DE102011078001A1 - Apparatus for regulating pressure in fluid delivery system, has control valve that is integrated in pressure regulator for controlling throttle between two switching positions so as to generate negative pressure pulse in pressure line - Google Patents

Abstract

The apparatus has a throttle for connecting a pressure line with a return line. A control valve is integrated in pressure regulator for controlling the throttle between two switching positions so as to generate negative pressure pulse in pressure line. A throttle plate (5) is axially preloaded by the spring force of a spring element (10) with respect to the valve seat (9). An independent claim is included for fluid delivery system.

Description

The present invention relates to a device for pressure control and / or pressure relief in a fluid delivery system, in particular a metering system for a urea-water solution for exhaust aftertreatment, with the features of the preamble of claim 1. Furthermore, the invention relates to a metering system with such a device.

State of the art

From the DE 10 2009 001 736 A1 , which relates to a method for operating an SCR catalyst, a metering system of the type mentioned is apparent. The metering system comprises a pump, by means of which an aqueous urea solution stored in a tank can be fed via a line to a metering device for metering in the aqueous urea solution into an exhaust gas line of an internal combustion engine. The line is connected via a throttle valve with a return line through which the aqueous urea solution can be fed back to the tank.

Furthermore, in the DE 90 17 096 U1 discloses a hydraulic throttle valve having a housing with an inlet and an outlet opening and a guided in a bore of the housing closing member for switching the openings. The closing member is pressurized by the spring force of a spring and closes the inlet opening, which is constantly connected via an opening arranged in the throttle restriction with the outlet opening. The closure member is formed as a flat valve disc and has in the radial direction outside of the throttle body having, centrally located closing surface control openings which lie in the region of an inlet opening bounding annular stop surface of the housing. With increasing flow through the throttle point of the valve disc, the pressure gradient rises progressively until the valve plate lifts off from the annular stop surface of the housing against the spring force of the spring and the control ports releases as additional flow openings. The pressure difference occurring at the throttling valve disc increases now with increasing flow only by a comparatively very small amount, which corresponds to the increasing spring force of the spring. As a result, energy losses with increasing flow rate can be kept low, so that the throttle valve is also suitable for use in the main stream. By varying the spring and the valve disc also any characteristics should be displayed.

Based on the above-mentioned prior art, the present invention has the object to provide a device with a throttle, which allows both a pressure control and a pressure relief in a fluid delivery system, in particular a metering system for a urea-water solution for exhaust aftertreatment. A pressure line of the fluid delivery system is connected via the throttle with a return. The pressure relief should also allow the realization of a Rücksaugfunktion, by means of which an at least partial emptying of the system is effected. When the device is used in a metering system, it is also intended to effect opening of a metering valve of the metering system and suction of air via the opened metering valve via the suckback function, the air protecting the system from damage by ice pressure at low temperatures.

Disclosure of the invention

The proposed device for solving the problem comprises a throttle, via which a pressure line with a return line is connectable. According to the invention, the throttle is adjustable and has an integrated directional control valve. The directional control valve allows in a first switching position, a pressure control and in a second switching position, a sudden pressure relief for generating a negative pressure pulse in the pressure line.

The controllable throttle of the device according to the invention therefore has a largely linear characteristic over a portion of the control range.

At the edge of the control range, a relief cross section is opened via the integrated directional control valve, which is significantly larger in relation to the controllable throttle cross section. As a result, a pressure relief is abruptly effected by switching the directional control valve from the first to the second switching position. The characteristic curve of the throttle therefore does not run linearly at the edge of the control range. The directional control valve is preferably designed as a 2/2-way valve. By integrating the directional valve in the throttle only a driven actuator to realize the functions pressure control and pressure relief is required.

When using the device in a metering system for a urea-water solution for exhaust aftertreatment causes the sudden pressure relief when switching the directional control valve from the first to the second switching position that on the back-flowing fluid due to inertia effects, a vacuum pulse is established before the metering valve of the metering. The metering valve opens and air is sucked in. The intake air protects the system from damage due to ice pressure at low temperatures.

