JP2006506572A - Radial piston pump with a planar sealing member between the flange and the housing - Google Patents

Abstract

A radial piston pump comprising a flange portion, a housing portion, a pump element disposed in the housing portion, and an eccentric drive shaft, wherein the drive shaft is driven in the pump element. A piston that is movable in a radial direction with respect to the shaft is operated, and the piston seals the pump volume movably. When the pump volume is enlarged, fuel is pumped from the suction chamber into the pump volume. When the pump volume is reduced, the fuel in the pump volume is pressurized and sent out from the pump volume under a high pressure, and further, an inner chamber that accommodates the eccentricity, and the inner chamber and the suction chamber There is provided a type in which an intersecting, separating plane between the housing part and the flange part is provided. The radial piston pump is excellent in that a single plane integral sealing member that seals the suction chamber, the surrounding environment of the radial piston pump and the inner chamber from each other is arranged on the separation plane. Yes.

Description

BACKGROUND ART The present invention is a radial piston pump,
-A flange part, a housing part, an inner chamber and a suction chamber are provided;
-At least one pump volume movably sealed by a piston in the housing part;
An eccentric drive shaft extending axially through the inner chamber is provided, the drive shaft actuating the piston in the radial direction, whereby the piston pumps fuel from the suction chamber into the pump volume The fuel is pressurized in the pump volume and delivered from the pump volume under high pressure;
-It relates to a type in which a separation surface intersecting the suction chamber is provided between the housing part and the flange part.

  A radial piston pump of this construction type is used in an injection system for a combustion process, in particular in a common rail direct injection system for a fuel process, to generate an injection pressure exceeding 1000 bar.

  German Patent 19848035 describes a radial piston pump of this type of construction.

  In known radial piston pumps, fuel is supplied to the suction chamber from the low-pressure pump via a plurality of holes and passages extending inside the flange and housing, and via a controllable metering unit. A radial piston pump generally has a plurality of pump elements, which are arranged radially with respect to a central drive shaft. The fuel supply to the pump volume of the pump element takes place in the region outside the radial piston pump on the opposite side of the drive, i.e. on the side away from the pump center as seen in the radial direction.

  The fuel supply to the individual pump elements is performed in multiple ways by a plurality of passages formed in the radial direction. These passages extend through the flange parallel to the separation surface and open into one central supply line common to all pump elements. The central supply line is supplied with fuel by a single supply passage extending axially through the radial piston pump. This supply passage penetrates the separation surface between the flange and the housing.

  Similarly, the pump volume of the pump element located radially further outside is also connected to a respective axially arranged passage. Each of these passages has a corresponding supply hole extending radially outward. In known radial piston pumps, these passages also penetrate the separation surface between the flange and the housing. Further, this separation surface is provided with a plurality of other passages depending on the configuration of the radial piston pump, for example, a passage serving to vent the inner chamber, and an inflow pipe for a fuel low pressure feed pump flanged to the radial piston pump It can be penetrated by the road.

  Due to the axially and centrally arranged drive shaft guide, another opening is created in the flange and the housing. These openings are rotationally symmetric in known radial piston pumps. The drive shaft rotates in the inner chamber of the radial piston pump, and this inner chamber is generally filled with fuel. However, the fuel pressure in the inner chamber does not correspond to the fuel pressure in the suction chamber.

  If a fuel flow is generated between the inner chamber and the suction chamber and the associated supply passage, the subsequent supply of fuel to the pump volume may be impaired. In order to prevent such undesirable fuel flow between the inner chamber and the suction chamber, the suction chamber must be sealed to the inner chamber. Furthermore, in order to ensure that the entire pump is tight, the suction chamber and the supply passage, which are arranged radially outward and which guide the fuel, must be sealed off from the surrounding environment. For this reason, all the passages and / or chambers guiding the fuel, which are intersected by the separation surface, must be sealed at the separation surface. In known radial piston pumps, these seals are provided by a number of O-rings made of elastomeric material.

  Such a seal type is relatively time consuming when manufacturing a radial piston pump. That is, each of the multiple O-rings must be accurately fitted individually into a receiving groove provided for receiving the O-ring on the face of the flange and / or housing. Such receiving grooves must be produced by a corresponding material removal process for each O-ring, such as milling, drilling, bracing or turning.

