JP2007162547A - Liquid-cooled fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid-cooled fuel injection valve enabled to improve a cooling effect of a nozzle tip without increasing an outer diameter of the fuel injection valve and with a relatively simple construction. <P>SOLUTION: The liquid-cooled fuel injection valve, that is constructed to form a cooling chamber in the nozzle tip in which a needle valve is fitted for reciprocation and which is fixed to a cylinder cover, and to supply cooling liquid into the cooling chamber to cool the nozzle tip and its peripheral members, is characterized in that the cooling chamber is comprised of a cooling groove which is spirally scored in an outer periphery of a cylinder portion of the nozzle tip to extend from an upper side to an end side of the nozzle tip, and an outer periphery of the cooling groove is covered in a fluid tight manner with a cylindrical nozzle cap. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is mainly applied to a fuel injection valve for a large diesel engine, a needle valve is fitted in a reciprocating manner inside, a cooling chamber is formed in a nozzle tip fixed to a cylinder cover, and a cooling liquid is formed in the cooling chamber. And a liquid-cooled fuel injection valve configured to cool the nozzle tip and its peripheral members.

  In a large diesel engine using heavy oil as a fuel, the heavy oil is preheated to about 130 ° C. by a fuel preheater, the viscosity is lowered, and the fuel is supplied to the fuel injection device. Such a fuel injection valve that injects high-temperature fuel (heavy oil) forms a cooling chamber in a nozzle tip that becomes high temperature as disclosed in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 6-123255). The fuel injection valve is cooled by flowing cooling water through the room.

FIG. 4 is a longitudinal sectional view of the nozzle tip 01 in the liquid-cooled fuel injection valve disclosed in Patent Document 1.
In FIG. 4, reference numeral 011 denotes a main body of the nozzle tip 01, and a needle valve hole 02 into which a needle valve (not shown) is slidably fitted is formed in the center of the main body 011 in the axial direction. A seat surface 08 with the needle valve is formed at the bottom of 02. Reference numeral 04 denotes a nozzle hole that is perforated at the tip of the nozzle tip 01.

09 is a cap fixed to the lower portion of the main body 011 by welding or brazing (010 is a welding or brazing portion). An annular water chamber 05 is formed by the inner surface of the cap 09 and the lower side surface of the main body 011. ing. The water chamber 05 has a cooling water inlet hole 06 and a cooling water outlet hole 07 which are drilled in the axial direction of the main body 011.
Cooling water for cooling the nozzle tip 01 flows through the cooling water inlet hole 06 as indicated by an arrow C1 and enters the water chamber 05, and flows in the water chamber 05, thereby causing a high temperature portion below the nozzle tip 01 to flow. Is cooled, flows through the cooling water outlet hole 07 as indicated by the arrow C2, and is sent to the cooling water outlet pipe.

JP-A-6-123255

  In the conventional liquid-cooled fuel injection valve provided in Patent Document 1 and the like as shown in FIG. 4, an annular water chamber 05 is provided around the high temperature portion near the tip of the nozzle tip 01. The cooling water inlet hole 06 and the cooling water outlet hole 07 which are formed and penetrated in the axial direction from the upper end of the main body 011 of the nozzle chip 01 are connected to the water chamber 05. Therefore, the outer diameter of the nozzle tip 01 increases over the entire length in order to form the water chamber 05 and the two cooling water passage holes 06 and 07.

  However, in a diesel engine in which the liquid-cooled fuel injection valve is arranged at the center of the cylinder, an intake valve, an exhaust valve, and a water injection valve in the case of a water injection engine are arranged around the fuel injection valve. Therefore, when the outer diameter of the nozzle tip 01 is increased over the entire length and the outer diameter of the fuel injection valve is increased as in the prior art, the space around the fuel injection valve becomes narrow and the intake air is reduced. It becomes easy to generate a situation in which the required arrangement of devices and members such as valves, exhaust valves, and water injection valves becomes difficult.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and a liquid-cooled fuel injection valve capable of improving the nozzle tip cooling effect without increasing the outer diameter of the fuel injection valve and with a relatively simple structure. The purpose is to provide.

