KR101773210B1

KR101773210B1 - High pressure pump

Info

Publication number: KR101773210B1
Application number: KR1020127003483A
Authority: KR
Inventors: 아르놀트 겐테; 맛티아스 그라이너
Original assignee: 로베르트 보쉬 게엠베하
Priority date: 2009-08-10
Filing date: 2010-08-03
Publication date: 2017-08-31
Also published as: CN102472258A; WO2011018389A1; DE102009028394A1; CN102472258B; EP2464866A1; KR20120052293A; EP2464866B1

Abstract

The present invention relates to a high pressure pump (1) for use as a radial piston pump or reciprocating piston pump for a fuel injection system of an internal combustion engine, in particular a pneumatic and self-igniting internal combustion engine, comprising a pump assembly (6) and a drive shaft ). The drive shaft 3 includes a cam 5 assigned to the pump assembly 6. The pump assembly 6 also includes a pump piston 11, a roller 21 that rolls on the cam surface 22 of the cam 5, and a roller tappet 20 that receives the roller 21. In this case, the pump piston 11 can be operated along the pump assembly 6, and the tilting of the roller tappet 20 relative to the main shaft 7 of the pump assembly is achieved by the pump piston 11 and the roller tappet 20, Because the convexly formed roller tappet 20 is radially supported within the housing bore 8.

Description

[0001] HIGH PRESSURE PUMP [0002]

The present invention relates to a high pressure pump, in particular a radial piston pump or a reciprocating piston pump. More particularly, the present invention relates to the field of fuel pumps for fuel injection systems of internal combustion engines that are pneumatic and self-igniting.

DE 10 2005 046 670 A1 discloses a high-pressure pump for a fuel injector of an internal combustion engine. The known high-pressure pump includes a pump housing in which a pump member is disposed, the pump member including a pump piston driven in a head movement through a drive shaft. The pump piston is displaceably guided within the cylinder bore of a portion of the pump housing and limits the pump operating chamber within the cylinder bore. Such a pump piston is indirectly supported by a drive shaft via a cylindrical tappet, which is guided displaceably in the longitudinal direction of the pump piston in a bore of a part of the pump housing.

The high pressure pump known from DE 10 2005 046 670 A1 has the disadvantage that a certain structural height is required for the tappet body to ensure reliable guidance in the pump housing in the longitudinal direction of the pump piston. This affects the structure size of the high-pressure pump. There is also a need for a support member that is inserted into the end region facing the drive shaft in the tappet to support additional components, particularly rollers.

The high pressure pump according to the present invention having the features of claim 1 has the advantage that a compact structure of the pump assembly is possible and thus the space required for the high pressure pump is reduced. In particular, the configuration of the pump assembly can be simplified.

Through the means illustrated in the dependent claims, preferred improvements of the high-pressure pump described in claim 1 are possible.

Preferably, the roller tappet is radially supported with respect to the main shaft of the pump assembly within the bore formed in the at least one housing portion of the high-pressure pump. This allows the lateral force to be supported by the housing portion through the roller tappet without the roller tappet being obstructed by tilting in the housing portion. This may result in an increased torque introduction at the end or lower end of the pump piston. However, even when the dock introduction is increased, the functional performance of the pump assembly is assured. In particular, unlike the configuration based on an eccentric polygon, a relatively low force ratio or torque ratio is always obtained.

In this case, the roller tappet is formed as at least substantially one roller tappet portion, the roller tappet portion receiving the roller, and the roller tappet portion being radially supported with respect to the main shaft of the pump assembly within the bore of the housing portion. In particular, an integral configuration of the roller tappet can be realized. Thus, the number of necessary parts can be optimized. For this reason, the roller tappet may be formed to be relatively small. As a result, the restorative spring (tappet spring) etc. can also be made weaker if necessary, and thus can be reduced much more, since a smaller volume of tappet spring must be involved. This can likewise achieve, for example, a pronounced weight reduction of 50%, i.e. a reduction in the volume of the parts of the pump assembly. The reduction of the restoring spring may also cause a major reduction in the size of the camshaft (drive shaft) relative to the cylinder head upper side. This advantage results in an additional weight reduction of the cylinder head and pump housing. Additional advantages are thus obtained from said reduction and from the volume reduction of the roller tappet accordingly.

In a preferred manner, the roller tappet is formed convexly in at least one support region where the roller tappet is radially supported within the bore of the housing portion. This convex shape can be achieved, for example, by grinding the outside of the roller tappet. In particular, the roller tappet can be raised convexly in the support region.

