EP1144859B1 - Injection device and method for injection of fluids - Google Patents

Abstract

The present invention relates to an injection device having an injection valve (12), a valve device (18, 20) for controlling the injection, and a setting element (22) for operating the valve device (18, 20), the valve device having at least one first valve (18) and a second valve (20) which can be operated by the settling element (22) via a common hydraulic coupling space (24). The present invention further relates to a method for injecting fluid in which a setting element is (22) is activated, a valve device (18, 20) is operated by the setting element (22), and an injection valve (12) is opened, the first valve (18) and a second valve (20) of the valve device (18, 20) being operated by the setting element (22) via a common hydraulic coupling space.

Description

State of the art

The invention relates to an injection device with a Injection nozzle, a valve device for controlling the Injection and an actuating element for actuating the valve device. The invention further relates to a method for injecting fluid in which activates an actuator is, a valve device actuated by the actuator and an injection nozzle is opened.

A generic device and a generic method are known for example from EP 0 562 046 B1. The basic requirement of such a system is the fuel injection with the largest possible injection pressure make. A high injection pressure has positive Influences on the function of an engine; for example Be the pollutant emissions and fuel consumption reduced. To realize the high injection pressure is a pressure booster can be provided which by a hydraulic translation a primary, about one Accumulator provided pressure in the desired high injection pressure. By the appropriate Choice of pressurized areas of the intensifier and the counterforces of elastic means may be appropriate Pressure gain can be adjusted.

To control the injection, is a valve device provided in turn by an actuator, such as a Solenoid valve or a piezoelectric actuator is operated. These Valve device serves both the supply of the primary to amplifying pressure to the pressure intensifier as well as to Relief and refilling the pressure intensifier after successful pressure boost and the associated injection through the injector.

The prior art uses as a valve device 3/2-valve. In a first switching state of the 3/2 valve is the fuel flow between a fuel inlet and the primary side of the booster locked. on the other hand is a connection between the primary side of the booster and the leak system. Will now be the actuator actuated the injector, the 3/2-valve goes into a transient state in which both a connection between the fuel inlet and the primary side of the booster as well as between the primary side of the booster and the leak system. Upon further actuation of the actuating element is the second switching state of the 3/2 valve assumed in which the connection of the primary side the booster with the leak system is locked, the Connection between the fuel inlet and the primary side however, remains open. When unloading or when Refilling the pressure booster takes the 3/2 valve the mentioned switching states in reverse order.

In the described solution of the prior art it has proved to be particularly problematic that high leakage rates occur. These worsen the efficiency of the Injection system. There is also a 3/2 valve for high pressure applications only conditionally suitable, in particular with regard to Manufacturing and sealing.

A generic pressure amplification is particularly related useful with a common rail system. In the Memory injection "common rail" are the primary pressure generation and the injection decoupled. The injection pressure becomes independent of the engine speed and the injection quantity generated and in the "rail" (fuel storage) for injection provided. In this way you can basically realize a favorable injection course, in particular Injection pressure and injection quantity for each operating point of the motor can be set independently. However, the pressure in the common rail is currently still up about 1600 bar limited, so that for emission reasons and reasons of fuel consumption, an increase in pressure desired is. A pressure amplifier in combination with a Common rail system could thus have particularly good results deliver. Nevertheless, the problems mentioned above exist by using the 3/2 valve, giving a total of one harmful influence on the function of the injection system takes.

Advantages of the invention

The injection device according to the invention according to claim 1 builds on the state of the art in that the valve device at least a first valve and a second Valve, which of the actuating element via a common hydraulic coupling space are actuated. On this way, e.g. avoided the disadvantages with the Use of a 3/2-valve in the prior art occur. Since the two valves actuated by the same actuator are at this point the equipment in the Not compared to using a single 3/2 valve increased so that there is an overall improvement of the system. For example, it can be achieved that the valves by a suitable adjustment of elastic means to different Time points on the operation by the Actuate react. The hydraulic coupling space is used also a possibly required force-displacement-translation and the compensation of tolerances, e.g. Changes in length.