According to a preferred embodiment of the invention, the throttle comprises a throttle plate with a central recess and a cooperating with the recess, axially adjustable and at least partially conical control piston. The remaining between the control piston and the recess of the throttle plate throttle cross section is variable via an axial adjustment of the control piston. The axial adjustment can be effected for example via a stepper motor. Alternatively or additionally, the recess of the throttle plate may be at least partially conical, so that, if necessary, a conically formed portion on the control piston is unnecessary.

Further preferably, the throttle plate limits a pressure chamber in which system pressure prevails. The system pressure holds the throttle disk in the first switching position of the directional valve in contact with a valve seat. Accordingly, the throttle disk also serves as a valve closing element, which tightly seals the valve seat and thus the relief cross section in the first switching position of the directional control valve. To form the valve closing element, the throttle disk can be designed in one or more parts. Preferably, it is at least partially elastic. For example, the throttle plate may be injected into a membrane. So that in the pressure chamber system pressure prevails, the pressure chamber is directly or indirectly connected to the pressure line.

Advantageously, the throttle plate is axially biased by the spring force of a spring element relative to the valve seat. If, for example, the system pressure in the pressure chamber first has to be established in order to start up the fluid delivery system, the spring force of the spring ensures the installation of the throttle plate on the valve seat. This ensures a quick pressure build-up.

Further preferably, the valve seat has an annular sealing surface whose inner diameter is greater than the opening diameter of the central recess. This ensures a tight contact of the throttle disk with the valve seat.

Furthermore, it is proposed that the valve seat is formed on a sleeve-shaped component, which surrounds the axially adjustable control piston and is at least partially double-walled to form an annular valve space. The annular sealing surface of the valve seat is then preferably formed by an end face of the sleeve-shaped component. Alternatively or in addition to the double-walled embodiment, the sleeve-shaped component may have a radially projecting flange which cooperates with a housing part of the device such that an annular valve space is formed. The annular valve space is furthermore preferably connected directly or indirectly to the pressure line, so that system pressure prevails in the valve space. The connection to the pressure line can be made for example via at least one radial bore in the double wall of the sleeve-shaped component and / or the housing part.

The valve chamber is connectable in the second switching position of the directional control valve via the valve seat with the return. To connect the valve chamber with the return, the throttle plate is lifted from the valve seat. The force required for this purpose is applied by the control piston on the throttle plate by this retracts with a portion in the recess of the throttle plate, which has a larger outer diameter than the opening cross-section of the recess. The throttle cross section is reduced in this way to zero, at the same time opens the directional control valve and releases a relief cross section for pressure relief in the pressure line. Opens the directional control valve abruptly, the desired negative pressure pulse for realizing a Rücksaugfunktion is created in the pressure line.

According to a further preferred embodiment of the invention, the valve chamber is connected via a plurality of bores in the throttle disk with the pressure chamber on the other side of the throttle disk. In this way, only one connection of the device to the pressure line is required. The pressure chamber is preferably supplied via the valve chamber with system pressure. The plurality of bores are furthermore preferably arranged annularly around the central recess of the throttle disk.

To achieve the object mentioned above, a metering system for a urea-water solution for exhaust gas aftertreatment with a device according to one of the preceding claims and a delivery unit is further proposed. The device is arranged on the pressure side of the delivery unit and connects via a throttle a pressure line with a return. The advantages which result from the use of a device according to the invention in a metering system have already been mentioned above. In particular, the integration of a directional control valve into the throttle allows a sudden pressure relief of the system, so that a Rücksaugfunktion can be realized. This makes it possible to use a simple and cost-effective delivery unit, such as a diaphragm pump, since this no longer has to effect a reversal of the conveying direction for sucking back the fluid. In the closing position of the directional control valve, the pressure line is above the throttle cross section between the throttle plate and the control piston continues to be connected to the return, so that the device according to the invention can also be used for pressure control. It can therefore also be used as a delivery unit, a pump that promotes a constant volume flow. In addition, the control piston can be retracted so far into the recess of the throttle disc, that the throttle cross section is equal to zero. Then the connection of the pressure line to the return line is interrupted to allow, for example, when restarting the system a rapid pressure build-up.