  Furthermore, the O-ring exhibits a reliable sealing action only when it is laid in an annular shape. This leads to structural and manufacturing technical disadvantages when manufacturing the radial piston pump. That is, for example, a radially extending connection passage between a supply line arranged in the center of the radial piston pump and a connection located radially outward of the pump volume is guided inside the flange or housing. Must be connected through holes provided in the separation surface.

  The radially extending holes are generally formed by perforations made from the outside inward in the radial direction. This leaves a hole in the outer wall of the radial piston pump which is inconvenient in itself, and is closed by a sealing sphere made of metal, for example, press-fit by press fitting. Such a closure of the hole is an additional work step during manufacture, and such an additional work step makes production expensive. Furthermore, a sphere that is press-fit by press fitting deviates from the ideal of finding a pump housing that is as closed as possible in principle.

  Furthermore, the O-ring used on the separation surface itself is in principle easy to age, so that it can later cause non-sealability in the radial piston pump.

  In view of such a background, an object of the present invention is to provide a sealing device between a flange portion and a housing portion in a radial piston pump that does not have the disadvantages described above.

  The problem is that, in the radial piston pump of the type described at the beginning, an integral planar sealing member consisting of a single part is arranged on the separation surface to seal the suction chamber against the surrounding environment of the radial piston pump. Is solved.

Advantages of the Invention Such a solution has the following advantages. That is, the integral planar sealing member can be assembled particularly easily and with high reliability. This is because if an accurate position is obtained with respect to two points of the planar seal member, an accurate position of all other points is automatically provided. As a result, it is possible to avoid that the seal structure located in the center range of the radial piston pump slips without being noticed during assembly, particularly at the moment of joining the flange and the housing.

  Furthermore, it is not necessary to stock several types of O-rings. This is because all different sizes of seal contours can be taken into account when designing a planar seal member.

  Another advantage resides in that the planar seal member can achieve a seal profile different from the O-ring circular shape. This is advantageous because it gives a greater degree of freedom in the structure of the part to be sealed, as will be explained in more detail below.

  In an advantageous configuration of the invention, the separation surface intersects the suction chamber and the inner chamber, the integral planar sealing member seals the inner chamber from the suction chamber, and this suction chamber is in the surrounding environment. It is sealed against. Such a configuration has the following advantages. In other words, a close separation between the suction chamber and the inner chamber and a close separation between the suction chamber and the surrounding environment can be performed by a single component, that is, a planar seal member.

  In another advantageous configuration of the invention, the planar sealing member has a sheet metal layer.

  The metal thin plate sealing member is aging resistant and fuel resistant, and is shape-stable and inexpensive.

  In a further advantageous configuration of the invention, the sheet metal sealing member has a covering.

  When the covering body contains an elastic material that is stretchable and flexible, this covering body can further improve the sealing action of the metal thin plate sealing member.

  Therefore, it is further advantageous that the covering contains an elastic plastic material.

  In a further advantageous configuration of the invention, the planar sealing member has an indented or embossed part extending between the inner chamber and the suction chamber in the mounted state.

  The pushing portion or the embossed portion further improves the sealing action of the planar seal member, so that a particularly good seal between the inner chamber and the suction chamber can be obtained.

  According to a further advantageous configuration of the invention, the planar sealing member has an indented or embossed part extending between the suction chamber and the surrounding environment in the mounted state.

  This indented portion or embossed portion also improves the sealing action of the planar seal member, so that a particularly good seal between the suction chamber and the surrounding environment can be obtained.

  In a further advantageous configuration of the invention, the thickness of the sheet metal is 0.1 to 0.3 mm.

  In a further advantageous configuration of the invention, the indented or embossed part has a height of 0.2 to 0.4 mm.

  These dimensions produced a particularly reliable seal.

  In a further advantageous configuration of the invention, the suction chamber is supplied with fuel, at least in part, by a groove provided in the housing or flange, which opens towards the separating surface.

  Such a configuration is further related to the means for realizing a seal profile having a shape different from the circular shape of the O-ring using the planar seal member described above. Thus, it is no longer necessary to extend the radially extending fuel passages described above into the interior of the flange material or housing material and then connect the passages with a plurality of holes that penetrate the separation surface.

  Instead, when a planar sealing member is used, it is possible to move the passages, in particular the radially directed passages, to the separation surface, for example a square edge to be sealed. Is obtained. In that case, the sealing can be effected, for example, by an embossed part adapted in terms of shape. These embossed portions extend around an open passage located on the separation surface.

