GAS INJECTOR HAVING REDUCED WEAR AND DAMPING DEVICE

Abstract

A gas injector for injecting a gaseous fuel. The gas injector includes a solenoid actuator including an armature, an internal pole, and a coil; a closure element which opens and closes a gas path on a valve seat, the armature being connected to the closure element; a closed lubricant chamber filled with a lubricant and in which the armature is arranged, the lubricant ensuring the armature is lubricated; a flexible sealing element sealing the lubricant chamber in relation to the gas path, and a braking device which is arranged in the lubricant chamber and is configured to brake the closure element during a process of restoring the gas injector from the open into the closed state. The braking device has a brake pin, a damping chamber that is filled with lubricant and is in fluid communication with the lubricant chamber, and a resilient brake element.

Claims

1-10. (canceled)

11. A gas injector for injecting a gaseous fuel, comprising: a solenoid actuator including an armature, an internal pole, and a coil; a closure element which opens and closes a gas path on a valve seat, wherein the armature is connected to the closure element; a closed lubricant chamber filled with a lubricant and in which the armature is arranged, wherein the lubricant ensures the armature is lubricated; a flexible sealing element which seals the lubricant chamber in relation to the gas path; and a braking device arranged in the lubricant chamber and configured to brake the closure element during a process of restoring the gas injector from an open state into a closed state; wherein the braking device includes a brake pin, a damping chamber that is filled with lubricant and is in fluid communication with the lubricant chamber, and a resilient brake element, wherein the brake pin and the resilient brake element can be operatively connected to the closure element during the restoring process, and the brake pin is configured, during a process of restoring the gas injector, to displace lubricant out of the damping chamber into the lubricant chamber to damp the restoring of the closure element into the closed state.

12. The gas injector as recited in claim 11, wherein the brake pin includes a contact surface, which is arranged on a side of the brake pin pointing toward the closure element, can be operatively connected to the closure element, and is used as the stop surface for the brake pin.

13. The gas injector as recited in claim 11, wherein the resilient brake element is arranged in the damping chamber.

14. The gas injector as recited in claim 11, wherein the damping chamber is in fluid communication with the lubricant chamber by way of a guide play of the brake pin.

15. The gas injector as recited in claim 11, further comprising a choke, wherein the damping chamber is in fluid communication with the lubricant chamber by way of the choke.

16. The gas injector as recited in claim 11, further comprising an armature pin which abuts the closure element and is rigidly connected to the armature, wherein an end of the armature pin facing away from the valve seat of the gas injector abuts the brake pin when the gas injector is in the closed state.

17. The gas injector as recited in claim 16, further comprising an armature pin guide in which the armature pin is guided, wherein the armature pin guide is used as a stop for the brake pin when the injector is in the open state.

18. The gas injector as recited in claim 11, further comprising a guide member which is arranged in the lubricant chamber and is configured to guide the brake pin.

19. The gas injector as recited in claim 17, wherein, when the gas injector is in the closed state, a first gap between the brake pin and the armature pin guide has a first width that is smaller than a width of a second gap between the armature and the internal pole.

20. The gas injector as recited in claim 11, wherein: i) a restoring element for restoring the closure element is arranged in the lubricant chamber, and/or ii) a first guide region and a second guide region of the closure element are arranged in the lubricant chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the figures.

[0028] FIG. 1 is a schematic sectional view of a gas injector according to a first exemplary embodiment of the present invention.

[0029] FIG. 2 is an enlarged schematic sectional view of part of the gas injector from FIG. 1.

[0030] FIG. 3 is an enlarged schematic sectional view of part of a gas injector according to a second exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0031] Hereinafter, a gas injector 1 according to a first preferred exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

[0032] As can be seen from FIG. 1, the gas injector 1 for introducing a gaseous fuel comprises a solenoid actuator 2 which moves a closure element 3 (in this exemplary embodiment a valve needle that opens outward) from a closed state into an open state. In this regard, FIG. 1 shows the closed state of the gas injector.