  The present invention achieves such an object, and forms a cooling chamber in a nozzle tip fitted inside the needle valve so as to be reciprocally movable and fixed to a cylinder cover, and supplying a cooling liquid to the cooling chamber to supply the nozzle. In the liquid-cooled fuel injection valve configured to cool the tip and its peripheral members, the cooling chamber is formed in a spiral shape so as to extend from the upper side of the nozzle tip to the tip side on the outer periphery of the cylindrical portion of the nozzle tip. The cooling groove is engraved, and the outer periphery of the cooling groove is fluid-tightly covered with a cylindrical nozzle cap (Claim 1).

In this invention, specifically, the following configuration is preferable.
(1) The spiral cooling groove is formed by two spiral grooves, a cooling liquid inlet and a cooling liquid outlet are provided on the upper part of the nozzle tip, and the cooling liquid inlet is formed by the two spiral grooves. The cooling liquid outlet is connected to the other one of the spiral grooves, and the cooling groove has one of the spiral grooves extending from the cooling liquid inlet toward the tip of the nozzle tip. The other side of the spiral groove is connected to the other end of the spiral groove at a position close to the other end, and the other end of the spiral groove extends in the opposite tip direction of the nozzle tip and is connected to the coolant outlet.

(2) The upper end portion of the spiral cooling groove is connected to a coolant inlet provided at the upper portion of the nozzle tip, and a terminal portion on the tip end side of the nozzle tip is connected to a cooling chamber in the cylinder cover. A coolant discharge hole connected to the cylinder cover is connected, the coolant introduced into the coolant inlet is caused to flow through the spiral cooling groove toward the tip of the nozzle tip, and then the cylinder cover is passed through the coolant discharge hole. It discharges to the inside cooling chamber (claim 3).
Preferably, the spiral cooling groove is composed of two cooling grooves that rotate in opposite directions to each other, and both inlet sides of the two cooling grooves are provided in the upper part of the nozzle chip. In addition to being connected to the inlet, both the outlet sides of the cooling groove are connected to the coolant discharge hole.

(3) Water is used as the cooling liquid, and an upper end portion of the spiral cooling groove is connected to a cooling liquid inlet provided at an upper portion of the nozzle chip, and a terminal end of the nozzle chip is terminated at the water end. Is connected to a water injection hole for injecting into the combustion chamber of the engine, and the coolant introduced into the coolant inlet is caused to flow through the spiral cooling groove toward the tip of the nozzle tip and then through the water injection hole. It is configured to inject into the combustion chamber (claim 5).
Preferably, the spiral cooling groove is composed of two cooling grooves that rotate in opposite directions to each other, and both inlet sides of the two cooling grooves are provided in the upper part of the nozzle chip. Connected to the inlet and both outlet sides of the cooling groove are connected to a cooling water reservoir provided with a check valve so that the coolant is injected from the water injection hole into the combustion chamber via the check valve. (Claim 6).

According to the present invention, the cooling chamber formed in the nozzle tip is constituted by a cooling groove engraved in a spiral shape extending from the upper side to the tip side on the outer periphery of the cylindrical portion of the nozzle tip, Since the outer periphery is configured to be fluid-tightly covered with a cylindrical nozzle cap (Claim 1), the cooling chamber is a cooling groove having a small radial width and extending in the longitudinal direction of the nozzle tip. The amount of increase in the outer diameter of the nozzle tip by providing the groove is small, and a fuel in which an annular cooling chamber is provided on the outer periphery of the lower portion of the nozzle tip as in the prior art so as to cover the outer periphery with a member different from the nozzle tip The outer diameter of the fuel injection valve can be made smaller than that of the injection valve, and the fuel injection valve can be reduced in size.
As a result, the space around the fuel injection valve to which many devices and members such as water injection valves, intake valves, exhaust valves, etc. in the case of a water injection engine are mounted can be freed, and the arrangement of these devices and members can be reduced. In addition to being easy, it is possible to provide flexibility in arrangement.

  Further, since the cooling chamber is formed by a cooling groove that is spirally engraved so as to extend from the upper side to the tip side along the outer periphery of the cylindrical portion of the nozzle tip, the passage length of the cooling liquid for cooling the nozzle tip As a result, the heat transfer area between the nozzle tip and the coolant increases, and the increase in the outer diameter of the fuel injection valve due to the cooling groove can be minimized to improve the nozzle tip cooling effect.