In this case, it is preferable that the convex portion of the roller tappet in the support region is formed so that the length of the lever between the support point between the bore of the housing portion and the convex portion of the roller tappet and the rotation axis of the roller is relatively short. Preferably, the lever length is as short as possible, or at least short enough to cause the bending moment between the roller tappet and the pump piston to occur sufficiently low, for example in connection with the connection of the pump piston to the roller tappet, .

Preferably, a spring seat is provided that is connected to the roller tappet, which is connected to such a spring seat. Through this spring seat, the tilting movement of the roller tappet can be reliably limited. In particular, it is preferable that the pump piston is press-fitted into the spring seat. This can prevent the tilting movement of the roller tappet relative to the main shaft of the pump assembly.

In a preferred manner, the pump piston is configured at least substantially in the form of a cylinder. In this case, the piston bottom portion of the pump piston may be omitted. In particular, the pump piston can be manufactured from a bar material, and the diameter of the bar material is chosen to be optimally small in order to keep the cutting volume as low as possible through rotary machining and grinding.

The spring seat includes one or more support extensions which are laterally guided along the main axis of the pump assembly to be guided in contact with the roller tappet and protrude from the roller onto the roller tappet, the support extension extending from the side of the roller portion of the roller along the axis of rotation of the roller It is also desirable to limit. In particular, the spring seat comprises two support extensions which are guided in lateral contact with the roller tappet along the main axis of the pump assembly on the side opposite to each other and project from the roller onto the roller tappet, To limit the side of the rolling portion of the roller along the rotation axis of the roller. In this case, the support extensions may be formed corresponding to two ear-shaped parts or tabs that support the pump housing in front of the side rolling parts of the roller and keep the roller in the desired position. In this case, the force generated from the roller sliding portion to the support extending portion can be transmitted to the pump piston.

The pump piston includes a lower portion of the piston toward the roller tappet, and it is also preferable that the spring seat grips the lower portion of the piston of the pump piston from the back to connect the pump piston to the spring seat. As a result, the pump piston is connected to the roller tappet, and this connection is carried out by the spring seat. In this case, the lower part of the piston of the pump piston is supported by the roller tappet.

In this case, it is also preferable that the pump piston is formed in the form of a trunk. This allows a relatively small piston diameter of the pump piston to be achieved when the load of the curved moment is the same. It has been demonstrated by nature that this piston shape is very robust to curved loads. For example, tree trunks do not break even when very high loads are applied, such as when a storm is blowing. In this case, since the spring seat can be formed relatively easily, the force from the roller sliding portion is not transmitted to the spring seat, and therefore, is not transmitted to the pump piston. However, even in such a case, a configuration may be employed in which the spring sheet includes one or a plurality of support extensions for restricting the side surface of the rolling portion of the roller along the rotation axis of the roller.

However, it is also desirable that the cam or drive shaft provided with such cam comprises at least one guide web assigned to the cam, which restricts the side of the rolling portion of the roller along the axis of rotation of the roller. In particular, it is desirable to provide two guide webs that limit the side of the rolling portion of the roller along the rotational axis of the roller on both sides. Such a guide web is preferably formed as a blocked guide web surrounding the periphery. Such a guide web functions as a support extension for a spring seat or the like, so that the structure of the pump assembly is simplified. In addition, there is an advantage that the roller can not be rotated because it is guided directly on the cam track of the cam. Therefore, the support of the roller sliding portion of the camshaft, that is, the support of the roller or the roller sliding portion of the cam or drive shaft, and the guide of the roller can be performed. In this case, since the spring sheet is formed very simply, the total weight of the moving volume, in particular, the volume of the tappet body and the volume of the additional part connected to the tappet body are also optimized. As a result, the force of the tappet spring and the resulting structure height can be further reduced.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention are described in further detail in the following description with reference to the accompanying drawings, wherein like reference numerals are provided to corresponding parts.

1 is a cross-sectional view schematically showing only part of a high-pressure pump according to a first embodiment of the present invention by axial incision.
FIG. 2 is a cross-sectional view showing only part of the high-pressure pump shown in FIG.
Fig. 3 is a cross-sectional view showing only part of the high-pressure pump shown in Fig. 1 cut along the sectioned line indicated by III.
Fig. 4 is a view showing only a part of the high-pressure pump shown in Fig. 1, corresponding to the second embodiment of the present invention.
Fig. 5 is a view showing only a part of the high-pressure pump shown in Fig. 1, corresponding to the third embodiment of the present invention.

