DE102008044148A1 - Medium tank, particularly for use as hydraulic fluid storage tank of hydraulic power steering of motor vehicle, has rotation generating element arranged within medium tank, which extends in axial direction - Google Patents

Abstract

The medium tank is connected in a medium circulation, and has an inlet (4) and an outlet. A rotation generating element is arranged within the medium tank, which extends in axial direction viewed from the inlet in a direction to a tank end. A closing element (7) is provided at the end opposite to the inlet, where the rotation generating element and the closing element have an outer periphery.

Description

The The invention relates to a medium container which is in a medium circuit is integrated, wherein the medium container has an inlet and having an outlet.

such Medium containers are for example as storage containers for the hydraulic fluid (servo oil tank) a hydraulic power steering a motor vehicle known. Currently known, hydraulic power steering systems are exemplary in passenger cars, trucks or the like motor vehicles used, and have a medium pump z. B. a hydraulic pump on. The hydraulic pump causes a, from a speed of Internal combustion engine independent, constant fluid or Medium flow. The medium pump is connected to the outlet of the medium container connected. The medium pump causes a transport of the medium z. B. to a steering gear, from where the medium to the medium container is transported back. In this respect, the medium container Also referred to as a surge tank. The exemplary one Servo oil tank serves primarily to compensate for example, due to level fluctuations by thermal expansion, dissolved gas in the fluid and in the low Scope of system leakage.

The constant fluid flow is ensured via an internal control valve (flow control valve), which controls the discharge of the medium from the medium container into the medium circuit. However, these control valves are very susceptible to contamination which may be in the medium or fluid. Small particles, especially hard oxides such as silicon and / or aluminum oxides (SiO ₂ , AlO ₂ ) get into the gap between the control valve piston and its bore, and so can destroy the respective material or component and thus the entire control valve. Contamination causes the flow-limiting valve to become blocked or locked. As a result, the flow rate is pump speed dependent, resulting in different power assistance (depending on the engine speed).

Of course, the medium pump itself can be destroyed by the particles. Due to the high sensitivity of the pump to contamination of the fluid, in particular to particles entrained in the fluid or medium flow (eg SiO ₂ , AlO ₂ ), filter elements are provided which are arranged in connection lines or hoses or the medium container itself , The filter elements filter out the contaminants from the fluid stream, thus preventing the contamination from entering the pump or control valve, for example.

When a major disadvantage of such filter elements is to be considered that these negatively affect the medium flow, or the Disturb flow, because the free flow cross section is considerably limited. In addition, the filter element clogged increasingly after a certain period of operation, so that the aforementioned Disadvantages further amplify, resulting in even a pressure drop can result. Another disadvantage is the fact that the filter elements are very expensive.

The US 6,286,545 B1 discloses a medium container, in particular for a steering fluid of a power steering. The medium container has an input line and an output line, which are arranged parallel to each other in such a way that the liquid in the container is set in rotation. In this case, the liquid rotates in an annular channel around a filter carrier covered with a mesh filter, so that the liquid can pass through the mesh filter to the pump outlet. The liquid should have a particularly long residence time in the medium container so as to achieve effective cooling, whereby cool liquid can mix with heated liquid.

The US 5,879,545 deals with a cyclone filter in which unwanted solids are separated from a liquid by utilizing centrifugal forces. The cyclone filter has a vertically oriented cylindrical tube in which the laden with the heavy fluid is introduced tangentially. Via openings in an upper closure element, the liquid passes in a conically tapering region of a drop tube, which widens conically at the other end and opens into an opening of a lower closure element. In the drop tube, a central tube is arranged, which is spaced with its lower opening to the conically widening area. The central tube pierces the upper closure element in the conically tapering region of the downpipe, and passes through its upper end opposite the lower end laterally spaced apart the upper closure element and opens here in a filter chamber. On the inner wall of the cyclone filter, a filter element is arranged. The liquid is set in rotation on its way in the downpipe in the direction of the conically widening region, so that the heavy materials are transported by centrifugal force to the inner wall of the downpipe or of the conically widening region. In the region of the central tube then only solids-free liquid should be, which is transported via the central tube into the filter chamber. The solids pass through the lower opening into a collection area. With the US 5,879,545 on the one hand the centrifugal force is to be used for separating unwanted heavy substances from the liquid, but at the same time the filter element to serve as a cleaning filter and the other at the same time as a collection container for the heavy materials in the lower part of the cyclone filter.