  Further, the spiral cooling groove is formed by two spiral grooves, and each of the two spiral grooves is connected to a cooling liquid inlet and a cooling liquid outlet provided at an upper portion of the nozzle chip, thereby forming a nozzle chip. If the two are connected to each other at a portion closer to the tip (Claim 2), the cooling groove on the forward side and the cooling groove on the return side are different in the longitudinal direction, and in the radial direction, It is possible to avoid the increase in the outer diameter of the nozzle tip by providing the cooling groove on the return side in addition to the cooling groove on the forward side in the nozzle tip, thus forming the two spiral grooves. Thus, the heat transfer area can be further increased while suppressing an increase in the outer diameter of the nozzle tip.

In addition, a coolant discharge hole that communicates the end portion of the spiral cooling groove extending from the coolant inlet at the top of the nozzle tip toward the tip side of the nozzle tip to the cooling chamber in the cylinder cover. Since it is connected (Claim 3), there is no need to provide a cooling groove on the coolant outlet side on the outer periphery of the nozzle tip, the structure of the cooling passage of the nozzle tip is simplified and the number of processing steps of the cooling passage can be reduced.
Furthermore, since the exit side of the spiral cooling groove formed in the nozzle tip is opened to the cooling chamber in the cylinder cover having a large passage area, the flow resistance of the coolant passage is reduced and the flow rate of the coolant is increased. The cooling effect is improved by increasing the heat transfer coefficient between the coolant and the nozzle tip wall surface.

  Further, the spiral cooling groove is composed of two cooling grooves that rotate in opposite directions, and both the inlet sides of the cooling groove are connected to the coolant inlet, and both the outlet sides of the cooling groove are connected to each other. If connected to the coolant discharge hole (Claim 4), the cooling groove is formed into two cooling grooves that rotate in opposite directions, whereby the two cooling grooves are different in the longitudinal direction of the nozzle tip, In the radial direction, a layer having the same diameter can be formed, and the heat transfer area can be increased without increasing the outer diameter of the nozzle tip.

  In addition, the upper end of a spiral cooling groove composed of two cooling grooves that preferably use water as the cooling liquid and swirl in the opposite direction is connected to the cooling liquid inlet, and the end on the nozzle tip front end side Is preferably connected to the water injection hole via a cooling water reservoir having a check valve (Claims 5 and 6), in the water injection engine, the cooling water that has cooled the nozzle tip by passing through the cooling groove is supplied. The combustion can be caused by injecting into the combustion chamber from the water injection hole to suppress the generation of NOx, and the NOx generation can be suppressed by cooling the nozzle tip and injecting the water from the water injection hole into the combustion chamber. It can be used for both.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

FIG. 1 is a longitudinal sectional view showing a main part of a liquid-cooled fuel injection valve for a diesel engine according to a first embodiment of the present invention.
In FIG. 1, reference numeral 100 denotes a fuel injection valve, and this figure shows a main part around the nozzle tip. 1 is a nozzle tip, 2a is a needle valve hole drilled in the axial direction in the center of the nozzle tip 1, and 2b is a conical seat surface formed at the bottom of the needle valve hole 2a. Reference numeral 4 denotes a plurality of nozzle holes perforated at the tip of the nozzle chip 1, and reference numeral 11 denotes a sack portion formed between the sheet surface 2 b and the nozzle holes 4.

A needle valve 2 is fitted in the needle valve hole 2a so as to be reciprocally movable. A sheet portion 1a formed at the tip of the needle valve 2 is attached to and detached from the sheet surface 2b of the nozzle chip 1. .
That is, when high pressure fuel from a fuel passage (not shown) acts on the seat portion 1a of the needle valve 2 and the needle valve 2 overcomes the spring force of a needle valve spring (not shown), the high pressure fuel is sucked into the sack portion 11. It passes through the plurality of nozzle holes 4 and is injected into the combustion chamber 103.

A substantially lower half of the nozzle tip 1 is a cylindrical portion 1b having a diameter smaller than that of the large-diameter portion 1c of the upper half, and the outer periphery of the cylindrical portion 1b extends from the upper side of the nozzle tip 1 to the tip side. The forward-side cooling groove 5 and the return-side cooling groove 6 that are engraved in a spiral shape are formed by turning in opposite directions.
Inside the large-diameter portion 1 c of the nozzle tip 1, a cooling water inlet passage 7 and a cooling water outlet passage 8 extend from the upper side of the nozzle tip 1 in the axial direction and are perforated.

