Method and apparatus for diagnosing a water injection system

Abstract

This invention proposes a method and apparatus for diagnosing a water injection system having a pressure chamber (1) for water, wherein the pressure chamber (1) is connected to a pump (3), at least one pressure sensor (2), and a plurality of injection valves (4). The pump (3) is configured to generate water pressure in the pressure chamber (1), the pressure sensor (2) is configured to measure the water pressure in the pressure chamber (1), and the injection valves (4) are configured to inject water from the pressure chamber (1) into the intake manifold or combustion chamber of an internal combustion engine. With the pump (3) stopped, the plurality of injection valves are sequentially operated, and the pressure drop caused by operating each individual injection valve is measured. For each injection valve, the corresponding pressure drop for each operation is summed, and the resulting sum is used to diagnose the individual injection valves.

Description

Technical Field

[0001] This invention relates to a method and apparatus for diagnosing water jet systems. Background Technology

[0002] A water injection system with a common pressure chamber is known from document DE 10 2016 200 694. The system is constructed with a pressure chamber for storing water connected to a pump and multiple injection valves. Water is pumped from a tank into the pressure chamber, where the desired pressure is achieved. The water is then injected into the internal combustion engine or its intake manifold via the injection valves, thereby affecting the combustion temperature within the engine. This allows for a positive influence on the combustion process within the internal combustion engine. Summary of the Invention

[0003] This invention proposes a method and apparatus for diagnosing a water injection system having a pressure chamber for water, wherein the pressure chamber is connected to a pump, at least one pressure sensor, and a plurality of injection valves, wherein the pump is configured to generate water pressure in the pressure chamber, the pressure sensor is configured to measure the water pressure in the pressure chamber, and the injection valves are configured to inject water from the pressure chamber into the intake manifold or combustion chamber of an internal combustion engine, wherein, with the pump stopped, the plurality of injection valves are sequentially operated, and the pressure drop caused by operating each individual injection valve is measured; for each injection valve, the corresponding pressure drop for each operation is summed, and the resulting sum is used to diagnose the respective injection valves.

[0004] Advantages of this invention:

[0005] The method or apparatus according to the invention has the following advantages over the prior art: it enables particularly rapid and reliable diagnostics of the water injection system. Therefore, the function of the water injection system can be ensured, thereby also ensuring a positive impact on the combustion process in the combustion chamber. Thus, monitoring of all functional systems of the internal combustion engine, especially those affecting the exhaust gases, is ensured.

[0006] Further advantages and improvements are obtained from the preferred embodiments of the invention. Pump shutdown is particularly simple and reliable if a shut-off valve is implemented in the pipeline, or if the shut-off valve is closed in addition to the electric shutdown of the pump. This ensures that liquid is no longer pumped into the pressure chamber or that liquid can leak from the pressure chamber through the pump. The sums associated with each valve can be compared particularly easily with a threshold value for evaluating the injection valves. Furthermore, the sums of ...

[0007] According to one embodiment of the present invention, the pump is connected to a water tank via a first pipeline and to the pressure chamber via a second pipeline, wherein a shut-off valve is arranged in the first pipeline and / or the second pipeline, the shut-off valve being able to shut off the first pipeline and / or the second pipeline, and the first shut-off valve and / or the second shut-off valve being closed in order to stop the pump.

[0008] According to one embodiment of the invention, the formed sum is compared with a first threshold and a second threshold, respectively, and if the corresponding sum is less than the first threshold or greater than the second threshold, the corresponding injection valve is evaluated as faulty, and if the sum is between the first threshold and the second threshold, the corresponding injection valve is evaluated as "normal".

[0009] According to one embodiment of the present invention, the first threshold and the second threshold are formed based on the operating conditions of the internal combustion engine and / or based on the pressure in the pressure chamber.

[0010] According to one embodiment of the invention, the sums of individual injection valves are compared with each other.

[0011] According to one embodiment of the invention, an average value consisting of the sum of all injection valves is formed for comparison, or an average value consisting of the sum of all injection valves in the absence of injection valves being compared accordingly is formed.

[0012] According to one embodiment of the invention, the duration of actuation of a single injection valve is affected so that the individual injection valves are adapted to each other. Attached Figure Description

[0013] Embodiments of the invention are shown in the accompanying drawings and described in detail in the following description.

