JP4204057B2 - Cooling device for pilot fuel injection valve for gas engine - Google Patents

Description

  The present invention relates to a gas engine having a fuel injection valve for injecting a liquid fuel as a pilot fuel from a fuel injection valve, using a gas fuel such as natural gas as a main fuel and igniting the gas fuel. The present invention relates to a cooling device for a pilot fuel injection valve for a gas engine that improves the cooling capacity of the injection valve.

  In this type of gas engine, the lean burn method is becoming mainstream in order to reduce nitrogen oxide (NOx) in exhaust gas and improve fuel efficiency, and intake air is used to improve output. Since it is supercharged, the cylinder pressure of the gas engine is increased.

  From the viewpoint of effective energy use, some gas engines use digestion gas generated from sewage treatment plants and low-calorie special gas such as biomass gas made from dust and waste as the main fuel. Are known.

  Thus, under conditions where the in-cylinder pressure is high or the main fuel is a low-calorie special gas, an ignition system that generates large ignition energy is required to achieve stable ignition of the main fuel. Became.

For this reason, an ignition system based on pilot fuel injection, which generates ignition energy several thousand times that of a spar plug, is becoming mainstream from a general spark ignition system using a spar plug, and this pilot fuel injection is performed by a fuel injection valve. (For example, see Patent Document 1).
JP 2003-254195 A

  However, since the liquid fuel injected from the pilot fuel injection valve for ignition of the main fuel is very small, the fuel injection valve of a normal diesel engine injects a large amount of fuel. The cooling of the fuel injection valve by the liquid fuel itself, that is, the self-cooling of the fuel injection valve cannot be expected. Incidentally, the fuel injected from the pilot fuel injection valve of the gas engine is only 1 to 2% of the fuel injected from the fuel injection valve of the diesel engine of the same size.

  For this reason, the tip portion of the fuel injection valve is overheated, causing plastic deformation of the nozzle tip portion due to the impact at the time of closing the valve, closing of the injection hole due to fuel coking, seizure of the needle valve, etc. There is a problem of greatly shortening the lifespan.

  In order to solve such a problem, it is necessary to cool the tip of the fuel injection valve effectively. For this reason, in the valve holder used for attaching the fuel injection valve to the cylinder head or in the fuel It is conceivable that a cooling hole is formed in the nozzle body itself of the injection valve, and cooling water is guided into the cooling hole from the internal cooling water passage of the cylinder head itself.

  However, in the former method of guiding the cooling water into the former valve holder, the cooling water flowing through the cooling holes of the cylinder head is only replaced by natural circulation, so that the fuel injection valve is sufficiently cooled. On the other hand, if forced circulation by a dedicated pump is performed, there is a problem that the structure becomes complicated and the cost is increased.

  Further, in the conventional method for introducing the cooling water into the nozzle body, the cooling water is forcibly circulated by a pump or the like, so that the fuel injection valve can be expected to be cooled to a certain degree, but the structure inside the fuel injection valve is complicated. However, there is a problem that it can be applied only to a large fuel injection valve, and cannot be applied to a small fuel injection valve such as a pilot fuel injection from the viewpoint of processing technology and cost.

  The present invention has been made to solve such a problem, and can be applied to a small-sized injection valve, and can sufficiently exhibit the cooling effect of the fuel injection valve with a simple configuration and low cost. Another object of the present invention is to provide a cooling device for a pilot fuel injection valve for a gas engine.

  In order to solve the above-described problems, the means employed by the present invention is attached to a cylinder head of a gas engine via a valve holder, and injects liquid fuel as pilot fuel from an injection hole to self-ignite the liquid fuel. A fuel injection valve for igniting gas fuel as the main fuel, and a cooling water circulation path having an engine cooling path for passing cooling water in the cylinder head and forcibly flowing cooling water in one direction around the fuel injection valve; A cooling device for a pilot fuel injection valve for a gas engine, comprising: a valve holder cooling path provided in a tip portion of the valve holder and having one end communicating with an engine cooling path upstream of the fuel injection valve; and a fuel injection valve And a connecting path connecting the low-pressure portion of the cooling water circulation path whose pressure is lower than that of the upstream engine cooling path and the other end of the valve holder cooling path.

