DE102006022582A1 - Leak-free injection valve, injection device and method and apparatus for operating an internal combustion engine - Google Patents

Abstract

A leak-free injector (20) for metering fluid has an injector body having a recess of the injector body. Furthermore, the leak-free injection valve (20) has a needle body (45) which is arranged axially movable in the recess of the injector body and which in a closed position of the needle body (45) prevents fluid flow through an injection opening (58) of the injector body and otherwise releases. A cooling volume (70) is thermally coupled to the injector body and communicates through a cooling opening (68) in the injector body with the recess of the injector body. The cooling volume (70) has, downstream of the cooling opening (70), a return port (78) through which the fluid can exit from the leak-free injection valve (20).

Description

The The invention relates to a leak-free injection valve for metering of fluid. The leak-free injection valve has an injector body and a needle body. The injector body has a recess of the injector body. The needle body is axial movably arranged in the recess of the injector body. In a closed position of the needle body prevents the needle body a fluid flow through an injection port of the injector body and otherwise releases it. Furthermore, the invention relates to a Injector comprising the leak-free injector. Furthermore, the invention relates to a method and a device for operating an internal combustion engine.

at A lean operation of an internal combustion engine is a combustion chamber the internal combustion engine supplied less fuel than by the oxygen can be burned in the combustion chamber. This forms nitrogen oxides, then in the exhaust of the engine as pollutant emissions are included. The nitrogen oxide content of the exhaust gas can be reduced by adding a urea water solution, from which in a chemical reaction the ammonia emerges, in an exhaust tract of the internal combustion engine in front of an SCR catalyst is injected. An injection valve for metering the urea water solution into The exhaust tract may be due to during operation of the internal combustion engine heat up the prevailing temperatures in the exhaust system. This can deposits of urea of urea water solution at Favor injection valve.

It The object of the invention is a leak-free injection valve, a Injection device with the leak-free injection valve and a Method and an apparatus for operating an internal combustion engine to provide, the or simply a cooling of the leak-free injection valve and / or the injection device allows.

According to one In the first aspect of the invention, the invention is characterized by a leak-free injection valve for metering fluid. The leak-free Injection valve has an injector body and a needle body. Of the injector has a recess of the injector body. The needle body is arranged axially movable in the recess of the injector body. In a closed position of the needle body prevents the needle body a fluid flow through an injection port of the injector body and otherwise releases it. A cooling volume is thermal with the injector body coupled. Through a cooling hole in the injector communicates the cooling volume with the recess of the injector body. The cooling volume points downstream the cooling hole one Return connection on. Through the return connection the fluid can escape from the leak-free injection valve.

This allows to cool the leak-free injector with the same fluid, the is metered by the leak-free injection valve. Thereby Needless an extra coolant for cooling the leak-free injection valve. This simply allows the cooling of the leak-free injection valve. Leakage free in this context means that the leak-free injection valve has no leakage at for example, due to a hydraulic Hubübersetzung and / or at a hydraulic actuation of a nozzle needle of the injection valve and / or due to fluid pressures to to 2000 bar a self-unintentional leak between components of the hydraulic stroke ratio or between other components of the injector accepted is, for example, to reduce manufacturing costs for the injection valve. In injection valves with leakage in this sense, therefore, fluid connections are provided by regularly the leaking fluid can be recycled to a storage tank.

The Cool The leak-free injection valve is particularly advantageous in Associated with a metering of a urea water solution in one Exhaust tract of an internal combustion engine through the leak-free injection valve. For example, you can by metering the urea into the exhaust tract and mixing of the urea with an exhaust gas of the internal combustion engine, the nitrogen oxides in the exhaust gas in an SCR catalyst to elemental nitrogen and Hydrogen react. The high exhaust gas temperatures favor However, deposits of urea, especially at the injection port of the leak-free injection valve. Thus, the cooling of the leak-free injection valve help to avoid the deposits and thus the urea water solution over a Long life of the leak-free injection valve precise to meter in the leak-free injection valve.

In an advantageous embodiment of the first aspect of the invention For example, the leak-free injector includes a cooling housing. The cooling housing extends at least partially radially around the injector body. Together with the injector body, the cooling housing closes the cooling volume sealingly. this makes possible In a particularly simple way, the cooling of the leak-free injection valve.

