Engine system

Abstract

The airflow sensor and blow-by gas recirculation point need to be implemented in a space-saving manner. [Solution] An engine system having an air cleaner 7, a turbo unit, and an air flow sensor 3, wherein a throttling section 5 is provided in the middle of an intake pipe 2 connected to the outlet of the air cleaner 7, the air flow sensor 3 is provided upstream of the throttling section 5 of the intake pipe 2, and a blow-by gas recirculation section 4a is provided downstream of the throttling section 5 of the intake pipe 2, a part 2a of the intake pipe 2 upstream of the air flow sensor 3 is inserted inside the outlet pipe 7a connected to the outlet of the air cleaner 7, and the outlet pipe 7a and the part 2a of the upstream intake pipe 2 are connected by a connecting hose 8 that covers them from the outside.

Description

Technical Field

[0001] The present invention relates to an engine system having a blow-by gas reduction function.

Background Art

[0002] Conventionally, there is an engine provided with an air flow sensor for detecting the amount of air supplied to the engine. That is, for example, a clean air outlet is opened at the end of a filter element, a sealing material is provided on the opening end face of the clean air outlet, an inner folded-back portion folded back from the opening end face of the clean air outlet along the inner peripheral surface is provided on the sealing material, the clean air outlet of the filter element is communicated with the clean air inlet of a clean air outlet pipe, and an air flow sensor is arranged in the clean air outlet pipe. In an air cleaner, a clean air introduction cylinder is led out from the clean air inlet of the clean air outlet pipe along the inside of the inner folded-back portion of the sealing material, and an air cleaner in which the leading end of the clean air introduction cylinder protrudes significantly toward the clean air chamber side from the inner folded-back edge of the inner folded-back portion of the sealing material is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the mounting position of the air flow sensor and the blow-by gas reduction location need to be provided in the intake pipe (between the air cleaner and the turbocharger), and there is a problem that a large amount of space is required when they are provided separately.

[0005] In view of such problems of conventional engines, an object of the present invention is to provide an engine system that can configure the air flow sensor and the blow-by gas reduction location in a space-saving manner and prevent blow-by gas from flowing backward to the air flow sensor side. [Means for solving the problem]

[0006] The first invention is, An engine system having an air cleaner, a turbo unit, and an air flow sensor, A restrictor is provided in the middle of the intake piping connected to the outlet of the aforementioned air cleaner. The engine system is characterized in that the air flow sensor is provided upstream of the restricted portion of the intake pipe, and a blow-by gas recirculation point is provided downstream of the restricted portion of the intake pipe.

[0007] This allows for a space-saving configuration by placing the airflow sensor and blow-by gas recirculation point in the same intake piping. Furthermore, by incorporating a restriction in the piping and positioning the airflow sensor and blow-by gas recirculation point before and after it, it is possible to prevent blow-by gas from flowing back towards the sensor.

[0008] The second aspect of the present invention is: The first engine system of the present invention is characterized in that a portion of the intake piping upstream of the air flow sensor is inserted inside the outlet pipe connected to the outlet of the air cleaner, and the outlet pipe and the portion of the upstream intake piping are connected from the outside by a connecting hose.

[0009] This allows the air flow sensor pipe to be routed inside the air cleaner outlet pipe, ensuring the required straight-line distance is maintained without being affected by steps or unevenness at the hose connection points, thus ensuring the accuracy of the air flow sensor.

[0010] The third invention is, The second engine system of the present invention is characterized by having a rectifier plate placed near the upstream side of the air flow sensor.

[0011] By installing a rectifier plate at the intake pipe inlet, the accuracy of the airflow sensor can be ensured even if the intake pipe differs for each vehicle in which it is installed.

[0012] The fourth aspect of the present invention is: Equipped with a urea SCR system having a urea water tank, Exhaust gas from an EGR system having an EGR cooler flows into the aforementioned intake piping. The coolant that flows out of the engine cooling radiator cools the engine and then flows into the EGR cooler, and the coolant that flows out of the EGR cooler flows into the engine cooling radiator. A third engine system of the present invention is characterized in which a portion of the cooling water flowing into the EGR cooler is diverted, used to heat the urea water tank, and then rejoined with the cooling water flowing out of the EGR cooler.

