EP2016278B1 - Pressure control valve with limp-home and ventilation function - Google Patents

Abstract

The invention relates to a fuel injection system for internal combustion engines, having a high-pressure accumulator which has a cavity under system pressure. Provided to the high-pressure accumulator is a pressure control valve that can be actuated electromagnetically. The cavity can be connected by the latter to a low-pressure side of the high-pressure accumulator. Arranged between the cavity and the low-pressure side of the high-pressure accumulator is a check valve which enables the high-pressure accumulator to be filled from the low-pressure side to the system pressure side.

Description

State of the art

From the publication " Diesel Engine Management ", 2nd, updated and expanded edition, Viehweg 1998, Braunschweig; Wiesbaden, ISBN 3-528-03873-X, p. 270 Figure 9 is a pressure regulating valve known. The pressure control valve is used on a high-pressure pump, see page 267, Figure 7 of the same publication. The pressure regulating valve comprises a ball valve, which contains a ball-shaped closing body. Within the pressure control valve, an armature is received, which is acted upon on the one hand by a compression spring and on the other hand, an electromagnet is arranged opposite. The armature of the pressure control valve is lapped for lubrication and cooling of fuel.

If the pressure regulating valve is not actuated, the high pressure applied in the high-pressure storage space or at the outlet of the high-pressure pump is applied via the high-pressure inlet to the pressure regulating valve. Since the electroless electromagnet exerts no force, the high pressure force outweighs the spring force of a compression spring, so that the pressure regulating valve opens and this remains more or less open depending on the amount of fuel delivered.

If the pressure control valve is activated, d. H. when the electromagnet is energized, the pressure in the high-pressure circuit is increased. For this purpose, a magnetic force is generated in addition to the force exerted by the compression spring. The pressure control valve is closed until there is an equilibrium of forces between the high-pressure force on the one hand and the spring force and the magnetic force on the other hand. The magnetic force of the solenoid is proportional to the drive current I of the solenoid within the pressure control valve. The drive current I can be varied by clocking (pulse width modulation).

According to the above publication page 270, Figure 7, the pressure control valve is screwed into the high-pressure pump, for example. In this case, the problem arises that the necessary, exact characteristic p = f (I), where I is the drive current of the electromagnet is designated for q̇ = const. The air gap L is at the dismantling of the pressure control valve in a receiving body, here for example a high-pressure pump set. Depending on the air gap L, the characteristic of the pressure control valve p = f (I) is set. The required tolerance of said characteristic p = f (I) of the pressure regulating valve is set in a test point, which is defined by a selected value for the drive current I of the coil of the electromagnet. In this test point, a pressure tolerance ± Δp of the pressure control valve is determined. The smaller this tolerance fails, the better the control quality with regard to the control behavior of the pressure regulating valve is achievable and the more accurate the pressure regulating valve responds to pressure fluctuations between the high pressure side and the low pressure side. Since the air gap L is dependent on the assembly quality and can be adjusted with previous procedure only with great effort, depends in the checkpoint adjusting pressure tolerance ± Δp to a considerable extent on the quality of mounting the pressure control valve to a high-pressure pump or other high-pressure component acted upon from.

DE 102 14 084 A1 refers to an adjustable pressure control valve for fuel injection systems. The fuel injection system comprises a high-pressure storage space, which is acted upon by a high-pressure delivery unit with high-pressure fuel and the fuel injectors supplied with fuel. The high-pressure conveying unit is assigned a pressure regulating valve, which is arranged between a high-pressure side and a low-pressure side and comprises a valve element which can be activated via an electrical point. The pressure regulating valve comprises a housing component, which contains a deformable region, by means of which a gap L between surfaces of an electrically controllable location arrangement can be adjusted during assembly of the pressure regulating valve to a receiving body.

In high-pressure injection systems such as, for example, a common rail system for motor vehicles, a pressure regulating valve is used in connection with the two-position concept, which has the task of dynamic pressure reduction in leak-free injectors, such as by means of a piezoelectric actuator controlled fuel injectors in the lower speed and load range the internal combustion engine to allow a very good pressure control at low pressures. This can not be realized in the required quality by alone on the suction side of a high-pressure pumping unit effective regulations. In the case of commercial vehicles, the aforementioned lekage-free injectors have hitherto not been used, which means that the pressure reduction in this application only takes place via the system-inherent leakage of the fuel injectors. A known from the prior art pressure control valve ( FIG. 1 ) has the property of being fully open when de-energized, to ensure the filling of the high-pressure accumulator even after switching off the internal combustion engine and thus a quick restart of the internal combustion engine. For Commercial vehicles, such a solution from the customer side is not acceptable because, for example, in the event of an electrical failure such as a cable drop this fuel injection system is depressurized and thus has an immediate shutdown of the internal combustion engine result. This is not allowed because of the high required vehicle availability.