[0033] The solenoid actuator 2 comprises an armature 20 which abuts the closure element 3 by way of an armature pin 24. Furthermore, the solenoid actuator 2 comprises an internal pole 21, a coil 22, and a magnet housing 23 which ensures a magnetic return of the solenoid actuator.

[0034] Moreover, the gas injector 1 comprises a main body 7 having a connection tube 70 through which the gaseous fuel is supplied. In this case, a valve housing 8 in which the solenoid actuator 2 is arranged is secured to the main body 7. Adjoining the valve housing 8 is a housing sleeve 19 and a valve tube 90, on the free end of which there is provided a valve seat 11 at which the closure element 3 opens and closes a passage for the gaseous fuel.

[0035] FIG. 1 schematically shows an electrical terminal 13 which is guided through the main body 7 as far as the solenoid actuator 2.

[0036] Reference numeral 10 denotes a restoring element for the closure element 3 for restoring said closure element back into the closed state shown in FIG. 1 after an opening process.

[0037] FIG. 1 further shows a gas stream as a gas path 14 through the gas injector 1. The gas stream begins at the connection tube 70 and is then diverted into an annular chamber 80 between the valve housing 8 and the main body 7. In the process, the gas stream 14 proceeds past an external region of the solenoid actuator 2, through a filter 15, before reaching a position upstream of the valve seat 11. In this case, openings are accordingly provided in the relevant components, not all of which are shown in FIG. 1.

[0038] When the gas injector 1 is opened, the gaseous fuel then flows past the external circumference of the solenoid actuator 2 and past the open valve seat 11 into a combustion chamber of an internal combustion engine, as indicated by the arrows A in FIG. 1.

[0039] The closure element 3 thus opens and closes the gas path 14 at the valve seat 11. For the guidance, a first guide region 31 and a second guide region 32 are provided between the closure element 3 and a valve body 9, as can be seen in detail from FIG. 1. The first guide region 31 is formed close to the valve seat, directly between the closure element 3 and the valve body 9. The second guide region 32 is formed between a spring disk 16 and the valve body 9. The spring disk 16 is rigidly connected to the closure element 3, the restoring element 10 being supported between the valve body 9 and the spring disk 16.

[0040] In addition, the gas injector 1 comprises a closed lubricant chamber 4. The closed lubricant chamber 4 is filled either entirely or in part with a liquid lubricant, e.g., oil.

[0041] As can be seen from FIG. 1, the lubricant chamber 4 is delimited by a first flexible sealing element 51, the internal pole 21, the magnet housing 23, a guide member 18, and a second flexible sealing element 52. The first and second flexible sealing elements 51, 52 are each formed as bellows. In this case, the first and second flexible sealing elements 51, 52 are identical.

[0042] It should be noted that, for example, a membrane, a hose, or the like can be provided as the flexible sealing elements 51, 52 instead of a bellows.

[0043] As can also be seen from FIG. 1, the second flexible sealing element 52 is secured to a preloaded spring disk 41, for example by way of a welded joint. Furthermore, the gas injector 1 comprises a preloaded compression spring 40 which is supported on the main body 7 and preloads the second flexible sealing element 52 via the preloaded spring disk 41. Connecting holes 18a are provided in the guide member 18 such that the lubricant located in the lubricant chamber 4 is also located in the region inside the second flexible sealing element 52.

[0044] The first flexible sealing element 51 is secured directly to the closure element 3 and connected to the valve body 9 at the other end. In the process, cross-holes 91 are provided in the valve body 9 such that there is fluid communication between the inner chamber of the first flexible sealing element 51 and the inner chamber of the valve body 9.

[0045] Thus, the lubricant chamber 4 has two flexible sealing elements 51, 52 and the preloaded compression spring 40. The preloaded compression spring 40 exerts a certain preload, for example 1?10.sup.5 Pa, on the lubricant located in the lubricant chamber 4. If, during an opening process, the lubricant is then displaced by the stroke of the closure element 3 or even by the heat expansion or cooling of the lubricant, any excess pressure/negative pressure occurring in the interior of the lubricant chamber 4 can be compensated for by deflection at the second flexible sealing element 52 in conjunction with a contraction of the preloaded compression spring 40. The flexible sealing element 51 can thus prevent an undesirable force, acting via the active surface of the bellows, from being exerted on the closure element 3.