[0013] By drawing coolant from the EGR system's coolant piping, it can be configured in a space-saving manner on the engine exhaust side.

[0014] The fifth aspect of the present invention is: A fourth engine system of the present invention, wherein a solenoid valve that controls the flow of cooling water into the urea water tank is fixed to the alternator bracket.

[0015] The sixth aspect of the present invention is Equipped with a DPF system, When the load factor (X) of the engine falls below a predetermined value (A), and the amount of accumulated soot in the DPF reaches a predetermined value (B) or more, the urea injection of the urea SCR system is stopped, ammonia consumption control is entered, and after a predetermined time has elapsed, DPF regeneration is performed. The predetermined value (B) is a fifth engine system of the present invention, which is a predetermined amount smaller than the DPF regeneration threshold.

[0016] This eliminates the need to be forced into manual playback or have output restrictions, improving work efficiency.

[0017] The seventh aspect of the present invention is Equipped with a DPF system, In the temperature rising process due to the start of DPF automatic regeneration, the urea injection of the urea SCR system is stopped. When the actual time reaches the stop time corresponding to the preset average load rate during urea injection stop, the stop of the urea injection is released and post-injection is started. This is the engine system of the fifth aspect of the present invention.

[0018] By allowing a certain amount of ammonia slip, the DPF regeneration system can be protected and regeneration troubles can be prevented.

[0019] The eighth aspect of the present invention is The degree of increase in the post-injection amount at a predetermined time from the start of the post-injection is controlled to be less than the degree of increase in the post-injection amount when DPF automatic regeneration is not performed. This is the engine system of the seventh aspect of the present invention.

[0020] As a result, the rise in DPF temperature becomes gentle, and it becomes difficult for the ammonia accumulated in the SCR catalyst to be released at once, so the problem of the ammonia odor from the muffler is eliminated.

Brief Description of the Drawings

[0021] [Figure 1] (A) Partial perspective view of the engine system according to an embodiment of the present invention, (B) Partial perspective view of its intake pipe, (C) Longitudinal sectional view of its intake pipe [Figure 2] (A) Longitudinal sectional view of a part of the intake pipe of FIG. 1, (B) Longitudinal sectional view of a part of the intake pipe of FIG. 1 viewed from another direction, (C) Cross-sectional view taken along the arrow S-S of FIG. (B) [Figure 3] (A), (B), (C) Partial longitudinal sectional view for explaining the connection state between the outlet of the air cleaner and the intake pipe [Figure 4] (A) Perspective view of an engine or the like showing the flow of cooling water of the engine system of the same above, (B) Its partial enlarged view [Figure 5] (A) Perspective view of an engine or the like showing the flow of cooling water of the engine system of the same above, (B) Its partial enlarged view [Figure 6]A flowchart illustrating measures to prevent ammonia slippage in the same engine system. [Figure 7] A flowchart illustrating measures to prevent ammonia slippage in the same engine system. [Figure 8] A flowchart illustrating measures to prevent ammonia slippage in the same engine system. [Figure 9] A flowchart illustrating measures to prevent ammonia slippage in the same engine system. [Figure 10] A flowchart illustrating measures to prevent ammonia slippage in the same engine system. [Figure 11] A flowchart illustrating measures to prevent ammonia slippage in the same engine system. [Figure 12] Graph showing the change in post-injection amount during regeneration as a measure against ammonia slip in the same engine system. [Figure 13] A flowchart illustrating measures to prevent ammonia slippage in the same engine system. [Figure 14] A flowchart illustrating measures to prevent ammonia slippage in the same engine system. [Figure 15] A flowchart illustrating measures to prevent ammonia slippage in the same engine system. [Figure 16] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 17] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 18] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 19] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 20] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 21] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 22] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 23] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 24] A perspective view of the DPF and urea SCR system of the same engine system, and a graph showing the relationship between differential pressure and intake throttle amount. [Figure 25] (A) A graph showing how the amount of HC accumulated in the same engine system is proportionally converted to the soot value; (B) A diagram showing the configuration in which the soot value converted from the amount of HC accumulated and the soot value in the DPF are always selected to MAX. [Figure 26] In the same engine system, if the amount of HC accumulation is high, the accumulation threshold is lowered and regeneration is initiated. [Figure 27] A flowchart illustrating the relationship between HC amount and DPF deposit amount in the same engine system. [Figure 28] In the same engine system, a flowchart shows how to prevent urea precipitation by reducing the equivalent ratio of urea solution injection. [Figure 29] Flowchart for firing a DPF manual regeneration request in the same engine system. [Figure 30] In the same engine system, the graph shows the time threshold for regeneration transition in relation to exhaust gas flow rate and SCR temperature. [Figure 31] Flowchart for firing a DPF manual regeneration request in the same engine system. [Figure 32] The graph shows the change in SCR pre-pressure with respect to operating time in the same engine system. [Figure 33] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 34] In the same engine system, the level of accumulation of crystallized urea solution is calculated from the DPF post-temperature and urea solution injection amount, and the graph shows that if the time threshold exceeds a certain value, DPF regeneration is required. [Figure 35] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 36] Perspective view of the DPF and urea SCR system of the same engine system. [Figure 37] Perspective view of the DPF and urea SCR system of the same engine system. [Modes for carrying out the invention]