  Other advantages will be apparent from the description of the embodiments and the accompanying drawings.

  Of course, the features mentioned above and those described below can be used only in the respective combinations described, but also in other combinations or in a single form without departing from the scope of the invention. It becomes.

  In the following, embodiments of the invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing a known radial piston pump assembled and joined;
2 is a plan view schematically showing a flange of the radial piston pump shown in FIG. 1;
FIG. 3 is a sectional view showing a radial piston pump as an embodiment of the present invention;
4 is a plan view schematically showing a flange of the radial piston pump shown in FIG. 3;
FIG. 5 is a plan view showing a configuration of a planar seal member for placement on a separation surface between a housing portion and a flange portion of a radial piston pump;
6 is a cross-sectional view of the planar sealing member shown in FIG.

  In FIG. 1, a radial piston pump is indicated by reference numeral 10. The radial piston pump 10 includes a housing 12 and a flange 14. The housing 12 and the flange 14 are connected to each other at a separation surface 16, in which case a connecting element, for example a screw, is not shown for reasons of clarity of the drawing. The radial piston pump 10 is provided with a drive shaft 18. The drive shaft 18 is guided through the radial piston pump 10 at a central position and is supported in bearings 20 and 22. The drive shaft 18 has an eccentric range 24, which operates a piston 28 via a slide element 26. The piston 28 is disposed radially in a hole provided in the housing 12 and movably seals the pump volume 30 in the housing 12. The pump volume 30 communicates with the suction chamber 34 via a valve 32. Fuel is supplied to or supplied to the pump volume 30 through the suction chamber 34. Furthermore, the pump volume 30 is connected to a high pressure passage 38 via a valve 36. Through this high pressure passage 38, fuel is pumped from the pump volume 30 under high pressure.

  The piston 28 is periodically actuated by the drive shaft 18 rotating within the bearings 20, 22, so that the pump volume 30 is periodically reduced and expanded. When the pump volume 30 is enlarged, the valve 32 is opened and fuel flows from the suction chamber 34 into the pump volume 30. When the pump volume 30 is reduced, this causes the valve 32 to close and causes the valve 36 to open, subject to a sufficiently high pressure, through which the fuel is under high pressure. Discharged from the pump volume 30.

  The radial piston pump 10 is incorporated in a low pressure circuit (not shown). In this low-pressure circuit, fuel is supplied into a supply passage 40 provided in the housing 12 by a low-pressure feed pump (not shown). The fuel from the supply passage 40 is introduced into the first connection hole 42 provided in the flange 14 beyond the separation surface 16. The fuel flows from the first connection hole 42 into the annular passage or the annular groove 50 through the first radial hole 44 extending into the flange 14 and the second connection hole 48.

  The first radial hole 44 is drilled from the outside in the radial direction during manufacture, and the obstructive opening remaining in the housing 12 after the formation of the hole is tightly closed using the first closing sphere 46. . The annular groove 50 is guided around the central range of the radial piston pump 10 where the drive shaft 18 is rotatably supported. The fuel flows from the annular groove 50 into the second radial hole 54 via the third connection hole 52. Similar to the production of the first radial hole 44, the second radial hole 54 is formed by perforation performed from the outside to the inside. In this case too, the undesired opening leading to the outside remaining after drilling is closed by the closing sphere, ie in this case by the second closing sphere 56. The fuel flows from the second radial hole 54 into the suction chamber 34 through the fourth connection hole 58 that intersects the separation surface 16.

  Therefore, the radial piston pump 10 shown in FIG. 1 has a plurality of fuel passages intersected by the separation surface 16 between the flange 14 and the housing 12. Further, the separation surface 16 between the housing 12 and the flange 14 also intersects with an inner chamber 60 located inside the housing 12. In this inner chamber 60, the eccentric section 24 of the drive shaft 18 rotates and actuates the piston 28. The fuel passages (40, 42, 50, 54, 58) intersected by the separation surface 16 are under the pressure formed in the suction chamber 34. The inner chamber 60 is typically filled with fuel and / or is flowed by fuel. However, a pressure different from the pressure formed in the suction chamber 34 and the fuel passages (40, 42, 50, 54, 58) communicating with the suction chamber 34 is usually formed in the inner chamber 60.