[0014] The attached diagram shows:

[0015] Figure 1 Schematic diagram of a water jet system;

[0016] Figure 2 It has a well-functioning injection valve with a pressure profile;

[0017] Figure 3 Pressure curves of multiple injection valves;

[0018] Figure 4 Counter curves used to match different valves; and

[0019] Figure 5 The method steps according to the present invention. Detailed Implementation

[0020] exist Figure 1 The diagram illustrates a water jet system. Figure 1 The water injection system has a pressure chamber 1, the pressure of which is measured by a pressure sensor 2. Alternatively, the pressure sensor can also be arranged in a pressure line 12 between the pump 3 and the pressure chamber 1. The pressure chamber 1 is connected to a plurality of injection valves 4, through which water can be injected into the internal combustion engine, for example, into the intake manifold or directly into the combustion chamber. Furthermore, the pressure chamber 1 is connected to the pump 3. The pump 3 is connected to the water tank 5 via a first line 11, and furthermore, to the pressure chamber 1 via a second line 12 (pressure line). When the pump 3 is operated, it pumps water from the water tank 5 into the pressure chamber 1, thus applying an operating pressure to the water pumped into the pressure chamber 1. This operating pressure is measured by the pressure sensor 2 and transmitted (via electrical wiring not shown) to the control unit 6. Optionally, the pump can be connected to the tank via a return line (not shown in the figures), which is important for the function of the pump (particularly for flow control). A throttling valve or a check valve can be installed in the return line. Since the precise configuration of this return line or pump 3 is not important to this invention, these details are not included. Figure 1 As shown in the diagram, the control device 6 analyzes and processes the pressure in the pressure chamber 1 and accordingly operates the pump 3 (via electrical wiring not shown) to maintain the desired rated pressure in the pressure chamber 1. Furthermore, a shut-off valve 7 is shown in the first line 11, or a shut-off valve 8 is shown in the second line 12, by which reliable closure of the first line 11 or the second line 12 can be achieved.

[0021] exist Figure 1 The water injection system shown is configured to inject water into an internal combustion engine. For this purpose, injection valves 4 are respectively arranged in the intake manifold or cylinder head of the internal combustion engine, thus injecting water into the intake manifold or directly into the combustion chamber. Typically, a single injection valve 4 is provided for each cylinder or each combustion chamber of the internal combustion engine, depending on the number of cylinders. Alternatively, more than one valve may be provided for each cylinder, for example, one valve for water injection may be arranged directly in the combustion chamber, while another valve for water injection may be arranged in the intake manifold. Figure 1The diagram schematically illustrates four injection valves according to a four-cylinder internal combustion engine. Water injection is not performed in every operating state of the internal combustion engine. Furthermore, depending on the operating point of the internal combustion engine, it may be meaningful to change the operating pressure, i.e., the water pressure, which is stored in pressure chamber 1. This control of the pressure in pressure chamber 1 is achieved by controlling the pump, for example, via control device 6. Control device 6 is therefore connected to pump 3 via electrical control lines (not shown). Furthermore, control device 6 receives the pressure signal from pressure sensor 2 and analyzes and processes this pressure signal, particularly for controlling pump 3. Control device 6 can be configured as its own controller 6 solely for controlling water injection, or it can be part of a larger controller that also performs other processes besides water injection, preferably overall control of the internal combustion engine. According to the present invention, the pressure signal from pressure sensor 2 is used at a determined operating point for diagnosing the water injection system.

[0022] exist Figure 1 Two shut-off valves are shown, with shut-off valve 7 located in the first line 11 and shut-off valve 8 located in the second line 12. In a preferred embodiment of the invention, these shut-off valves are also operated by the control device 6, making it possible to restrict the shut-off and opening of both the first line 11 and the second line 12. Depending on the pump's construction, it may also be sufficient to have only a single shut-off valve located in either the first line 11 or the pressure line 12. This essentially depends on whether the pump 3 is sealed in the off state. Furthermore, there are pump types with purely mechanical check valves, such that a seal between the pump 3 and the pressure in the pressure chamber 1 is already present purely mechanically when the pump is off. Alternatively, the pump 3 may also operate and simply close shut-off valve 8 via a control signal. This is particularly possible when a very specific point in time at which the pump 3 stops is desired, and this point cannot be achieved so precisely by simply shutting down the pump 3. The pump 3 also briefly delivers some water during the gradual shutdown, but this no longer affects the pressure in the pressure chamber 1 by closing shut-off valve 8. Based on the construction of pump 3, instead of the two shut-off valves 7 and 8 shown, only a single shut-off valve can be installed in either the first or second pipeline. The pump can be stopped by the described measures, wherein, when the pump is stopped, if water is injected into the internal combustion engine, water is prevented from being pumped back into the pressure chamber. Under this boundary condition of pump stoppage, the operation of the injection valve can therefore be deduced from the pressure curve in pressure chamber 1.