Of the Invention is based on the prior art, the task, a medium container of the type mentioned with simple To improve means so that a separation of heavy substances, or undesirable solids from the liquid can be reached without using a filter element.

According to the invention the task by a medium container with the features of claim 1, wherein in the medium container a rotation generating element is arranged, extending in the axial direction seen from the inlet towards one opposite thereto Container end extends, and at its opposite to the inlet End having a closure element, wherein the rotation generating Element and the closure element each have an outer circumference which, in each case based on an inner wall of the medium container is spaced so that a rotational space for the medium is formed.

In In a preferred embodiment, the rotation-generating element is stationary arranged in the medium container, which means that the rotation generating element in the medium container itself do not turn around its central axis.

Appropriately Way, the rotation generating element deflecting elements, which are arranged on a central element. The middle element is preferably congruent to the central axis of the medium container, when the rotation generating element in the medium container is mounted. The deflectors are in the nature of turbine blades executed, so have a curved course of the central element to the opposite end of the deflecting elements.

Advantageous ends the deflecting elements with their opposite to the central element End spaced to the inner wall of the medium container, so that the rotation space is formed, in which the medium around the Central element rotates.

The Rotation generating element is in a preferred arrangement for the inlet in Spaced axially, but can also directly at the, the inlet assigned Be placed on the container end. Preferably, the inlet is on the bottom side arranged so that the rotation-generating element stands up on the ground or spaced therefrom with its bottom end.

Of the Inlet can now coincide with its central axis congruent to Central axis of the rotation generating element, or with his Center axis laterally offset to be arranged for this. Preferred way the inlet has a clear diameter, the smaller is the diameter of the central element, the clear diameter can be larger, so that the inlet Projected middle element in the radial direction. Naturally the clear diameter can also have the same amount like the diameter of the middle element. This can be in the medium container entering medium from the inlet to the central element flow past.

The Closing element is cheaper way than baffle plate executed, which at the opposite to the inlet End of the rotation generating element is arranged. The final element can have the same extent seen in the radial direction as the deflecting elements. The closure element can in the radial direction but also smaller or larger than that Be performed deflecting. Is the deflecting element in Seen radially larger than the deflecting elements, so that the closing element, the deflecting elements in the direction surmounted by the inner wall, is the outer circumference of the End element preferably dimensioned so that this Inner wall of the medium container is spaced, so that the rotation space also obtained in the region of the closure element remains.

Of the Medium tank can also be used as an expansion tank be designated, which a minimum and maximum medium level can have. Appropriately, the rotation generating element thereby executed in its axial extent, that this even at a minimal media level in the medium container is covered by the medium, that is, the rotation-generating element or its terminating element below the predetermined minimum Medium level (liquid level) is arranged.

Through the inlet, the medium flows axially to the central axis of the medium container or to the central element in the medium container. In this respect, the incoming medium has a linear flow. Due to the rotation generating element, the linear flow is converted into a rotational flow. In this case, the closing element is advantageously provided, which forces the incoming medium past the deflecting elements, so that a swirl or vortex of the medium is generated. In this respect, a linear flow is converted into a rotational flow. The spin or the rotation of the medium acts on the entrained particles or solids which are transported to the inner wall of the medium container. On the inner wall of the medium container is the Rotati Onsgeschwindigkeit of the medium so low that the particles fall due to gravity.

Usually The particles sink due to gravity to the bottom of the medium container, therefore bottom side, preferably in the edge region of the medium container, So in the region of its inner wall expedient Well depressions, ie collecting pockets are provided, in which the sinking particles arrive or are absorbed and accumulated become. The depressions are in a preferred embodiment provided with partitions, and form "dead water zones", So zones in which no or at least such a low flow It is true that particles remain in the wells or collection bags. In this respect, the wells prevent reintroduction of deposited or sedimented particles in the medium circuit. Of course, but can also be provided, a single seen in the circumferential direction continuous recess without partition at the bottom of the medium container or at its edge region to arrange so as a circumferentially continuous collection bag So to form "dead water zone".

better Way is provided that the outlet with its mouth is arranged within the rotation space, in the particle-free Medium can be aspirated. In more convenient Embodiment is provided that the outlet at the same Container end is arranged as the inlet, so preferably on the bottom side. In this respect, the medium enters axially flowing in the medium tank and is flowing axially sucked out of this (pump), since at least the resulting Middle axes of both (inlet, outlet) preferred can be arranged parallel to each other.

