WO2012069046A1

WO2012069046A1 - Radial piston pump

Info

Publication number: WO2012069046A1
Application number: PCT/DE2011/075268
Authority: WO
Inventors: Karl Prinzhorn
Original assignee: Ixetic Bad Homburg Gmbh
Priority date: 2010-11-24
Filing date: 2011-11-11
Publication date: 2012-05-31
Also published as: DE112011103896A5

Abstract

A radial piston pump (1) is proposed with a housing (3), a drive shaft (5), an eccentric (7) which is coupled fixedly to the drive shaft (5) so as to rotate with it, a cylinder block (9), at least one radial bore in the cylinder block (9), at least one piston which interacts with the eccentric (7) and can be moved in the radial bore, a radial shaft seal (15) which surrounds the drive shaft (5) and seals the housing (3) with respect to the surroundings, a suction region (14) which is arranged on that side of the at least one piston which faces the eccentric (7), and with a separate fluid connection (21) between that side of the radial shaft seal (15) which faces the inner side of the housing (3) and an intake region of the radial piston pump (1). The radial piston pump is distinguished by the fact that the separate fluid connection (21) is realized at least in regions by a screw hole (23).

Description

Radial piston pump

The invention relates to a radial piston pump according to the preamble of claim 1.

Radial piston pumps of the type discussed here are known. They have a housing with a drive shaft, which is associated with a non-rotatable eccentric. This lies within a cylinder block having at least one radial bore. In this a piston is movably arranged, which cooperates with the eccentric. A radial shaft seal surrounding the drive shaft seals the housing from the environment. The suction region of the radial piston pump is provided on the eccentric side facing the at least one piston and thus also surrounds the drive shaft. If a negative pressure occurs in the suction area, this can act up to the radial shaft seal, so that a secure seal of the housing is not guaranteed.

The object of the invention is therefore to provide a radial piston pump which does not have this disadvantage.

To solve this problem, a radial piston pump of the above type is provided, which comprises the features listed in claim 1. It has a separate fluid connection between the side of the radial shaft sealing ring facing the inside of the housing and a suction region of the radial piston pump. A vacuum in the suction area can not spread in this way to the radial shaft seal. Rather, it is ensured that sufficient pressure is applied to the radial shaft sealing ring in each operating state of the radial piston pump, so that the sealing effect can be taken over by a sealing lip of the radial shaft sealing ring. Dust lips of the radial shaft seal must therefore not support the sealing effect. The radial piston pump is characterized in that the separate fluid connection is realized at least partially by a screw hole. In order to realize the fluid connection, channels must be created in the housing of the pump, which, as stated, the radial shaft sealing ring with the Connect the suction area of the pump. If, as proposed here, existing screw holes is used, it is particularly easy to realize such a fluid connection, in particular without creating additional channels in the housing of the pump, whereby this would be weakened.

Particularly preferred is an embodiment of the radial piston pump, which is characterized in that the fluid connection comprises an additional channel between the radial shaft seal and the screw hole. It is thus possible to create a fluid connection to the radial shaft sealing ring from a screw hole, which is fixed in its position by the basic structure of the radial piston pump.

Also preferred is an embodiment of the radial piston pump, which is characterized in that the fluid connection comprises a provided in a contact region between the housing and cylinder block channel. The radial piston pump is usually realized by a plurality of components which are pressure-tightly secured to each other. It is possible here to realize a channel in the area of contact between two parts, in this case between the housing and the cylinder block. This is preferably feasible by a groove which is provided in the housing and / or in the cylinder block. Such a fluid connection is easily realized.

In a further preferred embodiment of the radial piston pump a preferably actively designed suction throttle is provided between the intake and suction. With this, the volume flow of the radial piston pump can be adjusted.

