Fuel injector for gaseous fuel and valve assembly therefor

Abstract

A fuel injector for gaseous fuel is provided. A fuel injector includes at least one valve having a valve seat and a plunger that engages the valve seat to prevent flow of gaseous fuel and is displaced from the valve seat to allow flow of gaseous fuel. Depending on the distance by which the plunger is lifted from the valve seat, the plunger is displaced away from the valve seat to open the at least one valve is resisted by the first plunger control mechanism and then resisted by the second plunger control mechanism.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority and filing date of U.S. Provisional Application Serial No. 63 / 580,777, filed on September 6, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates generally to a fuel injector for providing gaseous fuel to an internal combustion engine, and more particularly to a valve assembly for a fuel injector for gaseous fuel. Background Art

[0004] It is desirable that a fuel injector for an engine operating with gaseous fuel be able to inject the gaseous fuel into the combustion chamber of the engine at a precisely controlled amount, rate and timing. When a gaseous fuel injector begins to inject, the amount of gaseous fuel injected increases rapidly. This is caused by the ballistic nature of the axial travel of the plunger during the opening of the fuel injection valve and the delay in valve closing after the commanded opening time of the fuel injector has expired.

[0005] For gaseous fuel injectors, the rapid increase in injection volume at the beginning of valve opening is significantly greater than the increase in injection volume at higher injection volumes that occur while the valve remains open. As a result, gaseous fuel injectors tend to vary widely between injection events and between injectors. In addition, the rapid increase in injection volume at the beginning of injection tends to make the fuel injector less robust and more sensitive to other forces acting on the fuel injector, such as mechanical friction.

[0006] Gaseous fuel injectors may also cause an undesirable reduction or decrease in the amount of gaseous fuel injected during long opening times. This may be due to the plunger rebounding against the control surface of the fuel injector, thereby limiting the displacement of the plunger in the fuel injector. The mechanical rebound of the plunger causes the fuel injection valve to close prematurely and reduce the injection amount. Therefore, there is still a need for the unique apparatus, system and technology disclosed herein.

[0007] Disclosure of Illustrative Embodiments

[0008] For the purpose of clearly, concisely and accurately describing the illustrative embodiments of the present disclosure, the manner and process of making and using the same, and to enable the practice, making and using of the same, reference will now be made to certain exemplary embodiments, including those shown in the drawings, and specific language will be used to describe the exemplary embodiments. It will be understood, however, that no limitation of the scope of the invention is thereby incurred, and that the present invention includes and protects such changes, modifications and further applications of the exemplary embodiments as will occur to those skilled in the art. Summary of the invention

[0009] The present disclosure includes a fuel injector for providing a gaseous fuel to a combustion chamber. The fuel injector includes an injector body defining a fuel passage therein. The fuel passage extends from a gas inlet of the injector body to a gas outlet. The fuel injector includes a valve assembly at least partially located in the fuel passage. The valve assembly includes at least one valve that selectively opens and closes to control the flow of gaseous fuel to the combustion chamber through the fuel passage. The at least one valve includes a valve seat located in the fuel passage. The at least one valve also includes a plunger that contacts the valve seat to close the at least one valve, and the plunger is displaced from the valve seat to open the at least one valve. A first plunger control mechanism and a second plunger control mechanism resist displacement of the plunger away from the valve seat. The first plunger control mechanism and the second plunger control mechanism are configured to increase resistance to displacement of the plunger from the valve seat during opening of the at least one valve.

[0010] In one embodiment, a valve assembly for a fuel injector to selectively provide a gaseous fuel flow is disclosed. The valve assembly includes a valve seat, the valve seat including an opening to allow the gaseous fuel flow to pass through the opening. The valve assembly also includes a plunger, the plunger is movable to engage the valve seat to prevent the gaseous fuel flow from passing through the opening, and disengage the valve seat to allow the gaseous fuel flow to pass through the valve seat. The valve assembly also includes a first plunger control mechanism engaged to the plunger. The first plunger control mechanism is configured to resist the displacement of the plunger away from the valve seat during the opening of the valve assembly, and bias the plunger onto the valve seat to close the valve assembly. The valve assembly also includes a second plunger control mechanism, which is spaced apart from the plunger when the plunger is engaged to the valve seat. The second plunger control mechanism engages the plunger after the plunger is displaced away from the valve seat so as to work with the first plunger control mechanism to resist the displacement of the plunger away from the valve seat during the opening of the valve assembly.

[0011] This summary is not intended to identify the key or essential features of the claimed subject matter, nor is it intended to be used as an aid to limit the scope of the claimed subject matter. Additional embodiments, forms, objects, features, advantages, aspects and benefits will become apparent from the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The description herein refers to the accompanying drawings, wherein like reference numerals refer to like parts throughout the several views, and in which:

[0013] Figure 1 is a schematic diagram of the fuel injection system.

[0014] Figure 2 is a schematic cross-sectional view of a fuel injector in a closed state according to an embodiment of the present disclosure.