1 is a cross-sectional view schematically showing only part of the high-pressure pump 1 according to the first embodiment. The high-pressure pump 1 may be formed in particular as a radial piston pump or a reciprocating piston pump. In particular, the high-pressure pump 1 is suitable as a fuel pump for a fuel injection system of an internal combustion engine of pneumatic and natural ignition type. The high-pressure pump 1 is preferably used for a fuel injection system with a fuel supply rail that stores diesel fuel under high pressure. However, the high-pressure pump 1 according to the invention is also suitable for other applications.

The high-pressure pump (1) has a pump housing including one or a plurality of housing parts (2). In the housing part 2, a drive shaft 3 is disposed, and such a drive shaft is supported in the housing part 2. In this case, the drive shaft 3 is rotatable about the rotation axis 4, and driving through the internal combustion engine can be performed at this time.

The drive shaft 3 includes one or more cams 5. In this case, the cam 5 can also be formed as multiple cams. The cam 5 may also be formed through an eccentric section or the like of the drive shaft 3. [ A pump assembly (6) assigned to the cam (5) is arranged in the housing part (2).

The pump assembly 6 includes at least a main shaft 7 which appears similar to the rotational axis 4 of the drive shaft 3. The pump assembly 6 is disposed at least substantially within the bore 8 of the housing portion 2. In this case, the cylinder head 9 is connected to the housing part 2. The projections 10 of the cylinder head 9 project into the bore 8. The bore 8 is formed to be symmetrical with respect to the main shaft 7. Further, the projections 10 of the cylinder head 9 are formed to be symmetrical with respect to the main shaft 7.

The pump assembly 6 also includes a pump piston 11 which is guided along the main shaft 7 within the bore 12 of the projection 10. [ The pump piston (11) forms the boundary of the pump operating chamber (13) within the bore (12). The low-pressure fuel can be introduced into the pump operation chamber 13 from the pre-discharge valve or the like through the intake valve 14 when the pump piston 11 performs the intake stroke. While the discharge stroke of the pump piston 11 is being executed, the fuel in the high pressure state is discharged through the discharge valve 15 to the fuel supply rail or the like.

In addition, a roller tappet 20 accommodating the roller 21 is disposed in the bore 8. The roller tappet 20 is formed as an integral roller tappet portion. In this case, on the one hand, the roller tappet 20 can be supported radially with respect to the main shaft 7 in the bore 8 and on the other hand the roller 21 can be supported by the roller tappet 20 Lt; / RTI > The roller 21 rolls on the cam surface 22 of the cam 5 during operation. As a result, the head movement caused by the cam 5 is transmitted to the pump piston 11 through the roller 21 and the roller tappet 20.

The pump assembly (6) includes a spring seat (23) connected to the roller tappet (20). In this case, the pump piston 11 is connected to the spring seat 23. In this embodiment, the pump piston 11 is press-fitted into the spring seat 23. Further, a tappet spring 24 is provided, one side of which is supported by the cylinder head 9 and the other side is supported by the spring seat 23. Therefore, the force of the tappet spring 24 is applied to the spring seat 23, that is, the force is applied in the suction stroke direction of the pump piston 11. [ Thus, a desirable force transmission is ensured while the bi-directional movement of the pump piston 11 is carried out, and the roller 21 always contacts the cam surface 22 and contacts the roller tappet 20.

In this embodiment, the pump piston 11 press-fitted into the spring seat 23 is configured in the form of a cylinder. As a result, the pump piston 11 can be formed of a rod material, for example, advantageously in terms of cost.

The outer side of the roller tappet (20) includes a support region (30). In this support region 30, the roller tappet 20 is convexly formed. Thus, a convexly shaped support area 30 of the roller tappet 20 is obtained in which the roller tappet 20 comes into contact with the bore 8 in a radial direction with respect to the main shaft 7. In this case, the convexly-shaped support area 30 is formed between the support point 33 between the bore 8 of the housing part 2 and the support area (convexity) 30 of the convex shape of the roller tappet 20, 21) is relatively short (for example, 5 mm or less). In this case, depending on the embodiment, the lever length 31 may be negligibly small.

The roller tappet 20 is supported at the support point 33 at the bore 8 during operation so that a lateral force is generated in the radial direction with respect to the main shaft 7 at the support point 33. [ In this case, the roller tappet 20 is not disturbed by tilting in the bore 8. As a result, a certain amount of torque is introduced into the pump piston 11 through the spring seat 23. However, since the generated torque is sufficiently small, reliable operation is ensured.