Thereby, that the particles or solids in the medium due to the rotation of the medium transported to the inner wall of the medium container be, and there fall by gravity, and the rotation room Thus, particle-free, can on a filter element to catch the particles are dispensed with. In this respect, the outlet to Medium pump not affected in its passage, whereby it is ensured that the particles or interfering solids can not get back into the medium cycle, since these in the collection bags at the bottom of the medium container be collected safely. Compared with in medium containers used filter elements, the inventive Medium container no negative influences on the Effectiveness of the medium circulation, and can be much cheaper be made available because of a filter element can be waived. This is at low and / or very low Outside temperatures advantageous (no noise, low oil foaming). As a filter element this also can not clog, so too therefore no negative impact on the effectiveness the medium cycle are to be expected. Of course, too the wells after a certain period of operation of the medium container be so filled that a cleaning is required. The wells or collection pockets can but advantageously so be measured that also has a cleaning interval compared with Filter elements can be extended considerably. Naturally it is well within the meaning of the invention that the wells are designed or dimensioned so that they during the entire life of the vehicle does not need to be cleaned. However, the medium container according to the invention must if necessary, only be cleaned, ie emptied the collection bags whereas a clogged filter element usually does a new one must be replaced so that the original, but affected by the filter element effectiveness the medium cycle is reached again.

The Middle element is in a preferred embodiment at its to Inlet oriented end closed, leaving the medium flowed past the center element outside. The middle element can be used as a solid body or as a hollow body be executed. But it is also conceivable execution, in which the middle element is oriented at its inlet End is open, with the middle element designed as a tube is that at its opposite to the inlet End can be closed. The conclusion element can here have the diameter of the tube, or as previously seen in the radial direction equal to or greater than the radial extent be carried out of the deflection. The middle element or The tube can be in its wall outlet openings have, through which in the middle elements entering medium can emerge and so can hit directly on the deflecting elements. Thus, the same effect can be achieved as before, namely a linear flow into a rotary flow convert. Of course, the openings should be like that be measured that these are not due to the particles or solids be added. Appropriately, but should the entire incoming medium flow enter the middle element, wherein the medium flow then by the height direction and / or also in the radial direction spaced outlet openings can emerge, and meets the deflecting, so a rotational movement to reach the medium.

Further advantageous embodiments of the invention are in the subclaims as well as in the following description of the figures. Show it

1 a plan view of a rotation generating element according to the invention as a section,

2 a representation of the forces acting on particles, and

3 a velocity profile of the medium in a medium container according to the invention by a deflection element.

1 shows a plan view of a medium container, which as a section by means of its wall 1 is shown in cross section. The wall has an outside 2 and an inside 3 on. The inside 3 is hereinafter referred to as inner wall 3 designated. The medium container is in the illustrated embodiment with its wall 1 executed around.

Of the Medium container further has a bottom, not shown and an opposite, also not shown Head on.

Bottom side is an inlet 4 arranged. Not shown is an outlet.

In the medium container is a rotation generating element 6 arranged, viewed in the axial direction of the inlet 4 in the direction of an opposite end of the container, that extends from the bottom region in the direction of the head region. At his to the inlet 4 opposite end has the rotation generating element 6 a conclusion element 7 on, which by means of the circle line 8th shown as a phantom line. The rotation generating element 6 and the terminating element 7 each have an outer periphery, which in each case based on the inner wall 3 of the medium container is spaced, so that a rotation space 9 is formed for the medium.

The rotation room 9 is seen in the radial direction between the circular line 8th and the inner wall 3 arranged.

The rotation generating element 6 is fixedly arranged in the medium container, which means that the rotation-generating element 6 in the medium container itself does not rotate about its central axis.