[0015] Figure 3 is in open state Figure 2 of fuel injectors.

[0016] Figure 4 is a schematic cross-sectional view of a fuel injector in a closed state according to another embodiment of the present disclosure.

[0017] Figure 5 is in open state Figure 4 of fuel injectors.

[0018] Figure 6 is a longitudinal sectional view of a fuel injector according to an embodiment of the present disclosure.

[0019] Figure 7 According to the embodiments of the present disclosure, Figure 6 A longitudinal cross-sectional view of a valve assembly implemented in a fuel injector.

[0020] Figure 8 According to the embodiments of the present disclosure, Figure 6 A longitudinal cross-sectional view of a valve assembly implemented in a fuel injector.

[0021] Fig. 9 According to the embodiments of the present disclosure, Figure 6 A longitudinal cross-sectional view of a valve assembly implemented in a fuel injector.

[0022] Fig.10 is a longitudinal cross-sectional view of a fuel injector with a valve assembly according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0023] refer to Figure 1 , a fuel injection system 10 is shown, which includes at least one fuel injector 100a, 100b, 100c...100n for a corresponding combustion chamber 14 of an internal combustion engine 12. At least one fuel injector 100a, 100b, 100c...100n is in fluid communication with a fuel source 16 containing a gaseous fuel 18 and a fuel tank / regulator 20 and / or a common rail 22 to distribute fuel to the injector 100a, 100b, 100c...100n. Although Figure 1 100a, 100b, 100c, . . . 100n. In the following discussion, reference is made to a fuel injector 100a, 100b, 100c, . . . 100n. Figures 2 to 10 The fuel injector 100 is shown to describe fuel injectors 100a, 100b, 100c, ... 100n.

[0024] In one embodiment, the fuel injector 100 provides a gaseous fuel 18 to the combustion chamber 14. The fuel injector 100 includes an injector body 101 defining a fuel passage 102 therein. The fuel passage 102 extends from a gas inlet 104 of the body 101 to a gas outlet 106. The fuel injector 100 includes a valve assembly 160 at least partially located in the fuel passage 102. The valve assembly 160 includes at least one valve 162 that is selectively opened and closed to control the flow of gaseous fuel through the fuel passage 102 to the combustion chamber 14.

[0025] The at least one valve 162 includes a valve seat 168 located in the fuel passage 102. The at least one valve 162 also includes a plunger 164, which contacts the valve seat 168 to close the at least one valve 162, and the plunger 164 is displaced from the valve seat 168 to open the at least one valve 162. The valve 162 includes a first plunger control mechanism 120 and a second plunger control mechanism 130. The first plunger control mechanism 120 and the second plunger control mechanism 130 resist displacement of the plunger 164 away from the valve seat 168. The first plunger control mechanism 120 and the second plunger control mechanism 130 are configured to increase resistance to displacement of the plunger 164 from the valve seat 168 during opening of the at least one valve 162 based on the distance of the plunger 164 from the valve seat 168.

[0026] In one embodiment, a valve assembly 160 for a fuel injector 100 to selectively provide a gaseous fuel flow is disclosed. The valve assembly 160 includes a valve seat 168, the valve seat including an opening 210 to allow the gaseous fuel to flow through the opening 210. The valve assembly 160 also includes a plunger 164, the plunger being movable to engage the valve seat 168 to prevent the gaseous fuel from flowing through the opening 210, and disengage the valve seat 168 to allow the gaseous fuel to flow through the valve seat 164. The valve assembly 160 also includes a first plunger control mechanism 120 engaged to the plunger 164. The first plunger control mechanism 120 is configured to resist displacement of the plunger 164 away from the valve seat 168 during opening of the valve assembly 160, and bias the plunger 164 onto the valve seat 168 to close the valve assembly 160. The valve assembly 160 also includes a second plunger control mechanism 130, the second plunger control mechanism being configured not to resist movement of the plunger 164 engaging the valve seat 168. The second plunger control mechanism 130 resists the plunger 164 after the plunger 164 is displaced away from the valve seat 168 so as to work with the first plunger control mechanism 120 to resist displacement of the plunger 164 away from the valve seat 168 during opening of the valve assembly 160 .

[0027] refer to Figures 2 to 5 , an exemplary injector body 101 for one embodiment of a fuel injector 100 extends along a longitudinal axis A and includes a fuel passage 102 defined by the injector body 101. The fuel passage 102 provides a gaseous fuel flow path from a gas inlet 104 to a gas outlet 106. In the illustrated embodiment, the gas inlet 104 is a sidewall inlet of the injector body 101 that is transverse to the longitudinal axis A. The gas outlet is located at a distal end of the injector body 101 and is located on or extends along the longitudinal axis A. In the present disclosure, "proximal" or "proximally" refers to an axial position or upstream direction away from the gas outlet 106, while "distal" or "distally" refers to an axial position or downstream direction toward the gas outlet 106.

