JP3383856B2 - Dual fuel diesel engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-cycle type dual fuel diesel engine that uses both gas fuel and liquid fuel.

[0002]

2. Description of the Related Art As a gas fuel supply mode in an engine of this type, a premixing system (Japanese Patent Laid-Open No. 62-214238) for supplying gas fuel by dispersing it in suction air, and a gas fuel injection by an injector. There is a supply method. In the latter method, gas fuel is injected and supplied in the compression stroke (Japanese Patent Laid-Open No. 62-58031, Japanese Utility Model Publication 3-558).
No. 10). Often, for gas fuel injection, a gas injector similar to that for liquid fuel is used. For example, the above-mentioned actual fairness 3-
In Japanese Patent No. 55810, similarly to the liquid fuel injection pump, an actuator pump that is driven synchronously using engine power is provided, and the control oil controls the opening and closing of the gas injector. Regarding the gas fuel supply system and control system of the dual-fuel diesel engine according to the present invention, see Japanese Patent Publication No. 62-5006.
No. 74 is known.

[0003]

In the premixing system, the gas fuel is supplied together with the intake air during the intake stroke, so that
The gas fuel can be evenly dispersed in the combustion air, easily ignited, and advantageous for complete combustion. However, there is a waste of discharging a part of the gas fuel together with the exhaust gas as so-called raw gas in the early stage of the intake stroke. Gas concentration in the gas mixture to be inhaled rather than necessarily constant, yet easily occurs variation in gas combustion amount of each cylinder, a stable operating condition is hardly obtained.

In the method of injecting and supplying the gas fuel, since the gas fuel is supplied in the compression stroke, the raw gas is not discharged. The supply amount of gas fuel can also be set strictly. However, since it is necessary to supply relatively high-pressure gas fuel, the fuel supply device for that purpose must be complicated. For example, to control the opening and closing of the injector, a dedicated actuator pump must be provided and control oil must be supplied. There is. It is difficult to uniformly disperse the gas fuel in the compressed combustion air, and incomplete combustion is likely to occur. In particular, when the gas fuel is injected and supplied at the same time as the liquid fuel, both fuels cannot be uniformly mixed with the combustion air, and black smoke is likely to occur. Regardless of the fuel supply method, it is necessary to supply the gas fuel and the liquid fuel appropriately according to the purpose of use of the engine and the application environment, but the control device therefor is more complicated than that of an ordinary engine.

The conventional dual-fuel engine does not hinder the application to a newly manufactured engine, but in order to apply it to an existing engine, a large-scale modification of a head block, a cylinder block, etc. is indispensable, and modification cost is required. Bulky. It is unavoidable that the external dimensions of the engine will increase to some extent due to modification and addition of new parts, but in the case of in-vehicle engines such as trucks and buses, the engine room should be adjusted to the size of the existing engine. Since it has been secured, the modified engine may not be able to be stored again in the engine room. In such a case, the engine room has to be expanded, and a larger amount of cost is required to realize the dual fuel of the engine.

An object of the present invention is to provide a dual-fuel diesel engine capable of supplying gas fuel with a simpler fuel supply device and reducing emissions of raw gas and harmful components such as black smoke to a minimum. Especially. Another object of the present invention is to realize dual fuel conversion of a diesel engine by additionally equipping necessary equipment without redesigning or major modification of a cylinder block or a head block. It is to obtain a fuel supply system and its control system suitable for converting a diesel engine into a dual fuel at a lower cost.

Another object of the present invention is to minimize the increase in the outer dimension of the engine when converting an existing diesel engine into a dual fuel, and thus when the accommodation space does not have a sufficient margin like the vehicle-mounted engine. It is also to provide a dual fuel diesel engine that can be re-stored without any problems. Another aspect of the present invention is that the gas fuel delivered from the gas injector can be supplied in the vicinity of the intake valve at the far end of the intake port, and therefore the metered gas fuel is reliably delivered to the combustion chamber together with the intake air. It is to provide a dual fuel diesel engine capable of.