Reference numeral 3 denotes a nozzle cap formed in a cylindrical shape, and the cylindrical portion 1b of the nozzle tip 1 is fitted to the inner periphery of the nozzle cap 3, and the forward cooling groove 5 and the return side cooling are cooled by the nozzle cap 3. The outer periphery of the groove 6 is fluid-tightly covered to prevent leakage of cooling water from the forward cooling groove 5 and the return cooling groove 6. Reference numeral 12 denotes a fluid seal portion between the nozzle cap 3 and the cylindrical portion 1b of the nozzle tip 1, and the fluid seal portion 12 seals gas from the combustion chamber 103 side.
A joint portion 13 between the upper surface of the nozzle cap 3 and the lower surface of the large-diameter portion 1c of the nozzle chip 1 is joined by brazing.

  Reference numeral 9 denotes an inlet side cooling water reservoir carved on the upper surface of the nozzle cap 1. The lower end portion of the cooling water inlet passage 7 is opened in the inlet side cooling water reservoir 9 and the upper end of the forward cooling groove 5 is opened. The entrance is open. Reference numeral 10 denotes an outlet side cooling water reservoir carved on the upper surface of the nozzle cap 1. The lower end portion of the cooling water outlet passage 8 is opened in the outlet side cooling water reservoir 10 and the upper end of the return side cooling groove 6 is opened. The outlet is open. The forward cooling groove 5 and the return cooling groove 6 are communicated with each other at the lower ends.

  In the fuel injection valve 100 configured as described above, the cooling water flows from the cooling water inlet passage 7 as indicated by an arrow A, enters the inlet side cooling water reservoir 9, and passes through the inlet side cooling water reservoir 9 to form a spiral shape. And flows downward while swiveling the forward cooling groove 5 to cool the periphery of the cylindrical portion 1b of the nozzle tip 1 that is at a high temperature. The return side cooling groove 6 enters the return side cooling groove 6 from the communicating part with the return side cooling groove 6 and is swung in the direction opposite to the forward side cooling groove 5. To the upper part of the nozzle tip 1 to cool the periphery of the cylindrical portion 1b again, enter the cooling water outlet passage 8 through the outlet-side cooling water reservoir 10, and pass the cooling water outlet passage 8 in the direction indicated by the arrow A2. And flows out from the upper end outlet.

According to the first embodiment, the cooling chamber formed in the nozzle tip 1 is spirally rotated in opposite directions so as to extend from the upper side to the distal end side on the outer periphery of the small diameter cylindrical portion 1b of the nozzle tip 1. The forward cooling groove 5 and the return cooling groove 6 are configured so that the outer periphery of the forward cooling groove 5 and the return cooling groove 6 is fluid-tightly covered with the cylindrical nozzle cap 3. Since the cooling groove 5 and the return side cooling groove 6 are cooling grooves having a small radial width and extending in the longitudinal direction of the nozzle chip, the nozzle chip 1 is provided by providing the forward side cooling groove 5 and the return side cooling groove 6. The amount of increase in the outer diameter is small, and a fuel in which an annular cooling chamber 05 is provided on the outer periphery of the lower part of the nozzle tip 1 as in the prior art of FIG. Compared to the injection valve 100, the fuel injection valve 1 The outer diameter of 0 is reduced it is possible to miniaturize the fuel injection valve 100.
As a result, the space around the fuel injection valve 100 to which many devices and members such as a water injection valve, an intake valve, and an exhaust valve in the case of a water injection engine are mounted can be provided. Therefore, it is possible to provide a degree of freedom in arrangement.

  Further, since the cooling chamber is formed by the forward cooling groove 5 and the return cooling groove 6 which are spirally engraved so as to extend from the upper side to the tip side along the outer periphery of the small diameter cylindrical portion 1b of the nozzle tip 1, The passage length of the coolant for cooling the nozzle tip 1 is increased, the heat transfer area between the nozzle tip 1 and the cooling water is increased, and the fuel injection by the forward cooling groove 5 and the return cooling groove 6 is performed. The cooling effect of the nozzle tip 1 can be improved while minimizing an increase in the outer diameter of the valve 100.