A preferred embodiment of the invention will be described below with reference to the accompanying drawings. These show:

1 an exploded view illustrating the individual components of the preferred embodiment of a device according to the invention,

2 a sectional view of the device of 1 in assembled condition,

3 a longitudinal section through the device of 1 .

4 a plan view of the device of 1 .

5 a further longitudinal section through the device of 1 but against the 3 turned by 90 degrees,

6 a section of the 3 in an enlarged view,

7 a partial longitudinal section through the device of 1 , where the throttle is open (control mode),

8th a partial longitudinal section through the device of 1 , where the throttle is closed and

9 a partial longitudinal section through the device of 1 , where the throttle is closed and the directional control valve is open (return suction operation).

Detailed description of the drawings

The exploded view of the 1 the individual components of the preferred embodiment of a device according to the invention can be seen. These comprise a housing part 15 having all necessary fluid connections to the device to a pressure line 2 and a return 3 to connect (see 3 ). Furthermore, in the housing part 15 a cavity for receiving the components of a throttle 1 and a directional valve 4 educated. The components of the throttle 1 include a throttle plate 5 , which is injected into a membrane and a central recess 6 has. The recess 6 acts with an axially adjustable control piston 7 as another component of the throttle 1 in the way that together between the throttle plate 5 and the control piston 7 a throttle cross-section is formed, which by an axial adjustment of the control piston 7 is changeable. On the control piston 7 this is a conical section 25 formed its axial position with respect to the recess 6 determines the throttle cross-section.

In the throttle disc 5 are around the central recess 6 around more holes 14 arranged at equidistant distance from each other. About the holes 14 there is a pressure room 8th in conjunction with a valve chamber 13 which in turn has a radial bore 19 and an annulus 20 to the pressure line 2 is connected (see 5 and 7 ). Thus prevails in the normal operation of the device (see 7 ) System pressure, which the throttle plate 5 in contact with a valve seat 9 of the directional valve 2 holding. Furthermore, the throttle plate 5 via the spring force of a spring element 10 opposite the valve seat 9 axially biased. The valve seat 9 has an annular sealing surface 11 on, which on a sleeve-shaped component 12 is trained. The sleeve-shaped component 12 is also in the housing part 15 accommodates and seals the device via a radially extending flange 21 and a fitting thereto sealing ring 16 opposite the housing part 15 from. The sleeve-shaped component 12 is in this case designed double-walled, between the two walls of the valve chamber 13 train. Several over the outer circumference of the sleeve-shaped component 12 evenly distributed radial bores 19 connect the valve chamber 13 with another annulus 20 , which between the outer wall of the sleeve-shaped component 12 and the housing part 15 is formed (see 5 ).

The directional control valve therefore comprises the sleeve-shaped component 12 for the formation of a valve chamber 13 and a valve seat 9 , as well as the spring-loaded throttle plate 5 in the function as a valve closing element as essential components. In function as a valve closing element, the throttle plate acts 5 again with the control piston 7 together, which with its conical section 25 into the recess 6 the throttle disc 5 retracts that throttle plate 5 from the valve seat 9 is pushed away. This deforms around the throttle plate 5 injected membrane, the radially outward in the housing part 15 is clamped, and the directional control valve 4 opens to one Release relief cross section (see 9 , Suckback operation). The axial adjustment of the piston 7 is in this case of a stepper motor 18 causes, which on the back of the housing part 15 flanged is (see 2 ). For sealing is between the housing part 15 and the stepper motor 18 a membrane 17 inserted, which to the control piston 7 is injected and consequently also the leadership of the control piston 7 serves. A guide of the control piston 7 also takes place via a cylindrical approach 24 of the housing part 15 (please refer 7 to 9 ).