A fuel injection system according to the preamble of claim 1 is known from WO-03/100247 known.

Disclosure of the invention

In view of the indicated technical problem and the known from the prior art solutions, the present invention seeks to provide a pressure control valve for use in high-pressure accumulator injection systems, especially for commercial vehicles, which ensures a Notfahrfunktion.

According to the invention, this object is achieved in that the pressure control valve or the high-pressure accumulator body (common rail), a check valve is used, the opening direction is directed from the low pressure side to the high pressure side and which allows a connection of the low pressure side fuel return to the high pressure area of the high pressure accumulator, if by the Cooling in the high pressure accumulator resulting negative pressure of this check valve opens and thus ensures the filling of the high pressure accumulator. This ensures that the high-pressure accumulator is completely filled. Is in the high-pressure accumulator by the high pressure accumulator pressurizing high-pressure pumping unit, such as the high-pressure fuel pump, high pressure, d. H. Built system pressure, the check valve closes the high pressure area against the low pressure side return from.

The non-return valve separating the low-pressure side from the high-pressure side of the high-pressure accumulator can be integrated in the wall of the high-pressure accumulator chamber (common rail) or can also be accommodated in a base plate of the pressure control valve. Decisive for the installation point of the check valve is the fact that through the check valve the high pressure side and the low pressure side of the high-pressure accumulator space in one direction, ie from the low pressure side toward the high pressure side of fuel can flow and thus a constant filling of the cavity of the high pressure fuel accumulator (common Rail) is guaranteed. In the pressure regulating valve proposed according to the invention, the direction of action of the electromagnet and the closing spring are interchanged in comparison with the solution known from the prior art. This means that the electromagnet of the pressure regulating valve proposed according to the invention applies a force in the opening direction with respect to a closing element closing the high-pressure accumulator space at one end, while an armature pin which holds the closing element acted upon, acting closing spring acts in relation to the closing element in the closing direction. When the high-pressure storage body cools down, a negative pressure is created in the latter, as a result of which the valve opens and a subsequent flow of fuel from the low-pressure region into the high-pressure reservoir body results. This ensures a complete filling of the high-pressure accumulator body during system restart and thus a faster start possible.

drawing

With reference to the drawing, the invention will be described below in more detail.

Figur 1

ein aus dem Stand der Technik bekanntes Druckregelventil, bei dem der Elekt- romagnet in Schließrichtung wirkt und ein Federelement in Öffnungsrichtung wirkt,

Figur 2

eine Prinzipskizze des in Figur 1 dargestellten Druckregelventils,

Figur 3

ein Druckregelventil mit vertauschter Wirkrichtung von durch die Elektromag- netspule erzeugter Magnetkraft und durch eine Schließfeder aufgebrachter Schließkraft,

Figur 4

eine Prinzipskizze des erfindungsgemäß vorgeschlagenen Druckregelventils mit in Öffnungsrichtung wirkendem Elektromagneten und in Schließrichtung wir- kender Schließfeder und einer schematisch dargestellten Einbauposition eines Rückschlagventils und

Figur 5

einen Schnitt durch das erfindungsgemäß vorgeschlagene Druckregelventil ge- mäß der Prinzipskizze in Figur 4 und

Figur 5.1

ein in einen Sitzring integriertes Ventil zur Befüllung des Hochdruckspeichers.

It shows:

FIG. 1

a known from the prior art pressure control valve in which the elec- magnet acts in the closing direction and a spring element acts in the opening direction,

FIG. 2

a schematic diagram of the in FIG. 1 illustrated pressure control valve,

FIG. 3

a pressure regulating valve with an interchanged effective direction of magnetic force generated by the solenoid magnet coil and a closing force applied by a closing spring,

FIG. 4

a schematic diagram of the inventively proposed pressure control valve with acting in the opening direction of the electromagnet and in the closing direction wirk kender closing spring and a schematically illustrated installation position of a check valve and

FIG. 5

a section through the inventively proposed pressure control valve according to the schematic diagram in FIG. 4 and

Figure 5.1

a built-in a seat ring valve for filling the high-pressure accumulator.

variants

FIG. 1 is to be taken from a known from the prior art pressure control valve in which an electromagnet acts in the closing direction with respect to a closing element and a acting on the armature of the pressure control valve pressure spring acts in the opening direction with respect to the closing element.