Further preferred is an embodiment of the radial piston pump, which is characterized by a bearing for supporting the drive shaft in the housing and in that for its lubrication between the bearing and suction a fluid path is provided. About this fluid path, the funded by the pump medium can be used and used for lubrication of the bearing. Another preferred embodiment of the radial piston pump is characterized in that the fluid path continues to the suction region, wherein the flow resistance between the intake and bearing is smaller than that between the bearing and suction. As a result, the flow direction of the medium present in the intake region can be defined. It forcibly flows through the bearing when there is less pressure in the suction area than in the suction area. At the same time, it is prevented that a negative pressure in the suction area can have a negative effect on the radial shaft seal.

The invention will be explained in more detail below with reference to the drawing. Show it:

1 shows a radial piston pump in side view with partially weggeschnitte- areas and

Figure 2 is an end view of the reproduced in Figure 1 radial piston pump.

The radial piston pump 1 according to FIG. 1 serves to convey a medium, preferably oil, and has a housing 3 in which a drive shaft 5 is mounted with an eccentric 7 connected to it in a rotationally fixed manner. It also comprises a cylinder block 9 with at least one preferably radially extending bore, that is, with a bore which is perpendicular to a central axis 1 1 of the drive shaft 5 is arranged. In this at least one hollow piston, not shown here, is arranged to be radially movable, which cooperates with the eccentric 7. Upon rotation of the drive shaft and thus of the eccentric 7, the piston is pressed against the force of a spring radially outward, whereby the medium is conveyed into a pressure range, which is connected to a consumer, and whereby in the region in which the piston Excess 7 touches the suction area 14, a negative pressure is built up to suck the medium. Upon further rotation of the drive shaft of the at least one piston is pressed, for example by a spring inwardly in the direction of the central axis 1 1, whereby the conveying medium enters the piston. The medium passes from the outside into the intake region of the radial piston pump 1, preferably via a suction throttle 13. This can in particular be active be designed, for example by means of an electromagnet, so that they actively acted on the flow of the medium from the intake to the suction region 14 and thus the ejected by the radial piston pump 1 delivery volume can be influenced. If the suction throttle 13 is activated, the flow cross-section between the suction region and the suction region 14 decreases, so that a negative pressure in the suction region 14 is built up during operation of the radial piston pump 1. The function of a radial piston pump 1 is basically known, so that will not be discussed in detail here.

According to FIG. 1, the drive shaft 5 - here on the left - emerges from the housing 3. It is here provided in the outlet region for sealing the housing with a radial shaft sealing ring 15, which, seen in cross section, U-shaped, wherein a first leg 17 rests on the peripheral surface of the drive shaft 5 and a second leg 19 inside the housing 3. The enclosed by the two legs 17 and 19 cavity 20 opens inwardly into the housing. 3

The radial piston pump 1 has a separate fluid connection 21, which extends to the side of the radial shaft sealing ring 15 facing the inside of the housing, that is, up to the cavity 20 delimited by the legs 17 and 19. From the partial longitudinal section through the radial piston pump 1 according to FIG it can be seen that the separate fluid connection 21 is realized at least in regions by a screw hole 23. In the screw hole 23, a screw 25 is used, which has a screw head 27, a shaft 29 and an external thread 31. The screw 25 passes through a first housing part 33/1 and the cylinder block 9 and extends into a second housing part 33/2. The two housing parts 33/1 and 33/2 surround the cylinder block 9 and thus form the housing 3 of the radial piston pump first By the screw 25, the housing parts 33/1 and 33/2 are firmly connected and close the cylinder block 9 pressure-tight. The radial piston pump 1 has a plurality of such screws 25 in order to ensure a secure and stable connection of the housing parts 33/1 and 33/2. They are all housed in screw holes 23, at least part of which is the fluid connection 21. In the embodiment shown here, the second housing part 33/2 is formed as a central plate which separates the radial piston pump 1 from at least one further pump unit which is combined with the radial piston pump 1. This should not be discussed further here.

