Injector Integrated with Filter

Abstract

The present invention relates to an injector (1) for injecting a fluid, comprising a filter (6) for filtering the fluid to be injected, the filter (6) being arranged in a tube section (18) of the injector (1), the filter (6) having a sleeve (10) and a filter body (11), the sleeve (10) holding the filter body (11) in the tube section (18), the sleeve (10) having a fixing part (12) and a holding part (13), the fixing part (12) being connected to the filter body (11), the holding part (13) holding the sleeve (10) in the tube section (18) of the injector (1), the filter body (11) or a part of the filter body (11) being arranged only inside the fixing part (12).

Description

Technical Field

[0001] The present invention relates to an injector for an internal combustion engine for injecting a fluid, in particular a gaseous or liquid fuel, or urea or water.

Background Art

[0002] Injectors for internal combustion engines are known in various configurations from the state of the art. In the case of fuel injectors, for example, fuel is injected into the combustion chamber through a narrow passage opening. At this time, recent injectors are manufactured with extremely high precision and must be protected from damage and wear caused by particles in the fuel. For this reason, filters are usually used. At this time, it is also known to integrate the filter directly into the injector, preferably in the fuel supply area of the injector. In this way, the components of the injector can be protected from damage caused by particles in the fluid to be injected. However, this type of filter inside the injector causes undesirable flow losses. For example, in the case of a fuel injector, in order to provide a strictly accurate injection quantity, extremely narrow tolerances are imposed on the flow losses caused by the filter. However, this is not always guaranteed satisfactorily during the manufacture and assembly of the injector. In addition, due to manufacturing tolerances in particular, there is often a risk that the filter components will be damaged by excessive force.

Summary of the Invention

[0003] In contrast, the injector according to the present invention having the configuration of claim 1 has the advantage that the assembly of the injector, in particular the attachment of the filter of the injector, can be simplified, and the probability of the filter being damaged accidentally can be considerably reduced. Furthermore, the robustness of the injector can generally be improved.

[0004] According to the present invention, this is achieved by including a filter for filtering the fluid to be injected by the injector, with the filter being disposed within the pipe portion of the injector, and the filter having a sleeve and a filter body. At this time, the sleeve holds the filter body within the pipe portion. The sleeve has a fixed portion and a holding portion. The fixed portion is coupled to the filter body, and the holding portion holds the sleeve, and thus holds it within the pipe portion of the injector with respect to the filter. At this time, the filter body or a part of the filter body is disposed only inside the fixed portion of the sleeve.

[0005] In other words, the filter is formed with two parts fixedly coupled to each other, that is, preferably a filter body with a filter insert integrated therein for causing fluid filtration, and a sleeve provided for fixing the filter body within the pipe portion of the injector. At this time, in particular, the pipe portion forms a stationary member of the injector. At this time, the sleeve has two different parts, that is, a holding portion and a fixed portion. At this time, the filter body or a partial region of the filter body is disposed only inside the fixed portion with respect to the axial direction of the sleeve. That is, there is no material of the filter body inside the holding portion. Therefore, preferably, the holding portion and the fixed portion are arranged without overlapping with respect to the axial direction of the sleeve, that is, they are arranged axially separated from each other.

[0006] At that time, the special configuration of the sleeve, which is specially arranged only inside the fixed part relative to the filter body, produces the advantage of functionally separating the holding part and the fixed part. That is, by separating the holding part and the fixed part in the axial direction, these two parts can operate by optimally adapting their respective fixing functions independently of each other. Particularly advantageous in this case is that the manufacturing tolerances of the pipe part and / or the sleeve have little or no effect on the holding function of the fixed part in the filter body. Therefore, in particular, damage to the filter body due to deformation of the sleeve caused, for example, by manufacturing tolerances can be avoided. In addition, it is possible to design the sleeve such that the pressing force required to press-fit it into the pipe part depends only slightly on the various oversizes between the pipe part and the holding part due to, for example, manufacturing tolerances. In particular, this is made possible by the fact that the filter body does not limit the free deformation of the holding part.

