DE102024200265A1 - roller tappet - Google Patents

Abstract

Roller tappet (40) for a pump (1), in particular a high-pressure pump (1) for a high-pressure injection system for a motor vehicle for supporting a reciprocating pump piston (12) on a drive shaft (14), comprising a tappet body (8) for supporting a roller (46), a hollow-cylindrical roller (46), a bearing pin (52) arranged within the hollow-cylindrical roller (46) for supporting the roller (46), such that a radial bearing gap (38) is formed between the roller (46) and the bearing pin (52), a first lubricant channel (11a) formed in the tappet body (8) for supplying a lubricant to a first axial end region (29) of the roller (46) and/or the bearing pin (52), a second lubricant channel (11b) formed in the tappet body (8) for supplying a lubricant to a second axial end region (31) of the Roller (46) and/or the bearing pin (52), wherein the roller tappet (40) comprises a movable actuator (2) for changing the flow cross-sectional area of the first and/or second lubricant channel (11a, 11b) in order to achieve a reliable supply of the volume flow (Q1) of lubricant conducted through the first lubricant channel (11a) and the volume flow (Q2) of lubricant conducted through the second lubricant channel (11b).

Description

The present invention relates to a roller tappet for a pump according to the preamble of claim 1, a pump according to the preamble of claim 14 and an internal combustion engine according to the preamble of claim 15.

State of the art

In high-pressure injection systems for internal combustion engines, particularly in common-rail injection systems of diesel or gasoline engines, a high-pressure pump continuously maintains the pressure in the high-pressure accumulator of the common-rail injection system. The high-pressure pump can, for example, be driven by a camshaft of the internal combustion engine via a drive shaft. To pump the fuel to the high-pressure pump, pre-feed pumps, e.g., a gear or rotary vane pump, are used, which are connected upstream of the high-pressure pump. The pre-feed pump is driven by a mechanical coupling to a crankshaft depending on the speed of the internal combustion engine or electrically by an electric motor independently of the speed of the internal combustion engine. The pre-feed pump pumps the fuel from a fuel tank through a fuel line to the high-pressure pump.

Piston pumps, among others, are used as high-pressure pumps. A drive shaft is mounted in a pump housing. Pump pistons are arranged radially in cylinder bores. A drive shaft for the high-pressure pump is designed as a polygon or with at least one cam. A roller with a roller rolling surface, mounted in a roller shoe, rests on the drive shaft with at least one cam.

The roller shoe is connected to the pump piston, forcing the pump piston to perform an oscillating translational movement. A spring applies a force to the roller shoe directed radially toward the drive shaft, maintaining constant contact with the drive shaft. The roller's rolling surface is in contact with the drive shaft via a shaft rolling surface, the surface of the drive shaft, with at least one cam. The roller is mounted in the roller shoe by means of a plain bearing.

A roller tappet of the high-pressure pump comprises a tappet body and the idler roller. The tappet body is designed in two parts with the roller shoe and a tappet part or in one part. The hollow cylindrical idler roller is mounted on a bearing pin. A radial bearing gap occurs between the bearing pin and the idler roller. In addition, an axial bearing gap occurs between the idler roller and the bearing pin on the one hand and the roller shoe on the other. The axial bearing gap and the radial bearing gap are supplied with lubricant via a first lubricant channel and a second lubricant channel. The first lubricant channel has a first outlet opening and the second lubricant channel has a second outlet opening. An axial movement of the idler roller and the bearing pin due to axial play changes the hydraulic flow resistance of the lubricant at the first and second outlet openings. This changes the volume flow Q1 of lubricant that is discharged through the first outlet opening and the volume flow Q2 of lubricant that is discharged through the second outlet opening. With a small first axial distance between the first outlet opening and the roller and/or bearing pin, the first outlet opening is essentially closed, so Q1 is very small and Q2 is very large. This leads to uneven lubrication and thus unreliable lubrication of the radial bearing gap and the axial bearing gap, resulting in high mechanical wear and a resulting short service life of the roller tappet and the pump.

The DE 10 2012 223 413 A1 discloses a roller tappet for a pump, in particular a high-pressure fuel pump. The roller tappet is guided in a receptacle in the direction of its longitudinal axis and is driven in a reciprocating movement by a drive device. The roller tappet has a tappet part in which a roller is rotatably mounted, via which roller the roller tappet is supported on the drive device. The tappet part has at least one passage that connects an inner region of the tappet part, in which the bearing of the roller is arranged, to the outer casing of the tappet part. In at least one circumferential region of the tappet part adjacent to an end face of the roller pointing in the direction of its axis of rotation, at least one groove extending in the direction of the longitudinal axis of the roller tappet is provided in the inner casing of the tappet part, into which groove the at least one passage opens.

The DE 10 2018 214 200 A1 shows a roller tappet for a pump, in particular a high-pressure pump of a fuel injection system, for supporting a liftable pump piston on a drive shaft, in particular a cam, wherein the roller tappet is guided in a receptacle of a pump housing, comprising a tappet body and a hollow cylindrical roller, which is partially received in a front-side recess of the tappet body and is rotatably mounted directly or indirectly on a bearing pin, so that between the roller and the A radial bearing gap is formed between the bearing pin and the tappet body, which can be supplied with a lubricant via at least one passage formed in the tappet body and opening into the recess. The tappet body is constructed in several parts and comprises a roller shoe and a sleeve-shaped tappet part. The roller shoe is inserted into the tappet part in the direction of a longitudinal axis, and the bearing pin is held at least indirectly in the roller shoe. The passage is formed in both components, the roller shoe and the tappet part.