The drive shaft 5 is mounted via a bearing in the housing 3, here via a first bearing 35/1 in the first housing part 33/1 and via a second bearing 35/2 in the second housing part 33/2. The two bearings are here exemplified as plain bearings. From Figure 1 it can be seen that the drive shaft 5 protrudes from the second housing part 33/2 and engages in the at least one further pump unit, thus also serves as a drive shaft for the at least one further pump unit.

In the embodiment shown here, the external thread 31 of the screw 25 engages in an internal thread 37 in the second housing part 33/2, which is formed in the region of a blind hole 39.

FIG. 1 shows that the right end of the shaft 29 of the screw 25 engages in a blind hole 39. Thus, the right end of the screw is tightly closed. At the opposite end of the screw 25 is the screw head 27, which is in engagement with the housing 3, here with the housing part 33/3. Here in the region of the head 27 and the adjoining shaft 29 is ensured in a suitable manner that the screw hole 23 is sealed. For example, between the screw head 27 and the outer surface of the housing 3, an O-ring can be provided, which surrounds the shaft 29 and closes tight.

The shaft 29 of the screw 25 passes through the first housing part 33/1, and also the cylinder block 9. The screw hole 23 forming part of the fluid connection 21 extends from the first housing part 33/1 into the cylinder block 9 and ends in the blind hole 39 the contact area of the first housing part 1 with the cylinder block 9 must be ensured that a tight seal is given here. Preferably, an O-ring surrounding the screw hole 23 is provided between the first housing part 33/1 and the cylinder block 9, said O-ring surrounding the screw hole 23. dial piston pump 1 is clamped so that the screw hole 23 and thus the fluid connection 21 is sealed to the outside.

The fluid connection 21 comprises an additional channel 41, which extends between the screw hole 23 and the radial shaft sealing ring 15, more precisely ends on the inside of the housing 3 side facing and thus is also in fluid communication with the cavity 20.

In the area of contact between the cylinder block 9 and the second housing part 33/2 of the housing 3, a likewise the separate fluid connection 21 attributable channel 43 is provided, on the one hand with the screw hole 23 and on the other hand with a bore 45 in the second housing part 33/2 of the housing 3 in Connection stands. The bore 45, which also forms part of the fluid connection 21, is also connected to the suction region of the radial piston pump 1 in such a way that the suction throttle 13 has no influence on the flow cross section in the fluid connection between bore 45 and suction. In the illustrated embodiment of the radial piston pump 1, the screw hole 23 and the bore 45 are preferably parallel to the central axis 1 1 of the drive shaft fifth

The channel 43 can be realized by a groove arranged in the contact area between the cylinder block 9 and the housing 3, in this case the second housing part 33/2, which is provided either only in the surface of the cylinder block 9 or in the surface of the second housing part 33/2 is. This embodiment has the advantage that, for example, a known, unchanged cylinder block for the realization of the radial piston pump 1 can be used, which is combined with a modified second housing part 33/2.

Conversely, an existing second housing part 33/2 can be combined without groove with a cylinder block 9, which is designed with a groove for the realization of the channel 43. It is thus possible to use existing elements of a radial piston pump 1 for the realization of the channel 43. But it is also possible, in both adjacent part, ie in the cylinder block 9 and in the second housing part 33/2, which - as I said - can also be designed as a center plate, each introducing a groove to form the channel 43.

The fluid connection 21 is therefore after all connected on the one hand via the bore 45 with the suction of the radial piston pump 1, on the other hand with the cavity 20 of the radial shaft sealing ring 15th

Between the inside of the housing 3 facing side of the radial shaft seal 15 and the cavity 20 and the first bearing 35/1, a first portion 47/1 of a fluid path 49 is provided so that the funded by the radial piston pump 1 medium, in particular oil, for the lubrication of can serve the first camp 35/1. The fluid path 49 continues over a second section 47/2 to the suction region 14, the second section 47/2 extending between the first bearing 35/1 and the suction region 14. When the suction throttle 13 reduces the flow cross section between the suction region and the suction region 14, a negative pressure is generated in the suction region 14 which sucks the medium conveyed by the radial piston pump 1 from the separate fluid connection 21 via the fluid path 29. As a result, upon activation of the throttle 13, forced lubrication of the first bearing 35/1 is ensured.