[0007] The dependent claims show further advantageous configurations of the invention.

[0008] Advantageously, the sleeve is formed of metal, particularly preferably brass or steel. Preferably, the sleeve is a deep-drawn member. Thereby, the sleeve can be manufactured particularly simply and cost-effectively. In addition, the desired mechanical properties of the holding part can be adapted particularly flexibly and precisely, for example, by a corresponding adaptation of the wall thickness of the sleeve in order to ensure optimal deformation properties.

[0009] Preferably, the filter body is formed of plastic. Advantageously, the filter body is an injection-molded member. Thereby, the filter body can also be formed particularly simply, cost-effectively, and with a flexible geometric form.

[0010] Particularly advantageously, the filter body is at least partially cast into the fixed part, by which the fixed part of the sleeve and the filter body are joined to each other. In this case, in particular, the filter body is cast into the fixed part on the inner surface of the fixed part. Thus, at least the holding part of the sleeve projects beyond the filter body in the axial direction. Thereby, a functional separation between the holding part and the fixed part can be ensured particularly easily.

[0011] Even more advantageously, a press connection is formed between the holding part and the pipe part. In this case, the press connection causes the fixing of the filter inside the pipe part. Thus, it is ensured that the axial separation of the holding part and the fixed part of the sleeve does not cause a strong mechanical load on the filter body. This is preferably ensured by the holding part being formed such that it can plastically deform, especially when the sleeve has a larger oversize compared to the pipe part. For this reason, in particular, the press force is substantially independent of the oversize, and thus a reliable and optimally sized press connection is always ensured even when the manufacturing tolerances are relatively large.

[0012] Preferably, the holding part extends over at least 10%, maximally 40%, preferably 20% of the total axial length of the sleeve. Particularly advantageously, when the total axial length of the sleeve is 3 mm, the holding part has an axial length of 0.6 mm. Thereby, the holding part forms only a relatively small area of the sleeve, which particularly advantageously affects the easy installation of the sleeve in the pipe part of the injector, and thus the easy installation of the filter.

[0013] Particularly advantageously, the holding part has an outer diameter larger than that of the fixed part and the filter body. That is, the holding part forms the maximum outer diameter of the entire filter. Thus, the mechanical contact between the filter and the pipe part of the injector is exclusively in the area of the holding part.

[0014] Advantageously, the sleeve further has a connecting portion that connects the fixing portion and the holding portion to each other. That is, there is a connecting portion between the fixing portion and the holding portion, and thus the connecting portion creates an additional axial spacing between the holding portion and the fixing portion. There is no filter body material inside the connecting portion, as is the case with the holding portion. In addition, the connecting portion can be used as a guide when inserting the filter into the tube portion of the injector, providing for easy installation.

[0015] Preferably, at least a part of the connecting portion expands radially in the direction of the holding portion. For example, at least a part of the connecting portion may be formed to expand conically. This is particularly advantageous because the connecting portion can be used as a guide when inserting the filter into the tube portion. In addition, the deformability of the sleeve can be adapted, for example, by the length and / or degree of expansion of the connecting portion.

[0016] Particularly advantageously, the holding portion has a wall thickness of at least 0.1 mm to at most 0.5 mm, preferably at least 0.2 mm to at most 0.3 mm. In particular, the entire sleeve has a wall thickness of at least 0.1 mm to at most 0.5 mm over its entire axial length, preferably at least 0.2 mm to at most 0.3 mm. That is, the holding portion, and in particular the entire sleeve, is formed with a relatively thin wall, which enables reliable fixing and can easily and cost-effectively make the pressing force in the holding portion relatively small even when the oversize is relatively large.

