Gas injector for an internal combustion engine

Abstract

The invention relates to a gas injector for an internal combustion engine, comprising a housing (1) and an injector valve needle (3) arranged displaceably therein along its longitudinal axis (2) for introducing and metering the gas flow into the combustion chamber of the internal combustion engine, characterized in that the injector valve needle (3) is linearly guided at at least one bearing point (11, 12) by balls (13, 14) arranged axially circumferentially in a recirculating ball guide (16, 17). The invention further relates to a gas injector for an internal combustion engine, comprising a housing (1) and an injector valve needle (3) arranged displaceably therein along its longitudinal axis (2) for introducing and metering the gas flow into the combustion chamber of the internal combustion engine, characterized in that the injector valve needle (3) is guided at two bearing points (11, 12) by rolling elements (32, 33) arranged in a linear guide (30, 31, 35, 36, 38, 39).

Description

[0001] The invention relates to a gas injector for an internal combustion engine according to the type defined in more detail in the preamble of claim 1 or 7.

[0002] DE 10 2021 203 740 A1 discloses a gas injector for injecting a gaseous medium, in particular for injecting hydrogen. The gas injector comprises a closing element with an elongated valve needle and an actuator. The closing element further comprises a first needle guide and a second needle guide. Further injectors are known from DE 10 2022 204 538 A1 and DE 10 2014 206 969 A1.

[0003] The invention is therefore based on the object of proposing a gas injector of the aforementioned type in which wear during operation is reduced in a structurally simple and cost-effective manner.

[0004] The problem is solved by the features of claim 1 and alternatively by the features of claim 7. Further advantageous and claimed embodiments emerge from the respective subclaims, the description, and the drawings.

[0005] Accordingly, a gas injector for an internal combustion engine is proposed, comprising a housing and an injector valve needle arranged therein for displacement along its longitudinal axis for introducing and metering the gas flow into the combustion chamber of the internal combustion engine. In order to reduce wear during operation in a structurally simple and cost-effective manner, the injector valve needle is linearly guided at at least one bearing point by balls arranged axially circumferentially in a recirculating ball bearing guide.

[0006] As a result, the axially rotating balls enable precise guidance of the injector valve needle while significantly reducing friction and wear during adjustment, thus achieving high fatigue strength. This is particularly true for gas injectors operating with fast, short strokes and applications with a very high number of load cycles. Furthermore, the injector valve needle can be guided dry, eliminating the costly addition of an additional lubricant and enabling carbon-free combustion.

[0007] In a particularly preferred embodiment of the invention, a recirculating ball bushing with a plurality of recirculating ball channels evenly distributed over the circumference is provided for the ball guide of the injector valve needle. Within these channels, balls are arranged as an axially circumferentially guided row of balls. In this way, the injector valve needle, which is guided longitudinally displaceably in the recirculating ball bushing, can be arranged in linear rolling contact with the balls for the recirculating ball guide in a particularly simple manner.

[0008] Particularly advantageously, the recirculating ball bushing with its revolving balls can be inserted as a pre-assembled unit into a bore in the gas injector housing for assembly. The recirculating ball bushing is preferably pressed into the bore for fastening. Other fastening options, particularly welding, are also conceivable.

[0009] A simple arrangement of the balls in rolling contact with the injector valve needle can be achieved in that the ball circulation channels are preferably each designed with a linear support section on the inner diameter of the ball circulation bushing radially open towards the injector valve needle, so that the balls rotating on the support section are in linear rolling contact with the injector valve needle as a supporting part of the row of balls arranged in the ball circulation channels.

[0010] A simple axial return of the rotating balls to the respective support section is easily achieved if the ball circulation channels each have a ball return section connected to the respective support section and extending in the ball circulation bushing. Particularly advantageously, in the respective ball return section, the balls are returned in a revolving manner to the support section, out of contact with the injector valve needle and relieved of load.

