Patent Application
20240301846
The present invention relates to a gas injector for injecting a gaseous fuel, in particular hydrogen or natural gas or the like, having reduced wear and improved damping behavior, in particular for internal combustion engines. More particularly, the gas injector is configured for direct injection into a combustion chamber of an internal combustion engine.
Gas injectors are described in the related art in various configurations. An inherent problem in gas injectors is that because a gaseous injection medium is used, the medium cannot provide any lubrication, unlike, for example, in fuel injectors that inject gasoline or diesel. This results in excessive wear during operation in comparison with fuel injectors for liquid fuels. In this context, having a gas injector that has improved wear behavior would be desirable.
An advantage of the gas injector according to the present invention for injecting a gaseous fuel is that wear on the gas injector can be significantly reduced. As a result, the service life of the gas injector may be prolonged and may correspond substantially to the service life of a fuel injector for liquid fuels. In addition, during closure of the gas valve, a closure element can perform a closing process that is damped to a much better extent, so wear on the valve seat and on other components of the closure element is reduced or prevented. According to an example embodiment of the present invention, this may be achieved in that the gas injector has a lubricant located in a closed lubricant chamber in which moving parts of the gas injector are arranged. The gas injector comprises a solenoid actuator having an armature, an internal pole, and a coil. In this case, the armature, which is mechanically connected to a closure element that opens and closes a gas path on a valve seat, is provided for enabling a movement for opening and/or closing the injector. The armature, which is located in the lubricant chamber and pulled toward the internal pole of the solenoid actuator owing to electromagnetic forces when current is applied to the coil, is thus located in the interior of the lubricant chamber and is constantly supplied with lubricant and lubricated. This significantly reduces wear on the armature in comparison with conventional gas injectors from the prior art. To ensure the lubricant chamber is sealed, a flexible sealing element is provided, which seals the lubricant chamber at one portion. In addition, using the closed lubricant chamber filled with lubricant significantly prolongs the service life of the gas injector. Preferably, the lubricant chamber is entirely filled with lubricant.
According to an example embodiment of the present invention, the gas injector further comprises 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 comprises a brake pin, a damping chamber which is in fluid communication with the lubricant chamber, and a resilient brake element, in particular a spring. The brake pin and the resilient brake element are operatively connected to the closure element and/or to the armature during the restoring process, the brake pin furthermore being configured, during the restoring process, to displace lubricant out of the damping chamber in order to damp the restoring of the brake pin and thus the restoring of the closure element. Since part of the braking process is provided by hydraulic adhesion between the brake pin and a stop component which the brake pin abuts when the gas injector is in the open state, providing the damping chamber can prevent vapor bubbles from forming in the liquid lubricant when overcoming the hydraulic adhesion, and so wear by cavitation in particular can be prevented.
This is additionally assisted by the acceleration of the additional masses, which is provided by the braking device. Moreover, further braking is achieved by the displacement of the lubricant between the armature and the brake pin. Rubbing of guide elements or the like on the brake pin can also further reduce the restoring speed of the closure element. All this reduces the impact force of the armature on the stop, and so the service life of the armature can be prolonged further.
Preferred developments and example embodiments of the present invention are disclosed herein.
More preferably, according to an example embodiment of the present invention, the brake pin comprises in particular a main body having a contact surface, which is arranged on a side of the main body of the brake pin pointing toward the closure element, can be operatively connected to the closure element, and is used as a stop surface. The main body is preferably cylindrical. More preferably, an annular flange is arranged on the side of the main body pointing toward the closure element. The annular flange is preferably used as the stop surface.
According to a further preferred embodiment of the present invention, the resilient brake element of the braking device is arranged in the damping chamber. As a result, a particularly compact construction can be implemented. The resilient brake element is preferably a compression spring, in particular a cylinder spring.
More preferably, according to an example embodiment of the present invention, the damping chamber is in fluid communication with the lubricant chamber by way of a guide play of the brake pin.
Preferably, according to an example embodiment of the present invention, the gas injector further comprises a choke which connects the damping chamber to the lubricant chamber. The choke ensures that the damping process can take place in a defined manner since the lubricant is transferred out of the damping chamber then into the lubricant chamber via the choke. The choke is preferably a small connecting hole between the damping chamber and the lubricant chamber. The damping behavior of the braking device can be adjusted by selecting geometric dimensions of the connecting hole, for example the diameter and/or length of the hole.