[0008]

A dual-fuel diesel engine of the present invention includes a liquid fuel supply system 11 for supplying a liquid fuel and a gas fuel supply system 12 for supplying a gas fuel as shown in FIGS. 1 to 4. It has and. The gas fuel supply system 12 includes a gas cylinder 16 that stores fuel gas.
A regulator 18 for reducing the pressure of the gas supplied from the gas cylinder 16 to a predetermined pressure; and an electromagnetically operated gas injector for injecting the gas adjusted to the predetermined pressure into the cylinder 1a through the intake port 6. 19 and 19 are included. An electromagnetically operated pump actuator 32 for adjusting the fuel supply amount is attached to the fuel injection pump 14 that constitutes the liquid fuel supply system 11. The fuel injection timing of the gas injector 19 provided corresponding to each cylinder 1a is set between the time when the exhaust valve 5 is closed and the time when the intake valve 4 is closed in the intake stroke. An electronic controller 30 is provided which controls the operating states of the gas injector 19 and the pump actuator 32 to control the supply amounts of liquid fuel and gas fuel.

Specifically, an injection block 26 having a relay passage 27 for connecting each intake port 6 and the corresponding air passage 8a is interposed between the head block 2 and the intake manifold 8, and A gas injector 19 and a gas feed pipe 51 for feeding and guiding the gas fuel to the vicinity of the intake valve 5 are attached to the injection block 26.

Further, in the injection block 26 of the present invention, FIG.
To a narrow block main portion 43 that is clamped and fixed between the head block 2 and the intake manifold 8, as shown in FIG.
The block main part 43 is provided with a wide mounting part 44 projecting from the upper part corresponding to each intake port 6. The gas injector 19 is mounted on the upper surface of the mounting portion 44. Relay passage 27 in which one end of the gas supply pipe 51 is provided in the block main portion 43
Connect to the inner surface of.

Inside the injection block 26, a main gas passage 48 communicating with the outlet passage of the regulator 18 and a branch gas passage 49 communicating with the gas supply pipe 51 are provided, and the main gas passage 48 and the branch gas passage 49 are provided. The gas injector 19 is arranged between the two.

[0012]

The gas fuel is injected and supplied by the gas injector 19 from the time when the exhaust valve 5 is closed to the time when the intake valve 4 is closed in the intake stroke, so all the gas fuel is contained in the cylinder 1a. It is possible to eliminate the outflow of raw gas into the exhaust. Since the gas fuel is injected and supplied into the cylinder 1a through the intake port 6 together with the sucked air, the gas fuel can be uniformly mixed with the combustion air, and all the fuel is completely burned. Since the gas injector 19 is provided corresponding to each cylinder 1a, the gas fuel can be appropriately supplied without excess or deficiency. Since the gas fuel is injected into the negative pressure cylinder 1a during the intake stroke, the injection gas pressure can be reduced and the structure of the gas injector 19 can be simplified. Control peripherals such as actuator pumps can be omitted. The injection amount of the gas fuel is controlled by the electromagnetically operated gas injector 19, and the injection pump 14
Since the supply amount of the liquid fuel is controlled by the electromagnetically operated pump actuator 32 attached to, the supply control of the gas fuel and the liquid fuel can be easily integrated by the electronic controller 30, and the interlocking mechanism and the alignment required for the fuel control can be performed. Can be omitted.

Since the injection block 26 is mounted between the head block 2 and the intake manifold 8 and the gas injector 19 and the gas feed pipe 51 are mounted on the injection block 26, the injection block 26 can be easily added to an existing engine. There is no need to make major modifications to the head block 2, the cylinder block 1, etc.

As shown in FIG. 5, the injection block 26 is composed of a narrow block main portion 43 and a wide mounting portion 44 projecting from the upper portion thereof, and the gas feed pipe 51 is connected to the inner surface of the relay passage 27. Since the block main portion 43 is connected, the thickness dimension of the block main portion 43 can be reduced to a value obtained by adding a slight margin dimension to the diameter dimension of the gas supply pipe 51. That is, the increase in the overall width dimension of the engine due to the addition of the injection block 26 can be minimized.

As shown in FIG. 8, a main gas passage 48 and a branch gas passage 49 are provided inside the injection block 26, and the gas injector 19 is arranged between the two gas passages 48, 49. It is possible to simplify the operation and prevent the additional parts constituting the gas supply system from interfering with the work during maintenance work.

