EP1252437B1 - Injection device and method for injecting a fluid - Google Patents

Abstract

An injection device with an injection nozzle (42), a pressure intensifier (12) for intensifying a primary pressure, a first valve device (32) for triggering the pressure intensifier (12), and an actuator for actuating the first valve device (32), wherein the pressure intensifier (12) is activated in a first state of the first valve device (32), the pressure intensifier (12) is deactivated in a second state of the first valve device (32), and a limitation of the through flow quantity to the injection nozzle (42) is provided. The invention also relates to a method, which makes advantageous use of the device according to the invention.

Description

State of the art

The invention relates to an injection device with a Injector, a pressure booster to reinforce a primary pressure, a first valve device for actuation of the pressure booster and an actuator for actuation the first valve device. The invention relates a method for injecting fluid, in which in In a first phase, low-pressure injection takes place and in a second phase a high injection Printing takes place.

A generic device and a generic method are known. A basic requirement for such System is fuel injection with one to make the greatest possible injection pressure. A high injection pressure has a positive influence on the function of a motor; for example the pollutant emissions and the Reduced fuel consumption. However, it can be additional an injection with the same system to carry out with lower pressure. Such an injection Low pressure can be used, for example, for a pre-injection used, among other things, the noise reduction serves. By providing different For example, pressures during an injection cycle an advantageous "boot" form of the injection pressure curve be achieved.

A pressure booster is used to implement the high injection pressure provided by hydraulic translation a primary, for example from a pressure accumulator to Provided pressure in the desired high injection pressure implements. By choosing the right one with strength acted surfaces and the counter forces of elastic means can provide a suitable pressure boost in this way can be set.

A generic pressure boost is particularly related useful with a common rail system. In the Memory injection "common rail" are the primary pressure generation and decouples the injection. The injection pressure is generated by a high pressure pump and in the "rail" (fuel storage) provided for injection. To this In principle, a favorable injection course can be done realize, in particular injection pressure and injection quantity independent for each operating point of the engine can be determined from each other. However, the Pressure in the common rail is currently limited to approx. 1600 bar, so that for emission reasons an increase in pressure is desired. A pressure booster in combination with A common rail system could therefore give particularly good results deliver. However, with pressure-reinforced common rail systems for refilling the various functional spaces of the pressure booster additional valve devices be provided. According to the state of the art the entire high pressure space in the injector and in the Pressure booster relaxes, resulting in high relaxation losses leads.

FIG. 5 shows a common rail system in which an injector or a Injector 110 is coupled to a pressure booster 112. The control of the Pressure booster 112 takes place via a 2/2-way valve 114, which the pressure in space 134 controls, so that in comparison to the control with a 3/2-valve in the Pressure booster inlet have comparatively low relaxation losses. The Hydraulic circuit shown has a bypass path 116 to selectively one Injection with rail pressure or an injection with increased pressure too enable. The pressure booster 112 is activated or deactivated by opening or closing valve 114. However, this system is too note that rail pressure is always conducted to the injector 110 via the bypass path 116. A jamming of the injector needle or injector valve would therefore be one Generate continuous injection, which can ultimately destroy the engine. It it is therefore desirable to provide an intrinsically safe system which has a structurally determined maximum injection quantity, that is to say one Injection quantity that is not exceeded in the event of damage to a system component can.

An injection device is known from US Pat. No. 5,622,152, in which an injection with low pressure is done by direct fuel from the accumulator to the Injection valve is guided, and in which an injection takes place at high pressure, by fuel under pressure increased by means of the pressure booster the injection valve is fed.

For the sake of completeness, the other components of FIG described system described. A valve 118 is for stroke control via a Flow restrictor 120 connected to a control chamber 122 of the injector 110. The Control room 122 is also above a Inlet throttle 124 in connection with the fluid inflow. The fluid is also the Pressure chamber 126 fed to the injector 110. Located in the fluid supply line 116 on Check valve 128, which only transports fluid in the direction of the injection nozzle 126 permits. The pressure booster 112 has a low pressure space 130, one High-pressure space 132 and a differential space 134. The differential space 134 is over a Throttle 136 with the which allows fluid transport only in the direction of the injector 126. The Pressure booster 112 has a low pressure chamber 130, a high pressure chamber 132 and a difference space 134. The difference space 134 is connected via a throttle 136 Pressure accumulator ("Rail") 138 connected, while the low pressure chamber 130 and the High-pressure chamber 132 directly or via the check valve 128 with the pressure accumulator 138 are connected. The pressure accumulator 138 has a four-cylinder engine Connections to four injectors, to which he provides rail pressure. A Supply line to the pressure accumulator 138, in which a pressure sensor and a control circuit is provided, comes from a fuel tank 140 via a volume-controlled High pressure pump 142.