Disclosure of the invention

Advantages of the invention

A roller tappet according to the invention for a pump, in particular a high-pressure pump for a high-pressure injection system for a motor vehicle for supporting a pump piston that can be moved in a reciprocating manner on a drive shaft, comprising a tappet body for supporting a roller, a hollow-cylindrical roller, a bearing pin that is arranged within the hollow-cylindrical roller shell-shaped roller for supporting the roller, so that a radial bearing gap is formed between the roller and the bearing pin, a first lubricant channel formed in the tappet body for supplying a lubricant to a first axial end region of the roller and/or the bearing pin, a second lubricant channel formed in the tappet body for supplying a lubricant to a second axial end region of the roller and/or the bearing pin, wherein the roller tappet, in particular the tappet body, comprises a movable actuator for changing the flow cross-sectional area of the first and/or second lubricant channel in order to ensure a reliable supply of the volume flow Q1 of lubricant conducted through the first lubricant channel and the volume flow Q2 of lubricant conducted through the first lubricant channel and to reach the volume flow Q2 of lubricant directed through the second lubricant channel.

In a further embodiment, the first lubricant channel has a first outlet opening as one end of the first lubricant channel and the second lubricant channel has a second outlet opening as one end of the second lubricant channel.

In an additional variant, the flow cross-sectional area of the first and/or second lubricant channel can be changed in the flow direction of the lubricant upstream of the first and/or second outlet opening using the movable actuator, in particular the flow cross-sectional area of the first and/or second lubricant channel can be changed by at least 5%, 10%, 30% or 50%.

In a supplementary embodiment, the flow cross-sectional area of the first lubricant channel and the second lubricant channel can be changed simultaneously using the movable actuator.

Preferably, the flow cross-sectional area of the first lubricant channel and the second lubricant channel can be changed by the movable actuator in such a way that when the flow cross-sectional area of the first lubricant channel is increased, the flow cross-sectional area of the second lubricant channel can be reduced and vice versa.

In a further embodiment, the flow cross-sectional area of the first lubricant channel and the second lubricant channel can be changed by the movable actuator such that the flow cross-sectional area of the first lubricant channel is substantially, in particular with a deviation of less than 30%, 20% or 10%, indirectly proportional to the flow cross-sectional area of the second lubricant channel.

In a further variant, the tappet body is made up of several parts with a roller shoe for supporting the roller and a tappet part or is designed as a single part.

In a supplementary embodiment, the actuating element is designed as one, in particular only one, actuating piston.

In a supplementary embodiment, a bore is formed in the tappet body, in particular in the roller shoe, and the actuating piston is movably mounted in this bore as a sliding bearing.

The actuator expediently has a first axial end region and a second axial end region, and the first axial end region can be subjected to a first pressure force by the hydrostatic pressure of the lubricant in the first lubricant channel, and the second axial end region can be subjected to a second pressure force by the hydrostatic pressure of the lubricant in the second lubricant channel, and the first and second pressure forces are directed opposite to one another.

In a supplementary variant, the actuator can be moved into different positions by changing the amount of the first and/or second pressure force due to a change in the volume flow of lubricant conducted through the first and/or second lubricant channel.

In an additional embodiment, the roller and the bearing pin are mounted on the tappet body with an axial play as an axial bearing gap and the first and second outlet opening are aligned with the roller and/or the bearing pin in the direction of the rotational axis of the roller, so that a first axial distance in the direction of the rotational axis of the roller is formed between the first outlet opening and a first axial end of the roller and/or the bearing pin and a second axial distance in the direction of the rotational axis of the roller is formed between the second outlet opening and a second axial end of the roller and/or the bearing pin.

Preferably, the flow resistance of the volume flow of lubricant that can be conducted through the first outlet opening depends on a first axial distance in the direction of the axis of rotation of the roller between the first outlet opening and the roller and/or the support bolt and the greater this first axial distance, the smaller the flow resistance and vice versa and the flow resistance of the volume flow of lubricant that can be conducted through the second outlet opening depends on a second axial distance in the direction of the axis of rotation of the roller between the second outlet opening and the roller and/or the support bolt and the greater this second axial distance, the smaller the flow resistance and vice versa and the sum of the first and second distance is substantially constant, in particular with a deviation of less than 30%, 20% or 10%.

Pump according to the invention, in particular a high-pressure pump for a high-pressure injection system for a motor vehicle, comprising a pump piston, a housing with a cylinder bore, a roller tappet, and the pump piston is supported with the roller tappet on a drive region, in particular a drive shaft, wherein the roller tappet is designed as a roller tappet described in this patent application.

Internal combustion engine according to the invention with a high-pressure injection system, the high-pressure injection system comprising a high-pressure pump for conveying fuel to a high-pressure rail, a high-pressure rail, a pre-feed pump, a metering unit, wherein the high-pressure pump is designed as a high-pressure pump described in this patent application.

In a supplementary variant, the roller tappet is guided and/or mounted in a receptacle of a pump housing.

In a further embodiment, the high-pressure injection system comprises an overflow valve.