[0028] The fuel passage 102 receives a valve assembly 160 therein to control the flow of gaseous fuel from the gas inlet 104 to the gas outlet 106. The valve assembly 160 may also control the flow of combustion gases from the gas outlet 106 into the fuel passage 102. The valve assembly 160 may include one or more valves to control the flow of gaseous fuel out of and / or into the fuel passage 102. For example, the valve assembly 160 may include a second valve longitudinally spaced apart from the valve 162.

[0029] In the illustrated embodiment, the valve assembly 160 includes a valve 162 having a plunger 164 and a valve seat 168. The end face of the plunger 164 includes a seal 180 (see, e.g., Figure 7 ), when the injector 100 is in the closed position, the seal is in sealing engagement with the valve seat 168, such as Figure 2 and Figure 4 The gas outlet 106 is opened by axially displacing the plunger 164 away from the valve seat 168, as shown. Figure 3 and Figure 5 Other embodiments contemplate that the valve seat 168 is a radially positioned valve seat that is sealed by one or more seals extending around the outer sidewall of the plunger 164 .

[0030] In the illustrated embodiment, the plunger 164 moves proximally away from the valve seat 168 to open the valve 162. In other embodiments, the plunger 164 moves distally away from the valve seat 168 to open the valve 162. In other embodiments, the valve seat 168 can be displaced from the plunger 164 to open the valve 162.

[0031] The fuel injector 100 also includes one or more plunger control mechanisms 120, 130 that resist axial displacement of the plunger 164 to open the gas outlet 106 and / or bias the plunger 164 into sealing engagement with the valve seat 168 to close the gas outlet 106. As used herein, the plunger control mechanisms 120, 130 may act directly on the plunger 164, and / or may act on one or more components connected to the plunger 164 or moving with the movement of the plunger, such as an armature, a washer, a backing ring, a spring, etc.

[0032] exist Figures 2 to 5 , a first plunger control mechanism 120 is coupled between the injector body 101 and the plunger 164. The first plunger control mechanism 120 includes a first end 122 that can be directly coupled to the plunger 164 or to one or more components (such as an armature) that engage with the plunger 164. The first plunger control mechanism 120 includes an opposite second end 124 that can be directly coupled to the injector body 101 or to one or more components that engage with the injector body 101.

[0033] The first end 122 of the first plunger control mechanism 120 moves with the movement of the plunger 120 in response to the actuation of the plunger 164, and the second end 124 of the first plunger control mechanism 120 is fixed relative to the injector body 101. The first plunger control mechanism 120 includes at least one biasing element configured to provide a variable force resistance to the displacement of the plunger 164. The first plunger control mechanism 120 is effective at all lift or displacement positions of the plunger 164 relative to the valve seat 168. As the plunger 164 is displaced further away from the valve seat 168, the resistance provided by the first plunger control mechanism 120 may increase.

[0034] The fuel injector 100 also includes a second plunger control mechanism 130 engaged with the injector body 101. The second plunger control mechanism 130 includes a first end 132 that is spaced apart from the plunger 164 by a gap 126 when the plunger 164 is positioned to engage the valve seat 168. In one embodiment, such as Figure 3 to Figure 4 As shown, the first end 132 of the second plunger control mechanism 122 includes a second plunger 136 supported directly or indirectly by the injector body 101. The second plunger control mechanism 122 includes an opposite second end 134 that can be directly coupled to the injector body 101 or to one or more components coupled to the injector body 101.

[0035] When the plunger 120 is initially actuated to displace it from the valve seat 168, the first end 132 of the second plunger control mechanism 130 and / or the second plunger 136 do not move with or resist the movement of the plunger 164. Thus, only the first plunger control mechanism 120 resists the initial displacement of the plunger 164. When the plunger 164 travels a distance corresponding to the gap 126 (e.g., Figure 3 and Figure 5 126 ), the first end 132 and / or the second plunger 136 of the second plunger control mechanism 122 contact the plunger 164. The second plunger control mechanism 130 includes at least one biasing element configured to provide a second variable force resistance to the displacement of the plunger 164 once the gap 126 is eliminated to supplement or increase the resistance provided by the first plunger control mechanism 120. Therefore, the second plunger control mechanism 122 is only active when the distance between the plunger 164 and the valve seat 168 is at least as large as the gap 126.

[0036] The first plunger control mechanism 120 may include, for example, one or more biasing elements that resist displacement of the plunger 164 and bias the plunger 164 toward the valve seat 168. The one or more biasing elements may include, for example, springs, coil springs, wave springs, plungers, dampers, shims, disks, washers, Belleville washers, backing rings, and / or other devices that resist, work alone, or work together to control displacement of the plunger 164 away from the valve seat 168 in response to a fuel injection command.

[0037] The second plunger control mechanism 130 may include, for example, one or more biasing elements that resist displacement of the plunger 164 and bias the plunger 164 toward the valve seat 168 after the plunger 164 is displaced from the valve seat 168. The one or more biasing elements may include, for example, springs, coil springs, wave springs, plungers, dampers, washers, disks, washers, Belleville washers, backing rings, and / or other devices that resist, work alone, or work together to control displacement of the plunger 164 away from the valve seat 168 after the plunger 164 initially separates from the valve seat 168 in response to a fuel injection command.

