DE102006019584A1 - metering - Google Patents

Abstract

The invention relates to a metering pump, comprising a cylindrical housing with a pump piston (12) moved back and forth in the housing for conveying (delivery stroke), and suction (suction stroke) of a hydraulic fluid from an inlet region (2) into the outlet region (4) of the pump (1), a displacement (30) in which the fluid can be pressurized by means of the pump piston (12), an outlet valve (46) for the directed discharge of the hydraulic fluid located in the displacement (30) and an inlet valve (32) arranged in the pump piston (12) ) for the defined inflow of the hydraulic fluid from the inlet area (2) of the pump into the displacement (30). The invention is characterized in that at least one inlet valve (32) has control bores (36, 37) with which the inlet is opened until the piston reaches its final stroke (12), and this position interrupts the inlet to the displacement (30) is.

Description

The The invention relates to a metering pump according to the features of generic part of claim 1.

State of the art

Dosierpumpem of the type mentioned work on the principle of an electromagnetic or otherwise actuated axial reciprocating pump, the well-defined amounts of hydraulic fluid conveys from an inlet area into the outlet area of the pump. reciprocating pumps own a higher one Efficiency than other pumps. This allows a higher dosing accuracy realize better. A typical but not exclusive Application is the metering of fuel for one Combustion process, eg. B in an internal combustion engine in the vehicle.

dosing typically have an exhaust valve and an intake valve. The inlet valve serves to remove the hydraulic fluid from the inlet area the pump in metered quantities in the Hubkolbenbereich of the pump piston pour in allow. The fluid collected in the working chamber of the piston becomes conveyed by means of the outlet valve in the outlet of the pump and pushed out. At the beginning of a delivery stroke includes the inlet valve, allowing the inflow to the displacement through the lifting movement is closed. In the subsequent reverse running Suction stroke opens the inlet valve, the inlet is opened again and it flows through the resulting negative pressure a defined flow in the displacement.

By The strokes of the piston arise in the inlet area and outlet area Pressure peaks of the fluid, which can lead to over-delivery of the pump. to Avoidance of metering errors are therefore measures to avoid overflows through the valve necessary. The over-promotion makes itself felt especially with increasing pre-pressures of the pump. The aim is a pressure independent Performance curves. As solutions exist on the one hand a damping in the Inlet area, on the other hand, a pressure relief by an external Fluid line. Both solutions However, they are expensive.

DE 10 2004 028 889 A1 shows a metering pump in the function of a piston pump for the promotion of a hydraulic fluid, which is used in particular in brake systems of vehicles. The inlet of the hydraulic fluid takes place in the form of a slot-controlled inlet valve, which is arranged in the direction of movement of the pump piston. The fluid collected in the displacement of the pump is conveyed through an outlet valve in the form of a ball seat valve in the outlet of the pump.

at the known arrangement are the control bores for the inlet valve exclusively in the case arranged. The holes are however determined by the construction. A forced control, the occurring pressure peaks of the inlet area compensates or degrades, is not provided in the known arrangement. These are complex means, such as external fluid lines or damping measures required in the inlet area. Will on this extra activities is waived, is for the pump a stronger one Spring necessary. This in turn is a high operating force necessary, since the piston has a high restoring force in the form of a overcome strong spring got to.

DE 43 28 621 A1 shows a metering pump, are prevented in the overflow in Hubkolbenraum by damping measures in the form of a transverse and arranged longitudinal bore in the piston, but which relate exclusively to the inlet region of the pump and are permanently connected to this. The two holes on the inlet side is only a pressure pad, which smoothes the pressure profile of the pending between the inlet port and the inlet opening in the pumped medium. They contain air and are not suitable as feed. The longitudinal bore is closed at its end facing the displacement with a seal. The inflow into the displacement takes place exclusively through a suction hole in the housing, which is closed when the piston is passed over and reopened in a subsequent rearward suction stroke.