Preferred is a pressure intensifier for amplifying a primary Pressure provided, which of the valve device is operable. In this way, can be particularly good realize high injection pressure. Since it is no longer necessary is to provide a 3/2 valve, the large ones can Pressure differences arising due to the pressure booster be controlled while avoiding high leakage.

Preferably, the actuator is a piezoelectric actuator. piezo actuators have themselves as electronically controllable control elements proven, especially since they are compact in their construction and work reliably. Furthermore, the control function is through Modification of the parameters (voltage, pulse duration) of the control variable.

Preferably, the primary pressure is from a common rail made available. It is thus possible to take advantage a common rail system with the pressure-boosted injector to combine. The common rail pressure, which currently limited to about 1600 bar, can be pressure-boosted become; thus emissions and fuel consumption reduced.

Advantageously, the injection system is pressure-controlled. In this way it can be ensured that the injection nozzle actually only above a certain threshold pressure opens. This is the benefits of the injection guaranteed under high pressure under all circumstances.

Preferably, the first valve separates in a first state the primary pressure from a low-pressure chamber of the intensifier, and the first valve couples in a second state the primary pressure in the low-pressure chamber of the booster one. Thus, the first valve as a metering valve used, with its opening states the system supply determine with fuel decisively.

It is advantageous if the second valve in a first Condition a low-pressure chamber of the booster with a Leakage system couples and the second valve in a second Condition the low pressure chamber of the booster from the Leak system separates. The second valve can thus serve as a relief valve serve for the pressure booster; Furthermore, the Fill the pressure booster via the second valve.

It is particularly advantageous if the first valve and the second valve are coordinated so that by pressing of the actuating element initially from the second valve its first state into its second state convertible and then the first valve from its first state can be converted into its second state. It is thus achieved that the opening cross sections of the valves are not overlap. This leads to a significant reduction of accumulating leakage, because the second valve is already closed when the first valve is still in its closed position Initial state remains. Furthermore, a multiple (clocked) opening and closing the first valve at closed second valve possible.

Preferably, a low pressure space of the pressure booster with a high-pressure chamber of the pressure booster via a check valve connected, via which the high-pressure chamber filled is. Such a filling of the high-pressure chamber is required for each injection cycle, so that fluid for the High pressure injection is available. A check valve prevents the high pressure from the high pressure chamber of the pressure intensifier in the low pressure space of the pressure booster arrives; on the other hand allows the check valve the filling of the high-pressure chamber from the low-pressure chamber.

It can also be beneficial if a high pressure room of the Pressure booster with the leak system via a check valve connected is. In this way it is possible the low pressure space and the high-pressure chamber of the pressure intensifier completely decoupling from each other and refilling of the high pressure chamber by the existing in the leak system Make fluid.

Preferably, a differential space of the pressure booster is over a check valve connected to the leak system, so that the differential space is not filled. The check valve Although allows that occurring in the difference space Leakage leak into the leak system; the check valve prevents, however, that a filling of the difference space takes place, what the entire volume to be filled in an advantageous Way reduced.

It may also be advantageous if instead of the low pressure space the high pressure chamber of the booster over the second valve is relieved. This way a can faster relief of the injector made as in the Variant with a discharge on the low pressure side of the Booster. However, in the discharge of the High-pressure chamber via the second valve, that the valve system an increased load due to the high Pressure in the high pressure chamber learns.

It may be useful that the first valve and / or the second valve (on) 2/2 valve is / are. Hereby are the required logical switching functions executable, which be adopted in the art of a 3/2-valve.

Preferably, the first valve and the actuating element are so matched to each other, that the first valve continuously or in stages in different opening states different opening cross sections can be transferred. This can, for example, in connection with a pilot injection be beneficial. Via a throttle in the valve seat the first valve can be very small pre-injection quantities be realized with reduced injection pressure. To becomes the interplay of the first valve and the control element designed so that a continuous cross-sectional control the first valve or a gradual opening the first valve is enabled. This can be the fast Switching time of a piezoelectric actuator can be advantageously used. Also, due to the cross-sectional control of the first valve reaches a shaping of the injection curve become.