[0038] refer to Figure 6, shows an exemplary embodiment of a gaseous fuel injector 100 in which the valve assembly 160 including the plunger control mechanisms 120, 130 described herein may be implemented. The fuel injector 100 includes an injector body 101. The injector body 101 may be composed of multiple parts that are coupled to each other to form the injector body 101. In the illustrated embodiment, the injector body 101 includes a valve assembly receiving portion 140 extending from a gas outlet end 106 at its distal end to a proximal end 142, and an actuator mounting portion 144 that receives the proximal end 142 and is coupled to the valve assembly receiving portion 140. Other embodiments contemplate an injector body 101 made of a single body portion, or made of more than two body portions.

[0039] The actuator mounting portion 144 includes a flange end 146 to facilitate mounting the actuator 190 to the fuel injector 100. Features may also be provided on the injector body 101 to facilitate mounting the injector on the engine 12. In one embodiment, the actuator 190 includes an actuating portion 192 secured to the flange end 146 using a cap assembly 194. The cap assembly 194 includes a retainer 196 and a cap 198, the retainer being located in and engaged with the mounting member 144, and the cap being engaged to the retainer 196 to secure the actuating portion 192 between the cap 198 and the flange end 146. The actuator 190 also includes an actuated portion 200 in the actuator mounting portion 144 that engages the plunger 164.

[0040] The actuator 190 controls the opening of the gas fuel flow valve assembly 160 (including the valve 162). In one embodiment, the actuator 190 is an electronic actuator (such as a solenoid) that is electronically controlled by energizing and de-energizing a magnetic coil to actively and selectively control the opening and closing of the valve 162 of the valve assembly 160. In one embodiment, the actuating portion 192 is a solenoid, the retainer 196 is a stator, and the actuated portion 200 is an armature coupled to the plunger 164. In response to a fuel injection command, the actuating portion 192 causes the actuated portion 200 to axially displace in the injector body 101 to axially displace the plunger 164 away from the seat 168.

[0041] In the illustrated embodiment, the plunger 162 includes an axially extending rod 170 that extends from the valve assembly receiving portion 140 into the actuator mounting portion 144. The plunger 162 includes a plunger body 172 located at the distal end of the rod 170. The rod 170 is coupled to an actuated portion 200 of the actuator 190, such as an armature. The body 172 includes an internal chamber 174 and a plurality of sidewall openings 176 that allow gaseous fuel flow into the chamber 174. The distal end of the body 172 includes a seal 180 ( Figure 7) and a central opening 182 around which the seal 180 extends. The sidewall opening 176 is in fluid communication with one or more sidewall inlets 148 of the valve assembly receiving portion 140 to receive the gaseous fuel 18 from the fuel system 10.

[0042] The valve seat 168 is mounted at the distal end of the valve assembly receiving portion 140. The valve seat 168 includes a seat body 208 having an annular opening 210 that receives the flow of gaseous fuel when the plunger 164 is axially displaced away from the valve seat 168. In one embodiment, such as Figure 7 As shown, the seat body 208 includes a first annular protrusion 212 and a second annular protrusion 214 that are sealingly engaged by the seal 180 when the plunger 164 is in the closed position. The valve seat 168 also includes a flow path 216 from the opening 210 to the gas outlet 106.

[0043] The first plunger control mechanism 120 includes a first biasing element 220, such as Figure 6 The biasing element 220 is engaged to the actuated portion 200 (such as the armature and / or plunger 164) and to a spring guide 222 within the retainer 196. The biasing element 220 biases the plunger 164 distally so that the seal 180 sealingly engages the protrusions 212, 214 of the valve seat 168.

[0044] In an embodiment of the second plunger control mechanism 130, as Figure 7 As more clearly shown in FIG. 1 , the second biasing element 230 is spaced apart from the flange 184 of the plunger 164. The biasing element 230 may be, for example, a washer, a plate, a disk, a Belleville washer, a spring, or other device used in conjunction with the coil spring 220 to provide the desired variable axial force to resist displacement of the plunger 164. In other embodiments, a damping element, such as a viscoelastic damping element, may be employed that acts in parallel with the coil spring 220 and / or the biasing element 230.

[0045] In one embodiment, a shim or washer 232 is provided between the distally facing surface 150 of the receiving portion 140 and the biasing element 230. The shim 232 provides a gap 126 in which the biasing element 230 is spaced from the plunger 164 in the closed position of the plunger 164. When the plunger 164 is displaced against the coil spring 220 sufficiently to close the gap 126, as shown in FIG. Figure 7 As shown, the flange 184 of the plunger 164 contacts the biasing element 230 to provide additional resistance to axial displacement of the plunger 164. The biasing element 230 also resists or prevents the plunger flange 184 from striking or rebounding from the surface 150 of the valve assembly receiving portion 140.