[0011] In a further preferred embodiment of the invention, four recirculating ball channels are provided at at least one bearing point for the ball-bearing guidance of the injector valve needle. These channels are evenly distributed around the circumference of the recirculating ball bushing. In each of these channels, an axially circulating row of balls is arranged in linear rolling contact with the injector valve needle. This allows for optimal guidance of the injector valve needle with minimized friction and wear during adjustment.

[0012] A further development of the invention provides that the recirculating ball bushing comprises two bearing points at which the injector valve needle is linearly guided by balls arranged axially revolving in a recirculating ball guide.

[0013] The object of the invention is also achieved by a gas injector with a housing and an injector valve needle arranged therein so as to be displaceable along its longitudinal axis for introducing and metering the gas flow into the combustion chamber of the internal combustion engine. The injector valve needle is guided at two bearing points by rolling elements arranged in a linear guide. The rolling contact at two bearing points ensures low-friction and precise linear guidance of the injector valve needle and is easy to implement. Furthermore, the linear guide in rolling contact with the injector valve needle can be designed dry, thus avoiding the need for complex lubricant supply.

[0014] Preferably, for the linear guidance of the injector valve needle at the bearing points, a plurality of recesses arranged uniformly distributed over the circumference are provided on the inner diameter of a bore in the housing of the gas injector, in each of which at least one rolling element is guided linearly and arranged in linear rolling contact with the injector valve needle guided longitudinally displaceably through the bore.

[0015] The guidance of the injector valve needle can be further improved and the friction and wear during adjustment can be further reduced if, for linear guidance at the bearing points, preferably at least three recesses are provided on the inner diameter of the bore, which are evenly distributed over the circumference and in which the rolling elements are arranged in linear rolling contact with the injector valve needle.

[0016] Assembly and manufacture can be simplified if, for the linear guidance of the injector valve needle, a rolling element guide bushing is preferably provided which encompasses both bearing points and has a plurality of recesses arranged at the bearing points, each evenly distributed over the circumference on the inner diameter of the rolling element guide bushing, in each of which recesses at least one rolling element is linearly guided and arranged in linear rolling contact with the injector valve needle which is guided longitudinally displaceably through the rolling element guide bushing.

[0017] Preferably, for the linear guidance of the injector valve needle, at least three recesses are provided at the bearing points, which are distributed uniformly over the circumference on the inner diameter of the rolling element guide bush, with rolling elements guided linearly in these recesses in linear rolling contact with the injector valve needle.

[0018] In another particularly preferred embodiment of the invention, for linear guidance of the injector valve needle, four recesses are provided at each of the bearing points, distributed evenly around the circumference of the inner diameter of the rolling element guide bushing, with rolling elements arranged in these recesses in rolling contact with the injector valve needle. This ensures optimal guidance of the injector valve needle with minimized friction and wear during adjustment.

[0019] In a particularly advantageous manner, the rolling element guide bushing with the circumferentially guided rolling elements can be inserted as a pre-assembled unit into a bore in the housing of the gas injector for assembly. The rolling element guide bushing is preferably pressed into the bore for fastening. Other fastening options, particularly welding, are also conceivable.

[0020] Balls are preferred as rolling elements. The use of other rolling elements, particularly cylindrical rollers, is also conceivable.

[0021] It is also particularly advantageous if the balls described above for the recirculating ball bearing guide and the rolling elements described above for the linear guide each have a diameter of less than or equal to 1 mm. This ensures a complete rotation of the rolling elements when guiding the injector valve needle, even with very small strokes and very fast switching with high acceleration, and prevents a wear-causing wobbling movement of the rolling elements at one point.

[0022] Preferably, a bearing point with a recirculating ball bearing guide or a linear guide as described above is arranged in the immediate vicinity of the valve body of the injector valve needle for the precisely metered introduction of the gas flow into the combustion chamber of the internal combustion engine. A recirculating ball bearing guide or a linear guide for the injector valve needle is preferably also provided at the other bearing point. However, it is also conceivable to form an alternative guide for the injector valve needle, in particular a sliding guide, at the other bearing point located further away from the combustion chamber of the internal combustion engine. Materials that are not resistant to high temperatures, in particular plastic coatings, can also be used in this case.