  In order to prevent undesired fuel flow between the inner chamber 60 and each fuel passage (40, 42, 50, 54, 58), particularly the annular groove 50, an O-ring 62 is provided. The O-ring 62 is disposed concentrically with respect to the drive shaft 18 in a receiving groove provided in the flange 14. The annular groove 50 is also sealed against the surrounding environment by another O-ring 64 at the separation surface 16. The first connection hole 42 is sealed by another O-ring 66 at the separation surface 16. Similarly, the fourth connection hole 58 is sealed at the separation surface 16 by another O-ring 68.

  FIG. 3 schematically illustrates a radial piston pump 10 within the framework of the present invention. Unlike the known radial piston pump shown in FIGS. 1 and 2, the configuration of the radial piston pump 10 according to the invention shown in FIG. 3 has a separating surface 16 between the housing 12 and the flange 14 of the radial piston pump 10. Are not provided with O-rings 62, 64, 66 and 68. As a precaution, the same reference numerals denote the same features in the various drawings.

  The plurality of O-rings provided in the known radial piston pump shown in FIGS. 1 and 2 are replaced by a single planar seal member 70 in the configuration of the present invention shown in FIGS. 3 and 4. The planar seal member 70 is disposed on the separation surface 16 between the housing 12 and the flange 14. The structure of the planar seal member 70 will be described in detail further below with reference to FIGS. A great advantage of using the planar seal member 70 is that the planar seal member 70 allows for a modified fuel guide. That is, in the embodiment of the radial piston pump 10 according to the present invention shown in FIG. 3, the supply passage 40 opens into the radial groove 72. This radial groove 72 may open towards the separating surface 16. A radial groove 72 connects the supply passage 40 to the annular groove 50. Accordingly, the radial groove 72 replaces the first connection hole 42, the first radial hole 44 with the first connection sphere 46, and the second connection hole 48 in the configuration shown in FIG. Is. Similarly, the radial groove 74 in the configuration shown in FIG. 3 includes the third connection hole 52 in the configuration shown in FIG. 1, the second radial hole 54 with the second closing sphere 56, This is an alternative to the four connection holes 58. The radial groove 74 is also open to the separation surface 16.

  FIG. 4 shows a plan view of the flange 14 as seen from the front without the planar seal member 70. From the plan view of FIG. 4, both radial grooves 72, 74 are open and extend, the O-rings 62, 64, 66, 68 are not provided, and these O-rings are attached to the flange 14. It can be seen well that no corresponding receiving groove for receiving is provided.

  FIG. 5 is a plan view showing a configuration of a flexible planar seal member 70 used in the radial piston pump. This configuration corresponds to a radial piston pump that is actually used rather than the radial piston pump schematically illustrated in FIGS. The planar sealing member 70 shown in FIG. 5 must also be disposed on the separation surface 16 between the housing 12 and the flange 14 of the radial piston pump 10. The planar sealing member 70 has three regions 76, 78, 80 arranged in a star shape or a radial shape, and each of the three regions 76, 78, 80 has one opening 77, 79, 81, respectively. Is arranged. The three regions 76, 78, 80 arranged radially in the radial direction cover the open radial grooves provided in the flange 14 of the radial piston pump 10 in the mounted state.

  The associated radial piston pump has correspondingly three pump elements, which are also arranged radially in the radial direction. The radial groove is formed in the same manner as the radial groove 74 in the embodiment shown in FIGS. 3 and 4, for example. The openings 77, 79, 81 each allow the flow of fuel from the radial groove through the planar seal member 70 into the associated pump volume.

  In the configuration shown in FIG. 3, the openings provided in the planar seal member 70 that allow the flow from the radial groove 74 into the suction chamber 34 correspond to one opening 77, 79, 81, respectively. ing. Accordingly, a suction chamber pressure is formed in the range of these openings 77, 79, 81. This suction chamber pressure is sealed against the inner chamber of the radial piston pump by an embossed portion (Sicke) 82 located inside. This inner chamber corresponds to the inner chamber 60 in FIGS. The suction chamber is sealed to the outside by another embossing part 84. The embossed portion 84 extends in an annular shape so as to draw a single closed line around all three ranges 76, 78, and 80 that are radially arranged.