Advantages of the invention

On the one hand, the invention enables control of a Pressure amplifier made possible by a valve, with only slight relaxation losses occur, and this is according to the invention with a flow rate limitation Injector combined. It is therefore impossible that the Nozzle needle or the control valve of the injection nozzle for a continuous injection and could ultimately lead to the destruction of the engine.

The pressure booster has a low pressure chamber, a high pressure chamber and one Difference space, whereby the first valve device with a first connection is connected to the differential space, the first valve device connected to a return system with a second connection and the first valve device is in the first state is open so that the differential space with the return system connected is. When the valve is closed the piston of the pressure booster is therefore pressure balanced, since the rail pressure is established in the differential space. There is no pressure boost. However this valve relieves the pressure on the valve Differential chamber. So the pressure booster is activated and an injection with increased pressure can take place.

It is advantageous if the low pressure chamber of the pressure booster with the differential space of the pressure booster over a first throttle and a second valve device connected is, wherein the first throttle and the second valve device are arranged in parallel, the second valve device the flow of a fluid from the differential space to the low pressure space releases and the second valve means the flow a fluid from the low pressure space to the differential space locks. The second valve device thus enables that the differential space when the first valve device is open is depressurized, so that an activation of the pressure booster can be done. The second valve unit prevents in the differential space an overpressure compared to the low pressure space can build up. About the throttle, the differential space at reset the pressure booster.

The second valve device is preferably a check valve. One such is suitable, the ones described Perform functions of the second valve device.

The low-pressure chamber of the pressure booster is preferably with the high pressure chamber of the pressure booster via a second Throttle and a check valve connected, the check valve the flow of a fluid from the low pressure space releases to the high pressure chamber and the check valve Flow of a fluid from the high pressure space to the low pressure space locks. The check valve is useful so that the Pressure from the high pressure room does not move towards the low pressure room degrades. The throttle ensures that the Connection a sufficiently small flow cross-section has so that it does not act as a bypass for an injection can serve. With this measure, an undesired, increased leakage current in the injector, e.g. by needle clamps, a pressure difference between the low pressure space and the high pressure chamber of the pressure booster generated, whereby a pressure booster piston takes its maximum stroke. The Throttle can also be through a correspondingly small line or a correspondingly small opening cross section of the Check valve are formed. Basically, the serves Connection of the refilling of the high pressure chamber of the pressure booster when resetting the pressure booster piston.

It can also be provided that the difference space of the Pressure booster with the high pressure chamber of the pressure booster connected via a second throttle and a check valve wherein the check valve is the flow of a fluid from releases the differential space to the high pressure space and that Check valve the flow of a fluid from the high pressure space locks to the difference space. Meet the components mentioned thus the same purpose as in the case of the connection of the Low pressure room with the high pressure room. The second Throttle also eliminated and the differential space of the pressure booster with the high pressure chamber via a check valve be connected because of an undesirable leakage current in the injector at the first throttle between the low pressure space and the differential space generates a pressure difference.

Particular advantages of the invention show up when the pressure booster a flow connection from reaching a certain stroke from the pressure accumulator to the injection nozzle. This prevents, for example, jamming the injector or a jamming of the control valve the injector, a continuous injection and thus the engine is destroyed. Preferably points the pressure booster piston has a pressure surface that also after interrupting the flow connection to the injector the injector supply line is connected. So the remains Pressure booster piston controlled by pressure difference on his End stop. In this way, the corresponding injector switched off in the event of damage.

It is advantageous if the inlet line is closed is provided by a sealing device. The two components the sealing device then lead to closure the supply line when the pressure booster piston reaches its maximum Hub.

But it can also be advantageous if a closure the filling path is provided by a slide seal is. This slide seal can come from the pressure booster piston and the guide of the pressure booster piston are formed. Closing the supply line can therefore start at a certain point Stroke, which depends on which Place the fluid flow at the high pressure chamber of the pressure booster attaches.

Preferably elastic means for resetting the Booster piston provided. These can either be in Low pressure room, in the differential room or in the high pressure room or be arranged at another suitable location. The elastic means can for example by a spring in Low-pressure room can be realized.

Furthermore, it can be advantageous for at least one separate one Flow limiter is provided. According to more preferred Embodiments of the invention act on the pressure booster at the same time as a flow limiter. However, it can Under certain circumstances it may be useful to have a separate flow limiter to use. This can optionally be in the filling path the high pressure chamber or between the pressure booster and the injector.

It may also be advantageous to have a two-part pressure booster piston provided. The second valve unit, which parallel to the throttle the low pressure chamber of the Pressure booster connects to the differential space, as an overpressure due to the separation of the pressure booster pistons is prevented in the difference space.