The lateral force to be supported is generated as a force component of the roller force introduced perpendicularly to the main shaft 7 by the cam drive device. Regarding the force provided by the cam 5 on the roller 21, the lateral force at the normal cam slope takes up to a quarter of the force provided by the cam. Therefore, the piston operating force acting on the pump piston 11 in the direction of the main shaft 7 is much larger than the lateral force component.

In an ideal case, the roller tappet 20 is guided in the bore 8 such that the lateral force is introduced at least as high as the height of the rotary shaft 32. This means that the lever length 31 has disappeared. When such a state is impossible due to the reason of the structural space or the like, the tilting torque is applied to the roller tappet 20 via the lateral force supporting portion, and such tilting torque is supported through the pump piston 11. [ The longer the lever length 31, the greater the tilting torque that occurs. For example, the lever length 31 may be about 5 mm. When the cam engagement angle is 15 DEG, the generated tilting torque is lower than the product of the force acting on the pump piston 11 in the direction of the main shaft 7, the leverage length 31 of 5 mm, and the tangential line of 15 DEG . Therefore, the generated tilting torque is lower than the product of the force acting on the pump piston 11 in the direction of the main shaft 7 and the product of 1.25 mm.

In contrast, in the driving apparatus based on the eccentric polygon, a tilting torque occurs at the lower end of the piston, and this tilting torque is lower than the force acting on the pump piston 11 in the direction of the main shaft 7, for example, .

Accordingly, through the appropriate configuration of the pump assembly 6, it is ensured that the rigidity of the pump piston 11 is sufficient to accommodate the tilting torque generated by the roller tappet 20, even when the diameter of the pump piston 11 is relatively small . Specifically, the roller tappet 20 can be formed such that the force application point is not too far away from the ideal point of the height of the rotation axis 32 of the roller 21, that is, the lever length 31 is relatively short.

The torque acting on the pump piston 11 can further be reduced by offsetting the bore 12 of the projection 10 with respect to the rotational axis 4 of the drive shaft 3. In this case, the main shaft 7 of the pump assembly 6 appears slightly out of the rotational axis 4 of the drive shaft 3.

FIG. 2 schematically shows a cross-sectional view of the high-pressure pump 1 shown in FIG. 1 cut out along the sectioned line II. The spring seat 23 in this embodiment includes support extensions 35 and 36 which extend laterally to contact the roller tappet 20 and to the main shaft 7 of the pump assembly 6. [ Lt; / RTI > In this case, the supporting extensions 35, 36 are guided in the lateral direction on both sides in contact with the roller tappet 20, and these supporting extensions protrude above the roller tappet 20 on the side of the roller 21. [ The support extension (35) includes a stop surface (37). In addition, the support extension 36 includes a stop surface 38. The sides of the possible rolling parts of the roller 21 along the rotational axis 32 of the roller 21 are restricted through the stop surfaces 37 and 38 of the supporting extensions 35 and 36. In this case, the support extensions 35, 36 may have an ear shape.

3 is a cross-sectional view showing only a part of the high-pressure pump 1 shown in Fig. 1 cut along the sectioned line indicated by III. The roller tappet 20 includes bores 39, 40, 41, 42, which extend through the spring seat 23 as well. The inner space of the housing part 2 in which the drive shaft 3 is disposed is connected to the bore 8 of the housing part 2 through the bores 39 to 42. [ Bores 39-42 are used as compensation bores 39-42. In this case, the compensation bores 39 to 42 are used to enable the perfusion of the fuel. As a result, the fuel is prevented from being compressed through the roller tappet 20.

Fig. 4 shows only a part of the high-pressure pump 1 shown in Fig. 1 corresponding to the second embodiment. In this case, the cross-sectional view partially shown in Fig. 4 corresponds to the view shown in Fig. 2 in an incision along the folding line indicated by II in Fig. In this embodiment, the pump piston 11 includes a piston bottom end 50. The piston bottom end portion 50 includes an end surface 51 by which the piston bottom end portion 50 of the pump piston 11 contacts the roller tappet 20. In addition, the spring seat 23 includes a collar 52. The spring seat 23 is connected to the piston bottom end 50 of the pump piston 11 by this collar 52 in order to connect the pump piston 11 with the spring seat 23 and thus also with the roller tappet 20 ) From the rear. In this case, the pump piston 11 is constructed in the form of a tree trunk (as illustrated in FIG. 4). This ensures a high rigidity of the pump piston 11 even when a relatively high lateral force is generated which can result in a correspondingly high torque. Therefore, the pump piston 11 can receive the tilting torque acting on the roller tappet 20. The pump piston 11 is formed thicker at the lower end portion 50 of the piston toward the roller tappet 20 than at the cylindrical portion 53. [ Thus, a higher stability of the pump piston 11 is obtained.

