DE102011087749A1 - Internal gear pump e.g. feed pump, for use in fuel conveying device of internal combustion engine of aircraft, has two pairs of sealing sections attached to respective gear wheels and coaxially displaceable relative to each other - Google Patents

Abstract

The pump (10) has an internally-toothed gear wheel i.e. hollow wheel (20), and an externally-toothed gear wheel i.e. pinion gear (18), arranged in the internally-toothed gear wheel. The gear wheels are axially displaceable to each other. A pair of ring-shaped sealing sections (40) is attached front surfaces (28, 30) of the externally-toothed gear wheel, and another pair of ring-shaped sealing sections (50) is attached to front surfaces (34, 36) of the internally-toothed gear wheel, where the sections are coaxially and axially displaceable relative to each other and designed as cylinder rings.

Description

State of the art

The invention relates to an internal gear pump according to the preamble of claim 1.

Internal gear pumps for conveying liquid media are known from the market. They are used for a variety of tasks in hydraulic systems, such as in motor vehicles for the promotion of fuel (for example, as pre-feed pump) or for generating a hydraulic pressure in transmission controls. They have advantages in terms of pulsation and noise and are relatively robust compared to any polluted fluids.

Disclosure of the invention

The problem underlying the invention is solved by an internal gear pump according to claim 1. Advantageous developments are specified in subclaims. Features which are important for the invention can also be found in the following description and in the drawings, wherein the features, both alone and in different combinations, can be important for the invention, without being explicitly referred to again.

The invention has the advantage that a delivery volume of an internal gear pump can be controlled continuously and thus a delivery characteristic can be optimally adapted to a requirement. The control can be done in various ways, but especially hydraulically. Furthermore, end-side and head-side sections of the gears can be sealed particularly well by means of respective sealing sections, wherein hydraulic gaps can be at least partially compensated automatically. The friction of the movable elements of the internal gear pump can be reduced, whereby the risk of interference or jamming is minimized.

The internal gear pump according to the invention for conveying a fluid has an internally toothed gear ("ring gear") and an externally toothed gear ("pinion") arranged therein. Both gears have an unequal number of teeth to each other and mesh with each other over a certain angular range of its circumference. According to the invention, the ring gear and the pinion can be moved axially relative to each other. This is preferably done hydraulically. In this case, a first pair of annular sealing portions and the two end faces of the ring gear, a second pair of annular sealing portions is associated with the two end faces of the pinion. Thus, the pinion is axially guided and / or sealed by means of the first pair, and the ring gear is axially guided and / or sealed by means of the second pair. The two pairs are coaxial with each other and axially displaceable relative to each other. That is, a first annular seal portion of the first pair is coaxially disposed with a first annular seal portion of the second pair, and a second annular seal portion of the first pair is coaxially arranged with a second annular seal portion of the second pair. Preferably, the respective annular sealing portions are designed as separate elements, wherein the second annular sealing portion of the first pair may optionally also be a portion of a housing of the internal gear pump.

The internal gear pump according to the invention can be used in a variety of applications, where a delivery volume is to regulate or control. For example, it can be used as a prefeed pump or as a so-called high-pressure pump in a fuel delivery device for an internal combustion engine. It is also possible to use it in aircraft turbine injection systems, for pumping anti-lock braking systems (ABS), automatic slip control (ASR) or vehicle stabilization systems (ESP). Furthermore, the internal gear pump can also be used for feedwater pumps or to promote cooling lubricants or refrigeration media. In addition, the internal gear pump can be used as a hydraulic pump, as an engine oil pump or as a transmission oil pump or auxiliary pump.

In particular, the invention provides that the ring gear is axially displaceable with respect to the housing of the internal gear pump, wherein the first annular sealing portion of the second pair axially leads and seals a first end face of the ring gear, and wherein the second annular sealing portion of the second pair has a second end face the ring gear axially leads and seals, and wherein the first annular sealing portion of the second pair is pressed by means of hydraulic force against the first end face of the ring gear, and wherein the second annular sealing portion of the second pair is pressed by spring force against the second end face. As a result, the pinion can maintain its axial position when controlling the internal gear pump and thus be fixedly mounted on a shaft. Only the ring gear is moved axially during the rules. This allows the internal gear pump to build easier and cheaper overall. As an alternative to the hydraulic force, the first annular sealing section of the second pair can also be displaced by means of mechanical force, for example by an adjusting drive or an actuator.