[0046] Figure 8Another embodiment of the second plunger control mechanism 130 is shown. Figure 8 , the second plunger control mechanism 130 includes a second biasing element 240, a first shim 242 that separates the biasing element 240 from the distally facing surface 150, a second shim 244 that sets the distance that the biasing element 240 can be compressed relative to its free length, and a third shim 246. In one embodiment, the biasing element 240 is a wave spring. In one embodiment, the biasing element 240 is a single-turn overlapping wave spring.

[0047] In one embodiment, the first shim 242 sets the minimum air gap between the armature (e.g., the actuated portion 200) and the stator (e.g., the retainer 196) of the actuator 190. In one embodiment, the third shim 246 sets the distance that the plunger 164 is lifted before contacting the second biasing element 240, thereby establishing a minimum air gap such as Figure 2 Gap 126 is shown.

[0048] In the illustrated embodiment, the second gasket 244 extends axially from the first gasket 242 along the inside of the biasing element 240. In other embodiments, the second gasket 244 is located around the outside of the biasing element 240. When the plunger 164 is actuated, the flange 184 of the plunger 164 first compresses the first biasing element 220 of the plunger control mechanism 120 to close the gap 126. The plunger 164 then contacts the second biasing element 240 of the second plunger control mechanism 130 and continues to shift away from the valve seat 168 by compressing the biasing elements 220, 240 until the flange 184 contacts the second gasket 244.

[0049] Fig. 9 Another embodiment of the second plunger control mechanism 130 is shown. This embodiment includes a second plunger 136 as part of the second plunger control mechanism 130. Fig. 9 , the second plunger control mechanism 130 includes a second biasing element 250 and a second plunger 252 in contact with the second biasing element 250. The second plunger 252 is a plate in the form of a disc-shaped element having a concave surface portion 266 receiving the biasing element 250.

[0050] The second plunger control mechanism 130 also includes a first shim 254 in contact with the second plunger 252. The first shim 254 axially separates the second plunger 252 from the second distal flange 186 of the plunger 164, which is located at or adjacent to the first end 178 of the plunger 164. The first shim 254 has a selected height to axially separate the second plunger 252 from the second flange 186 of the plunger 164 to establish the gap 126. The shim biasing element 256 extends around the second plunger 252 and holds the first shim 254 in an axial position in the valve assembly receiving portion 140 of the injector body 101. In the illustrated embodiment, the second biasing element 250 and the shim biasing element 256 are coil springs.

[0051] The valve assembly receiving portion 140 also includes a plunger guide 258 located within the valve assembly receiving portion 140. The plunger guide 258 includes a radial portion 260 extending along the distally facing surface 150, and an axial portion 262 extending along the channel 264 to guide the rod 170. The second biasing element 250 and the shim biasing element 256 contact the radial portion 260 of the plunger guide 258. In one embodiment, the plunger guide 258 is made of a hardened, wear-resistant metal material.

[0052] During actuation, the first plunger 164 is axially displaced from the valve seat 168, and the displacement is resisted only by the biasing element 220. Once the plunger 264 is displaced to close the gap 126, the proximal end of the plunger 264 contacts the second plunger 252. The second biasing element 250 then cooperates with the first biasing element 220 to resist the axial displacement of the plunger 264 away from the valve seat 268.

[0053] Fig.10 Another embodiment of a fuel injector 100 is shown, which includes a second plunger control mechanism 130 with a second plunger 136. Fig.10 , the second plunger control mechanism 130 includes a second biasing element 270 and a second plunger 272 in contact with the second biasing element 270. The second plunger 272 is an elongated member having a proximal cover 274 for receiving and guiding the biasing element 270, a rod 276 extending to a distal end 278, and a flange 282 between the rod 276 and the cover 274. The distal end 278 is proximally spaced apart from the proximal end of the plunger 164 by the gap 126.

[0054] The second plunger control mechanism 130 also includes a first shim 280 located between the flange 282 and the inner lip 197 of the retainer 196, which establishes the gap 126. The second plunger 272 can be movably supported in an axially fixed upper plunger guide 284. The biasing element 220 of the first plunger control mechanism 120 can be located between the actuating member 220 and the plunger guide 284 to bias the plunger 164 to contact the seat 168. An optional shim 286 can be provided between the valve assembly receiving portion 140 and the actuator mounting member 144 to adjust the minimum axial air gap between the actuating portion 192 and the actuated portion 200 of the actuator 190.

[0055] During actuation, the first plunger 164 is axially displaced from the valve seat 168, and the displacement is resisted only by the biasing element 220. Once the plunger 264 is displaced to close the gap 126, the proximal end of the plunger 264 contacts the distal end 278 of the second plunger 272. The second biasing element 270 then cooperates with the first biasing element 220 to resist the axial displacement of the plunger 264 away from the valve seat 268.

