EP1375915A1 - Radial piston pump with improved efficiency for high pressure fuel supply in injection systems of internal combustion engines - Google Patents

Abstract

The pump has three cylinders (17) set in the housing (23) 120 degrees apart. Each piston has a hemispherical inner end (59) engaging a shoe which engages on a triangular ring (31) on an eccentric shaft. Two galleries (51a,51b) connect the working ends of two cylinders. The first has a side branch leading to a magnetic control valve (15) which releases fuel back to the inlet via a reservoir. The second is connected to a relief valve (55).

Description

State of the art

The invention relates to a radial piston pump for High pressure fuel supply at Fuel injection systems of internal combustion engines, especially with common rail injection systems, with preferably several with respect to one in one Pump housing mounted drive shaft radially arranged Pump elements, the pump elements of the Drive shaft are operated and one suction side and have a high pressure side and with high pressure channels in the Pump housing, each of which is the high pressure side of a Pump element with a high pressure connection in the Connect the pump housing.

Such radial piston pumps are for example High pressure generation in internal combustion engines with gasoline direct injection known. The pump is not regulated operated. The common rail injection systems required pressure control takes place via a Pressure control valve on the common rail. This means that in Partial load operation. significant part of that of the Radial piston pump pump work done subsequently in Pressure control valve is dissipated again, what a low efficiency of the fuel injection system Consequence. In addition, the efficiency is this Radial piston pump not yet satisfactory.

Advantages of the invention

In a radial piston pump according to the invention High pressure fuel supply at Fuel injection systems of internal combustion engines, especially with common rail injection systems, with preferably several with respect to one in one Pump housing mounted drive shaft radially arranged Pump elements, the pump elements of the Drive shaft are operated and one suction side and have a high pressure side and with high pressure channels in the Pump housing, each of which is the high pressure side of a Pump element with a high pressure connection in the Connecting the pump housing is a volume control valve provided, which is a hydraulic in the open state Connection between the high pressure ducts and the suction sides the pump elements manufactures, and are between Volume control valve and the suction sides of the pump elements a storage volume and a throttle are provided.

Due to the pressure control valve, the Flow rate of the radial piston pump over a wide range be managed. The regulation takes place via a suitable one Control of the fast switching flow control valve, see above that prevents unnecessary pump work and thus the Efficiency of the fuel injection system is increased. Through the storage volume and one with the storage volume cooperating throttle is prevented that the at Open the pressure control valve fully punch through to the suction side of the radial piston pump and there to impermissibly high pressure loads and unwanted dynamic disturbances.

In a variant of the invention it is provided that each High pressure duct the high pressure sides of two pump elements that connects hydraulically with one another in the shortest possible way the number of high pressure channels is 1 less than the number of Is pump elements, and that from a high pressure duct High pressure connection branches. Through these features the The number of high pressure ducts is minimized and the volume is also reduced this high pressure channels minimized. Thus on the High pressure side of the radial piston pump according to the invention harmful volume minimized, leading to another Increasing pump efficiency in all operating conditions leads. The volume control valve is hydraulic with one of the High pressure channels connected.

In an advantageous embodiment of the Radial piston pump according to the invention Storage volume through a puncture in the pump housing and bounded by a sleeve sealed against the pump housing, so that the desired storage volume is manufactured can be easily manufactured. It has gone further than proven advantageous if a throttle in the sleeve is provided, which is between the storage volume and the Suction side of the pump elements is arranged.

Alternatively, it is also possible to use the pump housing. run in two parts and the storage volume of one first housing part and a second housing part limit. This makes it possible to dispense with the sleeve, which helps to further reduce the assembly effort.

To further improve pump efficiency provided that each pump element a piston, a Cylinder bore and a cylinder head that the Piston oscillates in the cylinder bore and one Delivery space limits that on the suction side a first Check valve is arranged that the first Check valve is integrated in the piston, and that on a second check valve is arranged on the high pressure side is.