[0016]

According to the present invention, the gas fuel is injected and supplied by the gas injector 19, and the injection timing is set between the closing of the exhaust valve 5 and the closing of the intake valve 4 in the intake stroke. As a result, all the gas fuel can be contained in the cylinder 1a without the raw gas flowing into the exhaust gas. Then, the gas fuel is uniformly dispersed and mixed in the combustion air to completely burn all the fuel. Moreover, the gas fuel is supplied to each cylinder 1a according to the control purpose, and the performance of the dual fuel diesel engine as a whole can be improved.

Since the gas fuel is injected and supplied into the negative pressure cylinder 1a through the intake port 6, the injection gas pressure can be reduced, and the load amount can be reduced as compared with the injector for injecting and supplying the gas fuel in the compression stroke. The gas injector 19 having a small size and a simple structure can be applied. Further, the gas injector 19 is electromagnetically operated, and the liquid fuel supply control is electromagnetically operated pump actuator 3.
Since it is performed in step 2, it is possible to electrically control the supply of the entire fuel, simplify the device for fuel supply and the entire device for control, and provide the dual fuel diesel engine at low cost.

Since the injection block 26 is mounted between the head block 2 and the intake manifold 8 and the gas injector 19 is mounted on the injection block 26, it is possible to easily add the gas injector 19 to an existing engine. Conversion of a diesel engine to a dual-fuel diesel engine can be done at low cost with minimal effort.

Further, according to the injection block 26 constituted by the narrow block main portion 43 and the wide mounting portion 44, the gas feeding does not require the thickness dimension of the block main portion 43 to the left. Since it can be set based on the pipe 51, it is possible to minimize an increase in the overall width dimension of the engine due to the addition of the injection block 26.
Even if there is not enough room in the storage space, the modified engine converted to dual fuel can be re-stored without any problem.

Since the gas supply pipe 51 is attached to the injection block 26 so that the gas fuel delivered from the gas injector 19 can be discharged near the intake valve 4 inside the intake port 6, The generated gas fuel can be reliably sent to the combustion chamber together with the intake air without any response delay, and therefore, the engine operation control can be accurately performed in any operation mode in which the gas fuel is burned.

[0021]

EXAMPLES ( Comparative Example ) FIGS. 1 to 5 show a comparative example for explaining the basic principle of a dual fuel diesel engine according to the present invention. In FIG. 2, reference numeral 1 is a cylinder block, 2 is a head block, and 3 is a piston. An intake valve 4 and an exhaust valve 5 are arranged in the head block 2, and an intake port 6 and an exhaust port 7 which are opened and closed by the valves 4 and 5 are provided. Reference numeral 8 is an intake manifold, and 9 is an exhaust manifold.

The engine is provided with a liquid fuel supply system 11 for supplying a liquid fuel such as light oil and a gas fuel supply system 12 for supplying a gas fuel such as natural gas. In FIG. 1, the liquid fuel supply system 11 includes a fuel tank 13, a fuel pump (not shown), a fuel injection pump 14, a liquid injector 15 mounted on the head block 2, and the like.

The gas fuel supply system 12 includes a gas cylinder 16 for storing natural gas in a gas state, an electromagnetically operated on-off valve 17, and a regulator 18 for reducing the gas pressure.
And a gas injector 19 for injecting and supplying the gas supplied from the regulator 18, and a gas passage connecting each device. In the unused state, the gas cylinder 16 is filled with the natural gas pressurized to about 200 kg / cm ² . This high pressure gas is regulator 1
The pressure is adjusted at 8 and supplied to the gas injector 19. This supply pressure can be selected in the range of ^{2 to} 25 kg / cm ² . A heat exchanger 21 is incorporated in the regulator 18 in order to mitigate the cooling effect of the expanded gas when the pressure is reduced. The heat exchanger 21 uses hot water generated by the engine radiator as a heat exchange medium.