[0056] For various embodiments disclosed herein, the first plunger control mechanism 120 and the second plunger control mechanism 130 are configured to increase the resistance to displacement of the plunger 164 away from the valve seat 168 during the opening of at least one valve 162. In one embodiment, the first plunger control mechanism 120 and the second plunger control mechanism 130 are configured such that the second plunger control mechanism 130 gradually or sequentially engages the plunger 164 only when the plunger 164 is spaced apart from the seat 168 by more than a threshold distance, such as the gap 126, while the first plunger control mechanism 120 is always actively engaged to the plunger 164.

[0057] In one embodiment, the first plunger control mechanism 120 and the second plunger control mechanism 130 are configured such that the second plunger control mechanism 130 supplements the resistance to displacement of the plunger 164 provided by the first plunger control mechanism 120 only when the plunger 164 is spaced apart from the seat 168 by more than a threshold distance, such as the gap 126. In one embodiment, the first plunger control mechanism 120 and the second plunger control mechanism 130 are configured such that the second plunger control mechanism 130 actively engages the plunger 164 only when the plunger 164 is spaced apart from the seat 168 by more than a threshold distance, such as the gap 126, while the first plunger control mechanism 120 is always actively engaged to the plunger 164.

[0058] In one embodiment, the first plunger control mechanism 120 is located proximal to the second plunger control mechanism 130 in the injector body 101. In one embodiment, the first plunger control mechanism 120 is located distal to the second plunger control mechanism 130 in the injector body 101.

[0059] Additional written descriptions of a number of exemplary embodiments should now be provided. According to one aspect of the present disclosure, a fuel injector for providing a gaseous fuel to a combustion chamber is disclosed. The fuel injector includes an injector body defining a fuel passage therein. The fuel passage extends from a gas inlet of the injector body to a gas outlet. The fuel injector includes a valve assembly located in the fuel passage. The valve assembly includes at least one valve that selectively opens and closes to control the flow of gaseous fuel to the combustion chamber through the fuel passage. The at least one valve includes a valve seat located in the fuel passage. The at least one valve also includes a plunger that contacts the valve seat to close the at least one valve, and the plunger is displaced from the valve seat to open the at least one valve. A first plunger control mechanism and a second plunger control mechanism resist displacement of the plunger away from the valve seat. The first plunger control mechanism and the second plunger control mechanism are configured to increase resistance to displacement of the plunger from the valve seat during the opening of the at least one valve based on the distance of the plunger from the valve seat.

[0060] In one embodiment, the plunger includes an end surface that contacts the valve seat when the at least one valve is in the closed position. Only the first plunger control mechanism biases the plunger into contact with the valve seat.

[0061] In one embodiment, a gap is formed between the second plunger control mechanism and the plunger when the at least one valve is in the closed position. In other embodiments, the first plunger control mechanism is always connected to the plunger to bias the plunger toward the closed position onto the valve seat and resist displacement of the plunger from the valve seat during the opening of the at least one valve. In other embodiments, the second plunger control mechanism includes: a second plunger, which is spaced apart from the plunger when the at least one valve is in the closed position; and a biasing element, which resists displacement of the second plunger when the plunger is displaced a sufficient distance from the valve seat to contact the second plunger during the opening of the at least one valve.

[0062] In one embodiment, an actuator is actuatable to axially displace the plunger to open the at least one valve. The plunger includes a first end and an opposite second end, and the plunger includes a flange adjacent to the first end and an elongated stem extending to the second end. The elongated stem of the plunger is engaged to the actuator, and the first plunger control mechanism is engaged between the actuator and the injector body.

[0063] In other embodiments, the second plunger control mechanism includes a second plunger that is axially spaced from the second end of the plunger when the plunger contacts the valve seat. The second end of the plunger contacts the second plunger after the first end of the plunger is displaced away from the valve seat. The second plunger control mechanism also includes a biasing element that resists displacement of the second plunger by the plunger when the plunger moves away from the valve seat.

[0064] In other embodiments, the second plunger control mechanism includes a plate located in the fuel passage and a biasing element between the plate and the injector body. When the plunger contacts the valve seat, the plate is axially spaced from a flange of the plunger. After the first end of the plunger is displaced away from the valve seat, the flange of the plunger contacts the plate, and when the plunger moves away from the valve seat, the biasing element resists displacement of the plate by the plunger.

[0065] In other embodiments, when the plunger contacts the valve seat, the second plunger control mechanism is spaced apart from the flange of the plunger. The first plunger control mechanism resists displacement of the plunger in response to actuating the actuator to displace the first end of the plunger from the valve seat. After the first end of the plunger is displaced from the valve seat, the flange contacts the second plunger control mechanism.

[0066] In further embodiments, the actuator includes an armature to which the stem of the plunger is engaged, and the first plunger control mechanism includes a biasing element engaged to the armature to bias the plunger into contact with the valve seat.

[0067] In one embodiment, the second plunger control mechanism is located in the fuel passage and is coupled to the injector body. In one embodiment, the second plunger control mechanism includes at least one of a disk, a Belleville washer, a wave spring, and a coil spring.