[0017] Advantageously, the injector further includes a closing element for opening and closing at least one passage opening provided in the sealing seat, a return element installed to act on the closing element with a return force and a closing force for return, and an injector sleeve disposed at an operative coupling portion between the filter and the return element in the axial direction of the injector. At this time, the return element is directly or indirectly supported by the injector sleeve. At this time, the final axial position of the return element is determined by the position of the filter mounted in the injector. This is because the position of the filter also determines the position of the injector sleeve that directly or indirectly supports the return element. Particularly advantageously, the sleeve is a stationary member in the injector, i.e., it is held in the pipe portion using a press fit. A particular advantage lies in the fact that the filter can be mounted in the injector as the last component, so that, for example, damage or geometric displacement of the filter due to further mounting steps such as plastic coating of the injector does not occur.

[0018] Advantageously, the injector sleeve is in direct contact with the return element and in direct contact with the filter. Thereby, the number of components is kept as small as possible and rapid and simple assembly is made possible. Further, this avoids the addition of manufacturing tolerances having an undesirable effect on the final position of the injector sleeve and thus on the pre-tensioning force of the return element.

[0019] The filter body, particularly the entire filter, is particularly advantageously formed in a pot shape with a bottom region and a side region, and in this case the bottom region is arranged in the direction of the injector sleeve. This enables a robust structure of the injector, and the filter mounting tool can be positioned particularly inside the pot-shaped filter, thereby additionally contributing to the reinforcement of the filter during mounting.

[0020] The filter preferably does not have filter slots in the bottom region. Thus, the bottom region is preferably made of solid material, which further improves the rigidity of the filter. In this case, fuel flows into the pot-shaped filter and then passes through the filter via the filter slots provided in the side region.

[0021] More preferably, at least one slit, in particular two slits, is provided in the bottom region of the filter in order to provide a fluid connection to the inner region of the sleeve. Both slits are preferably arranged opposite each other.

[0022] Preferably, the present invention further relates to a method of assembling an injector comprising a closing element, a return element, an injector sleeve and a filter. In this case, in one assembly step, the filter is installed into the injector as follows, that is, the installation position of the filter also defines the installation position of the injector sleeve, and the pre-tension of the return element relative to the closing element is defined within the closed injector, and the filter is installed into the injector. Therefore, depending on the positioning of the filter, the return force of the return element and the closing force on the closing element can be adjusted.

[0023] In this case, the step of installing the filter is preferably the last assembly step when assembling the injector. In particular, if the injector has a plastic coating part for an electrical plug or the like, the last step for manufacturing the injector is the installation of the filter.

[0024] Particularly preferably, the installation of the filter in the injector is carried out using a stepped installation tool. The stepped installation tool preferably has first and second cylindrical regions with different diameters. In this case, the first cylindrical region is arranged within the inner space of the filter, and the second cylindrical region is arranged at the end of the filter opposite to the bottom region, in particular at the holding part of the sleeve of the filter. Thereby, damage-free installation of the filter can be guaranteed.

[0025] Next, the present invention will be described using one embodiment in relation to the drawings. In the drawings, functionally identical components are denoted by the same reference numerals.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0027] Next, with reference to FIGS. 1 to 5, the injector 1 according to an advantageous embodiment of the present invention will be described in detail.

[0028] The injector 1 is an injector for injecting a fluid, and in the present embodiment, it is formed as a fuel injector for injecting gaseous fuel into the combustion chamber of an internal combustion engine.

[0029] The injector 1 includes a closing element 2 for opening and closing a plurality of passage openings 3. At this time, the closing element 2 performs sealing at a sealing seat 4 provided at the first end of the injector 1.

[0030] The injector 1 further includes a return element 5, and the return element is installed to provide a return force F to the closing element 2 when the injector 1 is open and to provide a closing force for holding the injector 1 in a closed state. As is clear from FIG. 1, the closing element 2 is a hollow valve needle 2a having a sphere 2b that performs sealing at the sealing seat 4.

[0031] Figure 1 shows the closed state of the injector.

[0032] Furthermore, the injector 1 includes an injector sleeve 7 for flowing fuel in the direction of the closing element 2 and a filter 6.