[0046] The armature pin 24 having the armature 20 secured thereto is arranged in the closed lubricant chamber 4. Since the lubricant chamber 4 is filled with a lubricant, for example a liquid fuel such as gasoline or diesel, or a grease or the like, the armature 20 is continually lubricated. Thus, it is possible to compensate for the problem occurring with gaseous fuels in the prior art where the moving parts are inadequately lubricated.

[0047] As can be seen from FIG. 1, a filling duct 17a is provided for filling the closed lubricant chamber 4. The filling duct 17a is sealed in a fluid-tight manner using a locking ball 17.

[0048] Furthermore, a braking device 6 is arranged in the closed lubricant chamber 4. The braking device 6 comprises a brake pin 60, a damping chamber 62 filled with lubricant, and a resilient brake element 61. The damping chamber 62 is in fluid communication with the lubricant chamber 4.

[0049] The brake pin 60 and the resilient brake element 61 are operatively connected to the closure element 3 during a process of restoring the gas injector into the closed starting position. During the restoring process, lubricant is displaced out of the damping chamber 62 and into the lubricant chamber 4 in order to achieve additional damping when the brake pin 60 is restored into the closed state of the gas injector (FIG. 1).

[0050] In this case, the brake pin 60 is guided in the guide member 18. As can also be seen from FIG. 1, the damping chamber 62 is formed directly on the brake pin 60 on a side of the brake pin 60 facing away from the valve seat 11. This can be seen in detail from FIG. 2. The damping chamber 62 is connected to the connecting holes 18a, and thus to the main region of the lubricant chamber 4, by way of a choke 63, which is a small hole. The brake spring 61 is arranged in a spring chamber 67.

[0051] The brake pin 60 has a contact surface 60a that is in contact with the armature pin 24. In the closed state as shown in FIG. 2, there is a first gap 101 between the brake pin 60 and a stationary armature pin guide 25. The armature pin guide 25 guides the armature pin 24 during an opening and closing process.

[0052] As can also be seen from FIG. 2, the brake spring 61 is arranged between the brake pin 60 and the guide member 18. In this case, the brake pin 60 has a flange 60b that is provided with play in relation to the guide member 18. Moreover, there is provided in the guide member 18 a passage 65 which can be formed, for example, as a slot on the end of the guide member 18 pointing toward the armature pin guide 25. Thus, fluid communication out of the spring chamber 67 to the lubricant chamber 4, via the guide play 64 and the passage 65, can be provided for the lubricant.

[0053] Moreover, in the closed state, the first gap 101 is formed between the contact surface 60a of the brake pin 60 and the armature pin guide 25. In this case, the gap 101 has a first width B that is smaller than a second width C between the armature 20 and the internal pole 21 (cf. FIGS. 1 and 2) at the second gap 102. This ensures that a stroke of the brake pin 60, which is preloaded in the axial direction by the compression spring 61, is smaller than a stroke of the armature 20. As a result, during the injection process enough fluid can flow out of the lubricant chamber 4 into the damping chamber 62 via the choke 63.

[0054] During the closing process, the armature pin 24 strikes the contact surface 60a of the brake pin 60. The brake pin 60 is thus pushed against the fluid located in the damping chamber 62, as indicated by the arrow 66 in FIG. 2. Owing to the choke 63, the fluid cannot be pushed out of the damping chamber 62 immediately, but rather it is pushed out slowly so as to enable a damping action during the closing process. This prevents excessive wear occurring on the valve seat 11 and the armature 20 since the closing process is damped by the restoring of the brake pin 60.

[0055] Moreover, the damping process is assisted by the brake spring 61 and hydraulic adhesion of the brake pin 60 to the armature pin guide 25. In the process, the damping chamber 62 can prevent cavitation from occurring during the closing process in said region between the armature pin guide 25 and the contact surface 60a of the brake pin 60. The restoring process is also slowed down by the brake pin 60 rubbing in the guide member 18 and, in the lubricant chamber 4 as a whole, by the moving-component masses that are to be accelerated, which lead to displacement of the lubricant in the closed lubricant chamber and thus to additional braking during the closing process.