In a further advantageous embodiment of the first aspect of Invention, the leak-free injection valve comprises at least one Cooling channel. Of the cooling channel includes the cooling volume and extends away from the cooling opening into the injector body. This allows particularly effective cooling the leak-free injection valve.

In a further advantageous embodiment of the first aspect of In the invention, the leak-free injection valve comprises a cooling valve. The cooling valve is so with the cooling volume coupled that a cooling flow of the fluid through the cooling volume with the cooling valve can be specified. this makes possible the targeted specification of the cooling the leak-free injection valve.

In a further advantageous embodiment of the first aspect of Invention includes the injector body a drive body and a nozzle assembly. The drive body at least partially comprises an actuator which acts on the needle body. The nozzle assembly includes the injection port and the cooling hole. Further, the nozzle assembly thermally with the cooling volume coupled. This can contribute to a particularly precise metering of the fluid.

In a further advantageous embodiment of the first aspect of Invention includes the nozzle assembly a needle guide body with a recess. In the recess of the needle guide body of the needle body is guided. Further includes the nozzle assembly a nozzle body that the injection port and the cooling hole comprises and the thermal with the cooling volume is coupled. This can contribute to a particularly precise metering of the fluid.

According to one second aspect of the invention, the invention is characterized by an injection device with the leak-free injection valve, with a storage tank, and with a fluid pump. The storage tank communicates upstream with a fluid supply of the leak-free injection valve and downstream via the Return connection with the cooling volume the leak-free injection valve. The fluid pump is provided for pumping the fluid from the storage tank to the leak-free Injector. The fluid pump is preferably pressure-controlled.

In an advantageous embodiment of the second aspect of the invention The injection device comprises a pressure relief valve, which is designed and is arranged that it is the cooling flow through the cooling volume inhibited below a predetermined pressure of the fluid and otherwise free.

According to one third aspect of the invention, the invention is characterized by a method and an apparatus for operating the internal combustion engine. The internal combustion engine to summarizes an intake and an exhaust tract. The intake tract and the exhaust tract communicate with a combustion chamber a cylinder of the internal combustion engine depending on the switching position a gas inlet valve or a gas outlet valve. In the exhaust tract an SCR catalyst is arranged. Furthermore, the internal combustion engine comprises the leak-free injection valve and / or the injection device with the leak-free injection valve for metering fluid in the exhaust tract. The leak-free injection valve is the fluid fed. The fluid flow is in the leak-free injection valve in at least a Zumessstrom and in a cooling stream divided up. The metering flow is metered to the exhaust tract. Of the cooling flow is due to the cooling volume directed. The cooling volume is thermally with the injector body of the leak-free injection valve coupled.

This allows to cool the leak-free injector with the same fluid, the is metered by the leak-free injection valve. Thereby Needless an extra coolant for cooling the leak-free injection valve. This makes it particularly easy Specify the temperature range of the leak-free injection valve. The temperature range may be, for example, between a freezing temperature the urea water solution and for example 80 ° Celsius lie. This is particularly advantageous if with the leak-free injection valve a urea water solution is measured.

In an advantageous embodiment of the third aspect of the invention becomes a flow of the cooling flow through the cooling volume predetermined dependent from a temperature of the leak-free injection valve and / or a temperature of the injector. This makes possible, to reduce the nitrogen oxides of the exhaust particularly effective.

In a further advantageous embodiment of the third aspect of Invention is after an engine stop the internal combustion engine of Cooling current during a maintained time duration. This can be very easy contribute to deposits of urea on the leak-free injector to avoid and / or reduce.

In a further advantageous embodiment of the third aspect of Invention will depend on the length of time predetermined by the temperature of the leak-free injection valve. This can contribute to deposits of urea on the leak-free To avoid and / or reduce injector particularly effectively.

In a further advantageous embodiment of the third aspect of the invention, a storage tank of the injection device is heated downstream of the leak-free injection valve with the cooling flow. This can help, especially at cold ambient temperatures, in particular below the freezing temperature of the urea water solution, for example at -11 ° Celsius, to heat the fluid in the storage volume. This can be a mistake contribute to free operation of the injector.

