EP2016278A1

EP2016278A1 - Pressure control valve with limp-home and ventilation function

Info

Publication number: EP2016278A1
Application number: EP07726779A
Authority: EP
Inventors: Gerhard Geyer
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2006-05-04
Filing date: 2007-03-12
Publication date: 2009-01-21
Anticipated expiration: 2027-03-12
Also published as: WO2007128606A1; US20090199820A1; ATE447669T1; DE102006020692A1; EP2016278B1; JP2009535562A; DE502007001915D1

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

description

Pressure control valve with emergency drive and ventilation function

State of the art

Viehweg 1998, Braunschweig, Wiesbaden, ISBN 3-528-03873-X, p.270 Figure 9 shows a pressure regulating valve known from the publication "Diesel engine management", 2nd, updated and expanded edition - Set, compare page 267, Figure 7 of the same publication.The pressure regulating valve comprises a ball valve, which contains a ball-shaped closing body.In the pressure regulating valve, an armature is received, on the one hand acted upon 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 q = 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 control valve is set in a test point, which is defined by a selected value for the drive current I of the coil of the E lektromagneten. 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, depending on the test point adjusting pressure tolerance ± Δp on the quality of mounting the pressure control valve to a high-pressure pump or another with high pressure acted upon component.

DE 102 14 084 A1 relates to an adjustable pressure regulating 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 above-mentioned lekage-free injectors have hitherto not been used, which means that the pressure reduction in this application occurs only via the system-inherent leakage of the fuel injectors. A known from the prior art pressure control valve (Figure 1) has the property of being completely open in the de-energized state 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 permitted because of the high required vehicle availability.

Disclosure of the invention

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

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 region of the high pressure accumulator, if by the Cooling in the high-pressure accumulator resulting negative pressure opens this check valve 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, in comparison to the solution known from the prior art, the direction of action of the electromagnet and the closing spring are reversed. 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 which closes the high-pressure reservoir at one end, while an armature bolt, which closes the closing acted upon element acted upon 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. In this way, a complete filling of the high-pressure accumulator body is always ensured during system restart and thus a faster start is possible.

drawing

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

It shows:

FIG. 1 shows a pressure regulating valve known from the prior art, in which the electromagnet acts in the closing direction and a spring element acts in the opening direction;

FIG. 2 shows a schematic diagram of the pressure regulating valve shown in FIG. 1,

FIG. 3 shows a pressure regulating valve with a reversed effective direction of magnetic force generated by the electromagnetic coil and a closing force applied by a closing spring;

Figure 4 is a schematic diagram of the inventively proposed pressure control valve with acting in the opening direction electromagnet and acting in the closing direction closing spring and a schematically illustrated installation position of a check valve and

FIG. 5 shows a section through the pressure regulating valve proposed according to the invention, measured according to the schematic diagram in FIG. 4 and FIG

Figure 5.1 a valve integrated in a seat ring for filling the high-pressure accumulator.

variants

FIG. 1 shows a pressure regulating valve known from the prior art, in which an electromagnet acts in the closing direction with respect to a closing element, and FIG 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 control valve 10 as shown in Figure 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 Figure 1, the aforementioned magnetic coil 26 is added. 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 is formed spherical in the illustration of Figure 1. 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 a high-pressure pump, which is not shown in the illustration according to FIG. 1, but is connected to the high-pressure accumulator 34.

In the case of the pressure regulating valve 10 illustrated in FIG. 1, in the event of a fault such as, for example, a cable drop at the electrical connection 12, the fuel stored in the cavity 46 of the high-pressure accumulator 34 loses the pressure required for the injection. 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 ment 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 embodiment variant of the pressure regulating valve 10 shown in FIG. 1, the entire fuel injection system can become pressureless in the event of a fault such as a cable waste, which leads to the immediate shutdown of the internal combustion engine, which is unacceptable for reasons of availability in commercial vehicle applications.

FIG. 2 shows a schematic view of the directions of action of the electromagnet and of the compression spring in the exemplary embodiment according to FIG. 1.

The illustration according to FIG. 2 shows that the magnetic coil 26 shown in FIG. 1 acts on the anchor bolt 20 in a first effective direction 62, whereby the closing element 48 is placed in the seat ring 42. If the solenoid 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 fuel is stored, is depressurized via the low-pressure bores 36, since the closing element 48 is open.

The illustration of Figure 3 is a schematic diagram of a pressure control valve can be removed, in which the directions of action of the electromagnet and the valve spring in comparison to the representation of Figure 2 are reversed.

According to the schematic diagram shown in FIG. 3, the magnetic coil 26, as shown in FIG. 1, acts in a second effective direction 72, ie. H. 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 uncontrolled outflow of the fuel volume stored in the cavity 46 of the high-pressure accumulator 34 into the low-pressure bores 36 and thus into the solenoid coil 26 (see illustration according to FIG the return line 38 is prevented to the tank of the vehicle. However, refilling the cavity 46 according to the illustration in FIG. 3 is not possible with the thematic basic structure shown there.