[0023] In a further preferred, particularly advantageous embodiment of the invention, rolling contact surfaces are provided in the area of ​​the bearing points on the outer diameter of the injector valve needle for rolling contact with the balls of the previously described recirculating ball bearing guide or with the rolling elements of the previously described linear guide. The rolling contact surfaces are preferably designed to reduce friction and / or be wear-resistant, for example, coated with a ceramic coating.

[0024] Alternatively or additionally, the balls or rolling elements can be designed to be friction-reducing and / or wear-resistant, for example coated with a ceramic coating or made entirely of a friction-reducing and / or wear-resistant material.

[0025] A further reduction in friction and wear during operation can be achieved in a particularly advantageous manner, preferably by separators arranged between the balls or rolling elements. This prevents direct contact between the balls or rolling elements during rolling contact guidance. The separators are preferably made of friction-reducing and / or wear-resistant material or are at least partially coated with such a material.

[0026] Further claimed features of the invention will become apparent from the following description and the drawings, which further explain the present invention. They show: Fig. 1 a sectional partial view of a gas injector according to the invention for an internal combustion engine in a first embodiment, Fig. 2 the gas injector without the injector valve needle, Fig. 3 and Fig. 4 further sectioned partial views of the gas injector, Fig. 5 an enlarged cross-section of the gas injector at a bearing point of the injector valve needle, Fig. 6 a sectional partial view of a gas injector according to the invention for an internal combustion engine in a second embodiment, Fig. 7 a cross section of a bearing point of the injector valve needle without the housing of the gas injector Fig. 6, Fig. 8 a sectional partial view of a gas injector according to the invention for an internal combustion engine in a third embodiment, Fig. 9 a sectional partial view of a gas injector according to the invention for an internal combustion engine in a fourth embodiment, Fig. 10 an enlarged cross-section of the gas injector Fig. 9 at a bearing point of the injector valve needle.

[0027] The figures show various views and embodiments of a gas injector according to the invention for an internal combustion engine by way of example.

[0028] The Fig. The gas injector illustrated in Figures 1 to 5 in a first exemplary embodiment comprises a housing 1 and an injector valve needle 3 arranged longitudinally displaceably within the housing along its longitudinal axis 2 for introducing and metering the gas flow, preferably hydrogen, into the combustion chamber of the internal combustion engine. The longitudinal axis 2 also forms the center axis of the injector valve needle 3. The injector valve needle 3 is displaceably arranged in a central axial bore 4 in the region of the needle guide housing 5, which is integrally formed with the rest of the housing 1 and offset from the latter. The housing 1 can also be constructed in multiple parts.

[0029] The injector valve needle 3 is according to Fig. 1 with a central axial needle bore 6 designed as a hollow needle for passing the gas. The gas exits through outlet openings 7 in the area of ​​the valve body 8 of the injector valve needle 3 into the bore 4 and can be metered into the combustion chamber via the valve body 8.

[0030] To actuate the injector valve needle 3, an actuating member 9 is arranged in the housing 1 and is coaxially displaceably connected to the injector valve needle 3. The actuating member 9 is preferably designed as a magnet armature of an electromagnet (not shown in detail) integrated into the gas injector. By energizing the electromagnet, the actuating member 9 can be directly controlled, and the injector valve needle 3 connected to it can be displaced into an open position for introducing the gas into the combustion chamber. To return the injector valve needle 3 to the closed position when the electromagnet is deenergized and the gas supply is interrupted, return spring means 10 are provided operatively between the actuating member 9 and the housing 1.

[0031] The injector valve needle 3 is Fig. 1 to 4 are arranged at two bearing points 11, 12 in the bore 4 in the needle guide housing 5. A first bearing point 11 is located in the immediate vicinity of the valve body 8 of the injector valve needle 3 at the free end of the needle guide housing 5 for introducing the gas into the combustion chamber ( Fig. 1). The second bearing point 12 is located in the area of ​​the end of the needle guide housing 5 facing away from the combustion chamber.