[0022] The embodiments of the present invention will be described in detail below with reference to the drawings.

[0023] Figure 1(A) is a partial perspective view of an engine system according to an embodiment of the present invention, Figure 1(B) is an enlarged perspective view of a part of the intake piping 2 upstream of the turbo section, and Figure 1(C) is a longitudinal cross-sectional view of a part of the intake piping 2 viewed from the front.

[0024] In Figure 1, the engine system according to this embodiment is an engine system having an air cleaner 7 (see Figure 3), a turbo unit (not shown), and an air flow sensor 3. A throttling section 5 is provided in the middle of the intake pipe 2 connected to the outlet of the air cleaner 7, the air flow sensor 3 is provided upstream of the throttling section 5 of the intake pipe 2, and a section 4a is provided downstream of the throttling section 5 of the intake pipe 2 where blow-by gas is returned through a blow-by gas hose 4. Note that 14 is a DPF and 15 is an SCR.

[0025] This configuration allows for a space-saving design by placing the airflow sensor 3 and the blow-by gas recirculation point 4a in the same intake piping 2.

[0026] Furthermore, by providing a throttling section 5 in the intake pipe 2 and arranging the air flow sensor 3 and the blow-by gas return section 4a before and after it, it is possible to prevent blow-by gas from flowing back to the air flow sensor 3 side.

[0027] Figure 2 shows an example in which a flow straightening plate 6 is added to the intake piping 2 in Figure 1. Figure (A) corresponds to Figure 1(C), Figure (B) is a vertical cross-sectional view seen from the upstream side of the airflow sensor 3, and Figure (C) is a horizontal cross-sectional view of SS as directed by the arrow in Figure (B).

[0028] As can be seen in Figure 2, two parallel rectifier plates 6 are arranged vertically near the upstream side of the airflow sensor 3. By providing the rectifier plates 6 near the airflow sensor 3 in the intake pipe 2 in this way, the accuracy of the airflow sensor 3 can be ensured even if the intake pipe 2 differs for each vehicle in which it is installed.

[0029] Figures 3(A), (B), and (C) show another embodiment, mainly illustrating the intake piping 2 upstream of the air flow sensor 3. Ideally, to ensure the accuracy of the air flow sensor 3, a straight-line distance of 1 to 3 times the inner diameter of the pipe is required upstream of the air flow sensor 3. However, depending on the vehicle layout, if a sufficient straight-line distance cannot be secured, accuracy may not be ensured. Figure 3 illustrates this. Normally, the outlet pipe 7a of the air cleaner 7 and the intake piping 2 are connected by a connecting hose 8. However, the airflow from the air cleaner 7 tends to be turbulent at the step in the connecting hose 8, as shown in the figure. This turbulent air flows into the intake piping 2, but if the air flow sensor 3 is close to the connecting hose 8, a sufficient straight-line distance cannot be achieved, and the turbulent air reaches the air flow sensor 3, leading to a decrease in sensor accuracy.

