EP1045975B1 - Control unit for controlling the build-up of pressure in a pump unit - Google Patents

Description

The present invention relates to a control unit for Control of pressure build-up by a pump unit in a system, the control unit being a control valve and a valve actuation unit connected to it has and the control valve as a in the flow direction inward-opening I-valve is formed, the one in a housing of the control unit axially displaceable has mounted valve body, which when closed Control valve from the inside on a valve seat of the Control valve sits. The control unit has one Throttle arrangement through which the flow through the Control valve when opened by a small stroke Control valve is throttled.

The present invention also relates to a Injection system for supplying fuel to one Combustion chamber of direct injection Internal combustion engines with a pump unit for Build up an injection pressure and then to inject the Fuel through an injector in the Combustion chamber.

Finally, the present invention also relates to a Method for controlling the pressure build-up by means of a Control unit with a control valve and one with this connected valve actuation unit, the Control valve as an inward flow direction opening I-valve is formed, the one in one Housing of the control unit mounted axially displaceable Has valve body, when the control valve is closed from the inside sits on a valve seat of the control valve.

State of the art

To control the pressure build-up of any pump units Control units are known from the prior art. she are used, for example, to control the fuel supply in a combustion chamber of direct injection Internal combustion engines used. The Internal combustion engines have a pump unit Build up an injection pressure and then to inject the Fuel through an injection nozzle into the combustion chamber on. The injection system of the internal combustion engine can For example, as a pump-nozzle unit (PDE) or as a pump-line nozzle (PLD) system.

These known control units are usually called Solenoid valves designed. Here is the Valve actuation unit designed as an electromagnet, which actuates the control valve. The solenoid valve is in the open state. This is a free one Flow from the pump unit to the low pressure area given the injection system and thus filling the Pump room with fuel during the suction stroke of the Pump piston and a backflow of fuel during of the delivery stroke possible. A control of the solenoid valve during the delivery stroke of the pump piston closes it Bypass. This leads to a pressure build-up in the High pressure area of the system. Thus, by means of Control unit of the pressure build-up in the pump unit to be controlled.

The control valve is downstream as one in the flow direction internally opening I-valve. I valves have small strokes are usually very steep Flow curve. The course is in a flow curve the flow through a valve depending on the Stroke of the valve applied. Because of the steep course the flow curve of I-valves with small valve strokes already lead to slight fluctuations in the valve lift relatively large fluctuations in the flow rate. Basically, a fluctuation in the flow rate would have small strokes hardly affect the total amount of funded medium. However, there are applications where the flow rate through the valve at small Valve strokes should be as independent of the valve stroke as possible should and where it should be as flat as possible the flow curve arrives at small strokes.

Such an application is, for example, the control of the Direct injection fuel supply Internal combustion engines. There is often a so-called Pre-injection performed, d. H. before the actual Main injection a small amount of fuel into the Injection chamber injected. With the help of the pre-injection can the noise and exhaust behavior of the Internal combustion engine can be influenced positively. The Amount of pre-injected fuel needs to be accurately determined can be the behavior of the To be able to control the internal combustion engine in a targeted manner. The Pre-injection takes place with small strokes of the control valve instead of. Already have slight fluctuations in the valve lift large in the prior art control unit Effects on the amount of pre-injected Fuel. To the pre-injection quantity as accurately as possible To be able to determine, it would therefore be advantageous if the Flow curve with small strokes a flat course having.

The course of the flow curve for small strokes Training as flat as possible, it is from the state of the art Technology known to electronically increase the flow rate Taxes. However, electronic control is complex and expensive.

In addition, a control unit is known from US 4,470,548 of the type mentioned, in which the Flow rate through a mechanical throttle arrangement is throttled. However, the flow rate is there through the control unit through a cross section of a Expiration of a housing of the control unit throttled.

From the aforementioned disadvantages of the prior art there is the object of the present invention, a Control unit of the type mentioned in this regard to further develop the flow curve for small strokes of the control valve is as flat as possible.

To achieve this object, the invention is based on from a control unit of the type mentioned Control unit in front by a throttle arrangement is characterized by the flow through the Control valve when opened by a small stroke Control valve is throttled.

With the control valve open by a large stroke control unit according to the invention is a free flow from the pump unit via the valve seat of the control valve to a low pressure area of a system in which the Pressure build-up to be controlled is given. So is a Filling the pump room with the pumped medium during the suction stroke of the pump piston and a backflow of the medium possible during the delivery stroke. In the system so no pressure is built up.