2 shows the device of 1 in the assembled state, with a sector-shaped cutout a look at the in the housing part 15 absorbed components of the throttle 1 and the directional valve 4 should allow.

Even clearer is the interaction of the components of the 3 to 6 which has already been partially referred to. Again 3 can be seen in particular, the housing part 15 a connection to the pressure line 2 and a connection to the return 3 on. These are each by a radial bore in the outer wall of the housing part 15 realized. The connection connecting the device to the pressure line 2 connects, first flows into an annulus 20 , which between the housing part 15 and the sleeve-shaped component 12 is formed (see 5 ). From here, the fluid passes through further radial bores 19 , which this time in the sleeve-shaped component 12 are formed in the valve chamber 13 , The valve room 13 in turn is over several annularly arranged holes 14 in connection with the pressure chamber 8th , which over the throttle cross-section of the throttle 1 with the return 3 is connectable. The 3 to 6 show the device with the directional valve closed 4 and closed throttle 1 ,

To clarify the operation of the device is on the 7 to 9 directed. The arrow 22 represents the adjustment direction of the control piston 7 darts while the arrows 23 indicate the fluid flow direction.

In the 7 the device is shown in the operating mode control mode. That means that the directional control valve 4 closed (first switching position) and the throttle 1 is open. Via the pressure line 2 , the radial bores 19 in the housing part 15 and sleeve-shaped component 12 the fluid enters the valve chamber 13 , About the annular in the throttle plate 5 arranged further holes 14 the fluid is then the pressure chamber 8th fed. The throttle disk injected into a diaphragm 5 lies tight against the valve seat 9 of the directional valve 4 at. On the one hand, the system is the throttle disk 5 at the valve seat 9 through the pressure room 8th prevailing system pressure, on the other by the spring force of the throttle plate acting in the closing direction spring element 10 ensured. As the 7 clearly shows, is the control piston 7 in normal operation of the device so far into the recess 6 Retracted that a certain throttle cross-section between the control piston 7 and the throttle disc 5 remains open. The throttle cross section is by an axial adjustment of the control piston 7 along the arrow 22 variable. In this way, the system pressure can be adjusted very accurately and highly dynamically with changing volumetric flow requirements.

The fluid flows in the control mode in the direction of the arrows 23 over the throttle cross section a return 3 (please refer 3 ) too. About the return 3 the fluid is a storage tank (not shown) or the intake of a delivery unit (not shown) of the delivery system fed. The deduction amount thus remains in the system. The delivery unit may be, for example, a simple diaphragm pump.

If very large volume flow quantities are required, the throttle can 1 also be closed. This operating state is in the 8th shown. The control piston 7 is so far into the recess 6 the throttle disc 5 retracted that the throttle area is reduced to zero. In the pressure room 8th is still system pressure, which the throttle plate 5 in contact with the valve seat 9 holds, so that also the directional control valve 4 is closed (first switching position). The Indian 8th shown operating state also proves to be advantageous for a first or re-commissioning of the system, for example, after a vent. Because of the closed throttle no Absteuermenge can be supplied to a return, so that a rapid pressure build-up in the system.

Will the control piston 7 about in the 8th illustrated closed position of the throttle 1 out in the direction of the pressure room 8th moves, this leads to the opening of the directional control valve 4 (second switch position). Because the control piston 7 whose conical section 25 the throttle disc 5 engages, presses the throttle disc 5 from the valve seat 9 path. In this case, a relief cross section is released, which is significantly larger than the throttle cross section over the entire control range. The fluid is now from the valve chamber 13 over the valve seat 9 or the released relief cross section directly, that is without detour via the pressure chamber 8th , the return 3 fed. Preferably, the control piston moves 7 at maximum speed into the throttle plate 5 one. The relief cross-section thus opens in a short time, which has a sudden reduction of the system pressure on the pressure side result. This in turn leads to the generation of a Vacuum pulse in the pressure line 2 , When the device is used in a metering system, the vacuum pulse when the metering valve is open causes fluid to be sucked back and air to be sucked in. The air is used to protect the system from damage due to ice pressure at low temperatures.