[0033] Details of the filter 6 are apparent from FIGS. 2 to 4. The filter 6 basically has a filter body 11 in a pot-like form and includes a bottom region 60 and a side region 61.

[0034] As is apparent from FIG. 1, the filter 6 is arranged such that the bottom region 60 is directed in the direction of the closing element 2. As a result, fuel flows into the interior of the pot-like filter at the supply end of the injector 1 and flows out of the filter 6 through the side region 61 where the filter cloth is arranged. Therefore, if the fuel contains solid substances, the filter 6 can filter the fuel when it enters the injector 1 and collect it in the pot-like interior of the filter 6.

[0035] The filter 6 has a sleeve 10 and a filter body 11. The filter body 11 is an injection-molded member formed of plastic. An integrated filter element 17, such as a net-like one, is provided in the filter body 11 to filter the fluid to be injected.

[0036] The sleeve 10 is a tubular deep-drawn member formed of metal, such as brass or steel.

[0037] At this time, the sleeve 10 has a holding portion 13 at the upper end in the axial direction of the sleeve 10. At this time, the holding portion 13 is provided to hold the sleeve 10 by the pipe portion 18 of the injector 1 (see FIG. 1). For this reason, the holding portion 13 of the sleeve 10 has the maximum outer diameter of the entire filter 6. As a result, when arranged inside the pipe portion 18 as shown in FIG. 1, only the holding portion 13 is in contact with the inner wall of the pipe portion 18.

[0038] At that time, the holding portion 13 of the sleeve 10 is formed such that a press joint is formed between the holding portion 13 and the pipe portion 18 in the attached state of the filter 6. For this reason, the holding portion 13 is formed to be oversized compared to the pipe portion 18. In this way, the filter 6 is fixed inside the pipe portion 18 by the press joint.

[0039] The sleeve 10 further has a fixing portion 12 coupled to the filter body 11. At that time, the fixing portion 12 and the filter body 11 are coupled to each other by the filter body 11 being cast into the fixing portion on the inner surface 12a of the fixing portion 12 (see particularly FIG. 3). That is, the filter body 11 is inside the fixing portion 12 of the sleeve 10.

[0040] Moreover, between the fixing portion 12 and the holding portion 13, there is a coupling portion 14 that couples the fixing portion 12 and the holding portion 13 to each other. At that time, a part of the coupling portion 14 that abuts on the holding portion 13 is formed to expand conically. Thereby, the coupling portion 14 is also used for centering and guiding when the filter 6 is pushed into the pipe portion 18.

[0041] At that time, there is no material in the holding portion 13 and the coupling portion 14, that is, the inside is completely hollow. In other words, some portions of the filter body 11 are only inside the fixing portion 12, particularly when observed with respect to the axial direction X-X. In this case, the remaining portion of the filter body 11 extends downward beyond the fixing portion 12. Thereby, the holding portion 13 can be freely deformed radially inward when being press-fitted into the pipe portion 18 of the injector 1, and the filter body 11 is not mechanically strongly loaded.

[0042] Therefore, there is an axial separation between the holding part 13 and the fixed part 12, whereby a functional separation between the holding part 13 and the fixed part 12 is achieved. Thereby, when the sleeve 10 is press-fitted into the pipe part 18 using the holding part 13, the holding part 13 can be deformed freely, and there is an advantage that the filter body 11 does not need to be deformed together. Thereby, for example, damage to the filter body 11 due to excessive pressurization can be avoided.

[0043] A particularly advantageous structure of the sleeve 10 is achieved by a relatively thin-wall configuration. For this reason, the entire sleeve 10 has a wall thickness of 0.2 mm.

[0044] Due to the thin-wall configuration of the sleeve 10, it is achieved that the holding part 13 undergoes plastic deformation when it is pressurized. In this case, substantially the same pressing force is generated even when the tolerance between the holding part 13 and the pipe part 18 is relatively large. This is schematically illustrated in FIG. 5 in connection with this.