In particular, the drive area of the pump is formed by a drive shaft with at least one cam and/or a crank drive.

In a further embodiment, the internal combustion engine comprises a lubricating oil pump for conveying lubricating oil as a lubricant to a crankshaft of the internal combustion engine and an opening of the tappet part and/or into the first and second lubricant channels of the roller tappet.

In a supplementary variant, the actuator can perform a translational movement and/or a rotational movement based on the first pressure force and/or the second pressure force. A translational movement is possible, for example, with a straight bore for the actuating piston, and a rotational movement is possible with a curved bore for the actuating piston.

In an additional embodiment, the bore for supporting the actuator connects the first lubricant channel to the second lubricant channel, and a leakage volume flow of lubricant can be conducted through this bore from the first lubricant channel to the second lubricant channel, or vice versa, depending on the pressure of the lubricant in the first lubricant channel and the second lubricant channel. The actuator, in particular the actuating piston, which is mounted in the bore, is not completely sealed for technical reasons, so that a leakage volume flow of lubricant can be conducted through this bore.

In an additional embodiment, the tappet body, in particular the roller shoe and/or the tappet part, and/or the roller and/or the bearing pin are at least partially, in particular completely, made of plastic and/or metal, in particular steel and/or aluminum and/or at least one non-ferrous metal and/or brass and/or bronze.

In a further embodiment, the at least one recess is designed as a sliding bearing in the roller shoe for the bearing pin and/or the roller in a section perpendicular to the axis of rotation of the roller as a circular segment with an angle greater than 180° or greater than 190°, for example 200°.

In an additional embodiment, the roller is partially accommodated and/or mounted in a recess of the tappet body.

Preferably, the roller is rotatably mounted directly or indirectly on a bearing pin.

In a further embodiment, the tappet body is one-piece with the function of a roller shoe for supporting the roller and the function of the tappet part.

In a further variant, the volume flow of the entire lubricant introduced into the roller tappet, in particular the tappet body and/or the roller, is essentially constant, in particular with a deviation of less than 30%, 20% or 10%, in particular by means of a lubricant pump controlled essentially with a constant volume flow.

In a further variant, the sum of the volume flow (Q1 and Q2) of lubricant discharged from the first and second outlet opening is essentially constant, in particular with a deviation of less than 30%, 20% or 10%, in particular by means of a lubricant pump controlled essentially with a constant volume flow.

In a further embodiment, the first outlet opening is formed from a plurality of first partial outlet openings and/or the second outlet opening is formed from a plurality of second partial outlet openings. The sum of the volume flow of lubricant discharged through the first partial outlet openings is the volume flow Q1. The sum of the volume flow of lubricant discharged through the second partial outlet openings is the volume flow Q2.

In a supplementary variant, the volume flow of the fuel delivered from the pre-feed pump to the high-pressure pump can be controlled and/or regulated during operation of the internal combustion engine by using a metering unit to control and/or regulate the flow cross-sectional area of a flow channel from the pre-feed pump to the high-pressure pump.

In another variant, the pre-feed pump is a gear pump.

In a supplementary embodiment, the front feed pump is mechanically driven, in particular exclusively, by the internal combustion engine. The front feed pump is mechanically coupled and/or driven, for example, by a transmission and at least one shaft to the crankshaft of the internal combustion engine.

In a supplementary embodiment, the front feed pump is electrically driven by an electric motor, so that the feed rate of the pre-feed pump is controllable and/or adjustable, and preferably, the high-pressure injection system does not include a metering unit. The pre-feed pump is controllable and/or adjustable in its feed rate, so that the volumetric flow of fuel directed to the high-pressure pump is controllable and/or adjustable without the metering unit by means of the control and/or regulation of the pre-feed pump.

Preferably, the high-pressure pump comprises a lubrication chamber.

The pressure that can be generated by the high-pressure pump in the high-pressure rail is, for example, in the range of 1000 bar to 3000 bar for diesel engines or between 300 bar and 1900 bar for gasoline engines.

Short description of the drawings

• 1 eine Pumpe ausschnittsweise in einem Querschnitt,
• 2 einen in 1 mit II-II bezeichneten Schnitt der Pumpe mit einem Rollenstößel und einem angrenzenden Pumpengehäuse,
• 3 einen Ausschnitt der Pumpe in vergrößerter Darstellung mit dem Rollenstößel, dem angrenzenden Pumpengehäuse und mit einem Durchlass,
• 4 einen Ausschnitt gemäß 2 der Pumpe in vergrößerter Darstellung,
• 5 zwei perspektivische Darstellungen und einen Querschnitt des Rollenstößels.

In the following, exemplary embodiments of the invention are described in more detail with reference to the accompanying drawings. They show:

• 1 a pump section in a cross-section,
• 2 one in 1 section of the pump marked II-II with a roller tappet and an adjacent pump housing,
• 3 an enlarged section of the pump with the roller tappet, the adjacent pump housing and a passage,
• 4 an excerpt according to 2 the pump in enlarged view,
• 5 two perspective views and a cross-section of the roller tappet.