Conveniently, the rotation generating element has 6 deflecting 11 on which at a middle element 12 are arranged. The middle element 12 is with its central axis preferably way congruent to the central axis of the medium container. The deflecting elements 11 are designed in the manner of turbine blades, so have a curved course from the central element 12 to the opposite end 13 the deflecting elements 11 on.

Advantageously, the deflection ends 11 with her to the middle element 12 opposite end 13 spaced to the Innwand 3 of the medium container, so that the rotation space 9 is formed, in which the medium around the rotation-generating element 6 rotates.

The rotation generating element 6 is an example of the inlet 4 spaced in the axial direction. Exemplary is the intake 4 arranged on the bottom side.

In the illustrated embodiment, the inlet 4 with its central axis congruent to the central axis of the rotation-generating element 6 , In the preferred embodiment, the inlet 4 a clear diameter which is smaller than the diameter of the central element 12 , Of course, the clear diameter of the inlet 4 also be made larger, so that the inlet 4 the middle element 12 Seen in the radial direction, wherein also in its clear diameter equal to the inlet 4 can be provided. This can be in the medium container entering medium from the inlet 4 at the middle element 12 flow past.

The final element 7 is designed as a baffle plate, which at the inlet 4 opposite end of the rotation generating element 6 is arranged. The final element 7 has in the radial direction, for example, the same extent as the deflecting elements 11 ,

The medium tank is designed as a reservoir of a hydraulic circuit. The inlet 4 is exemplified with a steering gear. The outlet is connected to a medium pump. The medium pump causes a transport of the medium from the medium container to the steering gear and from there back into the medium container.

The rotation generating element 6 with its terminating element 7 extends from the bottom in the direction of the head region, but ends below a predetermined minimum medium level within the container, that is, it is always arranged below the liquid level in the medium container.

Through the inlet 4 the medium or liquid flows into the medium container linearly and at the middle element 12 past. Through the terminating element 7 , which is arranged below the liquid level, the medium is forced to the deflection elements 11 to pass, so that the linear flow is converted into a rotational flow. With the medium particles or solids are transported, which so to the inner wall 3 be transported.

In 3 is shown a velocity profile of the medium, which by the Umlenkelemen th 11 is effected. Visible is that on the Innwand 3 such a low velocity prevails that particles or solids can sink.

Therefore, the bottom side in the area of the inner wall 3 advantageous depressions 14 or collection bags 14 arranged in the medium container in which the sinking particles or heavy materials are deposited. The wells 14 or collection bags have example of partitions 16 on.

The following formulas are intended to describe the behavior of the heavy substances or particles in the medium, wherein the symbols in the 1 to 3 are shown.

The total velocity of the heavy materials or particles is:

a = F/m

The radial velocity of the particles is calculated with: v r = a · t = √ 2 * a * r = v ra + a · t

a = F / m

ṁ = const. vri/b ⌢ = vra/B ⌢ B ⌢/b ⌢·vri = vra B ⌢/b ⌢·f/b·h = vra vaa = tanβ·vra vri = f/Ai Ai = b·hh = Höhe (Länge) des Umlenkelementes vaa = tanβ·B ⌢·f/b ⌢2·h The vertical velocity of the particles is calculated with: v H = ve · √ 1 - e ↑ 2gh / ve²

ṁ = const. v ri / b ⌢ = v ra / B ⌢ B ⌢ / b ⌢ · v ri = v ra B ⌢ / b ⌢ · f / b · h = v ra v aa = tanβ · v ra v ri = f / A i A i = bh h = height (length) of the deflection element v aa = tanβ · B ⌢ · f / b ⌢ 2 ·H

To 2 Resulting centrifugal force F Zres = F ZC + F ZF F Zres = v 2 a / R (m C - m F ) F Zres = v 2 a / R (v c / ρ C - v F / ρ F F Zres = v2 a vc (1 / ρ C - 1 / ρ F ) With F Z = m · v 2 a / r F ZC = m c · v 2 a F ZF = m F · v 2 a m c = v c / ρ c m F = v F / ρ F v c = V F