FIG. 1 shows a pressure regulating valve 10, which has a magnetic coil 26 which can be supplied with current via an electrical connection 12 with a plug connection. The pressure regulating valve 10 as shown in FIG FIG. 1 comprises a housing 14, which is sealed by a sealing ring 16 against the electrical connection 12. In the housing 14 of the pressure regulating valve 10, a compression spring 18 is received, which encloses an anchor bolt 20 and an anchor plate 22 is acted upon in the opening direction. The armature plate 22 opposite is located on the plug 12, a stop 24. In the housing 14 of the pressure control valve 10 as shown in FIG FIG. 1 the already mentioned solenoid 26 is received. An end face 28 of the anchor plate 22 and an end face 30 of the housing 14 are facing each other, wherein the distance between these two end faces 28, 30 defines the stroke of the anchor bolt 20 when the solenoid 26 is energized.

The anchor bolt 20 is slidable in an anchor hole 32 of the housing 14 of the pressure regulating valve 10.

The housing 14 of the pressure regulating valve 10 is screwed by means of a thread 52 with a high-pressure accumulator 34. In the housing 14 of the pressure control valve 10 40 low pressure holes 36 are formed on both sides of a cavity, which open into a return line 38, flows back through the low pressure side fuel into a tank of a motor vehicle. In the housing 14, a seat ring 42 is disposed within a receptacle 44. In the seat ring 42, a seat 50 is formed for a closing element 48, which in the illustration according to FIG. 1 is formed spherical. In the high-pressure accumulator 34 (common rail), a tubular cavity 46 is formed in which fuel under system pressure is stored. The system pressure of the fuel is built up via a high-pressure delivery unit acting on the high-pressure accumulator 34, such as, for example, a high-pressure pump, which in the illustration in FIG FIG. 1 is not reproduced, but is connected to the high-pressure accumulator 34.

At the in FIG. 1 illustrated pressure control valve 10 loses in the case of a fault such as a cable drop at the electrical connection 12 of the stored in the cavity 46 of the high-pressure accumulator 34 fuel required for the injection pressure. This is caused by the fact that in the case of a Stromloswerdens the solenoid 26, the armature plate 22, the anchor bolt 20 and thus the ball-shaped closure member 48 is not applied in the closing direction, but the compression spring 18, the anchor plate 22 against the stop 24 at the electrical connection 12, so that the closing element 48 opens and stored in the cavity 46 of the high-pressure accumulator 34 pressure in the low-pressure side cavity 40 is reduced and flows from there via the low-pressure holes 36 in the return line 38 to the tank of the vehicle. Consequently, with the in FIG. 1 illustrated embodiment of the pressure control valve 10 in the event of an error such as a cable waste the entire fuel injection system are depressurized, resulting in the immediate shutdown of the internal combustion engine, which is unacceptable for availability reasons in commercial vehicle applications.

FIG. 2 shows in a schematic manner the effective directions of the electromagnet and the compression spring according to the embodiment FIG. 1 ,

From the illustration according to FIG. 2 it appears that the in FIG. 1 shown solenoid 26, the anchor bolt 20 is acted upon in a first direction of action 62, whereby the closing element 48 is placed in the seat ring 42. In the embodiment according to FIG. 1 If the solenoid coil 26 is de-energized, the first effective direction 62 of the magnetic force is released and the closing element 48 opens due to acting in the first direction of action 60 spring force of the valve spring of the compression spring 18, so that the space 46, in which fuel under system pressure is stored, is depressurized via the low-pressure bores 36, since the closing element 48 is open.

The representation according to FIG. 3 is a block diagram of a pressure control valve can be removed, in which the effective directions of the electromagnet and the valve spring in comparison to the representation according to FIG. 2 are reversed.

According to the in FIG. 3 shown schematic diagram acts the solenoid 26 as shown in FIG FIG. 1 in a second direction of action 72, ie with respect to the closing element 48 in the opening direction. In contrast, the compression spring 18 acts in the closing direction with respect to the closing element 48, so that when the magnetic coil 26 becomes de-energized (see FIG FIG. 1 ) Uncontrolled outflow of stored in the cavity 46 of the high pressure accumulator 34 fuel volume is suppressed in the low pressure holes 36 and thus in the return line 38 to the tank of the vehicle. A refilling of the cavity 46 as shown in FIG FIG. 3 However, this is not possible with the thematic basic structure presented there.

The representation according to FIG. 4 is a schematic diagram of the inventively proposed pressure control valve can be seen.