Although the gas injector 19 is not much different in basic structure from the fuel injection nozzle for liquid fuel, it is a point at which an on-off valve for opening and closing the fuel supply passage is switched by a solenoid, that is, an electromagnetically operated fuel injection. The difference is that it is configured as a valve. The maximum engine speed is 4000r
It reaches around pm and the injection timing of the gas fuel is limited to a very short time as described later. Therefore, as the gas injector 19, one having a sufficiently high response speed and no operation delay is applied. For example, an injector (model number SP051) manufactured by US Servo Jet Products International, Inc. is one example. In addition, the gas injector 19 changes the supply fuel amount by changing the opening / closing time of the opening / closing valve.

The gas injector 19 is for each cylinder 1
It is provided corresponding to a, and the gas fuel is injected and supplied to the combustion chamber together with the combustion air through the intake port 6. Therefore, the injection block 26 is interposed between the head block 2 and the intake manifold 8, and the gas injector 19 corresponding to each cylinder 1a is attached to the injection block 26. The injection block 26 is made of an aluminum alloy, and as shown in FIG. 2, a relay passage 27 that connects each intake port 6 and the air passage 8a of the intake manifold 8 is formed in a state of laterally traversing the block. . Further, a mounting hole 28 for mounting the gas injector 19 is formed on the upper surface of the block. As shown in FIG. 3, the injection block 26 is fastened and fixed together with the intake manifold 8 using the mounting screw 29 of the intake manifold 8. In FIG. 2, reference numeral 41 is a throttle lever.

Gas fuel is injected and supplied in the intake stroke. Generally, the intake stroke is started by opening the intake valve 4 at a predetermined angle before top dead center as shown in FIG. 4, closing the exhaust valve 5 at a predetermined angle after top dead center, and then performing a predetermined operation after bottom dead center. Although the intake valve 4 is closed at an angle to finish the operation, in the present invention, fuel injection is performed from the time when the exhaust valve 5 is closed to the time when the intake valve 4 is closed. For example, at the valve timing when the exhaust valve 5 closes at a position advanced 20 degrees from the top dead center and the intake valve 4 closes at a position advanced 55 degrees from the bottom dead center, the closed positions of both valves 5 and 4 are sandwiched. Fuel injection is performed within an angle range of 215 degrees. This is because part of the supplied gas fuel is discharged together with the exhaust gas through the exhaust valve 5 in the overlap period indicated by the symbol a in FIG.

In FIG. 1, a controller 30 having a microprocessor is provided to control the supply amounts of liquid fuel and gas fuel, and the fuel injection pump 14 is further provided.
An electromagnetically operated pump actuator 32 for operating the control rack is provided.

The controller 30 has a throttle lever 41.
(Or accelerator pedal) operation amount signal 33, engine speed signal, rack position signal output from rack position sensor 38, timing pulse output from timing sensor 34, intake air temperature signal output from intake air temperature sensor 35, A preset control algorithm that receives signals such as an intake pressure signal output from the intake manifold pressure sensor 36, a cooling water temperature signal output from the cooling water temperature sensor 37, and a primary side gas pressure signal as necessary. Based on the above, the operating states of the gas injector 19 and the fuel injection pump 14 are controlled. As a basic operation mode, a mode that always uses gas fuel as the main fuel,
There are modes that prioritize improvement of engine output, modes that prioritize reduction of harmful components in the exhaust gas (graphite, NO _x, etc.), and various modes can be set according to the purpose. Reference numeral 39 is a display device including various display lamps and the like.

In order to convert an existing diesel engine that is already in operation into a dual fuel diesel engine,
The following equipment can be supplied as a modification kit.
Each device constituting the gas fuel supply system 12, the injection block 26, the pump actuator 32 for the fuel injection pump 14, the controller 30, the above-mentioned sensors 34 to 38, and a bracket for fixing and fixing them. And a holder, a wiring cord, a display 39, and the like.

With this remodeling kit, it is only necessary to additionally equip the diesel engine with each device, and there is no need to change the structure of the cylinder block 1 or the head block 2 or to perform additional machining, so the cost required for remodeling is low. . Most of the remodeling cost is dominated by the remodeling kit, but both the gas injector 19 and the pump actuator 32 to be controlled are electromagnetically operated, so that the remodeling kit requires more control than mechanical control. It has a low total cost and can be converted to a dual fuel diesel engine at a low cost overall. The fuel pump 14 may be a distribution type pump other than the Bosch type. The injection block 26 can be divided into a plurality of parts.

