EP1058001A1 - High pressure feed pump - Google Patents

Abstract

The pump has a cylinder (8) with piston (9), a drive shaft (3) with eccentric (6) supporting a rolling ring (7). The ring has two apertures/recesses located in its outer wall, axially outside and on either side of the contact surface (16) between ring and piston. The aperture has an approx. rectangular cross section. The surface of the ring is curved.

Description

The present invention relates to a feed pump for high pressures and especially the drive of feed pumps, that work on the reciprocating principle. High pressure feed pumps have one in relation to the piston diameter relatively long piston stroke and are therefore suitable to generate high pressures. Such high pressure feed pumps are for example for the generation of the Injection pressure in fuel injection systems (e.g. Common Rail) used for internal combustion engines. A Generic high-pressure feed pump is in EP-A-881 380 A1.

High-pressure feed pumps of the generic type have one High pressure cylinder or plunger cylinder and one in this reciprocating cylindrical feed piston or plunger, the volume of the delivery chamber within the high pressure cylinder by the stroke movement of the Plunger is changed. With a filling stroke of the plunger is the delivery chamber via a filling valve with a Storage space for a fluid can be connected to the in Displacement increasing delivery volume with the medium to fill. During a subsequent funding stroke at When the filling valve is closed, the pressure in the delivery chamber increases until a pressure valve opens and thereby the delivery chamber connects a high pressure room. The exact design the high pressure pump is in said EP-A-0 881 380 A1 described, the disclosure of which is expressly made by this reference made the content of the present application becomes.

The plunger is driven by an eccentric drive, the one eccentric mounted on an eccentric shaft comprises, on which a rolling ring rotatably mounted is. During the rotation of the eccentric, the preload is on Delivery piston with one provided at one end plate-like extension on the rolling ring. Due to the force relationships when passing through the The gear ring rotates at top and bottom dead center here back and forth and changes per revolution of the eccentric shaft twice its direction of rotation. This can happen at high Speed of the drive shaft to damage the components of the eccentric drive.

It is therefore an object of the present invention to create a high pressure feed pump that works even at high Speed works without problems.

This task is solved with a high pressure feed pump, which has the features of claim 1.

According to the invention, the rolling ring has at least one recess or recess so that the moment of inertia of the rolling ring is reduced with respect to its axis of rotation. This reduction in the moment of inertia also the acceleration torque of the rolling ring when the direction of rotation changes reduced, causing damage to the Eccentric drive especially in the area of a contact surface between the rolling ring and the delivery piston.

This makes it possible to use a high-pressure feed pump of the generic type operate at higher speeds than before, without the adverse effect of a sliding movement occurs between the rolling ring and the piston foot. Further brings the reduction in the moment of inertia and thus relief of the total mass of the rolling ring the eccentric drive construction with it, since the bearings the drive shaft are exposed to lower loads.

Advantageous embodiments of the invention are in the Description, the figures and the subclaims described.

According to a first embodiment, the recess or Recess formed on the outer circumference of the rolling ring his. As a result, the stability of the rolling ring is not reduced, but at the same time the moment of inertia can be reduced.

According to a further embodiment of the invention, the rolling ring on its outer circumference and axially outside the Area of the contact surface at least one circumferential recess on. In this embodiment, the rolling ring lowered symmetrically outside the area of the contact surface, which in turn does not reduce stability, however the moment of inertia and therefore also the acceleration moment is reduced when the direction of rotation changes.

It is particularly advantageous if the rolling ring has two rotating ones Has recesses which the contact surface limit laterally, and each on the outer edge of the Rolling ring are provided. This is a symmetrical one Arrangement created in terms of reduction the moment of inertia is optimized. In this embodiment is only in the area of the contact surface the required outer diameter of the rolling ring is available. The rolling ring is outside the contact surface reduced mass.