[0045] Note that FIG. 5 is a graph 50 showing the course of the press-fitting force depending on the oversize between the holding part 13 of the filter 6 and the pipe part 18 of the injector 1. At that time, the axis 51 indicates the oversize, that is, the difference between the outer diameter of the holding part 13 and the inner diameter of the pipe part 18, and the axis 52 indicates the press-fitting force.

[0046] The minimum state when designing the press connection to be achieved is characterized by the dashed lines 53 and 54. At that time, the oversize 53 gives at least the necessary oversize, and the press-fitting force 53 gives the corresponding minimum press-fitting force generated in this case. This minimum press-fitting force is at least present when designing the holding part 13 in consideration of the manufacturing tolerance.

[0047] As can be seen in FIG. 5, the actually generated press-fitting force 55 rises only slightly when the oversize is relatively large. That is, if the manufacturing tolerance is relatively large, and thus if the oversize is relatively large, the actually generated press-fitting force 55 only slightly exceeds the designed state.

[0048] Subsequently, for a particularly targeted design and for easy assembly, the holding part 13 is formed to be relatively short. Specifically, the holding part 13 extends over approximately 20% of the total axial length 20 of the sleeve 10 in the axial direction X-X (see FIG. 3). As a result, the contact surface on the sleeve 10 used for press fitting is relatively small, which enables particularly easy attachment of the filter 6. In contrast, the fixing part 12 preferably extends over at least 30%, particularly advantageously up to 50%, of the total axial length 20 of the sleeve 10.

[0049] The injector 1 further includes an actuator 9, which is a magnetic actuator in this embodiment. Also, a plastic coating part 16 is provided, and the plastic coating part is installed for the placement of an electrical plug (not shown) to supply electricity to the actuator 9.

[0050] At this time, the function of the injector 1 is as follows. That is, when the actuator 9 is energized, the closing element 2 is pulled in the direction of the stationary member 8 inside the injector against the spring force of the return element 5. In this case, the sphere of the closing element 2 is separated from the sealing seat 4, and fuel can flow out through the passage opening 3.

[0051] The flow path of the fuel when the injector is open is indicated by arrows A to E in FIG. 1. The fuel flows into the pot-shaped interior of the filter 6 and flows out of the filter 6 through the side region 61 (arrow B), thereby performing the filtering process. The fuel further flows as suggested by arrow C and flows into the interior of the injector sleeve 7, and then into the interior of the hollow closing element 2 by the cylindrical return spring 5. At this time, the closing element 2 has a side opening 2c in the end region facing the sealing seat 4, and a second filter 15 is arranged in this side opening, so the fuel can flow out from the interior of the closing element 2 as suggested by arrow E. When the closing element 2 is separated from the sealing seat 4 at this time, the fuel flows into the passage opening 3 through the side of the sphere of the closing element 2.

[0052] To ensure the reliable and accurate function of the injector 1, the force F of the return element 5 for returning the closing element 2 to the closed starting state and the closing force of the return element 5 for holding the closing element 2 in the closed state by the sealing seat 4 must also be accurately adjusted. At this time, as is clear from FIG. 1, the return element 5 is supported at the first end by a step portion 2d provided on the closing element 2 and is directly supported by the injector sleeve 7 at the second end. Thereby, the position of the injector sleeve 7 determines both the closing force and the return force of the return element 5. In this case, a press fit portion 70 is provided between the injector sleeve 7 and the stationary member 8. At this time, the adjustment of the position of the injector sleeve 7 in the axial direction X-X is performed using the filter 6.

[0053] As is clear from FIGS. 2 and 4, two wide slits 63 are formed opposite to each other in the bottom region 60 of the filter body 11 of the filter. At this time, the slits 63 are used to introduce the filtered fuel into the injector 1 so that the entire assembly process of the injector 1 can be carried out. Therefore, for example, no undesirable changes in the filter, and thus no change in the flow rate in some cases, will occur during the manufacture of the plastic coating portion 16 or subsequent assembly steps.