(Embodiment 1 ) FIGS. 5 to 9 show Embodiment 1 of the present invention, which is different from the above-mentioned comparative example in that the injection block 26 is made thinner. In FIG. 5, the same members as those in the above-described comparative example are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 5, each of the intake port 6 and the exhaust port 7 is opened so as to be biased toward the exhaust port 7 side of the cylinder block 1,
The passage length of the intake port 6 is correspondingly longer.

In FIG. 6 and FIG. 7, the injection block 26
Is provided between the narrow block main portion 43, four wide mounting portions 44 projecting from the upper portion of the block main portion 43 corresponding to each intake port 6, and the projecting base end of each mounting portion 44. It is made of an aluminum block integrally provided with the passage portion 45. Reference numeral 52 is an insertion hole for the mounting screw 29.

In FIG. 6, the mounting portion 44 is formed to be wider than the block main portion 43 toward the intake manifold 8 side, and a mounting hole 28 for mounting the gas injector 19 is provided downward on the upper surface thereof. Has been formed. Of the four mounting portions 44, the center two front and rear dimensions are set larger than the other, and one of them is used to regulate the regulator 1.
Introducing passage 47 for connecting passage 46 derived from 8
Is formed downward. In order to connect the mounting hole 28 and the introduction path 47 at the same time, as shown in FIG. 6, a main gas passage 48 that longitudinally extends through the passage portion 45 is provided.
Both ends are closed with plugs. The gas fuel fed from the regulator 18 reaches the main gas passage 48 through the passage 46 and the introduction passage 47, and always fills the main gas passage 48.

In order to supply gas fuel from the main gas passage 48 to each intake port 6 in a branched manner, a branch gas passage 49 is formed upward from the inner wall of each relay passage 27, and the branch gas passage 49 is slanted with respect to the mounting hole 28. Are communicated with each other through a communication passage 50. The branch gas passage 49 also serves as a mounting hole for the gas supply pipe 51.

In FIG. 9, a gas injector 19 is provided.
Is composed of a solenoid portion 53 and a valve portion 54, and a ball valve 55 provided in the valve portion 54 is replaced with a spring 57 by a rod 56.
By pushing down against the inlet port 58
And the exit port 59 can communicate with each other. The space between the ports 58 and 59 is blocked by a sealing. The upper end of the rod 56 is fixed to the core 53a of the solenoid portion 53, and when the coil portion 53b is energized, the rod 56 can be pushed down and driven. The inlet port 58 communicates with the main gas passage 48, and the outlet port 59 communicates with the branch gas passage 49 via the communication passage 50. Reference numeral 60 is a connector for connecting a power supply line to the solenoid portion 53, and the power supply line is denoted by reference numeral 6 in FIG.
It is indicated by 0a.

The gas feed pipe 51 is formed by bending a stainless pipe material into a Z shape, and has a vertical connecting portion 62 which is inserted into the branch gas passage 49 and is connected to the connecting portion 62. The arm portion 63 extending in the same direction and the ejection portion 64 that bends obliquely downward from the tip of the arm portion 63 are integrally provided. The connecting portion 62 inserted into the branch gas passage 49 has the branch gas passage 4 from the corner adjacent to the attachment portion 44 and the passage portion 45.
A screw 65 (see FIG. 8) screwed in toward 9 is fixed inseparably.

As described above, according to the injection block 26 formed by the narrow block main portion 43 and the wide mounting portion 44, the thickness dimension of the block main portion 43 is made equal to the diameter dimension of the gas feed pipe 51. Since the thickness can be set to include a margin, it is possible to minimize an increase in the lateral width of the engine when the injection block 26 is added to the existing engine. Further, since the gas supply pipe 51 is provided to discharge the gas fuel near the intake valve 4 at the far end of the intake port 6, the gas fuel can be accurately supplied to the combustion chamber without a response delay. You can

The injection block 26 in the first embodiment described above.
Can be formed from an aluminum casting, but may be formed by cutting out from an aluminum block when the number of engines to be modified is small. The shape and length of the gas supply pipe 51 should be variously modified according to the shape of the intake port of the engine and the position of the intake valve, so the shape and length are not limited to the embodiment.