  According to the above-described cooling device for a pilot fuel injection valve for a gas engine, since there is a pressure difference between one end and the other end of the valve holder cooling path, the cooling water supplied to the engine cooling path of the cooling water circulation path A part flows in from one end of the valve holder cooling path and forcibly passes through the valve holder cooling path. At this time, the tip of the valve holder is directly cooled by the cooling water, and the nozzle tip of the fuel injection valve is indirectly cooled by the cooling water through the valve holder. Thereafter, the cooling water returns from the other end of the valve holder cooling path to the low pressure portion of the cooling water circulation path through the connection path.

  In this way, the cooling water is forced to flow in the valve holder cooling path due to the pressure difference, so that the flow rate is large, the cooling water in the valve holder cooling path is quickly replaced, and the tip of the valve holder and the fuel injection valve The nozzle tip is effectively cooled. Since the cooling path for cooling the nozzle tip of the fuel injection valve is provided in the valve holder and is not provided in the fuel injection valve main body, it can be applied to a small injection valve. Further, since the cooling water in the valve holder cooling path is forcibly circulated only by the pressure difference, a dedicated pump or the like that has been conventionally required is eliminated, and it can be implemented with a simple configuration and at a low cost.

  Alternatively, the means employed by the present invention is attached to the cylinder head of the gas engine via a valve holder, and injects liquid fuel as pilot fuel from the nozzle hole and supplies gas fuel as main fuel by self-ignition of liquid fuel. In a cooling device for a pilot fuel injection valve for a gas engine having a fuel injection valve to be ignited, it is provided at the tip of a valve holder and covers the nozzle tip of the fuel injection valve while allowing the injection of liquid fuel from the injection hole A heat shielding cap is provided.

  According to the above-described cooling device for a pilot fuel injection valve for a gas engine, the heat shielding cap reduces the radiant heat transferred from the high-temperature combustion gas generated by the combustion of the main fuel to the nozzle tip, and the nozzle tip Greatly suppresses temperature rise. Since the heat shielding cap is provided at the tip of the valve holder and is not provided in the fuel injection valve body, it can also be applied to a small injection valve. In addition, the heat shielding cap can be implemented with a simple configuration and at a low cost.

  Alternatively, the means employed by the present invention is attached to the cylinder head of the gas engine via a valve holder, and injects liquid fuel as pilot fuel from the nozzle hole and supplies gas fuel as main fuel by self-ignition of liquid fuel. A pilot for a gas engine having a fuel injection valve to be ignited and a cooling water circulation path having an engine cooling path for passing cooling water through the cylinder head and forcibly flowing the cooling water in one direction through the periphery of the fuel injection valve In a cooling device for a fuel injection valve, a valve holder cooling passage that is provided in a tip portion of the valve holder and has one end communicating with an engine cooling passage upstream of the fuel injection valve, and an engine cooling passage upstream of the fuel injection valve A connection path that connects the low pressure part of the cooling water circulation path having a lower pressure and the other end of the valve holder cooling path, and a liquid fuel from the nozzle hole provided at the tip of the valve holder It is to include a heat shield cap covering the nozzle tip of the fuel injection valve while permitting morphism.

  According to the above-described cooling device for the pilot fuel injection valve for a gas engine, the fuel by the synergistic effect of the cooling by the cooling water forcibly flowing in the valve holder cooling path and the cooling by the radiation shielding by the heat shielding cap. The nozzle tip portion of the injection valve can be cooled more effectively, and the life of the fuel injection valve can be greatly extended.

  In the cooling system for a pilot fuel injection valve for a gas engine, the cooling water circulation path preferably includes an orifice on the downstream side of the fuel injection valve, and the connection path is preferably connected to the cooling water circulation path on the downstream side of the orifice. . The orifice is a means by which a pressure difference can be easily created in the cooling water circulation path, whereby a desired pressure difference can be generated between both ends of the valve holder cooling path.

  In the cooling device for a pilot fuel injection valve for a gas engine, the valve holder cooling path may have an annular portion disposed between one end and the other end so as to surround the nozzle tip in the vicinity of the shielding cap. desirable. The cooling water flowing in such an annular portion uniformly cools the nozzle tip in the circumferential direction, and the heat shielding cap is provided at the tip of the valve holder, thereby contributing to the cooling.