The first annular sealing portion of the second pair is for example in one corresponding annular recess of the housing arranged displaceably. An axial length of the annular recess is at least the axial length of the first annular sealing portion of the second pair plus an axial displacement provided for the ring gear. On a side remote from the ring gear of the annular recess, a fluid - preferably the fluid to be delivered - are pressed into the annular recess. Thus, the ring gear can be acted upon at the first end face with a hydraulic force. At the second - opposite - end face of the ring gear an axial counterforce is formed by means of the second annular sealing portion of the second pair, which is preferably generated by one or more supported on the housing springs, which may be designed in particular as helical springs.

An embodiment of the internal gear pump provides that a first annular sealing portion of the first pair is radially immediately and fluidtightly adjacent the first annular sealing portion of the second pair, and / or a second annular sealing portion of the first pair is radially immediately adjacent to the second annular sealing portion of the second pair is fluid-tight adjacent. This makes it possible that the two pairs are axially displaceable relative to each other, wherein the mutually facing surfaces of the annular sealing portions can slide on each other. Preferably, this is done with a small radial clearance, so that each resulting cylindrical gap small and possible leaks are correspondingly low.

In addition, it is provided that the cylindrical gap between the first annular sealing portions and / or the cylindrical gap between the second annular sealing portions is sealed in each case by means of a radial sealing ring, for example in the form of a shaft sealing ring. As a result, leaks can be greatly reduced.

At an axially facing away from the pinion end face of the first annular sealing portion of the first pair and / or on a pinion axially remote end face of the second annular sealing portion of the first pair can by appropriate design of the elements in the operation of the internal gear pump (axial) hydraulic pressure fields for gap compensation build up between elements or sections, so that, for example, the said sealing portions lie particularly close to the end faces of the pinion and thus can seal very well. In addition, in the internal gear pump according to the invention also a radial and possibly dependent on the adjustment and variably designed hydraulic pressure field for gap compensation on the tooth head of pinion and ring gear, whereby each one of the sealing portions of a pair radially adjusted and thus reduced at the respective elements column and minimizes leakage can be. At the same time friction forces can be kept relatively small.

A further embodiment of the internal gear pump provides that between the first annular sealing portion of the first pair and the first annular sealing portion of the second pair and / or between the second annular sealing portion of the first pair and the second annular sealing portion of the second pair is arranged in each case at least one rotation , As a result, an undefined behavior or even wear of the annular sealing sections or of the radial sealing ring can be prevented during operation.

In particular, the rotation can be designed as axially extending and preferably cylindrical pin, which is arranged approximately in half in a radially outer recess of the respective annular sealing portion of the first pair and in a radially inner recess of the respective annular sealing portion of the second pair. This embodiment is particularly simple and inexpensive to produce.

The operation of the internal gear pump takes place particularly low-interference and wear-poor, if a center plane of the ring gear is slightly offset with respect to a median plane of the pinion in a set to a maximum capacity inner gear, so that the first annular sealing portion of the second pair of the pinion and the second annular Sealing portion of the first pair slightly overlaps the ring gear. As a result, an exactly identical axial position of the ring gear and the pinion or the radially adjacent annular sealing sections can be prevented. A possible jamming of the annular sealing portions or the pinion and the ring gear starting from the position with maximum promotion is thus avoided.

It is further provided that the first and the second annular sealing portion of the first pair have a radial clearance with respect to the housing. As a result, any tolerances of the ring gear and the pinion and the annular sealing portions can be compensated and the tightness can be improved in particular between a suction region and a pressure region of the internal gear pump.

In addition, it is provided that the ring gear radially leading bearing ring a Can perform pendulum movement about a pivot point in the housing, such that the tooth tips of the teeth of the pinion can seal against the tooth tips of the teeth of the ring gear at a transition from a suction to a pressure region of the internal gear pump. The bearing ring is arranged radially outwardly around the ring gear and can, for example, adapt to a possible slight angular misalignment of an axis line of the ring gear. The bearing ring can therefore perform a small pendulum motion in the housing so as to achieve a mutual sealing of the tooth tips from the transition from the suction to the pressure region.