The invention is based on the generic method according to Claim 13 characterized in that a first valve and a second Valve of the valve device from the actuator over a common hydraulic coupling space can be actuated. Although two valves used as a replacement for a 3/2 valve nevertheless, the procedure can be simple be designed. It is only a single control element and whose preferably electronic control required to operate both the first valve and the second valve.

Preferably, a pressure booster for amplifying a primary pressure actuated by the valve means. On this way can be in the system a beneficial high Realize injection pressure.

Preferably, the injector is opened when in its feed area a certain pressure is exceeded. One Such pressure-controlled system is particularly in the advantageous use of high injection pressures, because the controlling variable - the pressure - at the same time decisive parameters for the quality of the injection is.

Preferably, the method is developed so that when Actuate the actuator a low pressure chamber of the pressure booster from one leakage system by closing the second Valve is decoupled, then the primary pressure in the Low-pressure chamber coupled by opening the first valve is, then the pressure in a feed region of the injection nozzle exceeds a certain pressure, so that the Injector opens, then the first valve closes and then the second valve opens so that the injection stopped and the pressure intensifier is relieved. By This procedure is achieved that the opening cross-sections the two valves do not overlap, which leads to an advantageous reduction in the amount of leakage. Furthermore, the switching states are suitable for rapid Allow pressure build-up and also a reliable discharge pressure booster and injector. Furthermore, several switching operations of the first Valve possible with the second valve closed.

Preferably, the high-pressure chamber of the pressure intensifier via a check valve filled, over which he with the Low pressure space is connected. As in the low-pressure room with open Valve a sufficient fluid reservoir is present, is it useful for filling the high pressure chamber to use via a check valve. Conversely, through the check valve is the high pressure from the high pressure chamber do not pass into the low-pressure chamber of the booster; he is completely to control the injector used.

It may also be advantageous that the high pressure space of the Pressure booster is filled via a check valve, via which it is connected to the leak system. It lies then a complete decoupling of low pressure space and High-pressure chamber of the pressure intensifier, and nevertheless will a filling of the high-pressure chamber from a reservoir sufficient Size allows.

It can also be useful if the high pressure room of the Pressure booster is relieved via the second valve. This may lead to faster relief, However, it should be noted that the valve device must endure higher pressures.

Preferably, the first valve is continuous or stepwise transferred into different opening states. It leaves in this way with the first valve as a metering valve a shaping of the course of injection as well as a pre-injection with small pre-injection quantity and reduced injection pressure realize. This is favored by the with a piezo actuator possible fast switching times.

The invention is based on the surprising finding that through the use of two valves, an injection device, especially with pressure booster, in more reliable Way can be controlled. The disadvantages of the use of a 3/2 valve are eliminated; Furthermore, there is no unfavorable increase in the apparatus Effort. It should be emphasized that only one single actuator for operating both valves sufficient is.

drawing

The invention will now be described with reference to the accompanying drawing by way of example with reference to a preferred embodiment described.

FIG. 1 is a schematic representation of an injection device according to the invention.

Description of the embodiment

FIG. 1 shows an injection device 10, which in particular can be used in diesel engines. The injector 10 includes an injector 12 with which diesel fuel injected into the combustion chamber 14 of an engine becomes. The injector 12 becomes fuel at high pressure supplied from a pressure amplifier 16. This pressure booster 16 is operated by a valve device, a first 2/2-valve 18 and a second 2/2-valve 20 has. Both 2/2 valves 18, 20 are controlled by a single actuator operated, which in the present embodiment is realized as a piezoelectric actuator 22. The piezoelectric actuator 22 controls the two 2/2 valves via a common coupling space 24 on. The primary pressure is the first 2/2 valve of one Common rail 26 fed, in which usually a Pressure between 300 and 1000 bar prevails, whereby Maximaldrükke 1600 bar in the common rail 26 can be reached. The pressure in the common rail 26 is by a quantity-controlled high-pressure pump 28 constructed with a fuel tank 30 in Connection stands.