  In the cooling device for a pilot fuel injection valve for a gas engine, the valve holder cooling path includes an inner cylindrical inlet port for introducing cooling water into the annular portion and an inner cylindrical outlet port for discharging cooling water from the annular portion. Preferably, the inlet port and the outlet port are bored radially from the axis of the valve holder. As described above, the inner cylindrical inlet port and outlet port are formed in a radial manner from the axial center of the valve holder, and thus can be easily formed by drilling from the outside of the valve holder.

  In the cooling device for a pilot fuel injection valve for a gas engine, the engine cooling path preferably has a cooling jacket surrounding the valve holder from the outside. Such a cooling jacket can greatly contribute to cooling of the entire fuel injection valve.

  A cooling device for a pilot fuel injection valve for a gas engine according to the present invention is attached to a cylinder head of a gas engine via a valve holder, and injects liquid fuel as pilot fuel from an injection hole to self-ignite the liquid fuel. A fuel injection valve for igniting the gas fuel, and a cooling water circulation path having an engine cooling path for passing the cooling water in the cylinder head and forcibly flowing the cooling water in one direction through the periphery of the fuel injection valve A valve holder cooling path provided in the tip of the valve holder and having one end communicating with an engine cooling path upstream of the fuel injection valve, and a cooling water circulation path having a lower pressure than the engine cooling path upstream of the fuel injection valve And a connection path connecting the other end of the valve holder cooling path.

Or a fuel injection valve that is attached to a cylinder head of a gas engine via a valve holder and injects liquid fuel as pilot fuel from an injection hole and ignites gas fuel as main fuel by self-ignition of liquid fuel, A heat shielding cap is provided at the tip of the valve holder and covers the nozzle tip of the fuel injection valve while allowing injection of liquid fuel from the nozzle hole.

  Alternatively, the cooling device for a pilot fuel injection valve for a gas engine according to the present invention is attached to a cylinder head of a gas engine via a valve holder and injects liquid fuel as pilot fuel from a nozzle hole by self-ignition of the liquid fuel. A fuel injection valve for igniting gas fuel as the main fuel, and a cooling water circulation path having an engine cooling path for passing cooling water in the cylinder head and forcibly flowing cooling water in one direction around the fuel injection valve; A cooling device for a pilot fuel injection valve for a gas engine, comprising: a valve holder cooling path provided in a tip portion of the valve holder and having one end communicating with an engine cooling path upstream of the fuel injection valve; and a fuel injection valve Also provided at the tip of the valve holder and a connection path connecting the low pressure part of the cooling water circulation path whose pressure is lower than the engine cooling path on the upstream side and the other end of the valve holder cooling path ; And a heat shield cap covering the nozzle tip of the fuel injection valve while permitting injection of liquid fuel from the injection holes with the.

  Therefore, the pilot fuel injection valve cooling device for a gas engine according to the present invention can be applied to a small injection valve, and can sufficiently exhibit the cooling effect of the fuel injection valve with a simple configuration and low cost. There is an excellent effect. As a result, problems such as plastic deformation of the nozzle tip due to overheating, blockage of the nozzle hole due to fuel coking, and seizure of the needle valve can be avoided, and the life of the fuel injection valve can be extended.

  FIG. 1 shows a gas engine 2 used as a drive source of a power generation system, and an output shaft of the gas engine 2 is connected to a generator 4. The gas engine 2 includes, for example, six cylinders # 1 to # 6, and each cylinder # receives supply of liquid fuel used for ignition of the gas fuel in addition to gas fuel such as natural gas as a main fuel. This liquid fuel is injected into each cylinder # from the fuel injection valve 32 shown in FIG. 2, and the injected liquid fuel stably ignites the gas fuel as the main fuel by self-ignition.

  FIG. 1 shows a cooling water circulation path 6 for circulating cooling water through the cylinder head of the gas engine 2. The cooling water circulation path 6 includes an engine cooling path 8 that leads to the cylinder head, and an external cooling path 7 that connects the engine 2 and the cooler 18.