  The planar seal member 70 has other openings 86, 88, 90, 92. These openings 86, 88, 90, 92 are respectively surrounded by the associated, concentrically arranged embossed portions 87, 89, 91, 93. These openings 86, 88, 90, 92 are created by the separation surface 16 intersecting another passage and / or pressure chamber. That is, for example, the opening 92 may be arranged corresponding to the metering unit. The supply of fuel to the radial piston pump is controlled via this metering unit. The openings 86, 88, 90 may form inflow and outflow passages for a low pressure-gear feed pump, for example flanged to a radial piston pump. On the other hand, the opening 90 may be disposed corresponding to a vent hole for the inner chamber 60 of the radial piston pump, for example. The opening 95 serves to guide through a fixing member, for example a screw.

  Particularly from FIG. 5, it is possible to form a sealing contour in the form of an embossed part different from the concentric shape of the O-ring used for general purposes by using a planar sealing member. I understand. Further, the fuel passage extending radially outward may be moved into the separation plane as represented by the radial groove 74 in FIGS. Thereby, for example, the flange 14 in which the fuel supply portion extending in the radial direction is arranged can be more easily manufactured. That is, for example, in the case of the cast flange 14, the radial groove can be sufficiently preformed and formed corresponding to the radial groove 74 in FIGS. 3 and 4. Steps are not necessary enough. The same is true for the forged flange 14.

  FIG. 6 shows the planar seal member 70 shown in FIG. 5 in a cross-sectional state. The sheet-like sealing member 70 has a metal thin plate layer 94, and this metal thin plate layer 94 imparts structure and strength to the sheet-like sealing member 70. In the illustrated configuration, the sheet metal layer 94 is covered with a layer 96 made of a stretchable elastic elastic plastic, which improves the sealing action. The embossed portions 84 and 82 are visible as raised portions in the cross-sectional view shown in FIG.

It is sectional drawing which shows the radial piston pump by a well-known prior art in the state assembled and joined. FIG. 2 is a plan view schematically showing a flange of the radial piston pump shown in FIG. 1. It is sectional drawing which shows the radial piston pump as an Example of this invention. FIG. 4 is a plan view schematically showing a flange of the radial piston pump shown in FIG. 3. It is a top view which shows the structure of the planar sealing member for arrange | positioning on the isolation | separation surface between the housing part and flange part of a radial piston pump. It is sectional drawing of the planar sealing member shown in FIG.

Claims (10)

A radial piston pump (10),
A flange part (14), a housing part (12), an inner chamber (60) and a suction chamber (34) are provided;
-At least one pump volume (30) movably sealed by the piston (28) is provided in the housing part (12);
An eccentric drive shaft (18) extending axially through the inner chamber (60) is provided, the drive shaft (18) actuating the piston (28) in the radial direction, whereby the piston (28) pumps fuel from the suction chamber (34) into the pump volume (30), pressurizes the fuel in the pump volume (30) and delivers it from the pump volume (30) under high pressure. And
In a type in which a separating surface (16) intersecting the suction chamber (34) is provided between the housing part (12) and the flange part (14),
The separating surface (16) is provided with a single-piece, integral sealing member (70) that seals the suction chamber (34) against the surrounding environment of the radial piston pump (10). A radial piston pump.   The separation surface (16) intersects the suction chamber (34) and the inner chamber (60), and an integral planar seal member (70) seals the inner chamber (60) against the suction chamber (34). The radial piston pump according to claim 1, wherein the suction chamber (34) is sealed against the surrounding environment.   The radial piston pump according to claim 1 or 2, wherein the planar sealing member (70) has a thin metal plate layer (94).   The radial piston pump of claim 3, wherein the sheet metal layer (94) has a covering (96).   The radial piston pump of claim 4, wherein the covering (96) comprises an elastic plastic material.   The planar sealing member (70) has an embossed portion (82) extending between the inner chamber (60) and the suction chamber (34) in the mounted state. The radial piston pump of any one of Claims.   7. The embossed part (84) extending between the suction chamber (34) and the surrounding environment in a mounted state, the planar sealing member (70). The radial piston pump described in the item.   The radial piston pump according to any one of claims 3 to 7, wherein the thickness of the metal thin plate layer (94) is 0.1 to 0.3 mm.   The radial piston pump according to claim 6 or 7, wherein the height of the embossed portion is 0.2 to 0.4 mm.   Fuel is supplied to the suction chamber (34) by a groove (74) provided at least partially in the housing (12) or the flange (14) and opening toward the separation surface (16). The radial piston pump according to any one of claims 1 to 9.

Images