Embodiments of the invention

1 shows a schematic axial sectional view of a pump 1, which is designed as a high-pressure pump for a high-pressure injection system of an internal combustion engine and is preferably installed in a common rail injection system and which in particular has a roller tappet 40. Furthermore, the pump 1 has at least one pump element 10, which in turn has a pump piston 12, which is driven at least indirectly by a drive shaft 14 in a reciprocating movement in at least approximately a radial direction with respect to a rotational axis of the drive shaft 14. The drive shaft 14 can be part of the pump 1, or alternatively, it can also be provided that the pump 1 does not have its own drive shaft and the drive shaft 14 is part of the internal combustion engine. The drive shaft can, for example, be a shaft of the internal combustion engine, by means of which the gas exchange valves of the internal combustion engine are also actuated. The drive shaft 14 has a cam 19 or eccentric for driving the pump piston 12.

The pump 1 has a pump housing 17, which can be constructed in several parts. The pump piston 12 is tightly guided in a cylinder bore 18 of a housing part 20 of the pump 1, the first housing part 20 being referred to below as the cylinder head 20. With its end facing away from the drive shaft 14, the pump piston 12 defines a pump working chamber 22 in the cylinder bore 18. The pump working chamber 22 has a connection to a fuel inlet 26 via an inlet valve 24, which can be an inlet check valve opening into the pump working chamber 22. The fuel inlet 26 fills the pump working chamber 22 with fuel during the suction stroke of the pump piston 12 directed radially inward toward the axis of rotation of the drive shaft 14. The pump working chamber 22 also has a connection to an outlet 30 via an outlet valve 28, which is, for example, an outlet check valve opening out of the pump working chamber 22, which can lead to a high-pressure rail 32 and via which fuel is displaced from the pump working chamber 22 during the delivery stroke of the pump piston 12 directed radially outwards away from the axis of rotation of the drive shaft 14.

In addition, 1 It is shown that the pump piston 12 is supported by the roller tappet 40 on the cam 19 of the drive shaft 14. The roller tappet 40 has a tappet body 8 which is sleeve-shaped and which is guided displaceably in a receptacle 44 in the direction of a longitudinal axis 41 of the roller tappet 40. The receptacle 44 can be formed in the pump housing 17 of the pump 1 or in a part of the internal combustion engine, for example its cylinder head or engine block. Lubricant, for example lubricating oil or fuel, is fed into the receptacle 44 via a lubricant inlet 45. Preferably, lubricant under increased pressure is fed to the receptacle 44.

In the tappet body 8, a roller 46 is arranged around a rotation axis 15 (not shown in 1 , see 2 ) is rotatably mounted, with the roller 46 rolling on the cam 16 of the drive shaft 14. The roller 46 is located in a recess 5 of the tappet body 8. The roller tappet 40 and the pump piston 12 are urged towards the drive shaft 14 by a spring 37. The roller 46 is arranged in an inner region 35 of the tappet body 8 facing the drive shaft 14. In the 2 A bearing pin 52 is inserted into the tappet body 8 shown, the longitudinal axis of which runs essentially perpendicular to the longitudinal axis 41 of the roller tappet 40, in particular with a deviation of less than 30°, 20°, or 10°. The tappet body 8 has two diametrically opposed recesses or cutouts as plain bearings with a cross-sectional shape as a circular segment, through which the bearing pin 52 at least partially passes and/or is mounted in them. The roller 46 is hollow-cylindrical and is mounted on the pin 52 directly or via a bearing bush.

In 2 a sectional view of the schematically illustrated pump 1 is shown. The pump 1 has the tappet assembly, which in turn has further individual parts. The tappet body 8 is designed in several parts, wherein the tappet body 8 has a roller shoe 48 and a sleeve-shaped tappet part 42 and wherein the roller shoe 48 is inserted into the tappet part 42 in the direction of the longitudinal axis 41, wherein the bearing pin 52 is held at least indirectly in the roller shoe 48, in particular two recesses 47 of the roller shoe 48. The tappet body 8 is guided movably in the direction of the longitudinal axis 41 in the receptacle 44 of the pump housing 17.

In addition, a lubricant channel 11 is provided in the roller shoe 48, wherein the lubricant channel 11 is designed as an outwardly open groove 11 in the roller shoe 48, wherein this groove 11 is at least almost completely delimited to the outside by the tappet part 42, wherein in particular an interruption of the delimitation of the groove by the tappet part 42 takes place in the region of at least one opening 25 (shown in 3 ). The tappet part 42 is designed as an at least approximately cylindrical sleeve encircling the longitudinal axis 41 and/or wherein the roller shoe 48 is designed at least approximately cylindrical in the direction of the longitudinal axis 41.

Two channel bores 51, 51, 51b are formed in the roller shoe 48. The channel bores 51 open into the remaining circumferential lubricant channel 11 on the side facing the tappet part 42 and into an opening region 9 on the side facing away from the tappet part 42. The opening regions 9 are located opposite the first and second axial ends 29, 31 of the bearing pin 52 and the roller 46 in the direction of the axis of rotation 15, wherein on the one hand the opening regions 9 and/or the ends of the channel bores 51 as outlet openings 49, 50 and on the other hand the radial bearing gap 38 have a substantially equal radial distance from the axis of rotation 15 of the roller 46, in particular with a deviation of less than 30%, 20% or 10%. Through the channel bore 51 and/or the mouth area 9, a lubricant can be injected into the area of the recess 5 of the tappet body 8, wherein the lubricant is injected in particular into the area of the radial bearing gap 38. In the area of the bearing gap 38, a constant lubricating film should form between the roller 46 and the bearing pin 52 in the direction of the bore axis 43. which enables a wear-reduced bearing of the roller 46 on the bearing pin 52. The bearing pin 52 has a recess 7 in the area of its inner diameter running in the direction of the rotation axis 15.