A further embodiment of the internal gear pump provides that the first annular sealing portion of the second pair and / or the second annular sealing portion of the first pair are radially adjustable. As a result, gaps on the tooth tips of the pinion and the ring gear can be compensated particularly well. The radial adjustment is preferably carried out by a dependent of the adjustment and preferably designed variable hydraulic pressure field.

The internal gear pump operates better when it is designed so that in operation radially and / or axially acting hydraulic pressure fields can be formed, which act on at least one of the first and / or second annular sealing portions such that radial and / or axial gaps on the Pinion or its teeth and / or on the ring gear or its teeth can be reduced. In this case, the pressure fields can be built up in radial and / or axial gaps between the elements of the internal gear pump or form. For example, this is done by means of the leaking in operation.

The internal gear pump is particularly useful when it is a prefeed pump in a fuel delivery device of an internal combustion engine, or when it is a hydraulic pump of a hydraulic system of a motor vehicle. In these applications, it may be necessary to change the respectively required delivery volume during operation comparatively quickly and strongly. The continuous regulation of the internal gear pump made possible by the invention can prevent any excessively conveyed fluid quantities from having to be "deactivated". As a result, the efficiency of the fuel delivery device or of the hydraulic system can be improved.

Hereinafter, exemplary embodiments of the invention will be explained with reference to the drawings. In the drawing show:

1 an axial sectional view of an internal gear pump in a first operating condition;

2 an axial sectional view of the internal gear pump of 1 in a second operating state;

3 a first radial sectional view of the internal gear pump according to a view III-III of 1 ;

4 one too 3 opposite second radial sectional view of the internal gear pump according to a view IV-IV of 1 ;

5 a first radial sectional view of the internal gear pump according to a view VV of 1 ;

6 one too 5 opposite second radial sectional view of the internal gear pump according to a view VI-VI of 1 ; and

7 a representation of a rotation.

The same reference numerals are used for functionally equivalent elements and sizes in all figures, even in different embodiments.

1 shows an axial sectional view of an internal gear pump 10 , The internal gear pump 10 includes a first housing portion shown in the left portion of the drawing 12 , which with a second housing section shown in the right area 14 is connected in a manner not shown fluid-tight to the outside. Furthermore, the internal gear pump includes 10 a horizontally arranged in the drawing shaft 16 on which an externally toothed gear, hereinafter as a pinion 18 referred to, is arranged rotationally fixed. The wave 16 is in liners 19a respectively. 19b the housing sections 12 respectively. 14 radially guided and stored. The wave 16 protrudes in the left portion of the drawing from the housing section 12 out and can be driven by a drive - not shown - rotating.

The pinion 18 is radially within an internally toothed gear, hereinafter referred to as ring gear 20 designated arranged. The ring gear 20 is in a recess (without reference numeral) of the second housing portion 14 arranged and has one to the pinion 18 same axial length. However, in the present case of operation, the maximum fluid delivery is the ring gear 20 in terms of the pinion 18 slightly shifted axially and points with the pinion 18 an axial overlap 22 which is smaller than the axial length of the pinion 18 or the ring gear 20 is. A bearing ring 24 whose axial length is greater than that of the ring gear 20 is, surrounds and guides the ring gear 20 radial. A tooth circle of the ring gear 20 is in relation to a tooth circle of the pinion 18 larger, with the ring gear 20 and the pinion 18 in the upper part of the drawing. In the lower part of the drawing comb the ring gear 20 and the pinion 18 not, but it can be radially outer tooth portions of the pinion 18 and radially inner tooth portions of the ring gear 20 slide on each other.

The pinion 18 has teeth 26 and two oppositely disposed end faces 28 and 30 on. Likewise, the ring gear 20 teeth 32 and two oppositely disposed end faces 34 and 36 on. In the 1 is the ring gear 20 with the left in the drawing ("first") face 34 on a surface of the housing section 12 axially. This thus forms a kind of stop for the, as will be explained below, axially movable ring gear 20 , A first annular sealing portion 38 in the form of a cylinder ring lies axially on the left end face in the drawing 34 of the ring gear 20 and thus forms a kind of axial guidance. The annular sealing portion 38 is concentric to an axis line 39 the wave 16 and the pinion 18 arranged and has an inner diameter, which - with a minimum clearance - an outer diameter of the pinion 18 equivalent. The annular sealing portion 38 So can the face 34 of the ring gear 20 in an area or environment of the teeth 32 axially guide and fluidically seal and the pinion 18 seal radially.