The load capacity of the radial piston pump according to the invention, whose drive shaft in the pump housing of the Shaft plain bearing is further increased if the plain bearing of fuel, especially of the cool one flowing through the fuel connection Fuel that is flowed through. This is cooling and / or lubrication of the plain bearing, which is what Resilience and service life increased. The cooling of the Plain bearing can be further improved if in the Drive shaft or a bearing shell of the plain bearing multiple holes are provided by fuel be flowed through. It is for the invention Effect does not matter whether the holes are directly in the Drive shaft can be attached or in a on the Drive shaft applied sleeve are arranged.

In a further addition to the invention it is provided that the piston base plate is articulated on the piston, and that the lifting movement of the eccentric section of the Drive shaft via a polygon ring on the Piston base plate is transferred. It did Simulation calculations showed that this Design the mechanical stress of those involved Reduced components and reduced friction losses become.

Further advantages and advantageous configurations of the Invention are the following drawing, the Description and the patent claims.

drawing Show it:

Fig. 1:

a circuit diagram of a first embodiment a radial piston pump according to the invention;

Fig. 2:

an embodiment of an inventive Radial piston pump in longitudinal and cross section;

Fig. 3:

another embodiment of a Radial piston pump according to the invention in Longitudinal section as well

Fig. 4 u. 5:

Embodiments of an inventive Cooling the slide bearing of the radial piston pump.

Description of the embodiments

In Fig. 1 is a block diagram of an inventive Radial piston pump 1 shown. The radial piston pump 1 has a suction side 3 and a (high) pressure side 5, which over a third check valve 7 with a common rail 9 in Connection is established. The pressure control in the common rail 9 takes place via a pressure control valve 11, which excess fuel from the common rail 9 into one Fuel return 13 conducts. The fuel return 13 opens into the suction side 3 of the radial piston pump 1. The Suction side 3 is from a not shown here Fuel tank supplied with fuel.

Between pressure side 5 and fuel return 13, the again hydraulically connected to the suction side 3 stands, a volume control valve 15 is provided. If that Quantity control valve 15, as shown in Fig. 1, opened is on the pressure side 5 of the radial piston pump 1 Pressure build up take place because of a hydraulic connection over the fuel return 13 with the suction side-3. In this state, the radial piston pump 1 does not deliver Fuel into the common rail 9 because of the pressure in the common rail 9 much higher than the pressure on the suction side 3 the radial piston pump 1. If the volume control valve 15 is closed, is the hydraulic connection between Suction side 3 and pressure side 5 via the fuel return 13 interrupted, so that a pressure build-up in the Pump elements 17 of the radial piston pump 1 take place can. In this state, the radial piston pump 1 delivers Fuel into the common rail 9 as soon as that of the Pump elements 17 pressure greater than that in Common Rail 9 is prevailing pressure. Through this type of Flow control can be carried out by the radial piston pump 1 minimized pump work and thus the Degree of utilization of the invention Fuel injection system can be improved.

So that when opening the quantity control valve 15 occurring pressure surges in the fuel return 13 and the suction side 3 are minimized, is in the fuel return 13 a memory 19 and a downstream of the memory 19 Throttle 21 provided. The memory 19 and the throttle 21st reduce and dampen when opening the Volume control valve resulting pressure peaks on allowable dimension. First of all, this makes it impermissibly high Pressure on the suction side 3 avoided. Second, the intake of fuel through the Pump elements 17 not by the damped pressure surges more impaired.

2 is an embodiment of one Radial piston pump 1 according to the invention in a longitudinal section (2a) and a cross section along the section line B-B (2b).

The radial piston pump 1 consists of a pump housing 23, which is made in two parts. The pump housing 23 thus consists of a first housing part 23a and a second housing part 23b. In the second housing part 23b a recess 25 incorporated in the assembled state together with the first housing part 23a, the memory 19 forms. Is between the memory 19 and the suction side 3 the throttle 21 is arranged.