In addition, 2 It is shown that the tappet part 42 forms an axial extension 36 parallel to the longitudinal axis 41, wherein the axial extension 36 extends in particular to the region of the rotation axis 15. In addition, the tappet part 42 has a circumferential inner collar 34 on its inner diameter, wherein the collar 34 serves in particular as a stop for the roller shoe 48 to be inserted into the tappet part 42 in order to prevent it from being inserted too far, in particular during assembly.

3 shows an enlarged section of the pump 1 with the roller tappet 40, the adjacent pump housing 17 and with a passage 11, 13, 25, 45, 51. The roller shoe 48 has the lubricant channel 11 as part of the passage 11, 13, 25, 45, 51, wherein the lubricant channel 11 runs in a ring-shaped manner around the longitudinal axis 41 on the outer diameter of the roller shoe 48. Furthermore, the tappet part 42 has at least one lubricant groove 13 running axially to the longitudinal axis 41 in its outer casing and/or the tappet part 42 has at least one opening 25, wherein the opening 25 connects the lubricant groove 13 and the lubricant channel 11 of the roller shoe 48 to one another in a fluid-conducting manner, at least indirectly. Furthermore, the lubricant groove 13, 13a, 13b connects the lubricant inlets 45, 45a, 45b in the pump housing 17 and the lubricant channels 11, 11a, 11b of the roller shoe 48, at least indirectly, in a fluid-conducting manner. A passage 11, 13, 25, 45, 51 is formed in each of the roller shoe 48 and tappet part 42 components and/or at least partially in the pump housing 17.

In addition, 3 shown that the lubricant is supplied from a region of the pump housing 17. The lubricant flows from the at least one lubricant inlet 45, 45a, 45b in the pump housing 17 in a flow direction 23 through the at least one lubricant groove 13, 13a, 13b and through the at least one opening 25, 25a, 25b in the tappet part 42 into the circumferential lubricant channel 11. It is shown that, according to an exemplary embodiment of the roller tappet 40, two oppositely arranged lubricant grooves 13a, b and two oppositely arranged openings 25a, 25b run in the tappet part 42.

4 shows a section according to 2 of the pump 1 in an enlarged view. It is shown that the passage 11, 13, 25, 45, 51 comprises the channel bores 51, 51a, 51b, so that the mouth region 9 of the first channel bore 51a as the first outlet opening 49 and the second channel bore 51b as the second outlet opening 50 faces an end face of the roller 46 and/or the bearing pin 52, in particular the inlet opening of the bearing gap 38. It is also shown that the circumferential lubricant channel 11 formed on the outside of the roller shoe 48 is delimited in this plane by the tappet part 42 on its side facing away from the roller 46. Furthermore, it is shown that the lubricant flows in the flow direction 23 from the circumferential lubricant channel 11 as the outwardly open groove 11 in the roller shoe 48 through the channel bores 51 and/or the mouth regions 9 into the radial bearing gap 38. In this case, one channel bore 51 runs at an acute angle to the longitudinal axis 41 through the roller shoe 48. The circumferential lubricant channel 11 is thus formed by the outwardly open groove 11 in the roller shoe 48 in cross section, and one lubricant channel 11a, 11b is formed by the channel bore 51 in the roller shoe 48 which is closed in cross section.

5 shows two perspective views and a cross section of the roller tappet 40. It is shown that the circumferential lubricant channel 11 connects the lubricant groove 13a and thus the opening 25 (not shown) of the tappet part 42 with the channel bore 51 of the roller shoe 48 at least indirectly in a fluid-conducting manner.

In the first perspective view of the roller tappet 40, only one lubricant groove 13a of the two oppositely arranged lubricant grooves 13, 13a, 13b is shown. The lubricant groove 13a, 13b is 3 shown lubricant inlet 45a, 45b as passage 45 in the pump housing 17 is fed with lubricant.

From the first perspective view and the second perspective view, it can be seen that the at least one opening 25 and the at least one channel bore 51 are aligned with each other such that they at least substantially do not overlap. According to the exemplary embodiment described above, the tappet part 42 has two openings 25a, b, of which, however, only the opening 25a is shown in the first perspective view (see 3 ), wherein the two openings 25a, b extend orthogonally to the longitudinal axis 41. Furthermore, the roller shoe 48, as shown in the cross section of the roller tappet 40, has two channel bores 51a, 51b as lubricant channels 11a, 11b. In the exemplary embodiment, the two channel bores 51a, 51b can run coaxially and thus offset by almost 180° in the roller shoe 48. The two openings gen 25a, 25b can be used according to the exemplary embodiment (as shown in 3 shown) coaxially and thus offset by almost 180° in the tappet part 42. As shown in 5 As shown, an opening 25a is always offset by almost 90° to a respective channel bore 51a, so that the lubricant must flow through almost a quarter of the total length of the circumferential lubricant channel 11 outside the channel bore 51 in order to get from the respective opening 25a, b to the respective channel bore 51a, b.

In addition, the section view in 4 shown that the lubricant flows through the channel bore 51a as lubricant channel 11a in the flow direction 23 and is injected from the channel bore 51a into the bearing gap 38 between the bearing pin 52 and the roller 46.