[0023] exist Figure 2 The diagram shows the pressure P in pressure sensor 2 of the water jet system with respect to time t, where initially only a single jet valve is checked. Starting from the pressureless state of the water jet system, pump 3 is turned on, causing the pressure P in pressure chamber 1 to rise. At time t1, the pump stops. The pump stops by turning off pump 3, and simultaneously shutting off... Figure 1The shut-off valves 7 and 8. Depending on the configuration of the water jet system, the pump can be stopped by simply shutting down the pump, or by shutting down the pump and closing the shut-off valves 7 or 8. Importantly, by stopping the pump 3, no further measures are taken to increase the pressure in the pressure chamber 1.

[0024] After time point t1, in the case of an optimized sealed water jet system, the pressure in pressure chamber 1 remains constant over time. This situation of the sealed water jet system 1 is shown by curve 41 from time point t1 to time point t2.

[0025] After time point t2, the injection valve to be inspected is now manipulated, as shown by manipulating pulse 42. Based on... Figure 2 In the water injection system, only a single injection valve 4 is checked. In response to the control pulse 42, a decrease in pressure in pressure chamber 1 is achieved during time intervals t2 to t3. Each time injection valve 4 is opened by the corresponding pulse, water is injected from pressure chamber 1 into the internal combustion engine. Because pump 3 is stopped, water is no longer supplied to the pressure chamber via pump 3. As a response to each injection pulse during time intervals t2 to t3, the pressure in pressure chamber 1 thus decreases, as shown by pressure curve 41 during time intervals t2 to t3. The pressure drop achieved by each opening of injection valve 4 can be demonstrated by measuring the pressure in pressure chamber 1.

[0026] To achieve a sufficiently stable pressure signal, it is advantageous to perform not only a single injection but also multiple injections sequentially. The analysis and processing of the pressure in pressure chamber 1 can be performed either after each injection or, since only a single valve is being checked, only at the end of multiple injections. Figure 2 The trend of pressure curve 41 corresponds to the normal operation of the water jet system, because the static sealing of the system has been proven at time point t2, and the function of the jet valve is proven by the analysis of the pressure during the time interval t2 to t3.

[0027] exist Figure 2 In addition to pressure curve 41, alternative pressure curves 43 and 44 are also shown. These alternative pressure curves 43 and 44 correspond to a normally functioning injection valve, but with a quantity deviation. Pressure curve 41 corresponds to the rated pressure trend, for which the injection valve is designed. Pressure trend 43 corresponds to an injection valve that injects a minimum quantity, and pressure trend 44 corresponds to an injection valve that injects a greater quantity, i.e., injects more than the normal injection valve of curve 41. This is particularly important when multiple injection valves 4 are installed. Each individual injection valve in each injection valve is tested, i.e., each of these injection valves 4 is checked in terms of injection performance.

[0028] If the difference in the pressure curves is determined here, the following possibility exists: compensation can be made for each jet valve accordingly. For this purpose, in the case of a jet valve showing a trend as shown by curve 43, the operating time is extended accordingly to minimize the compensation. In the case of a jet valve with a pressure trend corresponding to curve 44, the operating pulse is shortened accordingly to reduce the amount of water sprayed. Therefore, by this measure, each jet valve 4 can be kept in the same state by checking the spraying performance of each jet valve 4 during diagnostic operation and by extending the spraying duration to achieve quantity compensation.

[0029] In an internal combustion engine with multiple cylinders and a correspondingly large number of injection valves 4, according to Figure 2 This method necessitates the significant time commitment required to inspect each individual valve. Figure 3 The improved method shown in the figure enables faster inspection, especially in the case of multiple injection valves 4.