The advantageous embodiments of the third aspect of the invention can readily to the method and / or to the device according to the third Aspect of the invention transferred become.

The The invention is described below with reference to schematic drawings explained in more detail.

It demonstrate:

1 an internal combustion engine,

2 Fluid flow representation of an injection device,

3 a leak-free injection valve,

4 a program for cooling the leak-free injection valve.

elements same construction or function are cross-figurative with the same Reference number marked.

An internal combustion engine comprises an intake tract 1 , an engine block 2 , a cylinder head 3 and an exhaust tract 4 , The intake tract 1 preferably comprises a throttle valve 5 , a collector 6 and a suction tube 7 leading to a cylinder Z1-Z4 via an inlet channel into a combustion chamber 9 of the engine block 2 is guided. The engine block 2 includes a crankshaft 8th , which has a connecting rod 10 with the piston 11 of the cylinder Z1-Z4 is coupled. The internal combustion engine preferably comprises further cylinders Z1-Z4. The internal combustion engine is preferably arranged in a motor vehicle.

In the cylinder head 3 is preferably a fuel injection valve 18 arranged. If the internal combustion engine is not a diesel internal combustion engine, preferably each cylinder Z1-Z4 is assigned a spark plug. Alternatively, the fuel injection valve 18 also in the intake manifold 7 be arranged.

Furthermore, the exhaust tract 4 preferably associated with an injection device. The injection device comprises a urea tank 19 , a leak-free injection valve 20 and preferably a fluid pump. Downstream of the leak-free injection valve 20 is preferably a mixing device 21 intended. Further, downstream of the mixing device 21 an SCR catalyst 23 arranged.

If the internal combustion engine is operated with a lean mixture and is therefore in lean operation, so in a combustion process of the internal combustion engine, the combustion chamber 9 less fuel supplied than with the oxygen in the combustion chamber 9 can be burned. As a result, compared to a stoichiometric operation of the internal combustion engine nitrogen oxides are increasingly formed, which are then contained in the exhaust gas. In the presence of ammonia, the nitrogen oxides in the SCR catalyst 23 react to elemental nitrogen and water. That's why the exhaust tract 4 with the leak-free injection valve 20 Preferably, a urea water solution is metered, resulting in the ammonia in a chemical reaction. The urea water solution, in particular the urea, in particular the ammonia, mix mainly in the mixing device 21 with the exhaust gas of the internal combustion engine.

A control device 25 is provided, the sensors are assigned, which detect different parameters and each determine the value of the measured variable. Operating variables include the measured variables and variables derived therefrom of the internal combustion engine. Operating variables may be representative of a current operating state of the internal combustion engine, which may include a plurality of operating points BP of the internal combustion engine. The control device 25 determined depending on at least one of the operating variables at least one manipulated variable, which are then converted into one or more control signals for controlling the actuators by means of appropriate actuators. The control device 25 may also be referred to as a device for operating the internal combustion engine.

The sensors are, for example, a pedal position transmitter 26 , the accelerator pedal position of an accelerator pedal 27 detected, an air mass sensor 28 , the air mass flow upstream of the throttle 5 detected, a temperature sensor 32 sensing an intake air temperature, an intake manifold pressure sensor 34 , who has an intake manifold pressure in the collector 6 detected, a crankshaft angle sensor 36 , which detects a crankshaft angle, which is then assigned a speed of the internal combustion engine. Furthermore, an exhaust gas probe 38 provided downstream of the SCR catalyst 23 is arranged and detects, for example, the nitrogen oxide content and / or the urea content of the exhaust gas.

ever according to embodiment The invention may be any subset of said sensors be present or it can also additional Sensors be present.

The actuators are, for example, the throttle 5 , the gas inlet and outlet valves 12 . 13 , the fuel injection valve 18 , the leak-free injection valve 20 and / or optionally the spark plug.