A bore 16 for receiving an actuator 2 in the form of an actuating piston 3 is formed in the roller shoe 48. The bore 16 is essentially aligned parallel to the rotational axis 15 of the roller 46, in particular with a deviation of less than 30°, 20°, or 10°. The actuating piston 3 is arranged and mounted in the bore 16 with a substantially constant diameter, in particular with a deviation of less than 30%, 20%, or 10%. The outer diameter of the actuating piston 3 essentially corresponds to the inner diameter of the bore 16, so that with the actuator 2 in the form of the actuating piston 3, the bore 16 is essentially sealed in a fluid-tight manner. The actuator 2 in the form of the actuating piston 3 has a first axial end region 4 as a first axial end 4 and a second axial end region 6 as a second axial end 6. The cross-section of the bore 16 and the actuator 2 is arbitrary, for example circular or rectangular.

The lubricant channel 11 is formed in the tappet body 8, i.e., the roller shoe 48 and the sleeve-shaped tappet part 42. The lubricant channel 11 is supplied with lubricant, for example, lubricating oil or fuel, from two openings 25a, 25b in the tappet part 42. The first lubricant channel 11a, as the first channel bore 51a, has a first outlet opening 49 on the roller shoe 48 as the end of the first lubricant channel 11a. Analogously, the second lubricant channel 11b, as the second channel bore 51b on the roller shoe 48, has a second outlet opening 50. The lubricant is guided through the first lubricant channel 11a in a flow direction 23 through the first lubricant channel 11a. The lubricant is guided through the second lubricant channel 11b in the flow direction 23 through the second lubricant channel 11b. The roller 46 and the bearing pin 52 have a first axial end 29 in the direction of the rotational axis 15 as the longitudinal axis 15 of the roller 46. The roller 46 and the bearing pin 52 have a second axial end 31 in the direction of the rotational axis 15 as the longitudinal axis 15 of the roller 46. The first axial end 29 and the second axial end 31 are formed opposite one another on the roller 46 and the bearing pin 52. The roller 46 and the bearing pin 52 are movable in the axial direction, ie in the direction of the rotational axis 15 of the roller 46. The recess 47 ( 2 ) in the roller shoe 48 is according to the cut formation in 1 as a circular segment with an angle greater than 180°, for example 200°. This only requires a bearing of the bearing pin 52 in a radial direction, i.e. perpendicular to the rotational axis 15 of the roller 46, and thus also of the roller 46. The roller shoe 48 additionally functions as an axial stop or axial bearing for the roller 46 and the bearing pin 52. The length or the distance in the axial direction between the two axial stops or the axial bearing on the roller shoe 48 is greater than the length in the axial direction of the roller 46 and the bearing pin 52 in the area of these axial stops or the axial bearing. This creates an axial bearing gap 39 between the first axial end 29 of the roller 46 and the bearing pin 52 and the associated first axial stop 33 ( 4 ) on the roller shoe 48. In an analogous manner, an axial bearing gap 39 occurs between the second axial end 31 of the roller 46 and the bearing pin 52 and the associated second axial stop on the roller shoe 48.

During operation of the pump 1, an axial movement of the roller 46 and the bearing pin 52 occurs, which movement is limited by the first axial stop 33 and the second axial stop on the roller shoe 48. In the axial direction, i.e. in the direction of the rotation axis 15 of the roller 46, the first outlet opening 49 is aligned with the first axial end 29 of the roller 46 and the bearing pin 52. Accordingly, the second outlet opening 50 is also aligned in the axial direction with the second axial end 31 of the roller 46 and the bearing pin 52. The smaller the distance in the axial direction between the first outlet opening 49 and the first axial end 29 of the roller 46 and the bearing pin 52, the greater the hydraulic flow resistance of the volume flow of lubricant that can be discharged through the first outlet opening 49 and vice versa. The smaller the distance in the axial direction between the second outlet opening 50 and the second axial end 31 of the roller 46 and the bearing pin 52, the greater the hydraulic flow resistance of the volume flow of lubricant that can be discharged through the second outlet opening 50 and vice versa. A volume flow Q1 is directed through the first outlet opening 49 and through the second A volume flow Q2 of lubricant is directed through the outlet opening 50. The volume flow of lubricant directed through the first and second outlet openings 49, 50 serves to lubricate the radial bearing gap 38 and the axial bearing gap 39. For this reason, the volume flow Q1 and the volume flow Q2 should be essentially equal for uniform lubrication of the radial bearing gap 38 and the axial bearing gap 39. If the distance between the first axial end 29 of the roller 46 and the bearing pin 52 decreases, the hydraulic flow resistance at the first outlet opening 49 increases, so that the volume flow Q1 is reduced, and as a result, the pressure in the first lubricant channel 11a also increases. This also applies analogously to the second outlet opening 50.