Radially adjacent within the annular sealing portion 38 is another first annular sealing portion 40 arranged. The annular sealing portion 40 also has the shape of a cylinder ring and lies axially on the left in the drawing face 28 of the pinion 18 at. An outer diameter of the annular sealing portion 40 corresponds - again with a minimal clearance - the outer diameter of the pinion 18 , The annular sealing portion 40 So can the left in the drawing face 28 of the pinion 18 in an area or environment of the teeth 26 axially guide and fluidly seal. In a radially outer circumferential recess of the sealing portion 40 is a radial sealing element 42 ("Sealing ring") arranged in the manner of an O-ring, against a radially inner surface of the annular sealing portion 38 can dense.

The annular sealing portion 38 is in a circumferential recess 44 of the first housing section 12 arranged axially displaceable, wherein the recess 44 matching the annular sealing portion 38 is executed in the form of a cylinder ring. An axial length of the recess 44 However, it is larger than an axial length of the annular sealing portion 38 , This will be in the recess 44 in the drawing, left of the annular sealing portion 38 a hydraulic workspace 46 educated. The workroom 46 is about one in the first housing section 12 arranged hydraulic channel 48 connected to a hydraulic control device, not shown.

A second annular sealing portion 50 in the form of a cylindrical ring lies axially on the right in the drawing face 30 of the pinion 18 at. The annular sealing portion 50 is present - unlike the annular sealing portion 38 - axially not displaceable. The annular sealing portion 50 is concentric to an axis line 52 of the ring gear 20 arranged and has an outer diameter which is smaller than an outer diameter of the pinion 18 , The annular sealing portion 50 So can the face 30 of the pinion 18 in an area or environment of the teeth 26 axially guide and fluidly seal. Likewise, it can be seen in the lower part of the drawing that the annular sealing portion 50 on an axial section of the teeth of the teeth 32 slide and fluidly seal there.

Radially adjacent outside of the annular sealing portion 50 is a second annular sealing portion 54 arranged. The annular sealing portion 54 has the shape of a cylinder ring and guides the ring gear 20 axially on the right in the drawing face 36 , An inner diameter of the annular sealing portion 54 corresponds to an inner diameter of the ring gear 20 , The annular sealing portion 54 So can the right in the drawing face 36 of the ring gear 20 in an area or environment of the teeth 32 axially guide and fluidly seal. In a radially inner circumferential recess of the annular sealing portion 54 is a radial sealing element 56 ("Seal") arranged in the manner of an O-ring, which is against a radially outer surface of the annular sealing portion 50 can dense.

The first annular sealing portion 40 forms together with the second annular sealing portion 50 a first pair of annular sealing portions 40 and 50 with which the pinion 18 axially guided and sealed. The first annular sealing portion 38 forms together with the second annular sealing portion 54 a second pair of annular sealing portions 38 and 54 , with which the ring gear 20 axially guided and sealed.

In the drawing right of the annular sealing portion 54 are pressure-loaded coil springs 58 arranged, which on an axial inner surface of the second housing portion 14 are supported. The coil springs 58 act on the annular sealing portion 54 in the drawing to the left against the face 36 of the ring gear 20 , In the 1 are two coil springs 58 visible, noticeable.

In a transition region from a suction region to a pressure region of the internal gear pump 10 are by concerns of the annular sealing portions 38 and 50 at the respective end faces of the teeth 26 respectively. 32 the associated tooth chambers fluidly tight. There is no fluidic ring closure through a seemingly existing annular channel.

During operation of the internal gear pump 10 becomes the pinion 18 by means of the shaft 16 driven in rotation. The pinion 18 drives the partially meshing ring gear with him 20 at. For conveying fluid required hydraulic channels, which with the teeth 26 and 32 covered cavities are connected in the 1 but not shown or not visible. In the in the 1 shown axial position of the axially displaceable ring gear 20 this is - in the drawing left - on the housing section 12 struck. The overlap 22 and according to the possible capacity of the internal gear pump 10 are maximum. arrows 43 and 53 identify during operation of the internal gear pump 10 formed hydraulic pressure fields for gap compensation, by means of which the annular sealing portions 40 respectively. 50 especially close to the faces 28 respectively. 30 of the pinion 18 and thus can be particularly well-sealed.