The leak-free injection valve 20 is with the urea water solution from the storage tank 19 provided. A supply of urea water solution in the leak-free injection valve 20 is split into a metering current IV_SU and into a cooling current IV_CO ( 2 ). The Zumessstrom IV_SU is the exhaust tract 4 meted out. The cooling flow IV_CO is at least through a part of the leak-free injection valve 20 directed and to the storage tank 19 recycled. The leak-free injection valve 20 gives heat to the fluid in the leak-free single point valve 20 , in particular to the urea water solution. Passing the cooling flow IV_CO through the leak-free injection valve 20 causes a removal of heat from the leak-free injection valve 20 to the storage tank 19 , Thus, the cooling flow IV_CO cools the leak-free injection valve 20 , This is particularly advantageous in this context, since the urea water solution already at temperatures around 100 degrees Celsius tends to form deposits. The cooling of the leak-free injection valve 20 thus contributes to avoidance and / or reduction of deposit formation.

Furthermore, the removal of heat from the leak-free injection valve 20 to a heating of the storage tank 19 , This is particularly advantageous when low ambient temperatures prevail, for example below the freezing point of the urea. Frozen urea water solution in storage tank 19 can then be easily thawed with the heated cooling stream IV_CO. This has against a heated surface in the storage tank 19 for heating the storage tank 19 , For example, a heating devices, such as a heating loop, the advantage that arise during the thawing of the frozen urea between the heated surface and the frozen urea water solution no urea water solution-free spaces. This contributes to a reliable thawing of the urea in the storage tank 19 at.

Preferably, the cooling flow IV_CO through a cooling valve 39 controlled. The cooling valve 39 allows to specify a flow of the cooling flow IV_CO. This is advantageous in particular when the cooling flow IV_CO is dependent on a temperature IV_TEMP of the leak-free injection valve 20 is specified and then through the cooling valve 39 can be adjusted. The specification of the flow of the cooling flow IV_CO makes it possible to specify a temperature range within which the temperature IV_TEMP of the injection valve 20 should lie. Preferably, the leak-free injection valve comprises 20 the cooling valve 39 , Alternatively, the cooling valve 39 be arranged within the injection device so that through the cooling valve 39 the flow of the cooling flow IV_CO can be specified. Alternatively or in addition to the cooling valve 39 For example, the injector may comprise a relief valve starting from a predetermined pressure of the supply current of the leak-free injector 20 releases the cooling flow IV_CO and otherwise stops it. This is particularly advantageous if the fluid pump of the injection device is pressure-controlled. Then the pressure of the supply flow can be specified with the fluid pump and the cooling flow IV_CO is determined by the cooling volume 70 when the pressure of the supply flow is greater than the pressure at which the pressure relief valve releases the cooling flow IV_CO.

The leak-free injection valve 20 has an injector body with a recess ( 3 ). The injector body preferably comprises a nozzle assembly 40 and a drive body 49 , The nozzle assembly preferably has a needle guide body 42 with a recess and a nozzle body 44 with a recess. The recess of the injector body comprises the recess of the needle guide body 42 and the recess of the nozzle body 44 ,

A needle body 45 is axially movable in the recesses of the needle guide body 42 and the nozzle body 44 arranged. The needle body 45 includes, for example, a nozzle needle 46 and a nozzle needle anchor 48 , Through the needle body 45 , in particular through the nozzle needle 46 is in a closed position of the needle body 45 or the nozzle needle 46 a fluid flow through an injection port 58 of the nozzle body 44 prevented and otherwise released. Is the injection port 58 released, so the fluid flows, preferably the urea water solution from the storage tank 19 via a fluid connection 54 towards the injection opening 58 and is through the injection port to the combustion chamber 9 attributed to the internal combustion engine.

The drive body 49 includes an actuator through which the position of the needle body 45 is adjustable. Preferably, the actuator is a solenoid 50 , The magnetic coil 50 works with the nozzle needle anchor 48 together. The magnetic coil 50 is via an electrical connection 52 with the control device 25 electrically coupled. If through the solenoid coil 50 a suitable current flows, a magnetic force acts on the nozzle needle anchor 48 against the closing direction of the needle body 45 , A feather 56 exercises on the needle body 45 a force in the closing direction of the needle body. Once the magnetic force is greater than the force of the spring 56 gives the nozzle needle 46 the injection port 58 free.