[0032] At the bearing points 11, 12, the injector valve needle 3 is linearly guided by balls 13, 14 arranged axially circumferentially in a recirculating ball guide. For ball guidance, a recirculating ball bushing 15 is inserted into the bore 4 of the needle guide housing 5. For fastening, the recirculating ball bushing 15 is preferably pressed in with its outer diameter at the inner diameter of the bore 4. Other fastening methods, particularly by welding, are also conceivable.

[0033] For assembly, the ball bearing bushing 15 can be inserted at the end of the needle guide housing 5 facing away from the combustion chamber into the section 40 of the bore 4 which is widened accordingly on the inside diameter, the widened section forming an annular shoulder 41 as an assembly stop at the end.

[0034] The ball bushing 15 comprises both bearing points 11, 12 and is Fig. 5 at each bearing point 11, 12 with preferably four ball circulation channels 16, 17 evenly distributed over the circumference, in which the balls 13, 14 arranged therein as an axially rotating row of balls are guided. The injector valve needle 3 is guided longitudinally displaceably through the ball circulation bushing 15.

[0035] The ball circulation channels 16, 17 each have a linear axially extending radially inner support section 18, 19 on the inner diameter of the ball circulation bushing 15, which is designed to be radially open towards the injector valve needle 3 ( Fig. 2 to 5), so that on the support section 18, 19 the rotating balls 13, 14, as a supporting part of the respective row of balls, are in linear rolling contact with the outer diameter of the injector valve needle 3 and can move in the direction of movement thereof.

[0036] In the area of ​​the bearing points 11, 12, a slightly radially outwardly offset annular rolling contact section with an annular rolling contact surface 28, 29 is provided on the outer diameter of the injector valve needle 3 for rolling contact with the balls 13, 14, corresponding to the support sections 18, 19. The rolling contact surfaces 28, 29 can be coated to reduce friction and / or be wear-resistant, for example, with a ceramic coating.

[0037] Connected to the respective support section 18, 19 in the radially outer direction is a ball return section 20, 21 running closed in the ball bushing 15, in which the balls 13, 14 are recirculated unloaded from the injector valve needle 3 to the support section 18, 19. The ball return section 20, 21 running concealed in the ball bushing 15 and the balls 13, 14 running in it are each in Fig. 3 with hidden body edges indicated by dashed lines.

[0038] The ball return sections 20, 21 each consist of two curved ball deflection sections 22, 23 and 24, 25, respectively, which are each connected at one end directly to an axial end of the respective support section 18, 19 and at the other end to an axially extending radially outer linear section 26, 27 ( Fig. 3 to 5). The ball deflection sections 22, 23 and 24, 25 are each designed with equal curvature and are mirror-inverted to each other, each semicircular. At the linear sections 26, 27, the rotating balls 13, 14 are relieved of the injector valve needle 3 and are axially redirected out of contact with it, opposite to its direction of movement.

[0039] In the radial plan view according to Fig. 3 and Fig. 4, the ball circulation channels 16, 17 each run semicircularly on the ball deflection sections 22, 23 and 24, 25 respectively, and the linear support sections 18, 19 and the linear sections 26, 27 run parallel to each other.

[0040] Fig. 5 shows a cross-sectional view in the area of ​​the second bearing point 12 ( Fig. 1, Fig. 3 and Fig. 4) with the radially inner linear support sections 19 arranged evenly distributed over the circumference on the inner diameter of the ball bushing 15 and the respective corresponding radially outer linear sub-sections 27 arranged for the ball return. The respective supporting sections 19 and sub-sections 27 belonging to one another are connected to one another at their respective ends by the associated ball deflection sub-sections 24 and 25, respectively, which are shown concealed by dashed lines.

[0041] The first bearing point 11 is constructed analogously with the radially inner linear support sections 18 arranged evenly distributed over the circumference and the respective corresponding radially outer linear sections 26 arranged for the ball return as well as the ball deflection sections 22 and 23 connecting them.

