EP2986835A1

EP2986835A1 - Method and device for controlling a volume regulation valve

Info

Publication number: EP2986835A1
Application number: EP14711192.6A
Authority: EP
Inventors: Uwe Richter; Rainer Wilms; Joerg Kuempel; Matthias Maess
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2013-04-15
Filing date: 2014-03-12
Publication date: 2016-02-24
Also published as: CN105102795B; WO2014170068A1; US9714632B2; KR102114914B1; US20160076501A1; KR20150141959A; RU2015148817A; DE102013206674A1; CN105102795A; RU2651266C2

Abstract

In a fuel system (10) of an internal combustion engine, fuel is delivered to a fuel rail (18) by a high pressure pump (16). The volume of fuel delivered is influenced by a volume regulation valve (30) actuated by an electromagnetic actuation device (34). It causes a limit retaining current to be determined at which the volume regulation valve stays in its closed state or only just opens.

Description

description

Method and device for controlling a quantity control valve Prior art

The invention relates to a method for controlling a quantity control valve of a high pressure pump according to the preamble of claim 1. The invention also relates to a computer program, an electrical storage medium and a control and regulating device.

DE 101 48 218 A1 describes a method for operating a fuel injection system using a quantity control valve. The known quantity control valve is realized as a magnetically actuated by a solenoid solenoid valve with a magnet armature and associated Wegbegrenzungsanschlägen. From the market known are such quantity control valves, which are closed in the de-energized state of the solenoid. In this case, to open the quantity control valve, the solenoid is driven at a constant voltage or a pulsed voltage (Pulse Width Modulation - "PWM"), whereby the current in the solenoid coil is characteristically increased. After switching off the voltage, the current again falls in a characteristic manner, whereby the quantity control valve closes. Also known are solenoid valves that are open in the energized state of the coil. In these solenoid valves is moved accordingly, wherein when switching off the voltage and the characteristic drop of the current, the solenoid valve opens.

In order to prevent the armature from striking the stopper during the opening movement of the quantity control valve at full speed in the normally closed valve shown in DE 101 48 218 A1, which could lead to a significant noise development, the electromagnetic field is actuating device shortly before the end of the opening movement energized again like a pulse. By this current pulse, a braking force is applied to the armature, before it contacts the stop. The braking force reduces the speed, which reduces the impact noise.

In modern direct-injection engine systems with demand-controlled fuel delivery, a high-pressure pump is used to generate the necessary fuel pressure. The high-pressure pump is operated with volume control. For this purpose, the delivery rate of the pump can be set via a volume control valve from 0 to 100%. The control of this quantity control valve is of particular importance, since the switching operation of MSV must take place in a very short time and despite high magnetic forces due to the high speed and the associated high drive frequency, without the hub-to-stroke fluctuations and thus the flow rate fluctuations too large become. This would lead to a lack of quality railroad. On the other hand, very high demands are placed on the noise of the high-pressure pump at low engine speeds. For this reason, numerous control concepts have already been developed to reduce the impact dynamics and thus to reduce the acoustic level. In this case, both the tightening movement and the falling movement of the solenoid is slowed down.

From DE 10 2009 046 825 AI a control concept for a flow control valve is described, which is also referred to as "Current Soft Stop" (CSS).

Normally, the quantity control valve is kept closed above the top dead center by the pressure in the delivery chamber of the high-pressure pump. When the delivery chamber pressure drops, the quantity control valve falls back into the original, normally de-energized open position, spring-driven and unrestrained. In which

CSS method, the quantity control valve is supplied beyond the top dead center with a holding current, so that the MSV does not drop directly. Only after the pressure reduction in the delivery chamber, the current is lowered in a characteristic manner, so that the quantity control valve during this small

Current supply drops and falls back into the normally open position. By the counterpart induction and the flow through the quantity control valve, the movement is slowed down and the impact at the stop is much less fast and thus quieter. The holding current should be known as precisely as possible, so that the currents for holding and the start of the movement can be set as accurately as possible. The current supply must be completed before the following bottom dead center, so that the next delivery process is not disturbed.

The problem is that if the current is too low, the CSS process will bring only minor acoustic improvements, while currents that are too high will not bring about any improvement or even an acoustic deterioration

Raise pressure increase can cause. This is due to the fact that at high currents, the quantity control valve remains closed and does not open.