[0056] Selecting a diameter and/or a length of the choke 63 can adjust the damping behavior in a specific manner for each gas injector.

[0057] It should be noted that a stop surface between the damping pin 60 and the armature pin guide 25 can preferably be formed in a cuneiform manner, i.e., not at a right angle to a central axis X-X of the gas injector. Alternatively or additionally, radial slots can be provided in the contact surface 60a or in the end face of the armature pin guide 25 pointing toward the brake pin 60, thereby further reducing and preventing a cavitation effect.

[0058] In this case, the gas injector 1 shown in FIG. 1 is compressive force-balanced. In other words, the closure element 3 is connected to the valve body 9 by way of the first flexible sealing element 51, the first flexible sealing element 51, which is configured as a metal bellows, having an average diameter that is equal to a diameter at the valve seat 11 at which the closure element 3 provides sealing on the valve seat 11. As a result, there is no compressive force on the closure element 3, and so a magnetic force needed to open the closure element 3 can be kept very small and in particular is independent of a pressure of the gaseous fuel.

[0059] With the present invention, therefore, when the closure element 3 has been placed into the open state (movement of the closure element 3 to the left in FIG. 1) by actuating the solenoid actuator 2 and gas has been injected, reliable damping can be carried out during the restoring of the closure element 3, shortly before the closure element is pushed into the valve seat 11. In this case, the brake pin 60 is pushed in the direction of the damping chamber 62 by the armature pin 24 and thus only moves as slowly as the lubricant is pushed out of the damping chamber 62, through the choke 63, and into the lubricant chamber 4. A closure speed of the closure element 3 is thus significantly and effectively braked before the closure element strikes the valve seat 11. Consequently, wear on the valve seat 11 and the closure element 3 can be effectively reduced, the braking device 6 furthermore allowing the gas injector to be operated more easily. In addition, a so-called closure rebound, in which an element strikes strongly against a valve seat and bounces back, can be effectively prevented.

[0060] FIG. 3 is a section through part of a gas injector according to a second exemplary embodiment of the present invention. Identical or functionally identical parts are denoted by the same reference numerals as in the first exemplary embodiment.

[0061] FIG. 3 shows the braking device 6, which has a different configuration from that in the first exemplary embodiment. In the second exemplary embodiment, the damping chamber 62 is now connected to the lubricant chamber 4 not via a choke but via a guide play 64 between the brake pin 60 and the guide member 18. Communication with the lubricant chamber 4 is then ensured via one or more passages 65 formed in the radial direction on the end face of the guide member 18. In this case, the brake spring 61 is arranged in the damping chamber 62. As a result, an axial installation space for the braking device 6 can be reduced, meaning that the gas injector 1 as a whole can be formed to be shorter in the axial direction. In addition, a choke need not be provided as in the first exemplary embodiment. During a restoring process, therefore, the armature pin 24 pushes against the contact surface 60a of the brake pin 60 such that the brake pin is pushed toward the guide member 18 in the direction of the arrow 66. In the process, lubricant is pushed back out of the damping chamber 62 and into the lubricant chamber 4 via the guide play 64 and the at least one passage 65. A further advantage of the second exemplary embodiment is that there is a smaller volume of lubricant in the damping chamber 62. As a result, vibrations at the brake pin 60, which may result from an elasticity of the lubricant, can be lessened in particular.

[0062] Otherwise, the second exemplary embodiment corresponds to the first exemplary embodiment, and so reference should be made to the description in relation thereto.

[0063] Thus, the gas injector 1 as set out in detail in the two exemplary embodiments can provide reduced wear on the moving parts, in particular on the valve seat 11 and armature 20 and in the armature pin 24. Moreover, dissipation of heat from the solenoid actuator 2 can be considerably improved owing to the closed lubricant chamber 4 containing a liquid lubricant. Furthermore, the two flexible sealing elements 51, 52 can prevent undesirable forces from acting on the closure element 3.