since smoke is less likely to occur, the durability is improved if the catalyst is provided in the exhaust passage.

FIG. 4 is a detailed view of a row type fuel injection pump showing a second embodiment of the present invention, in which a plurality of communication passages 94 and pressure control means 96 are provided. When the pressure in the pressure chamber 36 drops when the plunger 24 descends, the pressure control means 9
Since there are a plurality of six, the amount of main fuel introduced into the pressure chamber is increased and the pressure drop in the pressure chamber can be suppressed faster than in the case where there is only one. Other configurations and operations are the same as those in the first embodiment.

FIG. 5 is a detailed view of a row type fuel injection pump showing a third embodiment of the present invention. The pressure control means 96 is composed of a solenoid valve 102 in a communication passage 94 provided in the pump housing 23, and a pressure sensor 104 which detects the pressure of the pressure chamber 36 by the solenoid valve. And this pressure sensor 10
When the pressure detection value of 4 falls below the pressure of the fuel chamber 32, the solenoid valve 102 is opened. By this control, the main fuel is introduced from the fuel chamber 32 into the pressure chamber 36, and the pressure drop in the pressure chamber 36 is suppressed to a small level. Other configurations and operations are the same as those in the first embodiment. Further, a position sensor is provided on the cam shaft (not shown), and the plunger 24
When the position sensor detects the position of the cam shaft reaching the top dead center, the solenoid valve 102 is opened, and when the position sensor detects the position of the cam shaft where the plunger 24 reaches the bottom dead center, the solenoid valve 102 is closed. But it's okay. The pressure in the pressure chamber 36 decreases when the plunger 24 descends, and the pressure in the pressure chamber 36 increases when the plunger 24 rises. Therefore, the pressure in the pressure chamber 36 is indirectly detected at the position of the plunger 24. It will be.

It is also conceivable to incorporate the above-mentioned pressure control means 96 into the plunger 24. For example, from the upper end surface of the plunger 24 to the side surface of the plunger 24, the plunger 2
4 is provided with a communication passage passing through the inside thereof, and a check ball and a spring for urging the check ball toward the side surface of the plunger 24 are provided in the communication passage. When the plunger 24 starts descending and the plunger lead 30 is cut off from the feed hole 34 on the side surface of the plunger 24 of the communication path,
At least configured to meet the feedhole 34. With this configuration, when the pressure in the pressure chamber 36 drops, the check ball compresses the spring, and the main fuel is introduced from the feed hole 34 into the pressure chamber 36 via the communication passage, and the pressure drop in the pressure chamber 36 is suppressed to a small level. . Other configurations and operations are the same as those in the first embodiment.

Further, since none of the pressure control means in the above embodiment is located in the middle of the main fuel pressure feed passage and the main fuel introduction passage, the main fuel is smoothly supplied to the fuel injection nozzle with a simple structure without causing resistance to the passage. It

[0028]

According to the present invention, the column-type fuel injection pump is provided with the pressure control means for connecting the pressure chamber and the main fuel intake / exhaust passage when the pressure of the pressure chamber becomes lower than the predetermined pressure when the plunger is lowered. Since the excess amount of pumping is reduced and it takes longer to reach the amount of secondary fuel that causes smoke, it is possible to prevent smoke from occurring even if acceleration or racing is performed from low-rotation, low-load operating conditions. .

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a multiple fuel supply system according to the present invention.

FIG. 2 is a detailed view of the row-type fuel injection pump in the first embodiment.

FIG. 3 is a detailed view of a pressure feeder according to the first embodiment.

FIG. 4 is a detailed view of a row-type fuel injection pump showing a second embodiment of the present invention.

FIG. 5 is a detailed view of a row-type fuel injection pump showing a third embodiment of the present invention.

[Explanation of symbols]

 10 ... In-line fuel injection pump 112, 212, 312, 412 ... Pressure feeder 114, 214, 314, 414 ... Fuel injection nozzle 46 ... Constant residual pressure valve 96 ... Pressure control means 102. ..Solenoid valve 104 ... Pressure sensor

Claims (1)

[Claims] 1. A column fuel injection pump for pumping main fuel, a pump for pumping sub fuel, a main fuel introducing passage for introducing main fuel, and a sub fuel introducing passage for introducing sub fuel. And a plurality of fuel injection nozzles in which the main fuel introduction passage and the sub fuel introduction passage are communicated with each other, wherein the row-type fuel injection pump has a plunger barrel having a pressure chamber communicated with the main fuel introduction passage. A main fuel intake / exhaust passage that is opened in the side surface of the plunger barrel and can communicate with the pressure chamber; a plunger that reciprocates in the plunger barrel to open / close the main fuel intake / exhaust passage; and a main fuel injection amount adjustment formed in the plunger. And a delivery valve provided in the middle of a route connecting the pressure chamber and the main fuel introduction passage for opening the route by the pressure of the pressure chamber during the main fuel pressure feeding, and the delivery valve provided in parallel with the delivery valve. Main fuel And a constant residual pressure valve that is opened by the residual pressure in the main fuel introduction passage during pressure feeding, wherein the pressure feeder is different from the pressure of the main fuel in the middle of being fed to the main fuel introduction passage of a certain fuel injection nozzle. In the dual fuel supply device configured to be operated by a pressure difference from the residual pressure of the sub fuel in the sub fuel introduction passage to pump the sub fuel to the sub fuel introduction passage, A dual fuel supply apparatus, characterized in that pressure control means is provided for communicating the pressure chamber and the main fuel suction / discharge passage when the pressure in the pressure chamber becomes equal to or lower than a predetermined pressure while the plunger is descending during non-pressurization of the main fuel.