In a not shown and slightly off the 1 deviating embodiment of the internal gear pump 10 have the bearing ring 24 and the first and second annular sealing portions 40 and 50 of the first pair with respect to the housing portion 12 respectively. 14 a radial play on. This allows any tolerances of the ring gear 20 and the pinion 18 and the annular sealing portions 40 . 50 and 54 balanced and the tightness in particular between the suction and the pressure range of the internal gear pump 10 be improved by allowing a pendulum motion.

2 shows the internal gear pump 10 of the 1 in a second operating state. Regarding the 1 is the ring gear 20 by means of in the work space 46 formed hydraulic force in the drawing to the right against the annular sealing portion 54 and against the force of the coil springs exemplified 58 moved axially. Accordingly, the axial overlap 22 and consequentially the capacity of the internal gear pump 10 less than in the 1 , The axially movable elements of the internal gear pump 10 are each performed with low friction. In the dimensioning of the said hydraulic force is preferably also a hydraulic delivery pressure of the internal gear pump 10 takes into account, if necessary, the pressure in the working space 46 can counteract.

By means of in the workroom 46 formed hydraulic force, the axial overlap 22 of the pinion 18 and the ring gear 20 between a minimum value required for safe combing and a through the axial lengths of the pinion 18 or the ring gear 20 certain maximum value be changed continuously. This will increase the capacity of the internal gear pump 10 accordingly changed continuously. In the in the 1 and 2 illustrated embodiment of the internal gear pump 10 is the possible axial displacement of the ring gear 20 However, by hitting the housing section 12 limited. Thus, the possible overlap 22 by a small amount smaller than the axial length of the pinion 18 or the ring gear 20 , This allows an exact same axial position of the ring gear 20 and the pinion 18 or the radially adjacent annular sealing portions 38 and 40 respectively. 50 and 54 be prevented. A possible jamming of the internal gear pump 10 is avoided.

3 shows a radial sectional view of the internal gear pump 10 according to a view III-III of 1 , In the present case, the pinion 18 fifteen radially outwardly directed teeth 26 and the ring gear 20 sixteen radially inwardly directed teeth 32 on. In the lower part of the drawing are in the gaps of the teeth 26 the second annular sealing portion 50 of the first couple and in the gaps of the teeth 32 the second annular sealing portion 54 the second pair visible.

4 shows one to the 3 opposite radial sectional view of the internal gear pump 10 according to a view IV-IV of 1 , In the lower part of the drawing are in the gaps of the teeth 26 the first annular sealing portion 40 of the first couple and in the gaps of the teeth 32 the first annular sealing portion 38 the second pair visible.

5 shows a radial sectional view of the internal gear pump 10 according to a VV view 1 , In the 5 In addition, in each case an axially extending and in the present view arcuate suction slot 60a and a curved pressure slot 60b visible in the left or right area of the drawing. The suction slot 60a and the printing slot 60b are each as recesses in the second annular sealing portion 54 radially outward of the radial sealing element 56 executed.

6 shows one to the 5 opposite radial sectional view of the internal gear pump 10 according to a VI-VI view 1 , In the present view are in the area of the suction slot 60a and the printing slot 60b also foot sections of the teeth 32 visible, noticeable.

7 shows a simplified scheme of anti-rotation 62 by way of example between the first annular sealing sections 38 and 40 , The present four anti-rotation 62 are designed as axially aligned cylindrical pins which are approximately half in each case in corresponding recesses of the annular sealing portions 38 and 40 are arranged. The anti-rotation devices 62 are designed so that the axial displacement of the annular sealing portions 38 and 40 not hindered.