[0042] In the Fig. 6 and Fig. In the second exemplary embodiment of a gas injector according to the invention shown in Figure 7, in contrast to the first exemplary embodiment, the injector valve needle 3 is guided at the bearing points 11, 12 by a simple linear guide in linear rolling contact with rolling elements 32, 33. Preferably, three recesses 30, 31 are provided on the inner diameter of the bore 4, distributed uniformly around the circumference, in each of which a rolling element 32, 33 is guided and is in linear rolling contact with the injector valve needle 3, which is guided longitudinally displaceably through the bore 4. During an adjustment, the rolling elements 32, 33 can each roll on rolling contact surfaces 28, 29 formed correspondingly on the outer diameter of the injector valve needle 3. The recesses 30, 31 each preferably have a rectangular cross-sectional profile that is open on one side.

[0043] Balls are preferably provided as rolling elements 32, 33. It is also conceivable to use cylindrical rollers as rolling elements 32, 33. For further details, please refer to the description of the Fig. 1 to 5.

[0044] Fig. Figure 8 shows a third embodiment in which, in contrast to the second embodiment according to Fig. 6 and Fig. 7 for the linear guidance of the injector valve needle 3, a rolling element guide bush 34 encompassing both bearing points 11, 12 is inserted into the bore 4 in the needle guide housing 5. The rolling element guide bush 34 has at each bearing point 11, 12 at least three recesses 35, 36 distributed evenly over the circumference on the inner diameter of the rolling element guide bush 34, in each of which a rolling element 32, 33 is guided and arranged in linear rolling contact with the injector valve needle 3, which is guided longitudinally displaceably through the rolling element guide bush 34. For further design, reference is made to the description of the Fig. 1 to 7.

[0045] In Fig. 9 and Fig. 10 shows a fourth embodiment in which, for the linear guidance of the injector valve needle 3 at the bearing points 11, 12, a different arrangement is used compared to the third embodiment according to Fig. 8 modified rolling element guide bushing 37 is provided. In this case, four recesses 38, 39 are provided at the bearing points 11, 12, each evenly distributed over the circumference on the inner diameter of the rolling element guide bushing 37, in which recesses four rolling elements 32, 33 are preferably guided and each arranged in linear rolling contact with the injector valve needle 3, which is guided longitudinally displaceably through the rolling element guide bushing 37. For this purpose, the recesses 38, 39 are each designed to be extended in the axial direction, so that the recesses 38, 39 each accommodate four rolling elements 32, 33 arranged one behind the other in a row, and these can roll one behind the other on the rolling contact surfaces 28, 29 arranged correspondingly on the injector valve needle 3 for axial guidance ( Fig. 9).

[0046] Fig. 10 shows a cross-sectional view in the area of ​​one of the bearing points 11, 12 ( Fig.9) with the four recesses 38 and 39 arranged on the inner diameter of the rolling element guide bush 37 at each bearing point 11, 12, evenly distributed over the circumference. The recesses 38, 39 each preferably have a rectangular cross-sectional profile open on one side. List of reference symbols 1 housing 2 Longitudinal axis, central axis 3 Injector valve needle 4 Hole 5 Needle guide housing 6 needle bore 7 outlet openings 8 valve bodies 9 Actuator, magnetic armature 10 return spring means 11 storage location 12 storage location 13 ball, row of balls 14 balls, row of balls 15 ball bearing bushing 16 Ball recirculating channel, ball recirculating guide 17 Ball recirculating channel, ball recirculating guide 18 supporting section 19 supporting section 20 Ball return section 21 Ball return section 22 Ball deflection section 23 Ball deflection section 24 Ball deflection section 25 Ball deflection section 26 linear section 27 linear section 28 Rolling contact surface, rolling contact section 29 Rolling contact surface, rolling contact section 30 Recess, linear guide 31 Recess, linear guide 32 rolling elements, ball, cylindrical roller 33 rolling elements, balls, cylindrical rollers 34 Rolling element guide bush 35 Recess, linear guide 36 Recess, linear guide 37 Rolling element guide bush 38 Recess, linear guide 39 Recess, linear guide 40 widened section 41 Ring shoulder, assembly stop D Diameter