In became a practical further development of the pump the sealing of the piston opposite the displacement through a valve cage replaced seat valve replaced with a certain and limited closing pressure, whereby also an inlet in the piston is made possible. The axial arrangement which defines the transverse bore connected to the inflow at the piston circumference only the Nutzhub of the displacement. Is the reciprocating piston at a delivery stroke arrived at his the exhaust facing stop, so is at the known arrangement does not ensure that the inflow through the transverse bore is closed. If the cross hole is not closed, so can when reaching the Förderendhubes due to the pressure peaks at the inlet area further fluid through the control bores arranged in the piston flow after. In order to there is a risk that the poppet valve from its closed position raised and leads to over-promotion.

Object of the invention

It is the object of the invention by To prevent over-promotion-related metering errors with simple means. The solution of the problem is in connection with the generic features of claim 1 by its characterizing features.

By the invention becomes a "positive control" by the positioning realized the feed, which is positioned so that it in each Examine the position of the piston connection between the inlet area and the Hubreich manufactures and only on reaching the Förderendposition is closed. This is an over-promotion and consequent Dosing error due to an inlet limitation controlled by the inlet valve while the delivery stroke realized. The inlet bore remains open until the piston has reached its end Funding completion achieved Has. Only when reaching this position is another inflow prevents the hydraulic medium in the displacement. There are no or only small extra activities for the Inflow required because in many applications these holes already available. However, they served according to the prior art exclusively as permanently open flow channel. A use as a control bore was not yet provided. The inlet bore used in the invention now as a control bore just has to be shaped so that a defined closing function is reached. By the inventive arrangement of the control bores will balance the pressure peak with the required dosing accuracy achieved and in displacement a compensation possibility for the delivery stroke occurring overpressure realized. This will be exclusive by modification of the bore, the "slot geometry", or other combinations of different sizes or reached various positioned holes. The installation of stronger Return springs and consequent higher driving forces not mandatory.

Of the Advantage of a slot-controlled known from the prior art Intake valve is additional through action improved against over-promotion. Thus, the conveying accuracy - depending on Design of the inlet and outlet valves and the operating point - by a many times independent from the form. This is a arranged in front of the working volume Inlet valve realized, which is a series connection of two intake valves includes.

In an advantageous embodiment According to the invention, the inflow comprises an additional inflow in the housing another inlet valve. Both intake valves have different Functions. That in the case arranged inlet valve is used in the delivery stroke for controlling and accurate fill of the displacement. The intake valve in the piston, on the other hand, reduces Rear / or Suction stroke of the piston the negative pressure in the displacement.

Of the Valve inlet in the housing may comprise a simple inlet bore with which during a suction stroke the delivery fluid promoted in the displacement of the piston will, and when crossing of the piston opens and / or closes. additionally However, such an inlet valve can also be designed slit-controlled, wherein a plurality of control slots may be provided, the are arranged concentrically with each other. The tax holes for such a Valve are advantageous in the space between the Innumfang of cylindrical housing and a guide sleeve for the piston arranged. The guide sleeve has an opening to the Displacement of the pump.

The Inlet valve in the pump piston advantageously comprises a blind bore in the direction of the inlet area with a subsequent transverse bore on, which opens in the inlet area of the pump. As lock is on the end face of the piston provided a seat valve. The longitudinal bore is through the seat body closed in the form of a ball. The mouth of the transverse bore to the inlet area remains opened so long until the piston reaches its end of delivery position has reached. The overpressure present in the inlet area is therefore also present on the seat valve at the mouth to the displacement of the piston.

There in the final position of the piston, the cross bore the inlet to the Ball seat valve closes, The pressure peak in the inlet area of the pump can cause the Do not open the ball seat valve. There is no over-promotion instead of. When return / or Suction stroke releases the cross-hole on the other hand. Now the overpressure can in the suction part of the pump opposite slightly open the ball seat valve to the negative pressure in the displacement thus a smooth-running To allow piston stroke.