Fig. 1

eine Schnittansicht einer Hochdruckförderpumpe mit einem Exzentertrieb;

Fig. 2

eine Schnittansicht entlang der in Fig. 1 gezeigten Ebene II-II, welche die Kontaktfläche zwischen dem Abwälzring und dem Förderkolben darstellt;

Fig. 3

eine Schnittansicht eines Exzentertriebs in der oberen Totpunktlage des Föderkolbens;

Fig. 4

eine Schnittansicht eines Exzentertriebs in der unteren Totpunktlage des Föderkolbens; und

Fig. 5

eine Schnittansicht eines Abwälzrings gemäss der vorliegenden Erfindung.

The invention is explained in more detail below by means of an advantageous embodiment purely by way of example and with reference to the attached figures. Show it:

Fig. 1

a sectional view of a high-pressure feed pump with an eccentric drive;

Fig. 2

a sectional view along the plane II-II shown in Figure 1, which represents the contact surface between the rolling ring and the delivery piston.

Fig. 3

a sectional view of an eccentric drive in the top dead center position of the plunger;

Fig. 4

a sectional view of an eccentric drive in the bottom dead center position of the plunger; and

Fig. 5

a sectional view of a rolling ring according to the present invention.

Figure 1 shows a longitudinal section through a high pressure feed pump with a housing 4 in which a high pressure cylinder 8 is inserted, in which a delivery piston 9 and can move here. The high pressure cylinder 8 is one Base body 11 clamped in the housing 4 by means of Bolt 18 and 18 'is screwed into the housing 4. In the base body 11 there is also an inlet valve 12 and an exhaust valve 13 is provided, the exhaust valve 13 opens the passage to a high pressure container 14 and closes.

In the housing 4 of the high pressure feed pump is also a Eccentric drive provided, which has a drive shaft 3, over bearings 5 and 5 'freely around an axis of rotation 1 is rotatably supported. The drive shaft 3 carries between the bearing points 5, 5 'with respect to the axis of rotation 1 of the drive shaft 3 arranged eccentrically Eccentric pin 6, the center axis 2 parallel to the axis of rotation 1 of the drive shaft 3 runs. On the eccentric pin 6 is a cambered on its outer circumference Rolling ring 7 rotatably mounted with respect to the eccentric pin 6.

In a substantially circular cylindrical bore 10 of the high pressure cylinder 8, the delivery piston 9 is sliding slidably guided. The delivery plunger 9 has on its the drive shaft 3 facing end a plate-like extension 15, which rests on the rolling ring 7. Here the reference numeral 16 denotes the contact point or Contact area between the rolling ring 7 and the extended End 15 of the delivery piston 9. By means of a compression spring 17, the one hand on the high pressure cylinder 8 and the other is supported on the plate 15, the delivery piston 9 biased against the rolling ring 7.

To compress and promote a medium, the Delivery piston 9 by the eccentric 3, 6, 7 up and down emotional. If the delivery piston 9 during a filling stroke Moving down, the delivery chamber of the high pressure cylinder fills up 8 via the inlet valve 12 with the pumped medium. If the delivery piston 9 in a following Moving the delivery stroke upwards, the pressure in the delivery chamber increases with inlet valve 12 closed until the outlet valve 13 opens and thereby the delivery room with the high pressure container 14 connects. The pumped medium is in the High pressure container 14 promoted.

Figure 2 shows a section along the line II-II of Figure 1, wherein the contact surface 16 along this section plane is hatched. As can be seen is against at high pressure loads on the delivery piston 9 the contact surface 16 occurring in the rolling ring 7 is elliptical, since the rolling ring 7 is slightly convex.

Figures 3 and 4 illustrate the operation of the Eccentric drive and the movement of the rolling ring 7 Go through the top and bottom dead center positions. Figure 3 shows the delivery piston 9 in the top dead center position. At a progressive rotation of the eccentric pin 6 or the drive shaft 3 in the counterclockwise direction shown 3, the contact surface 16 moves to the left, whereby the rolling ring 7 rotates clockwise. This is because the bias of the spring 17 and Pressure in the delivery chamber in the area of the top dead center on is largest, so that the force exerted by the spring 17 greater than the sliding friction force between the plate 15 and the rolling ring 7.