[0030] exist Figure 3 The figure shows the pressure P over time t in a water jet system with multiple valves, particularly eight jet valves. This differs from... Figure 2 However, instead of always operating only a single injection valve 4, all injection valves 4 are operated sequentially. After each injection, the pressure drop caused by the corresponding injection is measured. For this purpose, the pressure is measured before and after each injection and then subtracted. It is advantageous to preprocess the measured pressure values ​​using a suitable filter. Furthermore, the individual valves are assigned, for example, in the case of eight valves, simply by being numbered consecutively from 1 to 8. The pressure drop for each individual injection at the corresponding injection valve is summed separately, and the sum thus formed is assigned to the individual valve.

[0031] To ensure proper allocation of valves, a counter is changed with each pressure drop measurement, where the counter reading corresponds to the number of valves involved. Figure 4 In, in sync with Figure 3 The pressure drop shown indicates the counter's count from 1 to 8. With Figure 3 Each injection process and each pressure drop correspondingly increases the... Figure 4 The counter reading is shown in the image. If the counter reading has reached value 8, then... Figure 3 In the next measurement of the pressure drop, the counter jumps back to reading 1, as in this... Figure 4 As shown in the diagram. Based on the counter readings, the calculated pressure drops are distributed to injection valve 4.

[0032] For diagnostic purposes, the sum calculated for each injection valve will be analyzed. As a possibility, the calculated sum can be compared with comparison values, particularly a first threshold and a second threshold. This allows the injection valve to be classified as "normal" or "abnormal." If the sum calculated for injection valve 4 is not between the first and second thresholds, but is below the first threshold or above the second threshold, it is particularly likely to be abnormal.

[0033] When the amount of pressure drop considered for formation and is small, the first and second thresholds can be approximated, for example, by reading a table, based on the amount of pressure drop and the operating conditions of the internal combustion engine. If a large amount of pressure drop is considered for formation and, and / or if the operating conditions of the internal combustion engine are subject to strong fluctuations, and / or the pressure in pressure chamber 1 changes drastically during the measurement, these changes should be considered more accurately.

[0034] Furthermore, the diagnostic process can also compare the sums used for each injection valve 4 with each other individually. If this single valve 4 shows a strong deviation from the other valves, this indicates that the corresponding injection valve 4 is deviating. This can be used again for "abnormal" assessment in cases of very strong deviations. In particular, an average of the sums used for comparison can be formed, for example, by adding all the sums and dividing by the number of valves. Alternatively, the sums of the valves being compared can be omitted in the formation of the average. That is, if valve 1 is compared in the case of 8 valves, the average sum is formed only through valves 2 to 8. This reduces the influence of the faulty valve on the formation of the average. To form the average, the median or more complex functions can naturally be used.

[0035] Alternatively, in the case of a smaller deviation, the deviation of the corresponding valve 4 can be compensated by a corresponding change in the duration of manipulation.

[0036] exist Figure 5 The method steps for diagnosing a water jet system are illustrated exemplarily. The method begins in a first step 51. In the subsequent step 52, as already described above... Figure 1 As explained, pressure is first generated in pressure chamber 1, and then pump 3 is stopped. At this point, shut-off valve 7 or 8 is also closed to eliminate any potential pressure loss through pump 3. Next, step 52 is performed, in which water is injected into the internal combustion engine. In the immediately following step 54, after each injection, the pressure drop in pressure chamber 1 is measured by pressure sensor 2, such as for... Figure 3 As explained, here, the various pressure drops (i.e., the pressure difference before and after injection) are added together and assigned to the corresponding injection valves. The number of corresponding injection valves is obtained here by a counter, which... Figure 4As shown in the diagram. After storage and measurement, the counter is increased for the next measurement. In the following step 55, it is determined whether further measurement should be performed, or whether a sufficiently large sum or a sufficient number of injection processes have been measured. If not, the method continues with step 53 immediately after step 55. If it is determined in step 55 that the measurement has ended, step 56 is performed, in which analysis is conducted on the sums formed for the corresponding injection valves. Different methods can be applied here, such as using thresholds and / or by comparing the values ​​of different valves. After the diagnosis in step 56, the method ends.