For the closure the control bore or the transverse bore to the inlet area are not additional activities required. This is advantageous between the housing and arranged on the piston and / or bearing sleeve used. This type of storage of the piston is today's state of the art Technology. The axial length which is in the direction of the transverse bore extending sleeve bearing sleeve dependent on dimensioned by the piston stroke. The position of the transverse bore and the Ausraglänge the Guide sleeve is arranged so that when reaching the Förderendhubes the transverse bore from the spout length the sleeve covered in this direction and is closed. The sliding bearing the piston in the guide sleeve prevents that in the closed position Fluid material between piston and sleeve penetrate into the displacement can.

The dosing pump according to the invention is advantageously magnet-actuated. The stroke of the piston is produced with an integrated electromagnetic system, wherein the piston is fixedly connected to an armature of a lifting magnet, which is centrally surrounded by a coil. The pump piston forms an anchor rod arranged in the stroke direction of the armature, which engages through the cone of the magnet. In the de-energized state, all cavities in the inlet region and in the displacement of the piston are filled with hydraulic fluid. When the coil is energized, the armature displaces the piston against the force of a compression spring, which is arranged between the armature and the bearing sleeve of the piston. Due to the pumped medium collected in the displacement, the outlet valve is opened and the fluid is ejected. At the same time another inflow is blocked. During this time, further fluid material runs in the armature lifting space associated with the inlet area. If the power is turned off, the spring pushes the armature and thus the piston back to the starting position. It starts the backward suction stroke. This creates a vacuum in the displacement of the piston. About the now opened again inlet valve, both in the housing and in the piston, new fluid material can run in the displacement until a further delivery stroke takes place when energized again the magnet.

Further advantageous embodiments The invention will become apparent from the dependent claims and one in the drawing described embodiment.

embodiment

1 shows a cross-sectional view of the invention in a first position of the pump piston.

2 shows a section 1 ,

3 shows the section of 1 in a different position of the pump piston.

1 shows in a cross-sectional view of a solenoid-operated Kraftstoffdosierpumpe 1 , which is used for example for diesel injection or for use in automotive heating systems. The cylindrical pump piston 12 is fixed to the likewise cylindrical magnet armature 13 connected, the center of one in a bobbin 21 embedded magnetic coil 14 is surrounded. With the pump 1 Accurately metered amounts of fuel are pumped from a tank to a consumer. The flow direction of the fuel is from right to left in the direction of arrow X.

The pump 1 essentially comprises three areas, an inlet area 2 , a pump area 3 and an outlet area 4 , Inlet and pump area 2 . 3 are enlarged in 2 and 3 shown.

The inlet area 2 shows how out 1 on the far right is an intake manifold 5 with an axial bore 7 for sucking the fuel. The entrance of the hole 7 is with a protective cap 6 closed against contamination in the delivery and transport condition. From the intake manifold 5 the fuel flows through a filter 8th and gets into a zero 9 designated area. This area prevents the flow of fuel into the pump area 3 when the pump piston is not actuated 12 , The zero closure 9 includes a plastic sleeve 10 , in the opening area of the filter 8th is arranged. Its sleeve bottom has an axial passage opening 11 in the direction of the pump area 2 on, when not actuated armature 13 like this particular 2 it can be seen through one in the direction of the opening 11 extending rear spigot 15 is closed. Upon actuation of the pump piston 12 like this particular 3 it can be seen, the through hole 11 opened for the fuel. The secure seal between the opening 11 and the piston neck 15 is by a on the outer circumference of the piston nozzle 15 arranged first O-ring seal 16 ensured.