  Specifically, the engine cooling path 8 is attached to the outside of the cylinder head, the cooling water path 10 passing through the inside of the cylinder head, the branch path 14 branched from the cooling water path 10 and leading the cooling water to each cylinder #. The cylinder outlet branch pipe 15 for discharging the cooling water from each cylinder # and the cooling water outlet main pipe 16 for collecting the cooling water of the cylinder outlet branch pipe 15 are provided.

  The external cooling path 7 connects the cooling water engine inlet 2 a of the cooling water passage 10 and the cooling water engine outlet 2 b of the cooling water outlet main pipe 16, and a cooler for cooling the cooling water in the external cooling path 7. 18 is arranged. In the external cooling path 7, a pump 20 is interposed between the cooler 18 and the cooling water engine inlet 2a, and the pump 20 discharges cooling water toward the cooling water engine inlet 2a. For this reason, the cooling water in the cooling water circulation path 6 is forcibly circulated so as to flow from the cooling water path 10 to the cooling water outlet main pipe 16 via the branch path 14 and the cylinder outlet branch pipe 15.

In the external cooling path 7, a temperature adjustment valve 22 is inserted between the cooler 18 and the cooling water engine outlet 2 b, and the temperature adjustment valve 22 is interposed between the cooler 18 and the pump 20 via the bypass path 24. The external cooling path 7 is connected. Specifically, the temperature adjustment valve 22 is a three-way valve, and adjusts the distribution of the amount of cooling water flowing to the inlet side of the cooler 18 and the amount of cooling water flowing to the suction side of the pump 20, thereby cooling water discharged from the pump 20. Adjust the temperature.

  Here, reference numerals 26 and 28 in FIG. 1 denote a supply valve for supplying cooling water into the cooling water circulation path 6 and a discharge valve for discharging cooling water from the cooling water circulation path 6, respectively.

  FIG. 2 is a cross-sectional view of the cylinder head 30 of the gas engine 2. The above-described branch passages 14 are arranged on both sides so as to sandwich the fuel injection valve 32 of each cylinder #, and the branch passages 14 on both sides are annular. One end is connected by the connection chamber 14a. The cooling water that has passed through the periphery of the fuel injection valve 32 from the branch path 14 enters the upper cylinder head cooling chamber 12 (not shown), cools the cylinder head 30, and then the above-described cylinder outlet attached to the outside of the cylinder head 30. It is discharged to the branch pipe 15.

  The fuel injection valve 32 for each cylinder # is attached to the cylinder head 30 via a valve holder 34, and the valve holder 34 surrounds the tip of the fuel injection valve 32. 2 indicates a fuel path for supplying liquid fuel to the fuel injection valve 32, and a fuel pipe (not shown) passing through the fuel path 36 is connected to a fuel distribution pump (not shown).

  Since the tip end portion and its peripheral portion of the valve holder 34 paired with each fuel injection valve 32 have the same configuration, the tip portion of one valve holder 34 and its peripheral portion will be described with reference to FIG.

  A mounting hole 38 for the fuel injection valve 32 is formed in the cylinder head 30, and a cooling jacket 40 and an annular chamber 42 are formed vertically between the inner peripheral surface of the mounting hole 38 and the outer peripheral surface of the valve holder 34. ing. The cooling jacket 40 and the annular chamber 42 are provided independently of each other. The cooling jacket 40 extends in the axial direction of the valve holder 34, that is, in the axial direction of the fuel injection valve 32, and crosses the above-described branch path 14. Thus, the cooling jacket 40 cools the fuel injection valve 32 via the valve holder 34.

  A valve holder cooling path 44 is formed inside the tip of the valve holder 34, and the valve holder cooling path 44 has one end connected to the lower end of the cooling jacket 40 and the other end connected to the annular chamber 42. . Specifically, the valve holder cooling path 44 includes an annular portion 46 in a part thereof, and the annular portion 46 is disposed so as to surround the tip end portion of the nozzle body 48 of the fuel injection valve 32.

  As shown in FIG. 4, the annular portion 46 communicates with the cooling jacket 40 via two inlet ports 50 and communicates with the annular chamber 42 via two outlet ports 52. As shown in FIGS. 3 and 4, the inlet port 50 and the outlet port 52 include an axial portion extending from the annular portion 46 along the nozzle body 48, and the axial portion and the cooling jacket 40 or the annular chamber 42. And an inclined portion to be connected.