The nozzle body 44 has a cooling hole 68 , About the cooling hole 68 communicates the recess of the nozzle body 44 with a cooling volume 70 , The cooling volume 70 becomes sealed from a cooling housing 80 and the nozzle body 44 one closed. Alternatively, the cooling housing 80 also other elements of the leak-free injection valve 20 enclose, for example, the needle guide body 42 and / or the drive body 49 ,

The cooling housing 80 has a return port 78 on. The return connection 78 communicates with the storage tank 19 , The cooling valve 39 can be upstream or downstream of the cooling connection 78 be arranged. Further, preferably, a seal 82 provided for sealing the cooling volume 70 ,

A program for cooling the leak-free injector 20 ( 4 ) is preferably on a storage medium of the control device 25 saved. The program is preferably started in a timely manner to an engine start of the internal combustion engine in a step S1, in which variables are initialized if necessary.

In a step S2, preferably a temperature IV_TEMP of the leak-free injection valve 20 determined, for example, by detecting the temperature IV_TEMP with a temperature sensor.

If, in step S2, the temperature IV_TEMP of the leak-free injection valve 20 is determined is in a step S3 depending on the temperature IV_TEMP of the leak-free injection valve 20 a setpoint IV_CO_SP of the cooling flow IV_CO determined. The desired value IV_CO_SP of the cooling flow IV_CO can be determined, for example, on the basis of a first characteristic diagram and / or on the basis of a model calculation. The first map and possibly other maps can be recorded for example on an engine test bench. If, in step S2, not the temperature IV_TEMP of the leak-free injection valve 20 is determined, the setpoint IV_CO_SP the cooling flow IV_CO can be specified.

In a step S4, depending on the desired value IV_CO_SP of the cooling flow IV_CO, an actuating signal IV_CO_SIG for the cooling valve 39 determined. Dependent on the control signal IV_CO_SIG of the cooling valve 39 becomes the cooling valve 39 driven.

In In step S5, a set value IV_SU_SP of the metering current IV_SU is set determined, preferably dependent from an actual operating point BP of the internal combustion engine and dependent from the setpoint IV_CO_SP of the cooling flow IV_CO. The set value IV_SU_SP of the metering current IV_SU can be, for example on the basis of a second characteristic field and / or on the basis of a further model calculation be determined.

In a step S6, a control signal IV_SU_SIG for the leak-free injection valve 20 determined depending on the setpoint IV_SU_SP of the metering current IV_SU. Dependent on actuating signal IV_SU_SIG of the actuator 50 becomes the actuator 50 driven.

In a step S7, the program can be terminated. Alternatively, the program can be executed regularly during operation of the internal combustion engine. Preferably, however, after a shutdown of the internal combustion engine, the cooling flow IV_CO is maintained for a predetermined period of time DUR. The duration DUR is preferably dependent on the temperature IV_TEMP of the injection valve 20 specified. This helps to avoid deposits of urea water solution, which otherwise occurs after switching off the internal combustion engine due to the heated exhaust tract 4 can form.

Claims (14)