The magnet armature 13 has a continuous stepped anchorage hole 18 on, whose diameter is in the direction of his cone 17 slightly enlarged and in the other direction as a chamber 19 is configured, in which the fuel with open passage opening 11 can flow in. In the anchor hole 18 is the pump piston 12 firmly clamped as a rod. During a lifting movement of the anchor 13 opens or closes in the direction of Ansaugstutzens 5 directed piston neck 15 the passage opening 11 to the intake manifold 5 ,

The anchor 13 , the zero degree 9 and the filter 8th are of an anchor housing made of ferromagnetic material 20 surrounded and against the plastic sleeve 10 the zero-closing 9 and the intake manifold 5 by two O-ring seals each 54 . 55 sealed. The anchor 13 and thus the pump piston 12 is in the anchor housing 20 axially movable movable. The outer wall of the anchor 13 and the inner wall of the armature housing 20 are arranged at a distance to each other and form an inlet channel 42 who made a connection from the chamber 19 in the zero-degree 9 to the pump area 3 manufactures.

On the anchor housing 20 is in its left end of the bobbin 21 deferred, which expediently by brazing or welding with the anchor housing 20 connected, and of a magnet housing 22 surrounded at its in the direction of the inlet area 2 extending End with the anchor housing 20 is firmly connected.

From the other (left) side in 1 is in the bobbin 21 a likewise made of ferromagnetic material sleeve 23 inserted, whose the end cone 24 facing conical opening becomes effective as a magnetic pole, and which, as the armature housing 20 , in the press fit inside the bobbin 21 holds. In the sleeve 23 is a bearing sleeve 26 with a suction port 25 fitted, which as a plain bearing 27 into the anchor 13 pressed-in pump piston 12 ensures axial guidance. Between the sleeve 23 and the bearing sleeve 26 is another inlet channel 43 arranged, which the Hubankerraum 29 with the intake opening 25 combines.

The bobbin 21 is in the direction of the outlet area 4 through a cone disk 33 is limited, which forms the radial extending portion of the magnetic pole. The bobbin 21 has a radial cover at this end 35 on, axially from the sleeve 23 is penetrated and is firmly connected to this. The energization of the coil 14 via a protruding from the cover coupling plug 34 , The cover 35 is opposite the sleeve 23 through another O-ring seal 56 sealed. Another O-ring seal 57 seals it against the magnet housing 22 from.

The front sides of the sleeve 23 and the anchor 13 are in the middle of the bobbin 21 arranged at an axial distance from each other and form a Hubankerraum 29 , in the de-energized state through the inlet channel 42 is filled with fuel in the anchor area. In that area 29 is a compression spring 28 Arranged with your one end against the end cone 24 of the anchor 13 supports and with its other end against the protruding end of the bearing sleeve 26 supported. When energizing the coil 14 becomes the anchor 13 together with the pump piston 12 against the force of the preloaded compression spring 28 (to the left) in the direction of the cone 17 postponed ( 3 ).

The inlet channel 43 flows through the intake opening 25 in a cubic capacity 30 , which in the axial direction of Nutzhubbereich the pump 1 sets and two intake valves 31 . 32 comprising, of which the valve 31 in the housing and the valve 32 in the piston 12 are arranged. In the radial direction of the displacement 30 through the inner diameter of the sleeve 23 established.

The inlet valve 31 in the housing is through the suction port 25 and the stroke of the pump piston 12 educated. When crossing the opening 25 becomes the associated inlet channel 43 each by the position of the piston 12 opened or closed. By axial positioning of the suction port 25 and design of the opening holes are in this valve 31 also to realize control functions.

The other inlet valve 32 is at the front of the piston 12 arranged. It forms with a cross hole 37 and subsequent axial blind hole 36 a series-connected valve assembly which is positively controlled closed as soon as the piston 12 has reached the end of the delivery stroke. The transverse bore 37 that with the Hubankerraum 29 of the inlet area 2 is in communication, is positioned so that upon reaching the Förderendhubes of the piston 12 from the bearing sleeve 26 is closed. But this is due to the position of the piston 12 open, form the cross hole 37 and the axial blind hole 36 another inflow for the displacement 30 the pump 1 ,

The mouth area of the blind hole 36 has a seat valve 38 on. In the sitting position, the inlet is via the transverse and blind bore 36 . 37 in the displacement 30 locked. The closure is made by a seat body 41 and another compression spring 39 that are in the valve seat 40 supported.