  Further, the spiral forward cooling groove 5 and the return cooling groove 6 are formed by two spiral grooves that rotate in opposite directions, and the coolant inlet 7 and the coolant provided in the upper part of the nozzle chip 1 are formed. Each of the two forward-side cooling grooves 5 and the return-side cooling grooves 6 is connected to the outlet 8 and extends in the direction of the tip of the nozzle chip 1. The forward-side cooling groove 5 and the return-side cooling groove 6 Since the forward cooling groove 5 and the return cooling groove 6 can be formed of different layers in the longitudinal direction and layers of the same diameter in the radial direction, the forward cooling in the nozzle chip 1 can be performed. An increase in the outer diameter of the nozzle tip 1 due to the provision of the return cooling groove 6 in addition to the groove 5 can be avoided. Therefore, the outer diameter of the nozzle tip 1 can be prevented by forming the two forward cooling grooves 5 and the return cooling groove 6. Increase the heat transfer area while suppressing the increase of It is possible.

FIG. 2 is a longitudinal sectional view showing the main part of the liquid-cooled fuel injection valve according to the second embodiment of the present invention.
In this second embodiment, the forward cooling grooves 51 and 52 are constituted by two cooling grooves that rotate in opposite directions, and the upper inlet of the forward cooling grooves 51 and 52 is the upper surface of the nozzle cap 1. Are connected to inlet-side cooling water reservoirs 91 and 92 engraved in two circumferential directions, respectively, and the outlet sides of the two forward cooling grooves 51 and 52 are outlets of the outgoing cooling grooves 51 and 52, respectively. It is connected to a cooling water discharge hole 20 that communicates with the cooling chamber 102 in the cylinder cover 101 via an annular groove 21 that is open at the end.
The inlet-side cooling water reservoirs 91 and 92 are communicated with lower end openings of the cooling water inlet passages 7 and 71 that are perforated in the axial direction of the nozzle cap 1. Reference numeral 53 denotes an inlet annular groove through which the upper end openings of the cooling water inlet passages 7 and 71 communicate.
22 and 23 are seal rings provided above and below the annular groove 21, and are configured by heat-resistant O-rings such as heat-resistant rubber O-rings and metal O-rings.

  In the second embodiment, the cooling water flows in the cooling water inlet passages 7 and 71 as indicated by the arrow A, enters the inlet side cooling water reservoirs 91 and 92, and spirals through the inlet side cooling water reservoirs 91 and 92. Cools the periphery of the cylindrical portion 1b of the nozzle tip 1 that has entered the two forward cooling grooves 51, 52 formed in the nozzle and flows downward while swiveling the forward cooling grooves 51, 52 and is hot. Then, it flows out into the annular groove 21 and is discharged from the annular groove 21 through the cooling water discharge hole 20 to the cooling chamber 102 in the cylinder cover 101.

According to the second embodiment, the distal end side end portions of the two forward-side cooling grooves 51 and 52 connected to the cooling water inlet passages 7 and 71 in the upper part of the nozzle chip 1 are connected to the cylinder via the annular groove 21. Since it is connected to the cooling water discharge hole 20 communicated with the cooling chamber 102 in the cover 101, it is not necessary to provide a cooling groove on the cooling water outlet side on the outer periphery of the nozzle chip 1, and the structure of the cooling passage of the nozzle chip 1 is eliminated. Is simplified, and the number of processing steps for the cooling passage can be reduced.
Furthermore, since the outlet side of the spiral forward cooling grooves 51 and 52 formed in the nozzle chip 1 is opened to the cooling chamber 102 in the cylinder cover 101 having a large passage area, the flow resistance of the cooling water passage is small. As the flow rate of the cooling water increases and the heat transfer coefficient between the cooling water and the wall surface of the nozzle tip 1 increases, the cooling effect is improved.

Further, the spiral forward cooling grooves 51, 52 are constituted by two cooling grooves that rotate in opposite directions, and the inlet sides of both the forward cooling grooves 51, 52 are connected to the cooling water inlet passage 7, 71, and both outlet sides of the forward cooling grooves 51 and 52 are connected to the cooling water discharge hole 20, so that the forward cooling grooves 51 and 52 are configured as two cooling grooves that rotate in opposite directions. By doing so, the two cooling grooves can be formed of different layers in the longitudinal direction of the nozzle tip 1 and layers of the same diameter in the radial direction, thereby increasing the heat transfer area without increasing the outer diameter of the nozzle tip 1. be able to.
Other configurations are the same as those of the first embodiment shown in FIG. 1, and the same members are denoted by the same reference numerals.