Since the specimen scattering must be taken into account in the Stromat, the effect would be limited under these conditions, as is usually supplied in such a way that the quantity control valve opens safely. In other words, a lower current would be chosen. If necessary, only a slight acoustic improvement of the invention results from this low current

The invention relates to a quantity control valve which, when activated with a first activation value, assumes a closed state and the activation with a second activation value enables the quantity control valve to assume an open state.

Characterized in that a borderline holding current is determined, in which the quantity control valve still remains in its closed state or just opens, a much improved control is possible in which the acoustic behavior is significantly improved.

Since the properties of the quantity control valve differ from item to item, there is an effective reduction of the impact noise if during the current application specimen properties, such as the borderline holding stream, are taken into account. As a result of the actuation and adaptation according to the invention, the current level or the supply of the quantity control valve which is precontrolled by a PWM signal is thus adapted to the specimen tolerances, so that the CSS method for acoustic improvement functions optimally.

It is particularly advantageous if the marginal holding current is determined on the basis of a fuel pressure signal. Since the fuel pressure signal is evaluated, no further sensors are needed. Furthermore, this signal is available with sufficient accuracy.

A pressure increase can be detected simply by extending the flow of the quantity control valve beyond the bottom dead center.

It is particularly advantageous if the activation value is increased, starting from a start value at which the quantity control valve remains open, until an increase in the fuel pressure signal occurs, that the limit value holding current is determined starting from the activation signal at which the pressure increase takes place. In this case, the operation is only slightly disturbed and the driving behavior is not affected.

In an alternative embodiment, the drive value is reduced starting from a start value at which the quantity control valve remains closed until there is a drop in the fuel pressure signal, and the limit holding current is determined from the drive signal at which the pressure drop occurs.

Hereinafter, embodiments of the invention will be explained in more detail with reference to the accompanying drawings. In the drawing show:

Figure 1 is a schematic representation of a fuel injection system of an internal combustion engine with a high-pressure pump and a quantity control valve;

Figure 2 is a schematic representation of the relationship between the control signal and the state of the quantity control valve; FIG. 3 shows a second schematic representation of the time profile of the control signal and the time profile of the state of the quantity control valve;

FIG. 4 shows a flowchart for clarifying the procedure according to the invention.

In FIG. 1, a fuel injection system bears the reference numeral 10 as a whole. It comprises an electric fuel pump 12, with which fuel is supplied from one

Fuel tank 14 is conveyed to a high-pressure pump 16. The high-pressure pump 16 compresses the fuel to a very high pressure and promotes it further into a fuel rail 18. To this several injectors 20 are connected, which inject the fuel in them associated combustion chambers. The pressure in the fuel rail 18 is detected by a pressure sensor 22.

In the high-pressure pump 16 is a piston pump with a delivery piston 24, which can be offset by a camshaft, not shown, in a reciprocating motion (double arrow 26). The delivery piston 24 delimits a delivery chamber 28, which can be connected to the outlet of the electric fuel pump 12 via a quantity control valve 30. Via an outlet valve 32, the delivery chamber 28 can also be connected to the fuel rail 18. The quantity control valve 30 includes, for example, an electromagnetic actuator 34 which operates in the energized state against the force of a spring 36. In the form of the embodiment, the quantity control valve 30 is open in the de-energized state, in the energized state, it has the function of a normal inlet check valve.

The high-pressure pump 16 and the quantity control valve 30 operate as follows (see FIG. 2):

In Figure 2, a stroke of the piston 34 and below a drive signal over time are plotted above. The drive signal is denoted by the reference "A" designated. The value of the drive signal is between a first drive value, which is designated "0" in FIG. 2, and a second drive value, which is designated "1" in FIG. For example, the first drive value corresponds to the non-energized state of the electromagnetic actuator 34, and the second value corresponds to the energized state. The following is based on this embodiment.