Activating the valve actuation unit moves the valve piston in the direction of the closed position of the Control valve. This allows the control valve to turn around a small stroke open valve position. When the control valve is opened by a small stroke, after as before a flow, but only one throttled flow, from the pump unit through the Valve seat of the control valve and via the throttle arrangement given to the low pressure area of the system. So is conditional filling of the pump room with the pumped Medium during the suction stroke of the pump piston and a Backflow of the medium possible during the delivery stroke. In the high pressure area of the system becomes a low pressure built up.

Another actuation of the valve actuation unit during of the delivery stroke of the pump piston closes the control valve completely, causing the bypass from the pump unit to the low pressure area of the system is interrupted. This leads to the build-up of high pressure in the high pressure area of the system.

The flow rate of the flow through the control valve Medium does not fall off steeply during the closing process a maximum value when the control valve is fully open to zero when fully closed Control valve. Rather, when one reaches small hubs so long an almost constant small amount of the pumped medium through the control valve until the Control valve is completely closed. The course of the Flow curve of the control valve for small strokes is in advantageously very flat. This ensures that Fluctuations in valve lift hardly fluctuations in Cause flow rate. The flow rate is at small strokes almost independent of the valve stroke.

The throttle arrangement is integrated in the valve body. This has the advantage that it is not controlled separately must, but together with the valve body an inactive position when fully open Control valve in an active position at around a small Stroke open control valve can be brought.

According to an advantageous development of the invention on the valve body in the flow direction on the outside further valve body arranged, the small strokes of the Control valve is in a closed position and the has at least one throttle bore, which when open Control valve with an inlet and an outlet of the Control valve is connected.

The further valve body is preferably in the Valve body is axially displaceable. The other The valve body sits with the control valve closed and at a small stroke of the control valve in the direction of flow from the inside on another valve seat of the control valve. With the control valve fully open, i. H. at a large stroke, is the valve body of the control valve from which Valve seat and the further valve body of the Throttle assembly lifted from the further valve seat. The conveyed medium can through the valve seat and additional valve seat free from the pump unit to the Low pressure area of the system flow. With partial open control valve, d. H. with a small stroke, is the valve body of the control valve still from that Lifted valve seat, the further valve body of the Throttle arrangement, however, sits on the other Valve seat. The pumped medium can only be throttled through the valve seat and the throttle bore further Valve body flow. Doing so will result in the system low pressure built up. When completely closed Control valve sits on the valve body of the control valve the valve seat and the pumped medium is on the Valve seat retained. Now one in the system higher pressure built up.

The further valve body is advantageously replaced by a between the valve body and the further valve body acting spring element with closed control valve or with a small stroke of the control valve on the other Valve seat pressed.

The further valve body preferably has a stop on the with a large stroke of the control valve on the Valve body rests. With the control valve closed corresponds to the distance between the stop and the Valve body the size of the small valve lift during which the throttle arrangement is active.

Alternatively, the invention proposes that the further Valve body in the flow direction on the outside of the valve body is formed and that the further valve body at closed control valve and with a small stroke of the Control valve sealed in a mounting hole is included from which the drain from the control valve out leads. The further valve body and the Location bore form the further valve seat, which during the small strokes of the control valve are closed. at fully open control valve, d. H. with a big one Stroke, is the valve body of the control valve from which Lifted valve seat and the further valve body of the Throttle assembly is outside of the Bore. The funded medium can through the Valve seat and the other valve seat free from the Pump unit to the low pressure area of the system flow. With the control valve partially open, i.e. H. at a small stroke, is the valve body of the control valve still lifted from the valve seat, the other Valve body of the throttle arrangement is, however, of the Location bore sealed sealed. The funded Medium can only be throttled through the valve seat and the throttle bore of the further valve body flow. This creates a low pressure in the system. When the control valve is completely closed, the Valve body of the control valve on the valve seat and that conveyed medium is retained on the valve seat. In a higher pressure is now built up in the system.

The present invention also relates to a Injection system for supplying fuel to one Combustion chamber of direct injection Internal combustion engines with a pump unit for Build up an injection pressure and then to inject the Fuel through an injector in the Combustion chamber, the injection system means has to before the actual main injection small amount of fuel in the combustion chamber voreinzuspritzen.

In order to further develop such an injection system, that the fuel quantity of the pre-injection is particularly accurate and can be controlled reliably, suggests Invention before that the injection system is a control unit of the type mentioned above.