The illustration according to FIG. 4 shows a schematic schematic diagram of the pressure regulating valve proposed according to the invention. It can be seen from the illustration according to FIG. 4 that the reverse-acting pressure regulating valve 80 described in greater detail below in the magnet coil 26 has an electromagnet 26 which acts in the second direction of action 72, ie with respect 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, which in the illustration of FIG 4 in the second direction of action 70, ie the closing element 48 is acted upon in the closing direction and thus in the seat in the seat ring 42. When the magnet coil 26 is not energized, it is thus ensured that the fuel volume stored in the cavity 46 of the high-pressure accumulator 34 does not flow back into the low-pressure bores 36 and thus into the return line 38 to the tank of the vehicle without system pressure. 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 illustration according to Figure 5 is a section through the invention proposed pressure control valve with reversed sense of action of a closing spring and a Elektromag- neten in more detail to remove.

A pressure regulating valve 80 shown in FIG. 5 is screwed by way of the thread 52 to the high-pressure accumulator 34 (common rail) which is of tubular design here. 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 opposite to the closing element 48 shown in FIG. 5 in spherical form. In the housing 14 of the pressure control valve 80 with the reverse direction of action as shown in FIG. 5, the seat ring 42 is furthermore arranged inside the receptacle 44, in which the seat 50 is formed by the ball-shaped closing element 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.

The 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, which acts on the anchor bolt plate 86 of the anchor bolt 20, in the second direction of action

70 acting 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, the check valve 74 is located 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 can, as shown in Figure 5, be fixed by a pressed-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 area and low pressure area, the spherical closure member 108 and fixed by a ring spring 106 are integrally formed in the seat ring 42 and also provide a filling possibility of the cavity 46. By the check valve 74 in the wall of the high-pressure accumulator 34 (common rail), the fuel flow is suppressed by the pressurized system cavity 46 of the high-pressure accumulator 34 in the direction of a low-pressure side cavity 112, since the in the illustration of Figure 5 spherically shaped closing element 108 in his seat 110 is pressed in the wall of the high-pressure accumulator 34. On the other hand, it is achieved with the check valve 74 that when the fuel is cooled and the internal combustion engine is shut off, 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 cavity 46 is separated from the low-pressure side cavity 112 through the check valve 74 in that the here spherically shaped closing 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 to accommodate the non-return valve 74 shown in FIG. 5 also in the base plate 42 of the pressure regulating valve 80 with the reverse direction of action. For the installation location of the check valve 74 alone is decisive that is separated by the 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.

The pressure control valve 80 shown in Figure 5 with reverse direction of effect is used advantageously 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 pressure control valve 80 shown in Figure 5 de-energized, which may occur, for example, by a cable drop, it is on the closing spring 84, which acts in the second direction of action 70 on the ball-shaped closure member 48 ensures that he In the cavity 46, stored fuel does not flow via the open closing element 48 into the low-pressure side cavity 40 in the housing 14 and from there via the low-pressure bores 36 into the low-pressure-side return line 38 shown in FIG. 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 force fabric volume z. B. reduced by cooling and thus creates a negative pressure in the high pressure storage volume.

Claims

claims

A fuel injection system for internal combustion engines with a high pressure accumulator (34) having a system pressure under pressure cavity (46) and the accumulator (34) is associated with an electromagnetically actuated pressure control valve (80), with which the cavity (46) with a low pressure side (46 , 38, 40, 112) of the high-pressure accumulator (34), characterized in that between the cavity (46) and the low-pressure side (36, 38, 40, 112) of the high-pressure accumulator (34) a filling of the high pressure accumulator (34) from the low pressure side to the system pressure side enabling valve (74) is arranged.

2. Fuel injection system according to claim 1, characterized in that a magnetic coil (26) of the pressure regulating valve (80) generates in the opening direction (72) relative to a closing element (48) acting force.

3. Fuel injection system according to claim 1, characterized in that a closing spring (84) of the pressure regulating valve (80) generates a force acting in the closing direction (70) relative to the closing element (48).

4. Fuel injection system according to claim 3, characterized in that in the closing direction (70) acting force of the closing spring (48) via a in the housing (14) verschraub tes biasing member (96) is set.

5. Fuel injection system according to claim 1, characterized in that the valve (74) is designed as a check valve.

6. Fuel injection system according to claim 1, characterized in that the valve (74) either in the wall of the high-pressure accumulator (34) embedded in or in a base plate (42) of the pressure regulating valve (80) is formed.

7. Fuel injection system according to claim 3, characterized in that the closing spring (84) by an anchor bolt receptacle (98) is enclosed, which is spaced by a gap distance (94) of a closing spring receptacle (100).

8. Fuel injection system according to claim 7, characterized in that the gap spacing (94) between the anchor bolt receptacle (98) and the closing spring receptacle (100) defines a stroke of an anchor bolt (20) in the housing (14) of the pressure regulating valve (80).

9. A fuel injection system according to claim 1, characterized in that the cavity (46) of the high-pressure accumulator (34) with shut off internal combustion engine and build-up negative pressure in the cavity (46) due to cooling Kraft- substance via the valve (74) from the low pressure side ( 36, 38, 40, 112) is balanced and the cavity (46) is always filled.