FIG. 3 is a longitudinal sectional view showing the main part of the liquid-cooled fuel injection valve according to the third embodiment of the present invention.
In this third embodiment, the forward cooling grooves 51 and 52 are constituted by two cooling grooves that rotate in opposite directions, and the upper end inlet of the forward cooling grooves 51 and 52 is the upper surface of the nozzle cap 1. Are connected to inlet-side cooling water reservoirs 91 and 92 engraved in two circumferential directions, respectively, and the outlet sides of the two forward cooling grooves 51 and 52 are outlets of the outgoing cooling grooves 51 and 52, respectively. The two ends of the cooling water reservoirs 40, 40 that are open at the ends are connected to the water injection holes 31 that open to the combustion chamber 103. A check valve 32 is provided in the cooling water reservoirs 40 and 40, and blocks the gas flow from the combustion chamber 103 side to the cooling water reservoirs 40 and 40 and the outward cooling grooves 51 and 52 side.
The inlet-side cooling water reservoirs 91 and 92 are communicated with lower end openings of the cooling water inlet passages 7 and 71 that are perforated in the axial direction of the nozzle cap 1. Reference numeral 53 denotes an inlet annular groove through which the upper end openings of the cooling water inlet passages 7 and 71 communicate.

Reference numeral 39 is a cooling water pipe connected to the inlet annular groove 53, and 34 is an electromagnetic valve for opening and closing the pipe of the cooling water pipe 39. Cooling water pumped from a water pump (not shown) passes through the cooling water pipe 39 and the electromagnetic valve 34. The inlet annular groove 53 is passed through.
35 is a solenoid valve controller for controlling the opening and closing of the solenoid valve 34, 36 is a crank angle sensor for detecting the crank angle of the engine, 37 is a load sensor for detecting the engine load (engine output), and 38 is a cylinder of the engine. Is a cylinder identification signal oscillator that oscillates by detecting the ignition order of the engine, and detects the crank angle detection signal of the engine from the crank angle sensor 36, the detection signal of the engine load from the load sensor 37, and the cylinder from the cylinder identification signal oscillator 38. The ignition signal of the ignition order is input to the solenoid valve controller 35.

In the second embodiment, the solenoid valve controller 35 detects the engine crank angle detection signal from the crank angle sensor 36, the engine load detection signal from the load sensor 37, and the cylinder ignition signal from the cylinder identification signal oscillator 38. When the injection timing and injection period (that is, the injection amount) of water into the combustion chamber 103 are calculated based on the oscillation signal of the sequence, and the electromagnetic valve 34 is opened at the water injection timing and injection period set based on the calculation result. The cooling water from the cooling water pipe 39 is supplied to the inlet annular groove 53.
The cooling water flows in the cooling water inlet passages 7 and 71 as indicated by the arrow A, enters the inlet side cooling water reservoirs 91 and 92, and is formed in a spiral shape through the inlet side cooling water reservoirs 91 and 92. Cooling is performed after cooling the periphery of the cylindrical portion 1b of the nozzle tip 1 which has entered the two forward cooling grooves 51, 52 and flows downward while swiveling the forward cooling grooves 51, 52 and is at a high temperature. It enters the water reservoirs 40, 40, pushes the check valve 32 open, and is injected into the combustion chamber 103 from the water injection hole 31.

According to the third embodiment, the upper ends of the spiral cooling grooves formed by the two forward cooling grooves 51 and 52 swirling in opposite directions are connected to the coolant inlet passages 7 and 71. Since the end of the nozzle tip 1 on the tip side is connected to the water injection hole 31 via the cooling water reservoir 40 provided with the check valve 32, the forward cooling grooves 51 and 52 are passed through the water injection engine. Thus, the cooling water that has cooled the nozzle tip 1 can be injected into the combustion chamber 103 from the water injection hole 31 to cause combustion with suppressed generation of NOx, and cooling of the nozzle tip 1 and water injection can be performed for one system of water. This can be utilized for both NOx generation suppression operation by injection from the hole 31 into the combustion chamber.
Other configurations are the same as those of the first embodiment shown in FIG. 1 or the second embodiment shown in FIG. 2, and the same members are denoted by the same reference numerals.
In addition to the water as described above, a liquid such as oil can be used as the cooling liquid.

  According to the present invention, it is possible to provide a liquid-cooled fuel injection valve that can improve the cooling effect of the nozzle tip without increasing the outer diameter of the fuel injection valve and with a relatively simple structure.