It must be ensured that the negative pressure in the suction region 14 does not continue up to the cavity 20 of the radial shaft seal 15, because otherwise at least one of its legs 17 or 19 lifts and the sealing effect of the radial shaft seal 15 is released. In this case, therefore, the first leg 17 can lift off from the drive shaft 5 and / or the second leg 19 from the inside of the housing 3 and the first housing part 33/1. To ensure that the negative pressure in the suction region 14 does not continue to the cavity 20, it is provided that the flow resistance between the suction region (ie upstream of the suction throttle 13) and the first bearing 35/1 is smaller than the flow resistance between the first bearing This must apply to all operating conditions of the suction throttle 13 in order to ensure a safe contact of the legs 17 and 19 of the radial shaft seal 15 on the drive shaft 5 and on the inside of the housing 3. Figure 2 shows the radial piston pump 1 in front view, here is a view of the left side in Figure 1 side. The same and functionally identical parts are provided with the same reference numerals; In this respect, reference is made to the description of FIG. The representation according to FIG. 2 serves to clarify the sectional plane selected in FIG. For this purpose, this sectional plane is shown in Figure 1 by a dashed line ll. It runs from the top right to the middle of the screw 25 and from there to the bottom right through the central axis 1 1 of the drive shaft fifth

In Figure 2, the suction throttle 13 can be seen, also an intake port 51 through which the radial piston pump 1 sucks a medium. The flow direction of this medium is indicated by a double arrow 53. Thus, the intake of the radial piston pump 1 is quasi defined here.

LIST OF REFERENCES

I radial piston pump

3 housing

5 drive shaft

7 eccentrics

9 cylinder block

I I central axis

3 suction throttle

15 Radial shaft sealing ring

17 thighs 1

19 thighs 2

20 cavity

21 fluid connection

23 screw hole

25 screw

27 screw head

29 shaft

31 external thread

33 housing part / 1 and 12

35 bearings Π and 12

37 internal thread

39 blind hole

41 channel

43 channel

45 hole

47 1. section

49 fluid path

51 intake manifold

53 double arrow (flow direction)

Claims

claims

1 . Radial piston pump with

a housing (3),

a drive shaft (5),

a rotatably coupled to the drive shaft (5) eccentric (7), a cylinder block (9),

at least one radial bore in the cylinder block (9),

at least one piston which cooperates with the eccentric (7) and is movable in the radial bore,

a radial shaft sealing ring (15) surrounding the drive shaft (5) and sealing the housing (3) from the environment,

a suction region (14) which is arranged on the side of the at least one piston facing the eccentric (7) and with a separate fluid connection (21) between the side of the radial shaft sealing ring (15) facing the inside of the housing (3) and a suction region the radial piston pump (1),

characterized in that

the separate fluid connection (21) is realized at least in regions by a screw hole (23).

2. Radial piston pump according to claim 1, characterized in that the fluid connection (21) comprises an additional channel (41) between the radial shaft sealing ring (15) and screw hole (23).

3. Radial piston pump according to claim 1 or 2, characterized in that the fluid connection (21) in a contact area between the housing (3) and cylinder block (9) provided for channel (43), preferably by a groove in the housing (3) and / or in the cylinder block (9) is feasible.

4. Radial piston pump according to one of the preceding claims, characterized in that between the suction and suction region (14) a - preferably active - suction throttle (13) is provided.

5. Radial piston pump according to one of the preceding claims, characterized in that at least one first bearing (35/1) for supporting the drive shaft (5) in the housing (3) is provided and that for its lubrication between the bearing and the suction a fluid path (49) is provided.

6. Radial piston pump according to claim 5, characterized in that the fluid path (49) to the suction region (14) continues, wherein the flow resistance between the intake and bearing is smaller than that between the bearing and suction.