More preferably, according to an example embodiment of the present invention, the gas injector comprises an armature pin which abuts the closure element, the armature pin being connected to the armature. An end of the armature pin facing away from a seal seat of the gas injector is configured to come into contact with the brake pin when the gas injector is in the closed state. The closure element is preferably a valve needle. Alternatively, the closure element and the armature pin are preferably rigidly interconnected, particularly preferably by way of a spring disk.
Furthermore, according to an example embodiment of the present invention, the gas injector preferably comprises an armature pin guide in which the armature pin is guided. In this case, the armature pin guide forms a stop for the brake pin when the gas injector is in the open state. In the closed state, there is a small gap between the armature pin guide and the brake pin. During opening, this small gap is overcome by the compressive force of the spring of the braking device acting on the brake pin.
According to a further preferred embodiment of the present invention, the gas injector comprises a guide member arranged in the lubricant chamber and having a guide region for guiding the brake pin. Preferably, the guide member has a cut-out, in particular at an end of the guide member pointing toward the seal seat, in which cut-out the brake pin is guided.
Preferably, according to an example embodiment of the present invention, 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 B that is smaller than a second gap having a second width C between the armature and the internal pole. In this case, the axial gap B between the armature pin guide and the brake pin is preferably in a range from 1% to 90% of the axial gap C between the armature and the internal pole. Particularly preferably, the axial gap B between the armature pin guide and the brake pin is less than 25% of the axial gap C; more preferably, it is in a range from 3% to 20% of the axial gap C. The axial gap C preferably measures from 0.05 mm to 3 mm, in particular 0.8 mm. Alternatively, according to an example embodiment of the present invention, the first and second flexible sealing elements each have a membrane or each have a rubber element. The membrane may be single-layer or multi-layer and, for example, be secured to the relevant components for sealing the lubricant chamber using laser welding.
Preferably, according to an example embodiment of the present invention, the flexible sealing element of the lubricant chamber comprises one first and one second flexible sealing element. Particularly preferably, the two sealing elements are bellows. The lubricant chamber is thus sealed by two flexible sealing elements, as a result of which, when the lubricant in the lubricant chamber is displaced, the occurrence of unfavorable excess pressure or negative pressure can be prevented, which may exert an undesirable force on the closure element of the gas injector by way of, for example, components of the lubricant store. By providing two flexible sealing elements, balancing can be provided by the second flexible sealing element even when an unfavorable force is exerted on one of the sealing elements, which could lead to a pressure increase in the closed lubricant chamber. Thus, an undesirable pressure change in the interior of the closed lubricant chamber can be successfully prevented.
More preferably, according to an example embodiment of the present invention, the preloaded spring exerts a predetermined force on the lubricant in the closed lubricant chamber from the exterior. Preferably in this case, excess pressure of between 0.5 and 10×105 Pa, particularly preferably of 1 to 5×105 Pa, is exerted. Thus, the lubricant in the lubricant chamber can be placed under a predetermined preload, as a result of which undesirable deformations that could have an impact on a stroke of the closure element can be reliably prevented.
Particularly preferably, according to an example embodiment of the present invention, the first flexible sealing element is a first bellows, and the second flexible sealing element is a second bellows. More preferably, the first and second bellows are identical, i.e., they have the same average bellows diameter and the same number of bellows convolutions. As a result, particularly the production costs of the gas injector can be reduced.
More preferably, according to an example embodiment of the present invention, the second bellows is connected to the preloaded spring via a spring disk. A simple and cost-effective construction can thus be implemented. Furthermore, a certain preload can thus be exerted directly on the second bellows by way of the preloaded spring, whereby the rigidity of the second bellows is increased slightly compared with the first bellows.
According to a further preferred embodiment of the present invention, the gas injector further comprises a first and a second closure element guide. In this case, the first and second closure element guides are preferably both arranged in the lubricant chamber. Preferably, the closure element only has the two first and second closure element guides, and so all the guide elements for the closure element are arranged in the interior of the lubricant chamber filled with lubricant. This ensures lubrication of all the important components of the gas injector in the interior of the lubricant chamber. In practice, therefore, the service life of the gas injector can correspond to that of an injector for liquid fuels.