Finally, the present invention also relates to a Method for controlling the pressure build-up by a Pump unit in a system by means of a control unit, which is a control valve and one connected to it Has valve actuation unit, wherein the control valve as an I-valve opening inwards in the direction of flow is formed, the one in a housing Control unit axially displaceably mounted valve body has from the inside when the control valve is closed a valve seat of the control valve sits, and wherein to Building up a pressure in the system of the valve body Control valve from an open by a large stroke Position over a position opened by a small stroke is brought into a closed position.

So that the flow curve for small strokes of the Control valve is as flat as possible, the invention proposes that the flow through the Control valve from the time the valve body is open to a small stroke, up to the point of time which the valve body is closed by a in the Valve body integrated throttle assembly is throttled.

The method for controlling the Fuel supply into a combustion chamber direct-injection internal combustion engine with a Pump unit for building up an injection pressure and after for injecting fuel through an injector used the combustion chamber. Especially with one such use of the method according to the invention Advantages of the invention to bear. So it is with that inventive method possible Fuel quantity of a pre-injection is particularly accurate and to control reliably because the flow rate through the Control valve due to the flat course of the Flow curve is almost independent of the valve lift of the Control valve. With fluctuating small strokes it is Flow rate therefore only a small fluctuation subjected.

Fig. 1

ein Steuerventil einer erfindungsgemäßen Steuereinheit einer ersten Ausführungsform im Schnitt;

Fig. 2

ein Steuerventil einer erfindungsgemäßen Steuereinheit gemäß einer zweiten Ausführungsform und

Fig. 3

den Verlauf der Durchflusskurve durch ein Steuerventil einer erfindungsgemäßen Steuereinheit.

Two preferred exemplary embodiments of the invention are explained in more detail below with reference to the drawings. Show it:

Fig. 1

a control valve of a control unit according to the invention of a first embodiment in section;

Fig. 2

a control valve of a control unit according to the invention according to a second embodiment and

Fig. 3

the course of the flow curve through a control valve of a control unit according to the invention.

In Figure 1 is a control valve 1 of an inventive Control unit according to a first embodiment shown. The control unit is used to control the Pressure build-up by a pump unit in any System. It has the control valve 1 and one with it connected valve actuation unit (not shown) on. The control valve 1 is in the direction of flow 14 inward opening I-valve. It has one axially displaceable in a housing 2 of the control unit mounted valve body 3, the closed Control valve 1 from the inside on a valve seat 4 of the Control valve 1 sits. The control valve 1 has one Throttle arrangement 5 through which the flow through the Control valve 1 when opened by a small stroke Control valve 1 is throttled.

The throttle arrangement 5 is in the valve body 3 Integrated further valve body 6 formed. The further valve body 6 is in the direction of flow arranged on the outside of the valve body 3. The other Valve body 6 is at a small stroke of the control valve 1 in a closed position and has two throttle bores 7 which, when the control valve 1 is open, has an inlet 8 and an outlet 9 of the control valve 1 in connection stand. The further valve body 6 is in the valve body 3 axially slidably mounted. The further valve body 6 sits with control valve 1 closed and one small stroke of the control valve 1 from the inside on one further valve seat 10 of the control valve 1.

With control valve 1 open by a large stroke both the valve seat 4 and the further valve seat 10 open. There is free flow from the pump unit given to a low pressure area of the system, and thus is filling the pump room with the pumped medium during the suction stroke of the pump piston and a backflow of the medium possible during the delivery stroke. In the system no pressure is built up.

When the control valve 1 is open by a small stroke, the Valve seat 4 is still open, the other one Valve seat 10 is closed, however, so that conveyed medium through the throttle bores 7 through the Control valve 1 must flow. Because of this throttled Flow through the control valve 1 is in the High pressure area of the system built a low pressure.

When the control valve 1 is completely closed, both the Valve seat 4 as well as the further valve seat 10 closed, whereby the bypass is interrupted. This leads to the build-up of high pressure from the pump unit to the low pressure area of the system in which High pressure area of the system.

The further valve body 10 is by a between the Valve body 3 and the further valve body 6 acting Spring element 11 with closed control valve 1 or at a small stroke of the control valve 1 on the other Valve seat 10 pressed. The further valve body 6 has a stop 12 on the at a large stroke of Control valve 1 rests on the valve body 3. The further valve seat 10 is particularly flat, so with large strokes of the control valve 1 after opening of the further valve seat 10 as quickly as possible Flow value Q (see. Fig. 3) is reached.

In Figure 2 is a control valve 1 of the invention Control unit according to a second embodiment shown. In this embodiment, the other one Valve body 6 in the flow direction on the outside Valve body 3 formed. The further valve body 6 is with control valve 1 closed and with a small stroke of the control valve 1 sealed in a receiving bore 13 added. The drain 9 leads out of the receiving bore 13 out of the control valve 1. The further valve body 6 forms together with the edge of the receiving bore 13 another valve seat 10.