Claims (12)

Internal gear pump ( 10 ) for conveying a fluid, with an internally toothed gear ( 20 ) ("Ring gear") and an externally toothed gear arranged therein ( 18 ) ("Pinion"), characterized in that the ring gear ( 20 ) and the pinion ( 18 ) are axially displaceable to each other, and that the two end faces ( 28 . 30 ) of the pinion ( 18 ) a first pair of annular sealing portions ( 40 . 50 ) and the two end faces ( 34 . 36 ) of the ring gear ( 20 ) a second pair of annular sealing portions ( 38 . 54 ), wherein the two pairs are mutually coaxial and axially displaceable relative to each other. Internal gear pump ( 10 ) according to claim 1, characterized in that the ring gear ( 20 ) with respect to a housing ( 12 . 14 ) of the internal gear pump ( 10 ) is axially displaceable, wherein a first annular sealing portion ( 38 ) of the second pair has a first end face ( 34 ) of the ring gear ( 20 ) axially seals, and wherein a second annular sealing portion ( 54 ) of the second pair has a second end face ( 36 ) of the ring gear ( 20 axially seals, and wherein the first annular sealing portion ( 38 ) of the second pair by means of hydraulic force against the first end face ( 34 ) of the ring gear ( 20 ) is pressed, and wherein the second annular sealing portion ( 54 ) of the second pair by spring force against the second end face ( 36 ) is pressed. Internal gear pump ( 10 ) according to at least one of the preceding claims, characterized in that a first annular sealing portion ( 40 ) of the first pair of the first annular sealing portion ( 38 ) of the second pair is radially immediately adjacent and fluid-tight, and / or that a second annular sealing portion ( 50 ) of the first pair of the second annular sealing portion ( 54 ) of the second pair is radially immediately and fluid-tightly adjacent. Internal gear pump ( 10 ) according to at least one of the preceding claims, characterized in that a cylindrical gap between the first annular sealing portions ( 40 . 38 ) and / or a cylindrical gap between the second annular sealing portions ( 50 . 54 ) each by means of a radial sealing element ( 42 . 56 ) is sealed. Internal gear pump ( 10 ) according to at least one of the preceding claims, characterized in that between the first annular sealing portion ( 40 ) of the first pair and the first annular sealing portion ( 38 ) of the second pair and / or between the second annular sealing portion ( 50 ) of the first pair and the second annular sealing portion ( 54 ) of the second pair each have at least one anti-rotation device ( 62 ) is arranged. Internal gear pump ( 10 ) according to claim 5, characterized in that the rotation ( 62 ) is an axially extending and preferably cylindrical pin, which approximately in half in a radially outer recess of the respective annular sealing portion ( 40 . 50 ) of the first pair and in a radially inner recess of the respective annular sealing portion ( 38 . 54 ) of the second pair is arranged. Internal gear pump ( 10 ) according to at least one of the preceding claims, characterized in that with an internal gear pump set to a maximum delivery rate ( 10 ) a median plane of the ring gear ( 20 ) with respect to a median plane of the pinion ( 18 ) is arranged slightly offset, so that the first annular sealing portion ( 38 ) of the second pair the pinion ( 18 ) and the second annular sealing portion ( 50 ) of the first pair of the ring gear ( 20 ) overlap slightly. Internal gear pump ( 10 ) according to at least one of the preceding claims, characterized in that the first and second annular sealing portions ( 40 . 50 ) of the first pair with respect to the housing ( 12 . 14 ) have a radial clearance. Internal gear pump ( 10 ) according to at least one of the preceding claims, characterized in that a ring gear ( 20 ) radially leading bearing ring ( 24 ) a pendulum movement about a pivot point in the housing ( 12 . 14 ), such that the tooth tips of the teeth ( 26 ) of the pinion ( 18 ) against the teeth of the teeth ( 32 ) of the ring gear ( 20 ) at a transition from a suction region to a pressure region of the internal gear pump ( 10 ) can seal. Internal gear pump ( 10 ) according to at least one of the preceding claims, characterized in that the first annular sealing portion ( 38 ) of the second pair and / or the second annular sealing portion ( 50 ) of the first pair are radially adjustable. Internal gear pump ( 10 ) according to at least one of the preceding claims, characterized in that it has during operation at least temporarily radial and / or axially acting hydraulic pressure fields, which at least one of the first and / or the second annular sealing portions ( 38 . 40 . 50 . 54 ) act such that radial and / or axial gaps on the pinion ( 18 ) or his teeth ( 26 ) and / or on the ring gear ( 20 ) or his teeth ( 32 ) can be reduced. Internal gear pump ( 10 ) according to at least one of the preceding claims, characterized in that it is a prefeed pump in a fuel delivery device of an internal combustion engine, or that it is a hydraulic pump of a hydraulic system of a motor vehicle.

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