The weight is calculated assuming a spherical particle (spherical particles) with: F Gres = m c · a a = g · (1 - ρ F / ρ C - F RV / F G ) F Gres = m c · G (1 - ρ F / ρ C - F RV / F G ) With F G = m · g F RV = c ω / ρ C / 2 * v 2 Ha st A st = D 2 C · Π / 4 c ωKugel ≈ 0.4 so that F Gres = m c · G (1 - ρ F / ρ C - c ω · ρ C · v 2 H · A st / 2 * m * g F Gres = m c · G (1 - ρ F / ρ C - c ω · ρ C · v 2 H · D 2 C · Π / 8 * m * g

The resistance is calculated with: F RH = c ω · Ρ / 2 * v 2 r · A st F RV = c ω · Ρ / 2 * v 2 H · A st

It has been found that when the density of the heavy material ρ _C or the particle is greater than the density of the medium ρ _F that the centrifugal force F _ZC which acts on the particle, greater than the centrifugal force F _ZF , which on the medium acts. Become by this power imbalance Particles promoted to the outside more strongly than the surrounding medium. ρ C > ρ F => F ZC > F ZF

In this respect, particles will always sediment near the inner wall, ie sinking, when the centrifugal force F _ZC acting on the particle is equal to the centrifugal force F _ZF acting on the medium and when the density of the heavy material ρ _C or of the particle is greater than the density of the medium ρ _F.

This is the case in areas where there is no or very little speed, since the centrifugal force is a function of the speed: F ZC = F ZF and ρ C > ρ F then F ZC = F ZF if v = 0, because F ZX = f (vx).

It follows that particles with a higher density than the density of the medium (ρ _C > ρ _F ) accumulate in areas where no speed or very low speed prevails. This is the case, for example, when r = R (see 3 ). Because of the high shear forces within the medium or within the liquid, the velocity is in the area of the inner wall 3 equal to zero (see 3 ). The bottom-side depressions cause a "dead water zone" in which there is almost no flow velocity and thus the sedimented particles are not returned to the flow circuit.

In Preferred embodiment, the medium container as a surge tank or Servoölbehälter executed and serves primarily to compensate for level variations.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 6286545 B1 [0006]
• US 5879545 [0007, 0007]

Claims (13)

Medium container which is integrated in a medium circuit, wherein the medium container has an inlet ( 4 ) and an outlet, characterized in that a rotation-generating element ( 6 ) is disposed within the medium container, which viewed in the axial direction of the inlet ( 4 ) extends towards an opposite end of the container, and at its inlet ( 4 ) opposite end a termination element ( 7 ), wherein the rotation-generating element ( 6 ) and the terminating element ( 7 ) each having an outer periphery, which relative to an inner wall ( 3 ) of the medium container is spaced, so that a rotation space ( 9 ) is formed for the medium. Medium container according to claim 1, characterized in that the rotation-generating element ( 6 ) is fixedly arranged in the medium container. Medium container according to claim 1 or 2, characterized in that the rotation-generating element ( 6 ) Deflecting elements ( 11 ), which on a central element ( 12 ) are arranged. Medium container according to one of the preceding claims; characterized in that the rotation generating element ( 6 ) with bent deflection elements ( 11 ) is executed. Medium container according to one of the preceding claims, characterized in that the rotation-generating element ( 6 ) to the inlet ( 4 ) is spaced in the axial direction. Medium container according to one of the preceding claims, characterized in that the inlet ( 4 ) with its central axis congruent to the central axis of the rotation-generating element ( 6 ) is arranged. Medium container according to one of the preceding claims, characterized in that the inlet ( 4 ) has a clear diameter which is smaller than a diameter of a central element ( 12 ) of the rotation generating element ( 6 ). Medium container according to one of the preceding claims, characterized in that the closure element ( 7 ) is designed as a baffle plate. Medium container according to one of the preceding claims, characterized in that the rotation-generating element ( 6 ) is designed in its axial extension so that it is arranged below a minimal expected medium level in the medium container. Medium container according to one of the preceding claims, characterized by bottom-side depressions ( 14 ). Medium container according to one of the preceding claims, characterized in that the outlet with its mouth in the region of the rotational space ( 9 ) is arranged. Medium container according to one of the preceding claims, characterized by recesses ( 14 ) for receiving sedimented solids, wherein the depressions ( 14 ) in the region of the inner wall ( 3 ) are arranged. Medium container according to one of the preceding claims, characterized by recesses ( 14 ) which form dead water zones.