In addition, the high pressure pump 16 is shown schematically in various operating conditions. During a suction stroke (left illustration in Figure 2), the solenoid 44 is de-energized, whereby the actuating plunger 48 is pressed by the spring 36 against the valve member 38 and moves it to its open position. In this way, fuel can flow from the electric fuel pump 12 into the delivery chamber 28. After reaching the bottom dead center UT the delivery stroke of the delivery piston 24 begins. This is shown in Figure 2 in the middle. The solenoid 44 is still de-energized, whereby the mass control valve 30 is further forced to open. The fuel is discharged from the delivery piston 24 via the open quantity control valve 30 to the electric fuel pump 12. The exhaust valve 32 remains closed. A promotion in the fuel rail 18 does not take place. At a time t 1, the solenoid coil 44 is energized, whereby the actuating plunger 48 is pulled away from the valve element 38. It should be noted at this point that in Figure 2, the course of the energization of the solenoid 44 is shown only schematically. It should be noted that the actual coil current is not constant, but may simulate the course of typical transients due to mutual induction effects. In the case of a pulse-width-modulated drive voltage, moreover, the coil current is wavy or jagged.

By varying the time t 1, the amount of fuel delivered by the high-pressure pump 16 to the fuel rail 18 is influenced. The time tl is determined by a control and regulating device 54 (Figure 1) so that an actual pressure in the fuel rail 18 as closely as possible corresponds to a desired pressure. For this purpose, 54 signals supplied by the pressure sensor 22 are processed in the control and regulating device. Due to the pressure in the delivery chamber 28, the valve element 38 applies to the valve seat 42, the quantity control valve 30 is thus closed. Now, a pressure can build up in the delivery chamber 28, which leads to an opening of the exhaust valve 32 and to a delivery into the fuel rail 18. This is shown in Figure 2 on the far right. Shortly after reaching the top dead center OT of the delivery piston 24, the energization of the solenoid 44 is terminated, whereby the quantity control valve 30 returns to its forced open position.

When stopping the energization of the solenoid 44, the actuating plunger 48 is moved against a first stop 50. In order to reduce the impact velocity at the first stop 50, a temporarily falling waveform 56 is generated, by which the moving speed of the actuating plunger 48 is reduced before hitting the first stopper 50. During a second falling waveform 58, the drive signal is brought to the first drive value. This second falling signal curve 58 may be given, for example, by a rapid quenching of the coil current of the electromagnetic actuator 34.

FIG. 3 shows an exemplarily selected time course 100 of the drive signal designated by "A" and the time profile 102 of the state of the quantity control valve 30. "At time t1, the value of the drive signal is increased from the second drive value 64 to the first drive value 66 , As a result, the quantity control valve 30 goes from the open state 60 into the closed state 62 and closes

Event 104. During a hold phase 106, the quantity control valve 30 remains closed. Due to the pressure in the delivery chamber 28, which keeps the quantity control valve 30 closed, the activation signal can assume the second activation value 64 during a period of time 108, that is, for example, be de-energized. In a further variant of the method, the holding current can also be maintained during the period 108 by attaching the first actuation value. Before reaching the top dead center 120 of the delivery piston 24 or before opening 122 of the outlet valve 32, the value of the activation signal is raised again to the first activation value 66. From time 82, a new control. In order for the Reduced noise emissions, according to the invention, the value of the control signal at the time at which the pressure in the delivery chamber 28 has dropped so far that he no longer holds the quantity control valve 30 in the closed state 62, based on a limit holding current.

The borderline holding current is the holding current at which the quantity control valve remains in its closed state during a previous energization. If a higher current than the limit holding current is selected, the quantity control valve remains closed. If a smaller current is selected, the quantity control valve opens.

In order to detect whether the currently output current is above or below the borderline holding current, the current is extended beyond the bottom dead center of the high-pressure pump. If the quantity control valve is still tightened, because the current is above the borderline holding current, full delivery of the high-pressure pump takes place. This full delivery can be easily detected by the pressure increase in the rail with the rail pressure sensor. If the borderline holding current falls below, then there is no promotion and no pressure increase.

In the method according to the invention, starting from a current level at which the quantity control valve opens securely, the prolonged flow is successively raised progressively from delivery to delivery until an increase in pressure is detected. As a result, the borderline holding current associated with the currently present quantity control valve item is detected under the respective boundary conditions.

Alternatively, it can also be provided that, starting from a current level at which the quantity control valve remains closed, the extended flow is successively lowered progressively from delivery to delivery until a pressure drop is detected.

An embodiment of the procedure according to the invention is described by way of example with reference to FIG. 4. In a first step 300, the adaptation process starts. The following query 305 checks whether the switch-on conditions for the adaptation are fulfilled.