In this embodiment, the spring seat 23 includes support extensions 35, 36. In this case, both side limitations of the rolling portion of the roller 21 are ensured through the stop surfaces 37, 38 of the supporting extensions 35, 36.

Fig. 5 shows only a part of the high-pressure pump 1 shown in Fig. 1 corresponding to the third embodiment. In this embodiment, the cam 5 or the drive shaft 3 provided with this cam 5 is provided with guide webs 55, 56. In this case, the guide webs 55, 56 are assigned to the cam 5 and accordingly to the pump assembly 6. In this case, the guide webs 55 and 56 are formed so as to surround the periphery. The guide web 55 surrounds the periphery and includes a guide surface 57 located therein. The guide web 56 surrounds the periphery and includes a guide surface 58 located therein. The guide surfaces 57 and 58 are directed toward each other. The guide webs 55 and 56 having the guide surfaces 57 and 58 protrude above the cam surface 22 in the radial direction as viewed by the rotational axis 4 of the drive shaft 3. The guide surfaces 57 and 58 of the guide webs 55 and 56 limit the possible side portions of the roller 21 along the rotational axis 32 of the roller 21. [ In this case, the supporting extensions 35 and 36 may be omitted, for example, as shown in Figs. 2 and 4. Fig. Thereby, the volume of the moving parts of the pump assembly 6, particularly the volume of the spring seat 23, can be further reduced. This can further optimize the pump assembly 6.

Therefore, the structural height of the roller tappet 20 in the direction of the main shaft 7 can be optimized.

The present invention is not limited to the above-described embodiments.

Claims

A high pressure pump (1) comprising at least one pump assembly (6) and a drive shaft (3), the drive shaft comprising at least one cam (5) assigned to the pump assembly (6) A roller 11 rolling on the cam surface 22 of the cam 5 and a roller tappet 20 for receiving the roller 21 and the pump piston 11 is connected to the pump assembly 6 And the tilting of the roller tappet 20 relative to the main shaft 7 of the pump assembly is limited through the interaction of the pump piston 11 and the roller tappet 20,
Characterized in that the roller tappet (20) is convexly formed in at least one support region (30) in which the roller tappet (20) is radially supported in the bore (8) of the housing portion (2).

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The roller tappet (20) according to claim 1, wherein the roller tappet (20) is formed by one roller tappet (20) Is supported radially with respect to the main shaft (7) of the pump assembly (6) in the bore (8) of the pump assembly (6).

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2. The roller tappet of claim 1, wherein the convex portion (30) of the roller tappet (20) in the support region (30) is located between the bore (8) of the housing portion (2) and the convex portion (30) (31) between the rotary shaft (33) and the rotary shaft (32) of the roller (21) is 5 mm or less.

A high pressure pump according to any one of the preceding claims, characterized in that a spring seat (23) is provided which is connected to the roller tappet (20) and the pump piston (11) is connected to a spring seat (23).

The high-pressure pump according to claim 6, wherein the pump piston (11) is press-fitted into the spring seat (23).

7. A roller tappet (20) according to claim 6, wherein the spring seat (23) is guided by the roller tappet (20) laterally along the main shaft (7) of the pump assembly Wherein the support extensions (35, 36) limit the side of the rolling portion of the roller along the rotation axis (32) of the roller (21).

The high-pressure pump according to claim 6, characterized in that the pump piston (11) is configured in the form of a cylinder.

7. A pump according to claim 6, wherein the pump piston (11) comprises a piston bottom end (50) towards the roller tappet (20) and the spring seat (23) And grips the piston lower end portion (50) of the piston (11) from behind.

11. High pressure pump according to claim 10, characterized in that the pump piston (11) is configured such that the piston bottom end (50) towards the roller tappet (20) is formed thicker than the cylindrical part (53).

4. A device according to any one of the preceding claims, wherein the drive shaft (3) provided with the cam (5) or cam (5) comprises at least one guide web (55,56) assigned to the cam And restricts the side surface of the rolling portion of the roller along the rotation axis (32) of the roller (21).