[0068] According to another aspect of the present disclosure, a valve assembly for a fuel injector to selectively provide a gaseous fuel flow is disclosed. The valve assembly includes a valve seat, the valve seat including an opening to allow the gaseous fuel flow to pass through the valve seat. The valve assembly also includes a plunger, the plunger is movable to engage the valve seat to prevent the gaseous fuel flow from passing through the opening, and disengage from the valve seat to allow the gaseous fuel flow to pass through the valve seat. The valve assembly also includes a first plunger control mechanism engaged to the plunger. The first plunger control mechanism is configured to resist the displacement of the plunger away from the valve seat during the opening of the valve assembly, and bias the plunger onto the valve seat to close the valve assembly. The valve assembly also includes a second plunger control mechanism, the second plunger control mechanism is configured not to resist the movement of the plunger engaging the valve seat. The second plunger control mechanism engages the plunger after the plunger is displaced away from the valve seat so as to work with the first plunger control mechanism to resist the displacement of the plunger away from the valve seat during the opening of the valve assembly.

[0069] In one embodiment, the opening of the valve seat is formed by an annular channel between a first annular protrusion and a second annular protrusion, and the plunger extends between a first end and an opposite second end. The second end includes an end face having an annular seal that sealingly engages the first annular protrusion and the second annular protrusion to close the opening when the plunger is engaged to the valve seat.

[0070] In one embodiment, the first plunger control mechanism is a spring that is always engaged with the plunger. In one embodiment, the second plunger control mechanism includes at least one of a disc, a Belleville washer, a wave spring, and a coil spring that is spaced apart from the plunger when the plunger is engaged to the valve seat and engages with the plunger only after the plunger is displaced away from the valve seat.

[0071] In one embodiment, the plunger includes a rod and a plunger body at the distal end of the rod. The first plunger control mechanism is engaged to the rod, and only after the plunger is displaced away from the valve seat does the second plunger control mechanism engage the plunger body to resist displacement of the plunger. In one embodiment, when the plunger is engaged to the valve seat, a gasket supports the second plunger control mechanism so that it is in a spaced relationship with the plunger.

[0072] In one embodiment, the second plunger control mechanism includes a second plunger spaced apart from the plunger when the plunger is engaged to the valve seat, and a biasing element engaged to the second plunger. The biasing element resists displacement of the second plunger and the plunger in response to the plunger being displaced from the valve seat to contact the second plunger.

[0073] In one embodiment, the second plunger control mechanism includes a plate spaced apart from the plunger when the plunger is engaged to the valve seat, and a biasing element engaged to the plate. The biasing element resists displacement of the plate and the plunger in response to the plunger being displaced from the valve seat to contact the plate.

[0074] Although the illustrative embodiments of the present disclosure have been shown and described in detail in the drawings and the foregoing description, the illustrative embodiments of the present disclosure are actually considered to be illustrative rather than restrictive, and it should be understood that only certain exemplary embodiments have been shown and described and that it is desired to protect all changes and modifications within the spirit of the claimed invention. It should be understood that although the use of words (such as, preferably, preferred, preferred or more preferred as utilized in the above description) indicates that the features described in this way may be more desirable, it is not necessary and it is conceivable that embodiments without the words are within the scope of the present invention, which is defined by the appended claims. When reading the claims, it is intended that when words such as "one", "a kind", "at least one" or "at least one part" are used, it is not intended to limit the claim to only one item, unless there is a clear statement to the contrary in the claim. When the language "at least a part" and / or "a part" is used, the item may include a part and / or the entire item, unless there is a clear statement to the contrary.

Claims

1. A fuel injector for providing gaseous fuel to a combustion chamber, the fuel injector comprising: an injector body defining a fuel passage therein, the fuel passage extending from a gas inlet of the injector body to a gas outlet; as well as a valve assembly at least partially disposed in the fuel passage, the valve assembly comprising at least one valve that selectively opens and closes to control the flow of gaseous fuel through the fuel passage to the combustion chamber, wherein the at least one valve comprises: a valve seat located in the fuel passage; a plunger contacting the valve seat to close the at least one valve, wherein the plunger is displaced from the valve seat to open the at least one valve; and A first plunger control mechanism and a second plunger control mechanism, each of the first plunger control mechanism and the second plunger control mechanism resists displacement of the plunger away from the valve seat, and the first plunger control mechanism and the second plunger control mechanism are configured to increase the resistance to displacement of the plunger from the valve seat during opening of at least one valve based on the distance of the plunger from the valve seat.

2. The fuel injector according to claim 1, wherein: The plunger includes an end surface that contacts the valve seat when the at least one valve is in the closed position; and Only the first plunger control mechanism biases the plunger into contact with the valve seat. 3 . The fuel injector of claim 1 , wherein a gap is formed between the second plunger control mechanism and the plunger when the at least one valve is in the closed position.

4. The fuel injector of claim 3, wherein the first plunger control mechanism is always coupled to the plunger to bias the plunger onto the valve seat toward the closed position and resist displacement of the plunger from the valve seat during opening of the at least one valve.