The switch-on conditions should ensure as uniform as possible boundary conditions for the adaptation process. Therefore, the adaptation is carried out only in a certain speed range, vehicle speed range, battery voltage range, rail pressure range, load range, temperature range, preferably at idle the engine but also at a more uniform

Slow travel. Also, the target pressure specification of the rail pressure must not change.

In the subsequent step 310, a start value for the holding current is set. Furthermore, the energization is extended beyond the bottom dead center of the high-pressure pump. This ensures that the quantity control valve remains closed with appropriate energization until the next delivery stroke, which begins after bottom dead center. If the volume control valve is energized with a current value above the borderline holding current it remains closed in this case and there is a pressure build-up. If the quantity control valve is energized with a current value below the borderline holding current, the quantity control valve can open when the pressure has dropped. Preferably, the starting value is set so that the quantity control valve opens when the pressure has dropped.

In step 315, the current value is incremented by a certain value. In the subsequent step 320, the rail pressure in the high-pressure region after

High pressure pump detected.

The subsequent query 325 checks whether the rail pressure has risen. For this purpose, for example, it is checked whether the gradient of the rail pressure is greater than a threshold value. Respectively. it will check if since the last capture of

Rail pressure has risen by more than a threshold.

If this is not the case, that is, there is no pressure increase, then in step 315 the current value is incremented by a certain value. If a rail pressure rise is detected in step 325, step 330 follows. In step 330, the adaptation ends. The current value, or the current value before the last incrementation, is used as borderline holding current. Alternatively, a value calculated from the two values, in particular the mean value of these two values, can also be used as limit-value holding current.

In step 335, the parameters for the CSS current from the borderline holding current are determined. Furthermore, the duration of the

Current supply reset to the normal value.

In the subsequent step 340, the method ends.

This marginal holding current is then used for the correct CSS drive by calculating or correcting the current flow of the CSS method as a function of this detected borderline holding current.

The holding current before the CSS phase, which corresponds to the period before the delivery chamber pressure drops, is selected with a suitable increase relative to the determined borderline holding current so that the quantity control valve is reliably kept closed. The current value for the deliberate dropping into the open position of the quantity control valve is selected, for example, with a current reduced by a suitable amount compared to the determined marginal holding current. This is to be achieved on the one hand, that the quantity control valve is held reliably until the start of movement is to be initiated and on the other hand, the maximum braking effect of the current is achieved during the movement of the quantity control valve. In this phase, the current is chosen just below the holding current required for the specimen.

The characterization of the respective quantity control valve item obtained with the adaptation method can not only be used to improve the CSS method. An additional use would be in the context of normal control, the determination of the marginal holding current to reduce the effective current level and the power loss.

Claims

claims

1. A method for controlling a quantity control valve (30) of a high-pressure pump, wherein the quantity control valve (30) when actuated with a first Ansteuern ngswert (66) assumes a closed state (62) and the control with a second control value (64) the quantity control valve (30) allows to assume an open state (60), characterized in that a borderline holding current is determined, in which the quantity control valve still remains in its closed state or just opens.

2. The method according to any one of the preceding claims, characterized in that the borderline holding current is determined based on a fuel pressure signal.

3. The method according to any one of the preceding claims, characterized in that the energization of the quantity control valve is extended beyond the bottom dead center.

4. The method according to any one of claims 2 to 4, characterized in that the driving value, starting from a starting value at which the quantity control valve remains open, is increased until an increase of the fuel pressure signal is carried out that the limit value holding current starting from the drive signal in which the pressure increase is determined.

5. The method according to any one of the preceding claims, characterized in that the drive value is reduced, starting from a start value in which the quantity control valve remains closed until there is a drop, that the limit holding current is determined starting from the drive signal at which a pressure drop occurs ,

6. The method according to any one of claims 1 to 5, characterized in that the activation value, with which the quantity control valve (30) is acted upon after the top dead center, is predetermined based on the borderline holding current.

7. Computer program, characterized in that it is programmed for use in a method according to one of the preceding claims.

8. An electrical storage medium for a control and / or regulating device (54) of a fuel injection system (10), characterized in that a computer program for use in a method of claims 1 to 6 is stored on it.

9. control and / or regulating device (54) for a fuel injection system (10), characterized in that it is programmed for use in a method according to one of claims 1 to 6.