  That is, the valve holder cooling path 44 has an inner cylindrical inlet port 50 for introducing cooling water into the annular portion 46 and an inner cylindrical outlet port 52 for discharging the cooling water from the annular portion 46. As shown in FIG. 4, the port 50 and the outlet port 52 are formed by radial drilling from the axial center of the valve holder 34, and thus can be easily formed by drilling from the outside of the valve holder 34. The outlet of the inlet port 50 with respect to the annular chamber 42 and the inlet of the outlet port 52 are arranged so as to be separated from each other in the diameter direction of the annular chamber 42.

On the other hand, an internal connection path 53 extending from the annular chamber 42 is formed in the cylinder head 30, and this internal connection path 53 is connected to the valve holder cooling water collecting pipe via a connection branch pipe 54 attached to the outside of the cylinder head 30. 56 (see FIG. 1). Further, connection branch pipes 54 extending from the annular chambers 42 of the other cylinders # via the internal connection paths 53 are also connected to the valve holder cooling water collecting pipe 56.

  As shown in FIG. 1, the valve holder cooling water collecting pipe 56 is connected to an external connecting pipe 58 disposed outside the gas engine 2, and the external connecting pipe 58 is a low pressure section provided in the above-described cooling water circulation path 6. It is connected to the. Specifically, an orifice 60 is inserted in the external cooling path 7 of the cooling water circulation path 6, and the orifice 60 is disposed between the cooling water engine outlet 2 b of the cooling water outlet main pipe 16 and the temperature adjustment valve 22. ing.

  The orifice 60 restricts the flow rate of the cooling water flowing in the external cooling passage 7 to maintain the internal pressure of the external cooling passage 7 downstream of the orifice 60 at a lower pressure than the internal pressure of the engine cooling passage 8. Is connected between the orifice 60 and the temperature control valve 22 in the external cooling path 7. The annular chamber 42, the internal connection path 53, the connection branch pipe 54, the valve holder cooling water collecting pipe 56 and the external connection pipe 58 described above connect the valve holder cooling path 44 in the valve holder 34 to the low pressure portion of the cooling water circulation path 6. A connection path is formed.

  As shown in FIG. 3, a heat shield cap 62 is integrally attached to the distal end portion of the valve holder 34, and the heat shield cap 62 is disposed in the vicinity of the annular portion 46 of the valve holder cooling path 44 described above. . The heat shielding cap 62 covers the tip of the nozzle body 48 in the fuel injection valve 32 and has an opening 64 at a position corresponding to the nozzle hole drilled in the tip.

  The opening 64 allows the spray of liquid fuel injected from the nozzle hole to pass without being blocked when the fuel injection valve 32 is opened, and does not deteriorate the atomization characteristics of the liquid fuel. Specifically, for example, three injection holes of the fuel injection valve 32 are arranged at equal intervals in the circumferential direction, and each injection hole injects fuel at an injection angle of approximately 20 °. On the other hand, each opening 64 of the heat shielding cap 62 is formed in an inner cone shape having a wide outer side, and the opening angle of the inner cone is formed to be slightly larger than the fuel injection angle of the injection hole. Other configurations of the fuel injection valve 32 described above are known and are similar to conventional diesel engine engine automatic fuel valves and common rail electronically controlled fuel injection valves, for example, and thus detailed description thereof is omitted.

  According to the cooling device for the fuel injection valve 32 described above, one end of the valve holder cooling path 44 formed in the tip of the valve holder 34 is connected to the engine cooling path 8 of the cooling water circulation path 6, specifically, the cooling jacket 40. Since the other end is connected to the low pressure portion of the cooling water circulation path 6 on the downstream side of the orifice 60 via the connection paths 42, 53, 54, 56, 58, the valve holder cooling path 44 sandwiching the valve holder 34 A pressure difference occurs between both ends. For this reason, as shown in FIGS. 3 and 4, a part of the cooling water flowing in the engine cooling path 8 flows from one end of the valve holder cooling path 44 and passes through the annular portion 46 to the other part of the valve holder cooling path 44. Forced to flow out of the edge.