5. The fuel injector of claim 3, wherein the second plunger control mechanism comprises: a second plunger spaced apart from said plunger when said at least one valve is in said closed position; as well as A biasing element resists displacement of the second plunger when the plunger is displaced from the valve seat a sufficient distance to close the gap to contact the second plunger during opening of the at least one valve.

6. The fuel injector of claim 1 further comprising an actuator actuatable to axially displace the plunger to open the at least one valve, wherein: The plunger includes a first end and an opposite second end, the plunger including at least one flange adjacent the first end and an elongated stem extending to the second end; The elongated rod of the plunger is coupled to the actuator, and The first plunger control mechanism is engaged between the actuator and the injector body.

7. The fuel injector of claim 6, wherein the second plunger control mechanism comprises: a second plunger axially spaced from the second end of the plunger when the plunger contacts the valve seat, wherein the second end of the plunger contacts the second plunger after the first end of the plunger is displaced away from the valve seat; as well as A biasing element resists displacement of the second plunger by the plunger when the plunger moves away from the valve seat.

8. The fuel injector of claim 6, wherein the second plunger control mechanism comprises: a plate positioned in the fuel passage, wherein the plate is axially spaced from the at least one flange of the plunger when the plunger contacts the valve seat, wherein the at least one flange of the plunger contacts the plate after the first end of the plunger is displaced away from the valve seat; as well as A biasing element is provided between the plate and the injector body, wherein the biasing element resists displacement of the plate by the plunger when the plunger abuts the plate and moves away from the valve seat.

9. The fuel injector of claim 6, wherein: the second plunger control mechanism being axially spaced from the at least one flange of the plunger when the plunger is in contact with the valve seat; the first plunger control mechanism resisting displacement of the plunger in response to actuating the actuator to displace the first end of the plunger away from the valve seat; and The flange contacts the second plunger control mechanism after the first end of the plunger is displaced from the valve seat.

10. The fuel injector of claim 6, wherein: The actuator includes an armature; The rod of the plunger is engaged to the armature; and The first plunger control mechanism includes a biasing element engaged to the armature to bias the plunger into contact with the valve seat.

11. The fuel injector of claim 1 wherein the second plunger control mechanism is located in the fuel passage and is coupled to the injector body.

12. The fuel injector of claim 1, wherein the second plunger control mechanism includes at least one of a disk, a Belleville washer, a wave spring, and a coil spring.

13. A valve assembly for a fuel injector to selectively provide a flow of gaseous fuel, the valve assembly comprising: a valve seat including an opening to allow gaseous fuel to flow through the valve seat; a plunger, the plunger being movable to engage the valve seat to prevent the flow of gaseous fuel through the opening and the plunger being movable to disengage the valve seat to allow the flow of gaseous fuel through the valve seat; a first plunger control mechanism coupled to the plunger, the first plunger control mechanism being configured to resist displacement of the plunger away from the valve seat during opening of the valve assembly, and the first plunger control mechanism being further configured to bias the plunger against the valve seat; as well as A second plunger control mechanism, the second plunger control mechanism being configured not to resist movement of the plunger into engagement with the valve seat, the second plunger control mechanism resisting the plunger after displacement of the plunger away from the valve seat so as to work with the first plunger control mechanism to resist displacement of the plunger away from the valve seat during opening of the at least one valve.

14. The valve assembly of claim 13, wherein: The opening of the valve seat is formed by an annular channel between the first annular protrusion and the second annular protrusion; and The plunger extends between a first end and an opposite second end, and the second end includes an end face having an annular seal that sealingly engages the first and second annular projections to close the opening when the plunger is engaged to the valve seat.

15. The valve assembly of claim 13, wherein the first plunger control mechanism is a spring that is always engaged with the plunger.

16. The valve assembly of claim 13, wherein the second plunger control mechanism comprises at least one of a disk, a Belleville washer, a wave spring, and a coil spring that is spaced apart from the plunger when the plunger is engaged to the valve seat and engages with the plunger only after the plunger is displaced away from the valve seat.

17. The valve assembly of claim 13, wherein: The plunger includes a rod and a plunger body, the plunger body being located at a distal end of the rod; The first plunger control mechanism is coupled to the rod, and Only after the plunger is displaced away from the valve seat does the second plunger control mechanism engage the plunger body to resist displacement of the plunger.

18. The valve assembly of claim 13, further comprising a spacer that supports the second plunger control mechanism in spaced relationship with the plunger when the plunger is engaged to the valve seat.

19. The valve assembly of claim 13, wherein the second plunger control mechanism comprises: a second plunger spaced apart from the plunger when the plunger is engaged to the valve seat; as well as A biasing element is coupled to the second plunger, the biasing element resisting displacement of the second plunger and the plunger in response to the plunger being displaced from the valve seat into contact with the second plunger.

20. The valve assembly of claim 13, wherein the second plunger control mechanism comprises: a plate spaced apart from the plunger when the plunger is engaged to the valve seat; as well as A biasing element is coupled to the plate, the biasing element resisting displacement of the plate and the plunger in response to the plunger being displaced from the valve seat into contact with the plate.

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