Gaseous fuel injector

Abstract

To enable control of a dynamic flow rate in an injector having a solenoid valve that is closed by drawing a valve element to a valve seat.SOLUTION: An electromagnetic drive type gaseous fuel injector 1 includes: a cylindrical body 10 that forms a fuel passage 11; an on-off valve 20 for opening / closing the fuel passage 11; a solenoid 30 for opening the on-off valve 20; and a nozzle provided at a tip part of the body 10. The on-off valve 20 comprises: a valve element 21 that reciprocates together with a plunger 33 constituting the solenoid 30; and a valve seat 22 that comes into contact with / separates from the valve element 21. The plunger 33 is fixed to a retainer 40 provided upstream of the on-off valve 20. The retainer 40 is installed between a closing spring 41 for energizing the plunger 33 in a valve closing direction and an adjustment spring 42 for energizing the plunger 33 in a valve opening direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a normally closed gas fuel injector for directly injecting gas fuel into a cylinder at a flow rate required by an engine driven by gas fuel such as hydrogen gas, LPG, or CNG. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an electromagnetically driven injector is widely known, which operates an on-off valve by energizing and exciting an electromagnetic coil, thereby injecting fuel into a cylinder at a flow rate required by the engine.

[0003] Electromagnetic valves (solenoid valves) are classified into normally open and normally closed types, as well as into types that close by pressing the valve disc against the valve seat, and types that close by attracting the valve disc to the valve seat.

[0004] In in-cylinder direct injection injectors, solenoid valves that close by pressing the valve body against the valve seat are effective in preventing unintended valve opening (valve leakage) due to an increase in in-cylinder pressure. In order to adjust the dynamic flow rate, it was common to adjust the set load of the spring that generates a load in the valve closing direction, thereby adjusting the valve opening / closing delay time.

[0005] However, in an injector equipped with a solenoid valve that closes the valve by attracting a valve element 2A to a valve seat 3A, such as the fuel injection device 1A (see FIG. 2 of the attached drawings) described in JP-A-2009-526157 (Patent Document 1), it is structurally difficult to adjust the set load of the spring 4A, making it difficult to adjust the dynamic flow rate.

[0006] Therefore, there has been a demand for dynamic flow rate adjustment even in injectors equipped with electromagnetic valves that close the valve by attracting the valve disc to the valve seat. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2009-526157 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to enable dynamic flow rate adjustment in an injector equipped with a solenoid valve that closes the valve by attracting the valve element to the valve seat. [Means for solving the problem]

[0009] The present invention, which has been made to solve the above-mentioned problems, provides an electromagnetically driven gaseous fuel injector that directly injects gaseous fuel into a cylinder of an engine, comprising: a cylindrical main body having a fuel passage formed therein; an on-off valve disposed within the main body for opening and closing the fuel passage; a solenoid disposed within the main body for opening the on-off valve when energized; and a nozzle disposed at a tip of the main body downstream of the on-off valve, the nozzle having an injection hole formed at the tip for insertion into the cylinder, the on-off valve comprising a valve element fixed to a plunger constituting the solenoid and adapted to reciprocate axially together with the plunger; and a valve seat that comes into contact with and separates from the valve element to close the fuel passage, the plunger being fixed to a retainer disposed at a base end of the main body upstream of the on-off valve, the retainer being disposed between a closing spring that urges the plunger in a valve closing direction and an adjustment spring that urges the plunger in a valve opening direction.

[0010] In this way, by fixing a retainer to the valve body and combining a closing spring that urges the retainer in the valve closing direction with an adjustment spring that urges the retainer in the valve opening direction, it is possible to adjust the dynamic flow rate according to the set loads of both springs.

[0011] In the present invention, when the set load of the adjustment spring is set by a plug attached from the base end side of the main body, the adjustment spring can be easily assembled.

[0012] In the present invention, if the position of the plug is changeable in the axial direction and the set load of the adjustment spring is adjustable depending on the position of the plug, it becomes possible, for example, to set multiple set loads using one type of adjustment spring or to absorb manufacturing variations. [Effects of the Invention]

[0013] According to the present invention, dynamic flow rate adjustment can be easily performed in an injector equipped with a solenoid valve that closes the valve by attracting the valve element to the valve seat. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a longitudinal sectional view showing a main portion of a preferred embodiment of a gaseous fuel injector according to the present invention; [Figure 2] FIG. 1 is a vertical cross-sectional view showing a conventional fuel injection device. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In this specification, the term "gas fuel" refers to a fuel such as hydrogen gas, LPG, CNG, or LNG that is supplied to an engine in a gaseous state and burned.

[0016] FIG. 1 is a longitudinal sectional view showing the essential parts of a preferred embodiment of a gaseous fuel injector according to the present invention.

[0017] The gaseous fuel injector 1 is an electromagnetically driven gaseous fuel injector that is provided with: a cylindrical body 10 that defines a fuel passage 11; an on-off valve 20 that comprises a valve element 21 and a valve seat 22 and opens and closes the fuel passage 11; and a solenoid 30 that opens the on-off valve 20 when energized. The gaseous fuel injector 1 is an electromagnetically driven gaseous fuel injector that supplies gaseous fuel that has been reduced in pressure and adjusted to a predetermined level through a fuel injection hole formed in a nozzle (not shown) at a flow rate required by an engine.

[0018] In use, when current is passed through the electromagnetic coil 31 of the solenoid 30 to excite it, the fixed iron core 32 attracts the plunger 33, opening the on-off valve 20 and injecting gaseous fuel directly into the engine cylinder from the fuel injection hole.