From the illustration according to FIG. 4 shows that in the solenoid 26 of a pressure regulator valve 80 described in more detail below has an electromagnet 26 which acts in the second direction of action 72, ie in relation to the closing element 48 in the opening direction. In contrast, a closing force is applied by a closing spring described in more detail below, in the illustration according to FIG. 4 extends in the second direction of action 70, that is, the closing element 48 is acted upon in the closing direction and thus in the seat in the seat ring 42. In a Stromloswerden the solenoid 26 is thus ensured that the stockpiled in the cavity 46 of the high-pressure accumulator 34, under system pressure fuel volume does not uncontrollably flows back into the low pressure holes 36 and thus in the return line 38 to the tank of the vehicle. Between the cavity 46 of the high pressure accumulator 34 and the low pressure side - indicated here by the low pressure bores 36 - a check valve 74 is integrated. The check valve has an opening direction which is directed from the low-pressure region to the high-pressure region, ie to the cavity 46 in the high-pressure accumulator 34. Accordingly, the check valve 74 is closed when pressure is applied to the cavity 46 of the high-pressure accumulator 34 in the direction of the low pressure, whereas upon cooling of the high-pressure accumulator 34 and stored in the cavity 46 fuel volume and resulting from the associated decrease in volume of the fuel vacuum - when the Internal combustion engine - allows inflow of fuel from the low pressure side via the check valve 74 into the cavity 46.

The representation according to FIG. 5 is a section through the inventively proposed pressure control valve with reversed direction of action of a closing spring and an electromagnet to refer in more detail.

An in FIG. 5 illustrated pressure control valve 80 is screwed via the thread 52 with the tubular high-pressure accumulator 34 (common rail). In the housing 14 of the pressure control valve 80 with reverse direction of action, the magnetic coil 26 is received, the electrical connections 12 are each enclosed by sealing rings 82. In the housing 14 of the pressure control valve 80 with reverse direction of action are also an anchor bolt plate 86 enclosing anchor bolt receptacle 98 and a closing spring 84 enclosing closing spring receptacle 100. The anchor bolt receptacle 98 and the closing spring receptacle 100 are separated by a gap 92. A gap spacing 94 between the mutually facing end sides of the anchor bolt receptacle 98 and the closing spring receptacle 100 is indicated by reference numeral 94. In the housing 14 of the anchor bolt 20 is guided in the anchor hole 32, which on the one hand provided with the aforementioned anchor bolt plate 86 and on the other hand, at its the seat ring 42nd facing side has a flattening 90. The flattening 90 is the in FIG. 5 spherical closure member 48 opposite. In the housing 14 of the pressure control valve 80 with reverse direction of action as shown in FIG FIG. 5 is also disposed within the receptacle 44 of the seat ring 42, in which the seat 50 is formed by the ball-shaped closure member 48. A high pressure side of the seat ring 42 is identified by reference drawing 102, a low pressure side of the seat ring 42, which assigns the cavity 40 in the housing 14, is identified by reference numeral 104.

Both the closing spring receptacle 100 and partially enclosed by the anchor bolt receptacle 98 closing spring 84 is biased by a biasing member 96. About this biasing member 96, on which one end of the closing spring 84 is supported, acting on the anchor bolt plate 86 of the anchor bolt 20, acting in the second direction of action 70 spring force which is applied by the closing spring 84, can be adjusted. The other end of the closing spring 84 is supported on the anchor bolt plate 86 of the anchor bolt 20.

In the illustration according to FIG. 5 is the check valve 74 in the wall of the tubular high pressure accumulator 34 (common rail). The check valve 74 has a ball-shaped closing element 108, which is acted upon by a spring 106. The spring 106 may, as in FIG. 5 shown to be fixed by a pressed-in ring, so that the spring 106 has to apply only small spring forces. In Figure 5.1 a variant of the proposed solution according to the invention is shown, in which the components of the valve 74, designed as a check valve, between the high pressure region and low pressure region, the spherical closure member 108 and fixed by a ring spring 106 are integrally formed in the seat ring 42 and also a filling possibility of Provide cavity 46. By the check valve 74 in the wall of the high-pressure accumulator 34 (common rail), the fuel flow is prevented by the pressurized system cavity 46 of the high pressure accumulator 34 in the direction of a low pressure side cavity 112, as shown in the illustration FIG. 5 Spherically shaped closing element 108 is pressed into its seat 110 in the wall of the high pressure accumulator 34. On the other hand, it is achieved with the non-return valve 74 that when the fuel is cooled and the internal combustion engine is shut off via the low-pressure side cavity 112, the cavity 46, which in this case is not subjected to system pressure, is filled via the check valve 74 from the low-pressure side cavity 112. The check valve 74 is opened by adjusting itself in the cavity 46 of the high pressure accumulator 34 upon cooling of the fuel contained therein negative pressure, whereby a filling of the cavity 46 of the high pressure accumulator 34 via the low pressure side cavity 112 is possible. Will start the Internal combustion engine in the cavity 46 constructed by the over the internal combustion engine when spinning driven high-pressure pump system pressure, the check valve 74, the cavity 46 is separated from the low-pressure side cavity 112 in that the here spherical closure element 108 of the check valve 74 in its seat 110 in the wall of the high-pressure accumulator 34 (common rail) is pressed.