Claims

[1] Gas injector for an internal combustion engine, comprising a housing (1) and an injector valve needle (3) arranged therein so as to be displaceable along its longitudinal axis (2) for introducing and metering the gas flow into the combustion chamber of the internal combustion engine, characterized by that the injector valve needle (3) is guided linearly at at least one bearing point (11, 12) by balls (13, 14) arranged axially circumferentially in a recirculating ball guide (16, 17). [2] Gas injector according to claim 1, characterized by in that a ball bearing bushing (15) with a plurality of ball bearing channels (16, 17) arranged uniformly over the circumference is provided for the ball bearing guidance of the injector valve needle (3), and the balls (13, 14) arranged in these channels as an axially revolving row of balls are arranged in linear rolling contact with the injector valve needle (3) guided longitudinally displaceably through the ball bearing bushing (15). [3] Gas injector according to claim 2, characterized bythat the ball circulation channels (16, 17) are each designed with a linear support section (18, 19) on the inner diameter of the ball circulation bushing (15) radially open towards the injector valve needle (3), such that on the support section (18, 19) the rotating balls (13, 14) as a supporting part of the ball row are in linear rolling contact with the injector valve needle (3). [4] Gas injector according to claim 3, characterized by that the ball circulation channels (16, 17) each have a ball return section (20, 21) connected to the respective support section (18, 19) and extending in the ball circulation bushing (15), in which the balls (13, 14) are returned in a circumferential manner to the support section (18, 19) in a manner relieved of the injector valve needle (3). [5] Gas injector according to one of claims 2 to 4, characterized byin that for the ball-recirculating guidance of the injector valve needle (3) at at least one bearing point (11, 12) there are provided four ball-recirculating channels (16, 17) which are evenly distributed over the circumference of the ball-recirculating bushing (15), in each of which a row of balls (13, 14) guided axially circumferentially is arranged in linear rolling contact with the injector valve needle (3). [6] Gas injector according to one of claims 2 to 5, characterized by that the recirculating ball bushing (15) comprises two bearing points (11, 12) at which the injector valve needle (3) is linearly guided by balls (13, 14) each arranged axially circumferentially in a recirculating ball guide (16, 17). [7] Gas injector for an internal combustion engine, comprising a housing (1) and an injector valve needle (3) arranged therein so as to be displaceable along its longitudinal axis (2) for introducing and metering the gas flow into the combustion chamber of the internal combustion engine, characterized bythat the injector valve needle (3) is guided at two bearing points (11, 12) by rolling elements (32, 33) arranged in a linear guide (30, 31, 35, 36, 38, 39). [8] Gas injector according to claim 7, characterized by that for linear guidance at the bearing points (11, 12) at least three recesses (30, 31) are provided, which are distributed uniformly over the circumference on the inner diameter of a bore (4) in the housing (1), in each of which at least one rolling body (32, 33) is guided linearly and is arranged in linear rolling contact with the injector valve needle (3) which is guided longitudinally displaceably through the bore (4). [9] Gas injector according to claim 7, characterized byin that for the linear guidance of the injector valve needle (3), a rolling element guide bush (34) encompassing both bearing points (11, 12) is provided with at least three recesses (35, 36, 38, 39) arranged at each of the bearing points (11, 12) and distributed uniformly over the circumference on the inner diameter, in each of which at least one rolling element (32, 33) is guided linearly and is arranged in linear rolling contact with the injector valve needle (3) which is guided longitudinally displaceably through the rolling element guide bush (34). [10] Gas injector according to one of claims 1 to 9, characterized by that the balls (13, 14) used for the ball bearing guide according to one of claims 1 to 6 and the rolling elements (32, 33) used for the linear guide according to one of claims 7 to 9 each have a diameter (D) less than or equal to 1 mm.

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