Claims

1. A method for diagnosing a water injection system, the water injection system having a pressure chamber (1) for water, wherein, The pressure chamber (1) is connected to a pump (3), at least one pressure sensor (2), and a plurality of injection valves (4), wherein the pump (3) is configured to generate water pressure in the pressure chamber (1), the pressure sensor (2) is configured to measure water pressure in the pressure chamber (1), and the injection valves (4) are configured to inject water from the pressure chamber (1) into the intake manifold or combustion chamber of an internal combustion engine. The pump (3) is characterized by sequentially operating the plurality of injection valves when the pump (3) is stopped, measuring the pressure drop caused by operating each individual injection valve, summing the corresponding pressure drop for each operation for each injection valve, and using the resulting sum to diagnose each injection valve, wherein the sum is compared to a first threshold and a second threshold, respectively, and if the corresponding sum is less than the first threshold or greater than the second threshold, the corresponding injection valve is assessed as faulty; and if the sum is between the first threshold and the second threshold, the corresponding injection valve is assessed as "normal".

2. The method of claim 1, wherein, The pump (3) is connected to the water tank via a first pipeline and to the pressure chamber (1) via a second pipeline. A shut-off valve is arranged in the first pipeline and / or the second pipeline, through which the first pipeline and / or the second pipeline can be shut off, and the first shut-off valve and / or the second shut-off valve can be closed in order to stop the pump (3).

3. The method according to claim 1 or 2, characterized in that, The first threshold and the second threshold are formed based on the operating conditions of the internal combustion engine and / or based on the pressure in the pressure chamber (1).

4. A method for diagnosing a water injection system, the water injection system having a pressure chamber (1) for water, wherein The pressure chamber (1) is connected to a pump (3), at least one pressure sensor (2), and a plurality of injection valves (4), wherein the pump (3) is configured to generate water pressure in the pressure chamber (1), the pressure sensor (2) is configured to measure water pressure in the pressure chamber (1), and the injection valves (4) are configured to inject water from the pressure chamber (1) into the intake manifold or combustion chamber of an internal combustion engine. The pump (3) is characterized by sequentially operating the plurality of injection valves when the pump (3) is stopped, and measuring the pressure drop caused by operating each individual injection valve, summing the corresponding pressure drops for each operation for each injection valve, and using the resulting sums to diagnose the individual injection valves, wherein the sums for the individual injection valves are compared to each other to determine the deviation of the individual injection valve, such that in the case of a large deviation, the corresponding injection valve is assessed as "abnormal".

5. The method of claim 4, wherein, The pump (3) is connected to the water tank via a first pipeline and to the pressure chamber (1) via a second pipeline. A shut-off valve is arranged in the first pipeline and / or the second pipeline, through which the first pipeline and / or the second pipeline can be shut off, and the first shut-off valve and / or the second shut-off valve can be closed in order to stop the pump (3).

6. The method according to claim 4 or 5, characterized in that, For comparison, an average value is formed by the sum of all injection valves, or The average value is formed by the sum of all injection valves except the ones being compared.

7. The method according to claim 4 or 5, characterized in that, The duration of operation of individual injection valves is affected so that the sum of the individual injection valves is adapted to each other.

8. An apparatus for diagnosing a water injection system, the water injection system having a pressure chamber (1) for water, wherein The pressure chamber (1) is connected to a pump (3), at least one pressure sensor (2), and a plurality of injection valves (4), wherein the pump (3) is configured to generate water pressure in the pressure chamber (1), the pressure sensor (2) is configured to measure the water pressure in the pressure chamber (1), and the injection valves (4) are configured to inject water from the pressure chamber (1) into an internal combustion engine. The system is characterized by a mechanism for sequentially operating the plurality of injection valves when the pump (3) stops, and measuring the pressure drop caused by operating each individual injection valve for each injection valve. The valve sums the corresponding pressure drops for each operation and uses the resulting sum to diagnose each injection valve, wherein the sum is compared with a first threshold and a second threshold respectively, and if the corresponding sum is less than the first threshold or greater than the second threshold, the corresponding injection valve is assessed as faulty, and if the sum is between the first threshold and the second threshold, the corresponding injection valve is assessed as "normal", or the sums of individual injection valves are compared with each other to determine the deviation of individual injection valves, such that in the case of a large deviation, the corresponding injection valve is assessed as "abnormal".

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