[0019] The main body 10 has a cylindrical shape as a whole and includes an inlet body 12 on the side for introducing gaseous fuel and an outlet body 13 on the side for discharging gaseous fuel.

[0020] The present invention is characterized in that a retainer 40 capable of reciprocating in the axial direction is provided inside the inlet body 12, and that a closing spring 41 that biases the valve in the valve closing direction and an adjustment spring 42 that biases the valve in the valve opening direction are arranged on either side of the retainer 40.

[0021] One end of the closing spring 41 contacts the retainer 40 , and the other end contacts a stopper 43 formed inside the inlet body 12 .

[0022] The adjusting spring 42 has one end in contact with the retainer 40 and the other end in contact with a plug 44 whose position can be changed in the axial direction inside the inlet body 12 .

[0023] In this embodiment, the closing spring 41 and the adjusting spring 42 are compression coil springs, but other biasing means that exert elastic repulsive force may also be used.

[0024] The on-off valve 20 comprises a valve element 21 fixed to the plunger 33 and reciprocating axially together with the plunger 33, and a valve seat 22 having a seat surface 23 that contacts and separates from the valve element 21 and a valve hole 24 that passes through the center of the seat surface 23. The on-off valve 20 closes by attracting the valve element 21 to contact the valve seat 22.

[0025] The solenoid 30 includes an electromagnetic coil 31, a fixed iron core 32 located inside the electromagnetic coil 31, and a plunger 33 (movable iron core) provided opposite the fixed iron core 32.

[0026] The fixed core 32 is formed of a cylindrical boss portion that is a part of the outlet body 13, which is made of a magnetic material.

[0027] The plunger 33 is fixed to the retainer 40 arranged inside the inlet body 12 on the upstream side of the on-off valve 20. The retainer is installed between a closing spring 41 that urges the plunger 33 in a valve-closing direction (upward in FIG. 1) and an adjusting spring 42 that urges the plunger 33 in a valve-opening direction (downward in FIG. 1). The urging force of the closing spring 41 is set to be greater than the urging force of the adjusting spring 42, so that the on-off valve 20 is closed when not energized, which is a so-called normally-closed injector.

[0028] Next, we will explain the operation of the solenoid 30. When current is supplied to the electromagnetic coil 31 (when energized), the fixed iron core 32 generates a magnetic field, the plunger 33 is attracted to the fixed iron core 32, the retainer 40 fixed to the plunger 33 moves in the valve opening direction, and the valve element 21 moves in the valve opening direction in conjunction with the movement of the plunger 33, and the valve element 21 moves away from the seat surface 23 to close the valve.

[0029] When the current supply to the electromagnetic coil 31 is stopped (when not energized), the magnetic field of the fixed iron core 32 disappears, the attraction of the plunger 33 to the fixed iron core 32 is released, the retainer 40 fixed to the plunger 33 moves in the valve closing direction due to the biasing force of the closing spring 41, and as the plunger 33 moves, the valve body 21 moves in the valve closing direction, and the valve body 21 and the seat surface 23 come into close contact with each other to close the valve.

[0030] At this time, by using the closing spring 41 and the adjusting spring 42 arranged on either side of the retainer 40, it is possible to adjust the dynamic flow rate according to the set loads of both springs.

[0031] Furthermore, the set load of the adjustment spring 42 is set by the plug 44 attached from the base end side of the inlet body 12 in the main body 10, so that the adjustment spring 42 can be easily assembled.

[0032] Furthermore, in this embodiment, the assembly position of the plug 44 can be changed in the axial direction, and therefore the set load of the adjustment spring 42 can be adjusted by the position of the plug 44. For example, it becomes possible to set multiple types of set loads using one type of adjustment spring, or to absorb variations during manufacturing, and the on-off valve 20 can be configured stably and with high precision.

[0033] The plug 44 can be attached by any fixing method, such as by screwing or welding.

[0034] As described above, the present invention makes it possible to easily adjust the dynamic flow rate of a normally closed gas fuel injector that is electromagnetically driven to directly inject gas fuel into an engine cylinder. [Explanation of symbols]

[0035] 1 gas fuel injector, 10 main body, 11 fuel passage, 12 inlet body, 13 outlet body, 20 on-off valve, 21 valve body, 22 valve seat, 23 seat surface, 24 valve hole, 30 solenoid, 31 electromagnetic coil, 32 fixed iron core, 33 plunger, 40 retainer, 41 closing spring, 42 adjusting spring, 43 stopper, 44 plug

Claims

1. An electromagnetically driven gas fuel injector that directly injects gas fuel into a cylinder of an engine, a cylindrical body having a fuel passage formed therein; an on-off valve disposed in the main body for opening and closing the fuel passage; a solenoid disposed within the main body and configured to open the on-off valve when energized; a nozzle provided at a tip end of the main body downstream of the on-off valve, the nozzle having an injection hole formed at the tip end and inserted into the cylinder, the on-off valve includes a valve element fixed to a plunger constituting the solenoid and reciprocating together in an axial direction, and a valve seat that opens and closes the fuel passage by coming into contact with and separating from the valve element, The plunger is fixed to a retainer provided on the base end side of the main body, which is on the upstream side of the on-off valve, 10. The gaseous fuel injector, wherein the retainer is disposed between a closing spring that biases the plunger in a valve-closing direction and an adjusting spring that biases the plunger in a valve-opening direction.

2. 2. The gaseous fuel injector according to claim 1, wherein a set load of the adjustment spring is set by a plug attached from the base end side of the main body.

3. 3. The gaseous fuel injector according to claim 2, wherein the mounting position of said plug is changeable in the axial direction, and the set load of said adjustment spring is adjustable depending on the position of said plug.

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