It is a longitudinal cross-sectional view which shows the principal part of the liquid cooling type fuel injection valve for diesel engines which concerns on 1st Example of this invention. It is a longitudinal cross-sectional view which shows the principal part of the liquid cooling type fuel injection valve which concerns on 2nd Example of this invention. It is a longitudinal cross-sectional view which shows the principal part of the liquid cooling type fuel injection valve which concerns on 3rd Example of this invention. It is a longitudinal cross-sectional view of the nozzle tip of the liquid cooling type fuel injection valve which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle tip 1b Cylindrical part 2 Needle valve 3 Nozzle cap 4 Injection hole 5, 51, 52 Outgoing side cooling groove 6 Return side cooling groove 7 Cooling water inlet passage 8 Cooling water outlet passage 9, 91, 92 Inlet side cooling water reservoir DESCRIPTION OF SYMBOLS 10 Outlet side cooling water reservoir 12 Fluid seal part 20 Cooling water discharge hole 21 Annular groove 31 Water injection hole 34 Solenoid valve 35 Solenoid valve 40 Cooling water reservoir 100 Fuel injection valve 101 Cylinder cover 102 Cooling chamber 103 Combustion chamber

Claims (6)

  A cooling chamber is formed in the nozzle tip that is reciprocally fitted inside and fixed to the cylinder cover, and a cooling liquid is supplied to the cooling chamber to cool the nozzle tip and its peripheral members. In the liquid-cooled fuel injection valve, the cooling chamber is configured by a cooling groove that is spirally engraved on the outer periphery of the cylindrical portion of the nozzle tip so as to extend from the upper side to the tip side of the nozzle tip, A liquid-cooled fuel injection valve characterized in that the outer periphery of a cooling groove is fluid-tightly covered with a cylindrical nozzle cap.   The spiral cooling groove is formed by two spiral grooves, a cooling liquid inlet and a cooling liquid outlet are provided on the upper part of the nozzle chip, and the cooling liquid inlet is connected to one of the two spiral grooves. In addition, the coolant outlet is connected to the other of the spiral grooves, and the cooling groove is located near one end of the nozzle tip with one of the spiral grooves extending from the coolant inlet toward the tip of the nozzle tip. 2. The other end of the spiral groove is connected to the other end of the spiral groove, and the other end of the spiral groove extends in a direction opposite to the tip of the nozzle tip and is connected to the coolant outlet. Liquid-cooled fuel injection valve.   The upper end of the spiral cooling groove is connected to a coolant inlet provided at the upper part of the nozzle tip, and the end of the nozzle tip is communicated with the cooling chamber in the cylinder cover. A cooling liquid discharge hole is connected, and the cooling liquid introduced into the cooling liquid inlet is allowed to flow through the helical cooling groove toward the tip end side of the nozzle tip, and then cooled in the cylinder cover through the cooling liquid discharge hole. The liquid-cooled fuel injection valve according to claim 1, wherein the liquid-cooled fuel injection valve is configured to discharge into the chamber.   The spiral cooling groove is composed of two cooling grooves that rotate in opposite directions to each other, and both inlet sides of the two cooling grooves are connected to a cooling liquid inlet provided above the nozzle chip. 4. The liquid-cooled fuel injection valve according to claim 3, wherein both outlet sides of the cooling groove are connected to the coolant discharge hole.   Water is used as the cooling liquid, and the upper end of the spiral cooling groove is connected to a cooling liquid inlet provided at the upper part of the nozzle chip, and the end of the nozzle chip at the tip end side is connected to the engine. The coolant introduced into the combustion chamber is made to flow, and the coolant introduced into the coolant inlet is caused to flow through the spiral cooling groove toward the tip end side of the nozzle tip, and then through the water injection hole. The liquid-cooled fuel injection valve according to claim 1, wherein the liquid-cooled fuel injection valve is configured to inject into the fuel. The spiral cooling groove is composed of two cooling grooves swirling in opposite directions, and both inlet sides of the two cooling grooves are connected to a cooling liquid inlet provided in the upper part of the nozzle chip. In addition, both outlet sides of the cooling groove are connected to a cooling water reservoir having a check valve, and the cooling liquid is injected from the water injection hole into the combustion chamber via the check valve. 6. A liquid-cooled fuel injection valve according to claim 5, wherein

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