[Brief description of drawings]

FIG. 1 is an explanatory diagram conceptually showing the content of the present invention.

FIG. 2 is a schematic cross-sectional view of an essential part of an engine showing a comparative example .

FIG. 3 is a perspective view showing a structure of an injection block showing a comparative example .

FIG. 4 is an explanatory diagram showing injection timing of gas fuel.

FIG. 5 is a schematic cross-sectional view of an essential part of the engine according to the first embodiment.

FIG. 6 is a perspective view of the injection block of the first embodiment .

FIG. 7 is a side view of the injection block of the first embodiment .

FIG. 8 is a vertical cross-sectional view showing the internal structure of the injection block of the first embodiment .

FIG. 9 is a vertical sectional view showing the internal structure of the gas injector of the first embodiment .

[Explanation of symbols]

1 cylinder block 2 head blocks 6 intake ports 8 intake manifold 11 liquid fuel supply system 12 Gas fuel supply system Injector for 15 liquids 16 gas cylinders 18 Regulator 19 Gas injector 26 injection block 27 relay passage 30 controller 32 pump actuator

Front page continued (51) Int.Cl. ⁷ identification code FI F02M 21/06 F02M 21/06 F 51/00 51/00 F (58) Fields investigated (Int.Cl. ⁷ , DB name) F02D 19 / 08 F02D 19/10 F02D 41/40 F02M 21/02 301 F02M 21/06 F02M 51/00

Claims (2)

(57) [Claims] 1. A liquid fuel supply system 1 for supplying a liquid fuel
1 and a gas fuel supply system 12 for supplying a gas fuel, and the gas fuel supply system 12 sets a gas cylinder 16 for storing a fuel gas and a pressure of the gas supplied from the gas cylinder 16 to a predetermined pressure. between the regulator 18 steps down adjustment, and a gas injector 19 for injecting and supplying electromagnetic operable to adjust gas at a predetermined pressure through the intake port 6 in the cylinder 1a, a head block 2 and the intake manifold 8 Each intake
While connecting the port 6 and the corresponding air passage 8a
The injection block 26 having the connecting passage 27 is interposed
The gas injector 19 and the gas fuel near the intake valve 4.
The gas delivery pipe 51 that guides the delivery to the side is the injection blower.
Fuel injection pump 14 which is mounted on the fuel tank 26 and constitutes the liquid fuel supply system 11.
Is provided with an electromagnetically operated pump actuator 32 for adjusting the fuel supply amount, and when the fuel injection timing of the gas injector 19 provided corresponding to each cylinder 1a is the time when the exhaust valve 5 is closed in the intake stroke. Until the intake valve 4 is closed, the gas injector 19 and the pump actuator 3 are set.
In a dual-fuel diesel engine including an electronic controller 30 that controls the operating states of the fuel cells 2 and controls the supply amounts of the liquid fuel and the gas fuel , the injection block 26 includes the head block 2 and the intake manifold.
A narrow block main portion 43 that is clamped and fixed with the hold 8
And the upper part of the block main part 43 corresponding to each intake port 6
The wide mounting portions 44 protruding from the
The gas injector 19 is mounted on the upper surface of the mounting portion 44.
And one end of the gas supply pipe 51 is provided in the block main portion 43.
The inside of the block main portion 43 of the injection block 26 is connected to the inner surface of the relay passage 27, and
It is formed so as to pass through the passage portion 45 in the longitudinal direction, and
A main gas passage 48 communicating with the outlet passage of the vibrator 18 is provided.
The gas supply pipe 51 is mounted inside the injection block 26.
The branch gas passage 49 for storing is the inner wall of the relay passage 27.
Is formed upward from the main gas passage 48 and the branch gas passage 49.
The valve portion 54 of the injector 19 is arranged, and the inlet port 58 of the valve portion 54 is discharged to the main gas passage 48.
The mouth ports 59 communicate with the branch gas passages 49, respectively.
A dual fuel diesel engine characterized by: 2. A mounting portion 44 of the gas injector 19
But protrudes toward the intake manifold 8 side from the block main part 43
Dual fuel diesel engine as set forth in claim 1 being formed.