To initiate an injection process, the piezoelectric actuator 22 activated. The force of the piezoelectric actuator 22 is via the coupling space 24 simultaneously on the first 2/2-valve 18 and the second 2/2-valve 20 transmitted. In the initial state is the first 2/2 valve 18 is closed, while the second 2/2 valve 20 is open. The closed state of the first 2/2-valve 18 causes the low pressure chamber 32 of the Pressure booster 16 of the primary pressure in the common rail 26th is decoupled. The open state of the second 2/2 valve 20 has the consequence that the low pressure chamber 32 of the booster 16 is connected to a leak system 34. Will now the force from the piezoelectric actuator 22 via the coupling space 24th transferred to the 2/2 valves 18, 20, so closes first the second 2/2-valve 20, and only then opens the first 2/2 valve 18. This switching sequence can be adjusted reach the two involved 2/2-valves, in particular by a suitable choice of the involved hydraulic Attack surfaces as well as the elastic forces. By the switching sequence of the 2/2 valves is achieved that a Pressure build-up in the low-pressure chamber 32 of the booster 16 only takes place at a time when the connection between the low-pressure chamber 32 and the leak system 34 already is blocked by the second 2/2-valve 20. Of the Pressure build-up in the low-pressure chamber 32 of the booster 16 can thus be done quickly, and by a lack of overlap the opening cross sections of both 2/2-valves will be the occurring leakage significantly reduced. The one in the low-pressure room 32 of the booster 16 is generated pressure amplified by the pressure booster 16, so that a high pressure occurs in the high-pressure chamber 36 of the booster 16. This is transferred to the pressure-controlled injection nozzle 12, the Injector 12 opens when exceeding a threshold pressure, and the injection takes place at the corresponding high pressure point.

Now move the 2/2-valves 18, 20 - first, the first 2/2-valve 18 and then the second 2/2-valve 20 - through Deactivation of the piezoelectric actuator 22 back to its original position, so the pressure booster 16 via the second 2/2-valve 20 relieved and filled. The filling the high pressure chamber is carried out via a check valve 38, which between the low-pressure chamber 32 and the high-pressure chamber 36 of the booster 16 is arranged. At the previously described injection process has this check valve 38 the task a fluid flow from the high-pressure chamber 36th in the low pressure chamber 32 of the booster 16 to prevent. The others in the differential space 40 of the booster 16 occurring leakage is via a check valve 42nd discharged into the leak system 34. The provision of a check valve 32 avoids the filling of the difference space 40 during the discharge of the booster 16 and reduced thus the involved volumes to be filled in an advantageous Wise.

The basic procedure described can be in modify in a variety of ways, especially with regard to to a distinction between pilot injection and main injection as well as on the shaping of the course of injection. Such changes can be advantageously by an adaptation of the system of piezoelectric actuator 22 and the accomplish first 2/2-valve 18, in particular by a gradual opening of the first 2/2 valve in continuous or discontinuous manner. The adaptation of the first 2/2-Valves takes place via the involved hydraulic Cross-sections.

The preceding description of the embodiments according to The present invention is illustrative only And not for the purpose of limiting the invention. Within the scope of the invention are various changes and modifications possible, without the scope of the invention, such as defined in the claims to leave.