  Accordingly, since a large amount of cooling water flows through the inside of the tip end portion of the valve holder 34, overheating of the tip end portion of the valve holder 34, that is, the tip end portion of the fuel injection valve 32 is effectively prevented by this cooling water. For this reason, even if the needle valve 68 collides with the valve seat of the nozzle body 48 when the fuel injection valve 32 is closed, the impact does not cause plastic deformation at the tip of the nozzle body 48. Further, the nozzle hole of the nozzle body 48 is not blocked by the fuel coking, and the needle valve 68 is not seized against the nozzle body 48.

  As described above, the pressure difference between the both ends of the valve holder cooling path 44 can be obtained only by inserting the orifice 60 in the cooling water circulation path 6, so that the cooling water is forcibly introduced into the valve holder cooling path 44. A dedicated pump is not required, the tip portion of the fuel injection valve 32 can be effectively cooled with a simple structure and at a low cost, and the life of the fuel injection valve 32 is extended.

The annular portion 46 of the valve holder cooling path 44 surrounds the tip of the nozzle body 48, and the outlet of the inlet port 50 and the inlet of the outlet port 52 with respect to the annular portion 46 are separated from each other in the diametrical direction of the annular portion 46. Therefore, the cooling water in the annular portion 46 flows uniformly in the circumferential direction of the nozzle body 48, and the tip portion of the nozzle body 48 can be cooled uniformly in the circumferential direction.

  Furthermore, the heat shielding cap 62 attached to the tip of the valve holder 34 prevents the radiant heat resulting from the combustion of the gas fuel that is the main fuel from being applied to the tip of the fuel injection valve 32, that is, the tip of the nozzle body 48. This effectively prevents the nozzle body 48 from overheating. In addition, since the heat shielding cap 62 is disposed in the vicinity of the annular portion 46 of the valve holder cooling path 44, the heat shielding cap 62 is also cooled by the cooling water flowing in the valve holder cooling path 44, and the heat shielding cap 62 Overheating is also prevented.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the cooling device may include a pressure reducing valve instead of the orifice 60, and the specific layout of the valve holder cooling path 44 can be arbitrarily changed.

For the following two examples and one comparative example, the temperatures of the tip A point of the valve holder 34 and the tip B point of the nozzle body 48 shown in FIG.
(Implementation content)
Comparative Example: Fuel Injection Valve Implementing a Cooling Device by Conventional Circulation of Cooling Water Example 1: Fuel Injection Valve Implementing Only a Cooling Device by Forced Circulation of Cooling Water According to the Present Invention Example 2: According to the Present Invention Cooling by forced circulation of cooling water and cooling by heat shielding cap
Fuel injection valve with both rejection devices Engine: cylinder diameter 200mm, stroke 300mm
Engine operating state at the time of measurement: rotational speed 900 rpm, net average effective pressure 20 bar

(Implementation results)
Temperature at the tip of the valve holder Temperature at the tip of the nozzle body Comparative example: 305 ° C 350 ° C
Example 1: 195 ° C (110 ° C) 280 ° C (70 ° C)
Example 2: 170 ° C (135 ° C) 250 ° C (100 ° C)
The parentheses indicate the temperature difference from the comparative example.

(Conclusion)
The fuel injection valve in which the cooling device by forced circulation of cooling water according to the present invention is implemented has a temperature at the tip of the nozzle body of 70 ° with respect to the fuel injection valve in which the cooling device by natural circulation of conventional cooling water is implemented. Only C was improved. Further, in the fuel injection valve in which both the cooling device by forced circulation of the cooling water and the cooling device by the heat shielding cap according to the present invention are implemented, the temperature of the tip portion of the nozzle body is improved by 100 ° C. From this, the improvement of the cooling device by the heat shielding cap is estimated to be about 30 ° C.

  As described above, both the cooling device using forced circulation of cooling water and the cooling device using the heat shielding cap have greatly improved the temperature at the tip of the nozzle body.

It is the schematic which shows the electric power generation system using the gas engine as one Example. It is sectional drawing which shows the cylinder head of the gas engine of FIG. It is sectional drawing to which a part of FIG. 2 was expanded. It is sectional drawing which cut | disconnected the front-end | tip part of the valve holder of FIG. 3 along the valve holder cooling path.