The actuator 2, as the actuating piston 3, is subjected to the pressure of the lubricant in the first lubricant channel 11a at the first axial end region 4 or first axial end 4. Analogously, the second axial end region 6 or the second axial end 6 of the actuator 2 is subjected to the pressure in the second lubricant channel 11b at the second axial end region 6 or second axial end 6 of the actuator 2. Thus, a first compressive force resulting from the pressure of the lubricant in the first lubricant channel 11a acts on the actuating piston 2 at the first axial end region 4, and a second compressive force resulting from the pressure of the lubricant in the second lubricant channel 11b acts on the actuating piston 2 at the second axial end region 6. The first compressive force and the second compressive force are oppositely directed due to the geometry of the actuating piston 3. The flow resistance of the first lubricant channel 11a and the second lubricant channel 11b can be changed by moving the actuator 2. A movement of the actuating piston 3 as shown in 2 to the left causes a reduction in the flow cross-sectional area of the first lubricant channel 11a in the region of the first axial end region 4 of the actuating piston 3 and an enlargement of the flow cross-sectional area of the second lubricant channel 11b in the region of the second axial end region 6 of the actuating piston 3. The smaller the flow cross-sectional area, the greater the hydraulic flow resistance, and vice versa. If the roller 46 and/or the bearing pin 52 moves in the direction of the first outlet opening 49 and the hydraulic flow resistance at the first outlet opening 49 is thereby increased, this causes an increase in the pressure in the first lubricant channel 11a and a reduction in the pressure in the second lubricant channel 11b. The total volume flow of lubricant passed through the opening 25, i.e. the sum of Q1 and Q2, is essentially constant, in particular with a deviation of less than 30%, 20% or 10%, because the lubricant is introduced through the opening 25 with a lubricant pump (not shown) controlled with an essentially constant volume flow, and this is necessary for the function. The above-described increase in the pressure in the first lubricant channel 11a and reduction in the pressure of the lubricant in the second lubricant channel 11b causes an increase in the first pressure acting on the first axial end 4 of the actuating piston 3 and a reduction in the second pressure acting on the second axial end 6 of the actuating piston 3. This causes a movement of the actuating piston 3 as shown in 2 to the right, so that the flow resistance at the second lubricant channel 11b is increased by the actuating piston 3 and the flow resistance at the first lubricant channel 11a is reduced. The length of the actuating piston 3 and the diameter of the lubricant channel 11 are designed such that, during operation, the volume flow Q1 and Q2 is essentially constant, in particular with a deviation of less than 30%, 20%, or 10%, during the axial movement of the roller 46 and the bearing pin 52 by means of the change in the flow resistance at the first lubricant channel 11a and the second lubricant channel 11b due to the movement of the actuating piston 3.

In a further embodiment not shown, the tappet body 8 is formed in one piece, so that the one-piece tappet body 8 assumes the function of the roller shoe 48 and the tappet part 42. The circumferential lubricant channel 11 is, for example, integrated into the one-piece tappet body 8 or formed as a circumferential groove on the tappet body 8, and this groove is delimited on the outside by the pump housing 17 (not shown).

A combustion engine (not shown) as a reciprocating piston combustion engine is supplied with fuel by a high-pressure injection system. The high-pressure injection system (not shown) comprises a high-pressure pump for conveying fuel into a high-pressure rail. The fuel is injected from the high-pressure rail into combustion chambers with injection valves. A pre-feed pump conveys fuel from a fuel tank to the high-pressure pump. A metering unit controls and/or regulates the volumetric flow of fuel supplied to the high-pressure pump. The fuel conveyed by the high-pressure pump 1 into the high-pressure rail and not required by the combustion engine is returned to the fuel tank via a fuel return line after the pressure has been reduced by a pressure control valve (not shown) above a predetermined pressure. redirected to prevent the fuel pressure in the high-pressure rail from exceeding and to ensure that a specified fuel pressure is available to the injectors on the inlet side. The high-pressure pump is supplied with either fuel as a lubricant or lubricating oil as a lubricant from the combustion engine. When the high-pressure pump is supplied with fuel as a lubricant, the pressure of the fuel as a lubricant in a lubrication chamber of the high-pressure pump is controlled and/or regulated using an overflow valve.

Overall, the roller tappet 40 according to the invention, the pump 1 according to the invention, and the internal combustion engine according to the invention offer significant advantages. Due to the dimensioning and design of the actuator 2 and the lubricant channel 11, the change in flow resistance at the first and second outlet openings 49, 50 is compensated for by the change in flow resistance in the first lubricant channel 11a and the second lubricant channel 11b due to the movement of the actuating piston 3. Thus, despite the axial movement of the roller 46 and the bearing pin 52, a substantially constant and identical volume flow Q1 of lubricant can be discharged through the first outlet opening 49 and volume flow Q2 through the second outlet opening 50. The radial bearing gap 38 between the roller 46 and the bearing pin 52 and the axial bearing gap 39 between the roller shoe 49 on the one hand and the roller 46 and the bearing pin 52 on the other hand can thus be reliably and sufficiently supplied with lubricant, i.e., can be supplied with lubricant. Unnecessary mechanical wear can thus be advantageously avoided.