In the illustration according to FIG. 5 the check valve 74 is formed in the wall of the high pressure accumulator 34 (common rail). Alternatively, it is also possible in the FIG. 5 illustrated check valve 74 also in the base plate 42 of the pressure control valve 80 to accommodate with reverse direction of action. For the installation location of the check valve 74 alone is decisive that is separated by this system pressure leading cavity 46 of the high pressure accumulator 34 of the low pressure side of the pressure control valve 80 with reverse direction of action such that an opening direction of the check valve 74 results from the low pressure side to the high pressure side.

This in FIG. 5 illustrated pressure control valve 80 with reverse direction of action is advantageously used in motor vehicle or commercial vehicle applications, in which leak-free fuel injectors, which are controlled for example by means of a piezoelectric actuator, are used. If the solenoid 26 of the in FIG. 5 shown pressure control valve 80 de-energized, which may occur, for example, by a cable waste, it is ensured via the closing spring 84, which acts in the second direction of action 70 on the spherical closure member 48, that he not stored in the cavity 46 over the fuel opened closure member 48 in the low pressure side cavity 40 in the housing 14 and from there via the low pressure bores 36 in the in FIG. 1 illustrated low-pressure side return 38 flows. This ensures at a cable waste that stored in the cavity 46 under system pressure fuel is stored, so that an emergency drive function of the equipped with a high-pressure accumulator injection system with the present invention proposed pressure control valve 80 is maintained.

On the one hand, the anchor bolt 20 is acted upon by the closing spring 84 in the second direction of action 70, so that the closing element 48 remains in its seat 50 in the seat ring 42. Furthermore, it is ensured by the either in the wall of the high-pressure accumulator 34 (common rail) check valve 74 or recessed into a base plate of the pressure control valve 80 with reverse direction of action valve 74 that in the case of Stromlos becoming the solenoid 26 fuel in the cavity 46 of the high-pressure accumulator 34 (common rail) can flow from the low pressure region 112 when the fuel volume z. B. reduced by cooling and thus creates a negative pressure in the high pressure storage volume.

Claims (9)

1. Fuel injection system for internal combustion engines, comprising a high-pressure accumulator (34), which has a cavity (46) under system pressure, and the accumulator (34) has assigned to it a pressure control valve (80), which can be actuated electromagnetically and by means of which the cavity (46) can be connected to a low-pressure side (36, 38, 40, 112) of the high-pressure accumulator (34), characterized in that the cavity (46) and the low-pressure side (36, 38, 40, 112) of the high-pressure accumulator (34) have arranged between them a valve (74) which enables the high-pressure accumulator (34) to be filled from the low-pressure side to the system pressure side.
2. Fuel injection system according to Claim 1, characterized in that a magnet coil (26) of the pressure control valve (80) produces a force which acts in the opening direction (72) relative to a closing element (48).
3. Fuel injection system according to Claim 1, characterized in that a closing spring (84) of the pressure control valve (80) produces a force which acts in the closing direction (70) relative to the closing element (48).
4. Fuel injection system according to Claim 3, characterized in that the force of the closing spring (48) acting in the closing direction (70) is adjusted by means of a pre-loading element (96) screwed into the housing (14).
5. Fuel injection system according to Claim 1, characterized in that the valve (74) is constructed as a non-return valve.
6. Fuel injection system according to Claim 1, characterized in that the valve (74) is either let into the wall of the high-pressure accumulator (34) or is formed in a base plate (42) of the pressure control valve (80).
7. Fuel injection system according to Claim 3, characterized in that the closing spring (84) is surrounded by an armature-pin receptacle (98) which is spaced apart from a closing-spring receptacle (100) by a spacing gap (94).
8. Fuel injection system according to Claim 7, characterized in that the spacing gap (94) between the armature-pin receptacle (98) and the closing-spring receptacle (100) defines a travel of an armature pin (20) in the housing (14) of the pressure control valve (80).
9. Fuel injection system according to Claim 1, characterized in that, with the internal combustion engine switched off and a reduced pressure building up in the cavity (46) owing to the cooling of the fuel, the cavity (46) of the high-pressure accumulator (34) is equalized from the low-pressure side (36, 38, 40, 112) via the valve (74), and the cavity (46) is always full.

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