In Figures 1 and 2, the small strokes _are denoted by h _small . 3 shows the course of the flow curve Q = f (h) as a function of the stroke h of the control valve 1. The flow curve of the control valve 1 of the control unit according to the invention is shown as a solid line, whereas the flow curve Q through the control valve of a control unit according to the prior art is shown in broken lines. It can be clearly seen in FIG. 3 that the flow rate Q through the control valve 1 in the control unit according to the invention has a very flat, almost constant course for small strokes h _small . This has the advantage that in the control unit according to the invention the flow rate Q through the control valve 1 with small strokes h _small does not depend to the extent of the stroke h of the control valve 1 as is the case with the control unit from the prior art. With larger strokes between h _small and h _max , the flow rate increases rapidly to a value which is also achieved by the control units known from the prior art. The very steep increase between h _small and h _max results from the flat course of the further valve seat 10 (cf. FIG. 1).

Claims (9)

1. Control unit for controlling the build-up of pressure by a pump unit in a system, the control unit having a control valve (1) and a valve actuation unit which is connected thereto, and the control valve (1) being embodied as an I valve which opens inwards in the direction of flow and which has a valve body (3) which is mounted in an axially displaceable fashion in a housing (2) of the control unit and which, when the control valve (1) is closed, is seated from the inside on a valve seat (4) of the control valve (1), and the control unit having a throttle arrangement (7) by means of which the flow through the control valve (1) is throttled when the control valve (1) is opened by the amount equal to a small stroke (h_small), characterized in that the throttle arrangement (5) is integrated into the valve body (3).
2. Control unit according to Claim 1, characterized in that a further valve body (6) which is in a closed position when there is a small stroke (h_small) of the control valve (1) and which has at least one throttle hole (7) which is connected, when the control valve (1) is opened, to an inflow (8) and to an outflow (9) of the control valve (1) is arranged on the outside of the valve body (3) in the direction of flow.
3. Control unit according to Claim 2, characterized in that the further valve body (6) is mounted in an axially displaceable fashion in the valve body (3), and in that the further valve body (6) is seated, when the control valve (1) is closed and when there is a small stroke (h_small) of the control valve (1), from the inside on a further valve seat (10) of the control valve (1) in the direction of flow.
4. Control unit according to Claim 3, characterized in that the further valve body (6) is pressed onto the further valve seat (10) by a spring body (11) which acts between the valve body (3) and the further valve body (6), when the control valve (1) is closed or when there is a small stroke (h_small) of the control valve (1).
5. Control unit according to Claim 4, characterized in that the further valve body (6) has a stop (12) which rests on the valve body (3) when there is a large stroke (h > h_small) of the control valve (1).
6. Control unit according to Claim 2, characterized in that the further valve body (6) is formed on the outside of the valve body (3) in the direction of flow, and in that, when the control valve (1) is closed and when there is a small stroke (h_small) of the control valve (1) the further valve body (6) is held in a sealed fashion in a receptacle hole (13) from which the outflow (9) leads out of the control valve (1).
7. Injection system for feeding fuel into a combustion chamber of direct-injection internal combustion engines with a pump unit for building up an injection pressure and then for injecting the fuel into the combustion chamber via an injection nozzle, the injection system having means for pre-injecting a small quantity of fuel into the combustion chamber before the actual main injection, characterized in that the injection system has a control unit according to one of Claims 1 to 6.
8. Method for controlling the build-of pressure by a pump unit in a system by means of a control unit which has a control valve (1) and a valve actuation unit which is connected thereto, the control valve (1) being embodied as an I valve which opens inwards in the direction of flow and which has a valve body (3) which is mounted in an axially displaceable fashion in a housing (2) of the control unit and which, when the control valve (1) is closed, is seated from the inside on a valve seat (4) of the control valve (1), and the valve body (3) of the control valve (1) being moved, for the purpose of building up pressure, from a position which is opened by an amount equal to a large stroke, through a position in which it is opened by an amount equal to a small stroke, into a closed position, characterized in that the flow through the control valve (1) is throttled, by a throttle arrangement (7) integrated into the valve body (3), from the time at which the valve body (3) is opened by an amount equal to a small stroke (h_small), to the time at which the valve body (3) is closed.
9. Method according to Claim 8, characterized in that the method for controlling the supply of fuel is used in a combustion chamber of direct-injection internal combustion engines with a pump unit for building up an injection pressure and then injecting the fuel into the combustion chamber via an injection nozzle.

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