QUOTES CONTAINED IN THE DESCRIPTION

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Cited patent literature

• DE 10 2012 223 413 A1 [0006]
• DE 10 2018 214 200 A1 [0007]

Claims (15)

Roller tappet (40) for a pump (1), in particular a high-pressure pump (1) for a high-pressure injection system for a motor vehicle for supporting a reciprocating pump piston (12) on a drive shaft (14), comprising - a tappet body (8) for supporting a roller (46), - a hollow-cylindrical roller (46), - a bearing pin (52) arranged within the hollow-cylindrical roller (46) for supporting the roller (46), such that a radial bearing gap (38) is formed between the roller (46) and the bearing pin (52), - a first lubricant channel (11a) formed in the tappet body (8) for supplying a lubricant to a first axial end region (29) of the roller (46) and/or the bearing pin (52), - a second lubricant channel (11b) formed in the tappet body (8) for supplying a lubricant to a second axial end region (31) of the roller (46) and/or the bearing pin (52), characterized in that the roller tappet (40) comprises a movable actuator (2) for changing the flow cross-sectional area of the first and/or second lubricant channel (11a, 11b) in order to achieve a reliable supply of the volume flow (Q1) of lubricant guided through the first lubricant channel (11a) and the volume flow (Q2) of lubricant guided through the second lubricant channel (11b). Roller tappet after Claim 1 , characterized in that the first lubricant channel (11a) has a first outlet opening (49) as one end of the first lubricant channel (11a) and the second lubricant channel (11b) has a second outlet opening (50) as one end of the second lubricant channel (11b). Roller tappet after Claim 2 , characterized in that the flow cross-sectional area of the first and/or second lubricant channel (11a, 11b) can be changed in the flow direction of the lubricant in front of the first and/or second outlet opening (49, 50) by means of the movable actuator (2). Roller tappet according to one or more of the preceding claims, characterized in that the flow cross-sectional area of the first lubricant channel (11a) and the second lubricant channel (11b) can be changed simultaneously with the movable actuator (2). Roller tappet according to one or more of the preceding claims, characterized in that the flow cross-sectional area of the first lubricant channel (11a) and second lubricant channel (11b) can be changed by the movable actuator (2) in such a way that when the flow cross-sectional area of the first lubricant channel (11a) is increased, the flow cross-sectional area of the second lubricant channel (11b) can be reduced and vice versa. Roller tappet according to one or more of the preceding claims, characterized in that the flow cross-sectional area of the first lubricant channel (11a) and second lubricant channel (11b) can be changed by the movable actuator (2) in such a way that the flow cross-sectional area of the first lubricant channel (11a) is substantially indirectly proportional to the flow cross-sectional area of the second lubricant channel (11b). Roller tappet according to one or more of the preceding claims, characterized in that the tappet body (8) is made up of several parts with a roller shoe (48) for supporting the roller (46) and a tappet part (42) or is made in one part. Roller tappet according to one or more of the preceding claims, characterized in that the actuating element (2) is designed as one, in particular only one, actuating piston (3). Roller tappet according to one or more of the preceding claims, characterized in that a bore (16) is formed in the tappet body (8), in particular in the roller shoe (48), and the actuating element (2), in particular the actuating piston (3), is movably mounted in this bore (16) as a sliding bearing. Roller tappet according to one or more of the preceding claims, characterized in that the actuator (2) has a first axial end region (4) and a second axial end region (6) and the first axial end region (4) can be acted upon by a first pressure force from the hydrostatic pressure of the lubricant in the first lubricant channel (11a) and the second axial end region (6) can be acted upon by a second pressure force from the hydrostatic pressure of the lubricant in the second lubricant channel (11b) and the first and second pressure forces are directed opposite to one another. Roller tappet after Claim 10 , characterized in that with a change in the amount of the first and/or second pressure force due to a change in the lubricant channel guided through the first and/or second The actuator (2) can be moved into different positions depending on the volume flow of lubricant. Roller tappet according to one or more of the preceding claims, characterized in that the roller (46) and the bearing pin (52) are mounted with an axial play (39) as an axial bearing gap (39) on the tappet body (8) and the first and second outlet openings (49, 50) are aligned with the roller (46) and/or the bearing pin (52) in the direction of the rotational axis (15) of the roller (46), so that a first axial distance (27) in the direction of the rotational axis (15) of the roller (46) is formed between the first outlet opening (49) and a first axial end (29) of the roller (46) and/or the bearing pin (52) and a second axial distance in the direction of the rotational axis (15) of the roller (46) between the second outlet opening (50) and a second axial end (31) of the roller (46) and/or the position bolt (52). Roller tappet according to one or more of the preceding claims, characterized in that the flow resistance of the volume flow of lubricant that can be conducted through the first outlet opening (49) depends on a first axial distance (27) in the direction of the axis of rotation (15) of the roller (46) between the first outlet opening (49) and the roller (46) and/or the bearing pin (52), and the greater this first axial distance (27), the smaller the flow resistance, and vice versa. and the flow resistance of the volume flow of lubricant that can be conducted through the second outlet opening (50) depends on a second axial distance in the direction of the axis of rotation (15) of the roller (46) between the second outlet opening (50) and the roller (46) and/or the bearing pin (52), and the greater this second axial distance, the smaller the flow resistance, and vice versa, and the sum of the first and second distances (27) is essentially constant. Pump (1), in particular a high-pressure pump (1) for a high-pressure injection system for a motor vehicle, comprising - a pump piston (12), - a housing (20) with a cylinder bore (18), - a roller tappet (40) and the pump piston (12) is supported with the roller tappet (40) on a drive region, in particular a drive shaft (14), characterized in that the roller tappet (40) is designed according to one or more of the preceding claims. Internal combustion engine with a high-pressure injection system, comprising - a high-pressure pump (1) for conveying fuel to a high-pressure rail, - a high-pressure rail, - a pre-feed pump, - a metering unit, characterized in that the high-pressure pump (1) according to Claim 14 is trained.