A drive shaft 27 is rotatable in the pump housing 23 stored. The drive shaft 27 has an eccentric Section 29 with a polygon ring 31. The eccentric Section 29 reaches over the polygon ring 31 freely over the circumferentially distributed pump elements 17, of which in Fig. 2a only one is visible.

Each pump element 17 has a piston 33, which in a cylinder bore 35 is guided and a delivery chamber 37 limited. The pump elements 17 are radial from the outside inserted into the pump housing 23 and via a Fixing screw 39 clamped to the pump housing 23. A first check valve 41 is provided in the piston 33, which draws fuel into the delivery space 37 allows. Via a transverse bore 41 in the piston 33 hydraulic connection between the first check valve 41 and the suction side 3 manufactured. The one from not shown fuel drawn fuel flows onto the Intake side 3 of the radial piston pump 1 and flows through then a plain bearing 45 of the drive shaft 27 before it is sucked in by the pump elements 17.

2b shows the same embodiment along the Section line B-B shown. This representation becomes clearly that in a cylinder head 47 of the pump elements 17 a second check valve 49 is provided by that of the piston 33 from the delivery space 37 ejected, high pressure fuel in High pressure channels 51a and 51b arrives. The high pressure ducts 51a and 51b are part of those marked 5 in FIG Pressure side.

The high-pressure channels 51a and 51b connect the three pump elements 17 by the shortest route, ie in this case that the high-pressure channels 51a and 51b are designed in a straight line. In the exemplary embodiment shown here, there are three pump elements 17 and two high-pressure channels 51a and 51b. Transferred to radial piston pumps with a different number m of pump elements 17 applies to the number n of high-pressure channels n = m - 1.

The quantity control valve 15 is on the high-pressure duct 51a connected. When the quantity control valve 15 is open, As mentioned in connection with FIG. 1, one in FIG. 2b invisible hydraulic connection between the High pressure channels 51a and 51b on the one hand and the suction side 3 on the other hand.

A high-pressure connection 53 branches off from the high-pressure duct 51b. In the connection piece 55 is the third check valve 7 integrated.

From Fig. 2b it can be seen that the piston 33 with a Place piston base plate 57 on polygon ring 31. The Piston base plate 57 is connected via a ball joint 59 connected to the piston 33 so that the piston foot plate 57 optimally rests on the polygon ring 31. 'Optimal' means in this context that no local Stress peaks occur and depend on the dynamic load and the lubrication condition between Piston base plate 57 and polygon ring 31 the piston base plate 57 always rests on the polygon ring 31 over a large area.

Because of the ball joint 59, the piston foot plate 57 one caused by the axial and radial forces Take an incline. This will "edge up" the Piston base plate 57 counteracted on the polygon ring 31 become. As a result, the Piston shear forces in the cylinder guide, the mechanical Efficiency improves and lifespan or Resilience of the high pressure fuel pump improved.

In Fig. 3, another embodiment is one Radial piston pump 1 according to the invention in longitudinal section shown. The same components are the same Provide reference numerals, and that applies to a Embodiment said for the others Embodiments accordingly. With this In the exemplary embodiment, the housing 23 is in one piece executed. The memory 19 is a puncture 61 in the Pump housing 23 formed. This puncture is made by a Sleeve 63, which the storage volume of the storage 19 of hydraulically separates the suction side 3, seals. In the Sleeve 63, the throttle 21 is arranged. Thus, the Memory 19 according to the invention without major change on Pump housing 23 with both radial piston pumps 1 one-piece pump housing 23 or with two-piece Pump housing 23a and 23b are used.

The seal of the memory 19 to the suction side can 2 and 3 by O-rings, Metal sealing rings or bite edges are made.