Explanation of symbols

2 Gas engine 2a Cooling water engine inlet 2b Cooling water engine outlet 4 Generator 6 Cooling water circulation path 7 External cooling path 8 Engine cooling path 10 Cooling water path 12 Cylinder head cooling chamber 14 Branch path 14a Annular connection chamber 15 Cylinder outlet branch pipe 16 Cooling water outlet main pipe 18 Cooler 20 Pump 22 Temperature adjustment valve 24 Bypass path 26 Supply valve 28 Drain valve 30 Cylinder head 32 Fuel injection valve 34 Valve holder 36 Fuel path 38 Mounting hole 40 Cooling jacket 42 Annular chamber (connection path)
44 Valve holder cooling path 46 Annular part 48 Nozzle body 50 Inlet port 52 Outlet port 53 Internal connection path (connection path)
54 Connection branch pipe (connection path)
56 Valve holder cooling water collecting pipe (connection path)
58 External connection pipe (connection path)
60 Orifice 62 Heat shielding cap 64 Opening 68 Needle valve

Claims (5)

  It is attached to a cylinder head (30) of a gas engine (2) via a valve holder (34), and liquid fuel as pilot fuel is injected from an injection hole and gas fuel as main fuel is injected by self-ignition of the liquid fuel. Cooling water circulation having a fuel injection valve (32) to be ignited and an engine cooling passage (8) for passing cooling water through the cylinder head and forcibly flowing the cooling water in one direction through the periphery of the fuel injection valve In the cooling device for a pilot fuel injection valve for a gas engine provided with a passage (6), the valve holder is provided in the distal end portion of the valve holder and has one end communicating with the engine cooling passage upstream of the fuel injection valve. A cooling path (44) is connected to the low pressure portion of the cooling water circulation path whose pressure is lower than that of the engine cooling path upstream of the fuel injection valve and the other end of the valve holder cooling path. The cooling water circulation path has an orifice (60) on the downstream side of the fuel injection valve, and the connection path is on the downstream side of the orifice. And a cooling device for a pilot fuel injection valve for a gas engine, wherein the cooling device is connected to the cooling water circulation path.   It is attached to a cylinder head (30) of a gas engine (2) via a valve holder (34), and liquid fuel as pilot fuel is injected from an injection hole and gas fuel as main fuel is injected by self-ignition of the liquid fuel. Cooling water circulation having a fuel injection valve (32) to be ignited and an engine cooling passage (8) for passing cooling water through the cylinder head and forcibly flowing the cooling water in one direction through the periphery of the fuel injection valve In the cooling device for a pilot fuel injection valve for a gas engine provided with a passage (6), the valve holder is provided in the distal end portion of the valve holder and has one end communicating with the engine cooling passage upstream of the fuel injection valve. A cooling path (44) is connected to the low pressure portion of the cooling water circulation path whose pressure is lower than that of the engine cooling path upstream of the fuel injection valve and the other end of the valve holder cooling path. The nozzle tip portion of the fuel injection valve is provided at the tip (42, 53, 54, 56, 58) and the tip of the valve holder and allows the liquid fuel to be injected from the nozzle hole. A heat shielding cap (62) for covering, the cooling water circulation path having an orifice (60) downstream of the fuel injection valve, and the connection path downstream of the orifice to the cooling water circulation path. A cooling device for a pilot fuel injection valve for a gas engine, wherein the cooling device is connected. The valve holder cooling path (44) has an annular portion (46) disposed between the one end and the other end so as to surround the nozzle tip in the vicinity of the heat shielding cap (62). The cooling device for a pilot fuel injection valve for a gas engine according to claim 2 . The valve holder cooling passage (44) includes an inner cylindrical inlet port (50) for introducing the cooling water into the annular portion (46) and an inner cylindrical outlet port (for discharging the cooling water from the annular portion). The pilot fuel injection for a gas engine according to claim 3 , wherein the inlet port and the outlet port are radially drilled from an axis of the valve holder (34). Valve cooling system. The pilot fuel injection valve for a gas engine according to any one of claims 1 to 4 , wherein the engine cooling path (8) has a cooling jacket (40) surrounding the valve holder (34) from the outside. Cooling system.