Leak-free injection valve ( 20 ) for metering fluid with - an injector body having a recess of the injector body, - a needle body ( 45 ), which is arranged axially movable in the recess of the injector body and in a closed position of the needle body ( 45 ) a fluid flow through an injection port ( 58 ) of the injector body and otherwise releases, - a cooling volume ( 70 ) thermally coupled to the injector body and passing through a cooling port ( 68 ) in the injector body communicates with the recess of the injector body and the downstream of the cooling port ( 70 ) a return port ( 78 ), through which the fluid from the leak-free injection valve ( 20 ) can escape. Leak-free injection valve ( 20 ) according to claim 1, which is a cooling housing ( 80 ) which extends at least partially radially around the injector body and which together with the injector body, the cooling volume ( 70 ) sealingly encloses. Leak-free injection valve ( 20 ) according to claim 1, comprising at least one cooling channel ( 72 ), which determines the cooling volume ( 70 ) and extending away from the cooling port ( 68 ) extends into the injector body. Leak-free injection valve ( 20 ) according to one or more of the preceding claims, comprising a cooling valve, which is connected to the cooling volume ( 70 ), that a cooling flow (IV_CO) of the fluid through the cooling volume ( 70 ) can be specified with the cooling valve. Leak-free injection valve ( 20 ) according to one or more of the preceding claims, at the injector body a valve body ( 49 ), which at least partially comprises the actuator, and in which the injector body is a nozzle assembly ( 40 ), the injection opening ( 58 ) and the cooling opening ( 68 ) and which thermally with the cooling volume ( 70 ) is coupled. Leak-free injection valve ( 20 ) according to claim 5, wherein the nozzle assembly ( 40 ) a needle guide body ( 42 ) with a recess in which the needle body is guided, and in which the nozzle assembly ( 40 ) a nozzle body ( 44 ), the injection opening ( 58 ) and the cooling opening ( 68 ) and which thermally with the cooling volume ( 70 ) is coupled. Injection device with the leak-free injection valve ( 20 ) according to claim 6, with a storage tank ( 19 ), which upstream with a fluid supply of the leak-free injection valve ( 20 ) and downstream via the return port ( 78 ) with the cooling volume ( 70 ) and with a fluid pump for pumping the fluid from the storage tank ( 19 ) to the injection valve ( 20 ). An injection device according to claim 7, comprising a relief valve configured and arranged to provide a cooling flow (IV_SU) through the cooling volume (IV_SU). 70 ) is prevented below a predetermined pressure of the fluid and otherwise releases. Method for operating an internal combustion engine, comprising - an intake tract ( 1 ) and the exhaust tract ( 4 ), which is equipped with a combustion chamber ( 9 ) of a cylinder (Z1-Z4) of the internal combustion engine communicate depending on the switching position of a gas inlet valve ( 12 ) or a gas outlet valve ( 13 ), - an SCR catalyst ( 23 ) located in the exhaust tract ( 4 ), - a leak-free injection valve ( 20 ) and / or an injection device with the leak-free injection valve ( 20 ) for metering fluid into the exhaust tract ( 4 ), in which - the leak-free injection valve ( 20 ) the fluid ( 19 ), - the fluid flow in the leak-free injection valve ( 20 ) at the cooling opening ( 68 ) is divided into at least one metering current (IV_SU) and one cooling stream (IV_CO), - the metering current (IV_SU) the exhaust gas tract ( 4 ), - the cooling flow (IV_CO) through the cooling volume ( 70 ), which is thermally connected to the injector body of the leak-free injection valve ( 20 ) is coupled. Method according to Claim 9, in which a flow of the cooling stream (IV_CO) through the cooling volume ( 70 ) is given dependent of a temperature (IV_TEMP) of the injection valve ( 20 ) and / or the injector. Method according to one of claims 9 or 10, wherein an engine stop of the internal combustion engine, the cooling flow (IV_CO) during a is maintained for a predetermined period of time. Method according to Claim 11, in which the time duration depends on the temperature (IV_TEMP) of the leak-free injection valve (14). 20 ) is given. Method according to one of claims 9 to 12, wherein downstream of the leak-free injection valve ( 20 ) with the cooling stream (IV_CO) a storage tank ( 19 ) of the injector is heated. Device for operating an internal combustion engine, comprising - an intake tract ( 1 ) and the exhaust tract ( 4 ), which is equipped with a combustion chamber ( 9 ) of a cylinder (Z1-Z4) of the internal combustion engine communicate depending on the switching position of a gas inlet valve ( 12 ) or a gas outlet valve ( 13 ), - an SCR catalyst ( 23 ) located in the exhaust tract ( 4 ), - a leak-free injection valve ( 20 ) and / or an injection device with the leak-free injection valve ( 20 ) for metering fluid into the exhaust tract ( 4 ), wherein the device is designed to - supply the fluid from the storage tank ( 19 ) to the leak-free injection valve ( 20 ), - splitting the fluid flow in the leak-free injection valve ( 20 ) at the cooling opening ( 68 ) into at least one metering current (IV_SU) and one cooling stream (IV_CO), - metering the metering current (IV_SU) to the exhaust gas tract ( 4 ), - directing the cooling flow (IV_CO) to the storage tank ( 19 ), by the cooling volume ( 70 ), which is thermally connected to the injector body of the injection valve ( 20 ) is coupled.