The piston 12 pushes in his Förderendhub elastic against a stop 44 , which is designed as a damping disk and a central passage 45 for ejecting through a delivery stroke fuel, thereby in the outlet region 4 the pump 1 is encouraged.

The outlet area 4 essentially comprises an outlet valve 46 and an outlet port defining the pump 47 whose bore 40 in transport and storage condition of another protective cap 48 is closed.

The outlet valve 46 is also like the second inlet valve 31 executed in the piston as a seat valve. In the sleeve 23 is at her the exhaust valve 46 facing the associated valve seat 50 with a central opening 51 for the passage 45 of the fuel used. The associated seat body is as a ball 52 executed by another compression spring 53 the opening 51 closes. The delivery stroke of the fuel becomes the ball 52 from their sitting position against the force of the compression spring 53 lifted and conveys the fuel into the outlet 47 ,

The mode of action of a dosing pump constructed in this way 1 is as follows:
By 1 and 2 illustrated positions of the armature 13 show the de-energized state, with all the gaps in the pump 1 flooded with fuel. This concerns the Hubankerraum 29 in the inlet area 2 and in particular the displacement 30 in the pumping area 3 , The first one outlet valve 31 passing through the inlet channel 43 and the suction port 25 is formed is open. The second inlet valve 32 is closed against it, although the inlet in the piston 12 is still free, since the transverse bore acting as a control bore 37 not yet in this position of the bearing sleeve 26 is covered. The in the inlet area 2 occurring delivery pressure of the fuel is thus directly on the seat valve 38 at.

During a delivery stroke of the pump (to the left) becomes the coil 14 energized and the one with the anchor 13 connected pump pistons 12 will be in the direction of the attack 44 moved to its final delivery position. The intake opening 25 in the bearing sleeve 26 is positioned so that it already at the beginning of the delivery stroke by driving over the piston 12 is closed, so that no more fuel through the inlet channel 43 can flow.

The in cubic capacity 30 collected fuel is transported through the delivery stroke into the outlet area 4 the pump 1 pressed. The ball arranged there 52 the exhaust valve 46 is lifted and delivers the fuel into the outlet 47 , Upon reaching the Förderendhubes, like this 3 is apparent, is also the inlet via the second inlet valve 32 in the piston 12 locked, since according to the invention, the transverse bore 37 in this position from the bearing sleeve 26 is covered. This will be in the inlet area 2 occurring in the piston position pressure peaks no longer degraded, which leads to an over-promotion in Hubkolbenbereich 30 the pump 1 could lead.

With the beginning of the delivery stroke is simultaneously the closure of the zero closure 9 at the back end of the anchor 13 open, and at the same time new fuel flows into the Hubankerraum 29 to.

With reaching the (left) conveyor end position at the stop 44 the exhaust valve 46 is the energization of the coil 14 interrupted. By the restoring force of the first compression spring 28 in the armature lift 29 becomes the anchor 13 together with the piston 12 into its initial situation ( 2 ) pushed back, causing the displacement 30 a negative pressure is generated with a suction effect. As soon as the suction opening 25 and the transverse bore 37 by returning the piston 12 can be free again, new fuel in the cubic capacity 30 flow on until the piston 12 has returned to its starting position, and another inflow through the zero close 9 is stopped. Subsequently, another delivery stroke by renewed energization of the coil 14 ,

The present invention has been explained using the example of two inflows, each with two inlet valves. However, it is understandable without further explanation to those skilled in the art that the invention can also be used in metering pumps in which the inflow is exclusively via the second inlet valve 32 takes place in the piston and on the inflow via the first inlet valve 31 is omitted, so that the valve 32 in addition to control functions and at the same time the filling of the displacement 30 takes over. For this purpose, only the poppet valve provided there 38 interpreted accordingly.