The invention is based on the generic type according to claim 17 Process in that the high pressure under activation a pressure booster is generated by one with a Differential space of the pressure booster and a return system related valve device is opened and that limits the flow rate of the fluid to an injector becomes. It can thus be done by a simple operation a valve device while avoiding high relaxation losses a control, that is an activation or a pressure booster is deactivated. The Flow limitation prevents damage to the Motors, which are otherwise due to continuous injection when jamming the nozzle needle or the control valve Injector could be done.

The method is particularly advantageous when the maximum Injection quantity from the volume of a high-pressure chamber Pressure booster is limited. So the pressure booster is advantageously at the same time as its primary Purpose - the pressure boosting - used as well, in the sense intrinsic safety, to limit the flow rate.

However, it can sometimes be an advantage if the maximum injection quantity from a separate flow limiter is limited. This solution, which also in Combination with a flow limitation of the pressure booster can be provided is fundamentally more complicated. A separate flow limitation can, however, be considered advantageous to the design of the pressure booster his.

It is advantageous if the injector is stroke-controlled, whereby it is even conceivable that the control valve of the injector from the same control element, preferably a piezo actuator, is controlled, such as the valve device, which the Activates pressure booster. As an actuator can next to a Piezo actuator, for example, also provided a solenoid valve his.

The invention is based on the knowledge that a system with high intrinsic safety using a control a pressure booster can be provided, without great relaxation losses. The pressure booster can thus be activated optionally and it can an injection course shaping can be made. For example can be a pre-injection with low pressure and a Main injection take place under high pressure. So it can for example an advantageous "boot" form of the injection pressure curve can be achieved.

drawing

Figur 1 zeigt eine erste Ausführungsform einer erfindungsgemäßen Einspritzeinrichtung;

Figur 2 zeigt eine zweite Ausführungsform einer erfindungsgemäßen Einspritzeinrichtung;

Figur 3 zeigt eine dritte Ausführungsform einer erfindungsgemäßen Einspritzeinrichtung;

Figur 4 zeigt eine vierte Ausführungsform einer erfindungsgemäßen Einspritzeinrichtung;

Figur 5 zeigt eine Einspritzeinrichtung zur Erläuterung der erfindungsgemäßen Vorteile.

The invention will now be explained by way of example with reference to the drawing using specific embodiments.

Figure 1 shows a first embodiment of an injection device according to the invention;

Figure 2 shows a second embodiment of an injection device according to the invention;

FIG. 3 shows a third embodiment of an injection device according to the invention;

FIG. 4 shows a fourth embodiment of an injection device according to the invention;

FIG. 5 shows an injection device to explain the advantages according to the invention.

Description of the embodiments

In Figure 1 is a first embodiment of an inventive Injection device shown. A pressure accumulator 10 provides primary pressure. This will fed to a pressure booster 12 in its low pressure chamber 14. In addition to the low pressure chamber 14, the pressure booster has 12 a high-pressure space 16 and a differential space 18 on. The low pressure chamber 14 is a throttle 20 and a Check valve 22 connected to the high pressure chamber 16. The Check valve 22 closes in the direction of the low pressure chamber 14. The low pressure chamber 14 is also a throttle 24 and a check valve 26 connected in parallel therewith connected to the differential space 18 of the pressure booster 12. The pressure booster piston 28 is by a spring 30 to Force applied for the purposes of the provision. The check valve 26 locks in the direction of the differential space 18.

A valve device is used to control the pressure booster 12 32 provided which is connected to the Differential space 18 of the pressure booster 12 in connection stands. The other connection of the valve device 32 is with a return system 34 connected. With the valve device closed 32, the pressure booster piston 28 is pressure-balanced, since in the differential space 18 via the throttle 24 in the low pressure chamber 14 prevails rail pressure. The Pressure booster is deactivated, meaning that it cannot find one Pressure increase instead. Consequently, an injection is with Rail printing possible. The pressure booster piston moves 28 according to the amount injected without pressure boosting downward. The pressure booster 12 works here like a flow limiter. In particular has the pressure booster piston 28 has a valve seat at its end 36, so that when the maximum stroke is reached, the feed line 38 closes to the injector 40.

The injector 40 comprises an injection nozzle 42, the pressure chamber 44 with the inlet line 38, which is connected to the high-pressure chamber 16 of the pressure booster 12 is connected, is connected. The injector 40 is stroke-controlled, with a control valve 46 on the one hand with a return system 34 and on the other hand via an outlet throttle 48 with a control chamber 50 of the injection nozzle connected is. The control room 50 is also above a Inlet throttle 52 in connection with the supply line 38.