FIG. 4 shows the bottom dead center position of the delivery piston 9. The eccentric pin 6 moves in the direction of this lower one Dead center position, the contact surface 16 moves in Figure to the right, causing the rolling ring 7 to rotate counterclockwise. This is because again remember that the force exerted by the spring 17 also greater than that in the area of the bottom dead center position Sliding friction between the plate 15 and the rolling ring 7 is.

The rolling ring 7 thus moves relative to the plate 15 during the rotation of the eccentric 6 back and forth and changes its direction of rotation per revolution of the drive shaft 3 twice. This leads to a high speed of the drive shaft 3 to problems because the frequency of change of the direction of rotation Rolling ring 7 and thus also its acceleration torque increases. In the worst case it takes place between the plates 15 and the rolling ring 7 at rotational acceleration peaks Sliding instead of what can lead to damage.

To avoid the damage occurring at high speeds in the area of the contact surface 16 is according to the invention a rolling ring 7 'is provided, as in Figure 5 is shown in cross section. The rolling ring 7 'corresponds essentially the rolling ring 7 of Figures 1 to 4, but two on the outer circumference of the rolling ring 7 ' Recesses or recesses 20, 22 are provided. The Recesses 20, 22 are located axially outside the area the contact surface 16 and are each on the outside Edge of the rolling ring 7 'is provided. The one between the two circumferential recesses 20, 22 existing contact surface, i.e. the protruding part of the outer circumference of the rolling ring 7 'is again slightly cambered. The recesses 20, 22 of the rolling ring 7 'are seen in cross section roughly rectangular.

The rolling ring according to the invention has a smaller one Moment of inertia and a correspondingly lower acceleration torque, which is a higher frequency of rotation change of the rolling ring, a higher speed of the Drive shaft and thus a higher delivery capacity of the High pressure pump allows without the rolling ring 7 'on the plate 15 slides at acceleration peaks. A High-pressure pump with an eccentric drive according to the invention can therefore be operated at higher speeds, without damaging the components of the eccentric drive or excessive wear occurs.

Claims (11)

High pressure feed pump with a high pressure cylinder (8), a delivery piston (9) displaceable therein and a eccentric arranged on a drive shaft (3) (6) on which a rolling ring (7, 7 ') is rotatably mounted is on which the delivery piston (9) or a connected Part rests over a contact surface (16), characterized in that the rolling ring (7 ') at least a recess or recess (20, 22) having. High-pressure feed pump according to claim 1, characterized in that the recess or recess (20, 22) formed on the outer circumference of the rolling ring (7 ') is. High-pressure feed pump according to claim 1, characterized in that the rolling ring (7 ') on its outer circumference and axially outside the area of the contact surface (16) at least one circumferential recess (20, 22). High-pressure feed pump according to claim 1, characterized in that two circumferential recesses (20, 22) are provided, the contact surface (16) laterally limit and each on the outer edge of the rolling ring (7 ') are provided. High-pressure feed pump according to one of claims 1 to 4, characterized in that the recess (20, 22) of the rolling ring (7 ') seen in cross section approximately is rectangular. High-pressure feed pump according to one of claims 1 to 5, characterized in that the peripheral surface of the Rolling ring (7, 7 ') is convex. Rolling ring (7 ') for a high pressure feed pump at least one of the preceding claims, characterized characterized in that this has at least one recess or recess (20, 22). Rolling ring according to claim 7, characterized in that the recess or recess (20, 22) on the outer circumference of the rolling ring (7 ') is formed. Rolling ring according to claim 7, characterized in that two circumferential recesses (20, 22) are provided are, each on the outer edge of the rolling ring (7 ') are provided. Rolling ring according to one of claims 7 to 9, characterized characterized in that the recess (20, 22) in Cross section is approximately rectangular. Rolling ring according to one of claims 7 to 11, characterized characterized in that the peripheral surface of the rolling ring (7, 7 ') is domed.

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