1

pump

2

inlet area

3

pump area

4

outlet

5

intake

6

protective cap (Intake manifold)

7

drilling (Intake manifold)

8th

filter

9

null terminator

10

Plastic sleeve

11

Through opening

12

pump pistons

13

armature

14

Kitchen sink

15

sealing sleeve

16

O-ring seal (Zero degree)

17

cone

18

anchor hole

19

chamber

20

armature housing

21

bobbins

22

magnet housing

23

shell

24

cone

25

suction

26

bearing sleeve

27

bearings

28

compression spring (Anchor)

29

Hubankerraum

30

capacity

31

intake valve (Casing)

32

intake valve (Piston)

33

conical disc

34

coupling plug

35

cover

36

blind hole

37

cross hole

38

poppet valve (Piston)

39

compression spring (Piston)

40

valve seat (Piston)

41

Seat body (piston)

42

inlet channel (Anchor)

43

inlet channel (Piston)

44

attack

45

passage

46

outlet valve

47

outlet

48

protective cap (Outlet)

49

drilling (Outlet)

50

valve seat (Outlet)

51

opening

52

Bullet

53

compression spring (Outlet)

54

O-ring seal (Armature housing)

55

O-ring seal (Intake manifold)

56

O-ring seal (Cover)

57

O-ring seal (Magnetic body)

Claims (11)

Dosing pump comprising a cylindrical housing with a pump piston reciprocated in the housing ( 12 ) for conveying (delivery stroke), and suction (intake stroke) of a hydraulic fluid from an intake region ( 2 ) in the outlet area ( 4 ) of the pump ( 1 ), A displacement ( 30 ), in which the fluid by means of the pump piston ( 12 ) is pressurizable, an exhaust valve ( 46 ) to the directed output of the in cubic capacity ( 30 ) located hydraulic fluid and a pump piston ( 12 ) inlet valve ( 32 ) to the defined inlet of the hydraulic fluid from the inlet area ( 2 ) of the pump in the displacement ( 30 ), Characterized in that the at least one inlet valve ( 32 ) Tax bores ( 36 . 37 ), with which the inlet until reaching the Förderendhubes of the piston ( 12 ) is open, and by this position the inlet to the displacement ( 30 ) is interrupted. Dosing pump according to claim 1, characterized in that the inlet via a further inflow bore ( 25 ) in the housing with an additional inlet valve ( 31 ) he follows. Dosing pump according to claim 2, characterized in that the additional inlet valve ( 31 ) is slot-controlled. Dosing pump according to one or more of claims 1 to 3, characterized in that the control bore an axial blind bore ( 36 ) in the direction of the inlet region with a subsequent transverse bore ( 37 ). Dosing pump according to claim 4, characterized in that the transverse bore ( 37 ) is axially positioned so that it is closed when reaching the Förderendhubes. Dosing pump according to one or more of claims 1 to 5, characterized in that the inlet valve ( 32 ) the passage of the blind bore ( 36 ) to the displacement ( 30 ) controls. Dosing pump according to one or more of claims 1 to 6, characterized in that the inlet valve 32 ) a seat valve ( 38 ) with a blind hole ( 36 ) closing seat body ( 41 ). Dosing pump according to one or more of claims 1 to 7, characterized in that the piston ( 30 ) in a fixedly connected to the housing bearing sleeve ( 26 ) is slidably mounted. Dosing pump according to one or more of claims 1 to 8, characterized in that upon reaching the Förderendhubes the transverse bore ( 37 ) from the bearing sleeve ( 26 ) is closed. Dosing pump according to one or more of claims 1 to 9, characterized in that the piston ( 12 ) is electromagnetically actuated, in particular by a pushed onto the housing solenoid. Dosing pump according to claim 9, characterized in that the piston ( 12 ) fixed with a magnet armature ( 13 ) of the lifting magnet is connected.