After sucking back and re-starting the system is the control piston 7 returned to the "normal operation" position and the sealing disc 5 via the spring force of the spring element 10 to the valve seat 9 pressed. The spring element 10 Holds the throttle disk 5 in contact with the valve seat 9 until in the pressure room 8th system pressure prevails, which then the dense system of the throttle plate 5 at the valve seat 9 guaranteed.

The invention can be used in all systems in which a system pressure must be kept constant or regulated. In addition, it can be used in all systems in which an efficient and cost-effective manner, a rapid pressure relief - for whatever purpose - must be achievable. Consequently, the device according to the invention can be used in all pressure control circuits with rapid shutdown or rapid pressure relief.

LIST OF REFERENCE NUMBERS

1

throttle

2

pressure line

3

returns

4

way valve

5

throttle disc

6

recess

7

control piston

8th

pressure chamber

9

valve seat

10

spring element

11

sealing surface

12

sleeve-shaped component

13

valve chamber

14

drilling

15

housing part

16

seal

17

membrane

18

stepper motor

19

radial bore

20

annulus

21

flange

22

adjustment

23

Fluid flow direction

24

cylindrical approach

25

conical section

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009001736 A1 [0002]
• DE 9017096 U1 [0003]

Claims (9)

Device for pressure regulation and / or pressure relief in a fluid delivery system, in particular a metering system for a urea-water solution for exhaust aftertreatment, the device comprising a throttle ( 1 ) for connecting a pressure line ( 2 ) with a return ( 3 ), characterized in that the throttle ( 1 ) and an integrated directional control valve ( 4 ), in a first switching position, a pressure control and in a second switching position, a sudden pressure relief for generating a negative pressure pulse in the pressure line ( 2 ). Device according to claim 1, characterized in that the throttle ( 1 ) an orifice plate ( 5 ) with a central recess ( 6 ) and one with the recess ( 6 ) cooperating, axially adjustable and at least partially conical control piston ( 7 ). Apparatus according to claim 2, characterized in that the throttle disc ( 5 ) a pressure chamber ( 8th ), in which there is system pressure, which the throttle disk ( 5 ) in the first switching position of the directional control valve ( 4 ) in contact with a valve seat ( 9 ) holds. Apparatus according to claim 2 or 3, characterized in that the throttle disc ( 5 ) by the spring force of a spring element ( 10 ) opposite the valve seat ( 9 ) is axially biased. Device according to claim 3 or 4, characterized in that the valve seat ( 9 ) an annular sealing surface ( 11 ) whose inner diameter is greater than the opening diameter of the central recess ( 6 ). Device according to one of claims 3 to 5, characterized in that the valve seat ( 9 ) on a sleeve-shaped component ( 12 ) is formed, which the axially adjustable control piston ( 7 ) and for forming an annular valve space ( 13 ) is executed at least partially double-walled. Device according to claim 6, characterized in that the valve space ( 13 ) in the second switching position of the directional control valve via the valve seat ( 9 ) with the return ( 3 ) is connectable. Device according to claim 6 or 7, characterized in that the valve space ( 13 ) over several holes ( 14 ) in the throttle plate ( 5 ) with the pressure chamber ( 8th ), wherein the plurality of holes ( 14 ) preferably annular around the central recess ( 6 ) of the throttle disc ( 5 ) are arranged around. Dosing system for a urea-water solution for exhaust aftertreatment with a device according to one of the preceding claims and a delivery unit, wherein the device is arranged on the pressure side of the delivery unit and via a throttle ( 1 ) a pressure line ( 2 ) with a return ( 3 ) connects.

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