Claims (20)

1. Injection device having an injection nozzle (12), a valve device (18, 20) for controlling the injection and an actuating element (22) for actuating the valve device (18, 20), characterized in that the valve device has at least a first valve (18) and a second valve (20) which can be actuated by the actuating element (22) via a common hydraulic coupling space (24).
2. Injection device according to Claim 1, characterized in that a pressure booster for boosting a primary pressure is provided which can be actuated by the valve device (18, 20).
3. Injection device according to Claim 1 or 2, characterized in that the actuating element is a piezoelectric actuator (22).
4. Injection device according to Claim 2 or 3, characterized in that it is arranged in a common rail system.
5. Injection device according to one of the preceding claims, characterized in that it is pressure-controlled.
6. Injection device according to one of Claims 2 to 5, characterized in that the first valve (18) separates the primary pressure from a low-pressure space (32) of the pressure booster (16) in a first state, in that the first valve (18) couples the primary pressure into the low-pressure space (32) of the pressure booster (16) in a second state, in that the second valve (20) couples a low-pressure space (32) of the pressure booster (16) to a leakage system (34) in a first state, and in that the second valve (20) separates the low-pressure space (32) of the pressure booster (16) from the leakage system (34) in a second state.
7. Injection device according to one of the preceding claims, characterized in that the first valve (18) and the second valve (20) are adapted to one another in such a way that, by actuating the actuating element (22), first of all the second valve (20) can be transferred from its first state into its second state and, subsequently, the first valve (18) can be transferred from its first state into its second state.
8. Injection device according to one of Claims 2 to 7, characterized in that a low-pressure space (32) of the pressure booster (16) is connected to a high-pressure space (36) of the pressure booster (16) via a non-return valve (38), via which the high-pressure space (36) of the pressure booster (16) can be filled, and in that a high-pressure space (36) of the pressure booster (16) is connected to a leakage system (34) via a non-return valve.
9. Injection device according to one of Claims 2 to 8, characterized in that a differential space (40) of the pressure booster (16) is connected via a non-return valve (42) to a leakage system (34), with the result that the differential space (40) is not filled.
10. Injection device according to one of Claims 2 to 9, characterized in that a high-pressure space (36) of the pressure booster (16) can be relieved via the second valve (20).
11. Injection device according to one of the preceding claims, characterized in that the first valve (18) and/or the second valve (20) is/are a 2/2-way valve or 2/2-way valves.
12. Injection device according to one of Claims 1 to 10, characterized in that the first valve (18) and the actuating element (22) are adapted to one another in such a way that the first valve (18) can be transferred continuously or in steps into different opening states having different opening cross sections.
13. Method for injecting fluid, in which an actuating element (22) is activated, a valve device (18, 20) is actuated by the actuating element (22) and an injection nozzle (12) is opened, characterized in that a first valve (18) and a second valve (20) of the valve device (18, 20) are actuated by the actuating element (22) via a common hydraulic coupling space (24).
14. Method according to Claim 13, characterized in that a pressure booster (16) for boosting a primary pressure is actuated by the valve device (18, 20).
15. Method according to Claim 13 or 14, characterized in that the injection nozzle (12) is opened when a specific pressure is exceeded in its inlet region.
16. Method according to Claim 14 or 15, characterized in that, when the actuating element (22) is actuated, a low-pressure space (32) of the pressure booster (16) is decoupled from a leakage system (34) by closure of the second valve (20), the primary pressure is subsequently coupled into the low-pressure space (32) by opening the first valve (18), the pressure in an inlet region of the injection nozzle (12) subsequently exceeds a specific pressure, with the result that the injection nozzle (12) opens, the first valve (18) subsequently closes and the second valve (20) subsequently opens, with the result that the injection process is ended and the pressure booster (16) is relieved.
17. Method according to one of Claims 14 to 16, characterized in that a high-pressure space (36) of the pressure booster (16) is filled via a non-return valve (38), via which it is connected to a low-pressure space (32) of the pressure booster (16).
18. Method according to one of Claims 14 to 17, characterized in that a high-pressure space (36) of the pressure booster (16) is filled via a non-return valve, via which it is connected to a leakage system (34).
19. Method according to one of Claims 14 to 18, characterized in that a high-pressure space (36) of the pressure booster (16) is relieved via the second valve (20).
20. Method according to one of Claims 13 to 19, characterized in that the first valve (18) is transferred continuously or in steps into different opening states having different opening cross sections.

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