4 and 5 show the plain bearing 45 along one Section line I-I and a section line J-J (see Fig. 2a) in Detail. From Fig. 4 it can be seen that on the Drive shaft 27 a sleeve 65 was pressed into the Longitudinal grooves 67 are incorporated. The sleeve 65 is in one Bearing shell 69, which in the first housing part 23a is pressed, rotatably mounted. The grooves 67 will be like results from Fig. 2a in connection with Fig. 4, of which cool fuel drawn from the fuel tank flows through. As a result, the sleeve 65 and the Bearing shell 69 cooled, which is particularly important when using the radial piston pump according to the invention in Internal combustion engines with petrol direct injection very much is helpful. It is without for the invention Meaning whether the fuel through grooves 67 or in the Drive shaft 27 machined holes (not shown) flows. It is essential that the cool Fuel from the fuel tank to cool the Plain bearing 45 is used.

From Fig. 5 it can be seen that the plain bearing 45 so is designed that at the transition of the drive shaft 27 to eccentric section 29 in the bearing shell 69 channels 71 are provided by which the fuel which by the grooves 67 is flowed, can flow freely to the largest possible proportion of the fuel drawn to pass through the grooves 67. This will have the cooling effect further improved.

All in the drawing, its description and the Features mentioned claims can be both individually as well as in any combination with each other be essential to the invention.

Claims (9)

Radial piston pump for supplying high-pressure fuel in fuel injection systems of internal combustion engines, in particular in common rail injection systems, preferably with a plurality of pump elements (17) arranged radially with respect to a drive shaft (27) mounted in a pump housing (23), the pump elements (17) being driven by the drive shaft (27 ) are actuated and each have a suction side (3) and a high pressure side (5) and with high pressure channels (51a, 51b) in the pump housing (23), which each have the high pressure side (5) of a pump element (17) with a high pressure connection (53) in the Connect the pump housing (23), characterized in that a quantity control valve (15) is provided, which in the open state establishes a hydraulic connection between the high-pressure channels (51a, 51b) and the suction sides (3) of the pump elements (17), and that between the Quantity control valve (15) and the suction sides (3) of the pump elements (17), a memory (19) and a throttle (21) vo are seen. Radial piston pump according to claim 1, characterized in that each high-pressure channel (51a, 51b) hydraulically connects the high-pressure sides of two pump elements (17) to one another in the shortest possible way, that the number (s) of high-pressure channels (51a, 51b) is 1 less than the number ( m) of the pump elements (17), and that a high-pressure connection (53) branches off from a high-pressure duct (51b). Radial piston pump according to one of the preceding claims, characterized in that the accumulator (19) is delimited by a recess (61) in the pump housing (23) and a sleeve (63) sealed off from the pump housing (23). Radial piston pump according to claim 4, characterized in that the throttle (21) is arranged in the sleeve (63). Radial piston pump according to one of the preceding claims, characterized in that the pump housing (23) is designed in two parts and consists of a first housing part (23a) and a second housing part (23b), and that the accumulator (19) of the first and second housing parts (23a , 23b) is limited. Radial piston pump according to one of the preceding claims, characterized in that each pump element (17) has a piston (33), a cylinder bore (35) and a cylinder head (47), that the piston (33) oscillates in the cylinder bore (35) and one Delivery space (37) limits that a first check valve (41) is arranged on the suction side (3), that the first check valve (41) is integrated in the piston (33), and that on the high pressure side (5) a second check valve ( 49) is arranged. Radial piston pump according to claim 5, characterized in that the drive shaft (27) is mounted in the pump housing (23) by a slide bearing (45), and in that the slide bearing (45) forcibly flows through fuel, in particular fuel flowing through a fuel connection becomes. Radial piston pump according to one of the preceding claims, characterized in that one or more bores or grooves (67) are provided in the drive shaft (27) or a bearing shell (69) of the slide bearing (45), and in that these bores or grooves (67) be flowed through by fuel. Radial piston pump according to one of the preceding claims, characterized in that the piston base plate (57) is articulated on the piston (33). and that the lifting movement of the eccentric section (29) of the drive shaft (27) is transmitted to the piston foot plate (57) via a polygon ring (31).

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