Explanation of reference numerals

[0054] 1 Injector 2 Closing element 3 Passage opening 4 Sealing seat 5 Return element 6 Filter 7 Injector sleeve 10 Sleeve of the filter 11 Filter body 12 Fixed portion of the sleeve 12a Inner surface of the fixed portion 12 13 Holding portion of the sleeve 14 Connecting portion of the sleeve 18 Pipe portion of the injector Total axial length of the 20 sleeves 60 Bottom region of the filter 61 Side region of the filter 63 Slit Axial direction of the X-X injector

Claims

1. An injector for injecting the fluid, comprising a filter (6) for filtering the fluid to be injected, - the filter (6) is arranged in a pipe portion (18) of the injector (1), - the filter (6) has a sleeve (10) and a filter body (11), - the sleeve (10) holds the filter body (11) within the pipe portion (18), - the sleeve (10) has a fixing portion (12) and a holding portion (13), - the fixing portion (12) is coupled to the filter body (11), - the holding portion (13) is located upstream of the fixing portion (12) in the fluid flow path, - of the fixing portion (12) and the holding portion (13), only the holding portion (13) holds the sleeve (10) within the pipe portion (18) of the injector (1), - the filter body (11) is not arranged inside the holding portion (13) nor on the outer surface side of the holding portion (13), - a part of the filter body (11) is arranged only inside the fixing portion (12) Injector.

2. The injector according to claim 1, wherein the sleeve (10) is formed of metal and is a deep drawing member.

3. The injector according to claim 1 or 2, wherein the filter body (11) is formed of plastic and is an injection molding member.

4. The injector according to claim 1 or 2, wherein the filter body (11) is cast at least partially into the fixing portion (12), whereby the fixing portion (12) and the filter body (11) are coupled to each other.

5. The injector according to claim 1 or 2, wherein a press fit is formed between the holding portion (13) and the pipe portion (18).

6. The injector according to claim 1 or 2, wherein the holding portion (13) extends over any one of 10% to 40% of the total axial length (20) of the sleeve (10).

7. The injector according to claim 1 or 2, wherein the holding portion (13) has an outer diameter larger than that of the fixing portion (12) and the filter body (11).

8. The injector according to claim 1 or 2, wherein the sleeve (10) further has a connecting portion (14) that connects the fixing portion (12) and the holding portion (13) to each other.

9. The injector according to claim 8, wherein at least a part of the connecting portion (14) expands radially in the direction of the holding portion (13).

10. The injector according to claim 1 or 2, wherein the holding portion (13) has a wall thickness of at least 0.1 mm and at most 0.5 mm.

11. Furthermore, - a closing element (2) for opening and closing at least one passage opening (3) provided in the sealing seat (4); - a return element (5) installed to press the closing element (2) against the sealing seat (4) in a sealed manner by applying a return force and a closing force for return to the closing element (2); - an injector sleeve (7) disposed at an action coupling portion between the filter (6) and the return element (5) in the axial direction (X-X) of the injector; comprising - the return element (5) is supported by the injector sleeve (7); - the final axial position of the return element (5) is determined by the position of the filter (6) in the injector (1). The injector according to claim 1 or 2.

12. The injector according to claim 11, wherein the injector sleeve (7) is in direct contact with the return element (5) and in direct contact with the filter (6).

13. The injector according to claim 11, wherein the filter body (11) of the filter (6) is formed in a pot shape with a bottom region (60) and a side region (61), and the bottom region (60) is arranged in the direction of the injector sleeve (7).

14. The injector according to claim 13, wherein the bottom region (60) is composed of a solid material.

15. The injector according to claim 13, wherein the bottom region (60) of the filter (6) has at least one slit (63) to provide a fluid connection from the outer region of the filter (6) to the inner region of the injector sleeve (7) for the fluid to be injected.

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