Preferably, an oil, in particular mineral oil, is used as the lubricant. Alternatively, a liquid fuel, in particular diesel or gasoline, is used. As a further alternative, a grease, a polyalphaolefin (PAO) oil, an ester oil, or a polyglycol oil is used as the lubricant.
More preferably, according to an example embodiment of the present invention, the first and second flexible sealing elements each have a single-layer or multi-layer bellows. The bellows is preferably made of metal or alternatively of a plastics material. The first bellows is preferably secured by a first end directly to the closure element and by the other end to a housing component of the gas injector. In metal bellows, for example, the securing can be accomplished by way of a welded joint.
Preferably, according to an example embodiment of the present invention, a gas path of the gaseous fuel is provided in a region between a valve housing of the gas injector and an actuator housing of the gas injector. As a result, the actuator can be arranged in a housing and can be preassembled at least in part as an assembly. The lubricant chamber can thus also be arranged in the interior of the actuator housing in a relatively simple manner.
Alternatively, the gas path of the gaseous fuel is formed by a region of the solenoid actuator, in particular by the coil chamber in which the coil of the solenoid actuator is arranged. A separate actuator housing for the solenoid actuator can thus be omitted. Particularly preferably, an electrical contact is then guided through the gas path of the gaseous fuel. As a result, in particular the complexity of the construction of the gas injector can be reduced. It should be noted that the electrical contact guided through the gas chamber of course has to be sealed from the exterior.
More preferably, according to an example embodiment of the present invention, a filter is arranged in the gas path for the gaseous fuel in order to filter out any solids particles present in the gaseous fuel or to filter out any production-related or assembly-related solids particles. More preferably, a guide component is also provided on the closure element, in particular when the closure element is a long valve needle.
According to an example embodiment of the present invention, the gas injector is preferably an injector that opens outward. More preferably, the gas injector is compressive force-balanced. The force for opening the gas injector using the solenoid actuator is thus independent of the gas pressure. The time needed for opening and closing the injector after current begins to be applied and after the current supply is stopped, respectively, is thus also independent of the gas pressure. In turn, this allows for operation at various gas pressures. The gas pressure can be reduced when the injection volume is intended to be low, and the gas pressure can be increased when the injection volume is intended to be high. The injector is compressive force-balanced when the average diameter of the bellows is equal to the diameter of the seat contact line between the closure element and the valve body. However, the average bellows diameter can also be configured to be smaller or larger than the seat diameter. In the first case, the overall closure force on the valve needle is reduced at relatively high gas pressures, and the injector opens more quickly when current is applied and closes more slowly after the current supply is stopped. This results in a greater gas injection volume. In the second case, the closure force on the valve needle is increased at relatively high gas pressures. In turn, this can compensate for an increase in the seat leakage volume owing to the higher gas pressure.
Preferably, according to an example embodiment of the present invention, restoring is carried out by way of a restoring spring. In a pressure-balanced injector, when the gas injector is in the closed state there is in particular no compressive force on the valve needle from the gaseous fuel, and so the load on the closure element can be significantly reduced.
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the figures.
Hereinafter, a gas injector 1 according to a first preferred exemplary embodiment of the present invention will be described in detail with reference to
As can be seen from
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.
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.
Reference numeral 10 denotes a restoring element for the closure element 3 for restoring said closure element back into the closed state shown in
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
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
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.
As can be seen from
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.
As can also be seen from
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.
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 1×105 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.
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.
As can be seen from
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.
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 (
In this case, the brake pin 60 is guided in the guide member 18. As can also be seen from
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
As can also be seen from
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.
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
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.
Selecting a diameter and/or a length of the choke 63 can adjust the damping behavior in a specific manner for each gas injector.
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.
In this case, the gas injector 1 shown in
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
Otherwise, the second exemplary embodiment corresponds to the first exemplary embodiment, and so reference should be made to the description in relation thereto.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 200 689.2 | Dec 2021 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/085484 | 12/13/2021 | WO |