Figure 2 shows a second embodiment of an inventive Injector. Here is different from 1, the differential space 18 of the pressure booster 12 with the high pressure chamber 16 of the pressure booster 12 connected. The refilling of the high pressure room 16 thus takes place via this filling path. This too is with a throttle 56 and one towards the Differential space 18 provided check valve 58, these components being connected in series.

In Figure 3 is a third embodiment of an inventive Injection device shown. This corresponds largely the first embodiment shown in Figure 1 the invention. The sealing seat or sealing device 36 (Figure 1) for closing the inlet line 38 is, however replaced by a slide valve 60 (Figure 3), which the filling path 62 from a certain stroke of the pressure booster piston 28 closes.

Figure 4 shows a fourth embodiment of the invention. In the connection of the low pressure chamber 14 with the high pressure chamber 18, a separate flow limiter 64 is provided. alternative (or in addition) is a flow restrictor 66 in the connection between the high pressure chamber 16 of the pressure booster 12 and the injector 40. In the case of the arrangement the flow restrictor in the connection between the low pressure chamber 14 and the high pressure chamber 16 of the pressure booster 12 is again a check valve 68 with the Pressure booster 64 connected in series for pressure transmission from the high pressure space 16 into the low pressure space 14 to avoid.

The preceding description of the exemplary embodiments according to the present invention is for illustrative purposes only Purposes and not for the purpose of limiting the invention. Various changes and modifications are within the scope of the invention possible without the scope of the claims to leave.

Claims (12)

1. Injection device having an injection nozzle (42), a pressure amplifier (12) which serves to amplify a primary pressure, the said pressure amplifier (12) and comprises a low-pressure chamber (14), a high-pressure chamber (16) connected to the injection nozzle (42), and a differential chamber (18), and having a first valve device (32) which is connected to the differential chamber (18), is actuated by an actuating element, and by which the connection of the differential chamber (18) to a return system (34) is controlled in order to activate the pressure amplifier (12), the first valve device (32) opening the connection of the differential chamber (18) to a return system (34) in a first state in such a way that the pressure amplifier (12) is activated, and closing the connection in a second state in such a way that the pressure amplifier (12) is deactivated, characterized in that the first of two connections of the valve device (32) is connected to the differential chamber (18) and the second connection is connected to the return system (34), and the low-pressure chamber (14) of the pressure amplifier (12) is connected to the differential chamber (18) of the pressure amplifier (12) via a first restrictor (24), and the low-pressure chamber (14) or the differential chamber (18) is connected to the high-pressure chamber (16) via a second restrictor (20, 56, 64) and a non-return valve (22, 58, 68), the non-return valve (22, 58, 68) releasing the flow of a fluid to the high-pressure chamber (16) and blocking the flow from the high-pressure chamber (16), and throughflow limitation of fluid out of the high-pressure chamber (16) to the injection nozzle (42) being provided, which is performed by the pressure amplifier (12).
2. Injection device according to Claim 1, characterized in that the second valve device is a non-return valve (26).
3. Injection device according to Claim 1 or 2, characterized in that, in order to limit the throughflow, the pressure amplifier (12) closes a feed line (38) out of the high-pressure chamber (16) to the injection nozzle (42) once a certain displacement has been reached.
4. Injection device according to Claim 3, characterized in that a sealing seat (36) is provided in order to close the feed line (38).
5. Injection device according to one of Claims 1 to 3, characterized in that a slide seal (60) is provided in order to close a filling path (62).
6. Injection device according to one of the preceding claims, characterized in that at least one pressure-amplifier piston (28) controls a flow connection to an injector (40).
7. Injection device according to Claim 6, characterized in that, in its end position, the pressure-amplifier piston (28) interrupts a flow connection to the injector (40).
8. Injection device according to one of the preceding claims, characterized in that elastic means (30) are provided in order to restore the pressure-amplifier piston (28).
9. Injection device according to one of the preceding claims, characterized in that the pressure-amplifier piston (28) has two parts.
10. Injection device according to one of the preceding claims, characterized in that at least one separate throughflow limiter (64, 66) is provided.
11. Method for injecting fluid, in which, in a first phase, injection takes place at low pressure and, in a second phase, injection takes place at high pressure, characterized in that the high pressure is produced by activating a pressure amplifier (12), by opening a valve device (32) which is connected to a differential chamber (18) of the pressure amplifier (12) and a return system (34), and in that the throughflow of a fluid to an injection nozzle (42) is limited, the maximum injection quantity being limited by the volume of a high-pressure chamber (16) of the pressure amplifier (12).
12. Method according to Claim 12, characterized in that the maximum injection quantity is limited by a separate throughflow limiter (64, 66).

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