[0030] Therefore, in this embodiment, a portion 2a of the intake pipe 2 upstream of the air flow sensor 3 is inserted inside the outlet pipe 7a of the air cleaner 7, and the outlet pipe 7a and the portion 2a of the intake pipe 2 upstream are connected from the outside with a connecting hose 8.

[0031] By doing so, the required straight distance can be secured without being affected by the step at the connection point of hose 8, and the accuracy of the air flow sensor can be not reduced.

[0032] Furthermore, as shown in Figure 3(C), the outer diameter of a portion 2a of the intake pipe 2, which is inserted inside the outlet pipe 7a, is made smaller than the outer diameter of the main body portion 2b of the intake pipe 2.

[0033] This ensures sufficient diameter in the main body portion 2b of the intake pipe 2, while also making insertion easy even if the outlet pipe 7a is narrow. Even with this configuration, only the outside will have irregularities; the inside remains smooth, and there is no risk of creating air turbulence.

[0034] Figures 4 and 5 show another embodiment. Specifically, the engine system in this embodiment is equipped with an EGR system (exhaust gas recirculation system) and a urea SCR system, and in this example, the cooling water for the EGR cooler of the EGR system is used to heat the urea water tank 11 of the urea SCR system.

[0035] In other words, it is necessary to warm the urea solution in the urea solution tank 11, which may have frozen during cold weather, in order to accelerate its thawing.

[0036] Exhaust gas from the EGR system, which has an EGR cooler 9, flows into the intake pipe 2. On the other hand, the coolant that has been cooled and discharged from the engine cooling radiator cools the engine 1 and then flows into the EGR cooler 9 from point V as shown by the dotted arrow in the figure, and further, the coolant that has discharged from the EGR cooler 9 flows into the engine cooling radiator from point W as shown by the dotted arrow. 9a is the EGR valve.

[0037] Therefore, in this embodiment, a portion of the cooling water flowing into the EGR cooler 9 is diverted downwards as shown in the figure, passes through the solenoid valve 12, and is routed to the urea water tank 11. After the urea water is heated, it is then combined with the cooling water flowing out of the EGR cooler 9 as described above.

[0038] Conventionally, there is limited space for routing the cooling water piping that circulates within the urea water tank 11. However, as described above, by taking the cooling water from the cooling water piping of the EGR system, it is possible to configure it in a space-saving manner on the exhaust side of the engine 1.

[0039] As shown in Figure 5, it is desirable that the solenoid valve 12, which controls the circulation of cooling water to the urea water tank 11, be fixed to the alternator (power generation) bracket 13. Note that 10 is a bracket for the solenoid valve 12.

[0040] Next, we will describe an invention for preventing ammonia slippage in a urea SCR system.

[0041] Figure 6 is a flowchart showing the embodiment.

[0042] In agricultural machinery equipped with a DPF system and a urea SCR system, when operation continues at a load rate below a certain level, the amount of NH3 absorbed into the urea SCR system is reduced to prevent a prolonged ammonia consumption control period before the next regeneration is performed.

[0043] When DPF regeneration begins, the exhaust temperature rises, so the ammonia accumulated in the SCR catalyst can no longer be stored and is discharged outside, causing ammonia to slip. However, the above configuration prevents this slippage.

[0044] In other words, when it is determined that the system is operating at a relatively low load for an extended period, the amount of ammonia absorbed into the SCR is reduced, allowing for quick ammonia consumption before the next DPF regeneration. As a result, it is possible to avoid missing the timing for regeneration or excessive soot buildup in the DPF due to delays in regeneration.

[0045] Figure 7 is a flowchart of another embodiment.

[0046] In a combine harvester equipped with a DPF and SCR system, when the amount of unhulled rice in the grain tank exceeds a predetermined percentage and the amount of soot accumulated in the DPF approaches the regeneration start threshold, urea injection into the SCR is stopped and ammonia consumption control within the SCR is initiated. Then, when the rice discharge operation begins, automatic DPF regeneration is performed.

[0047] This ensures that the combine harvester's grain discharge process maintains a constant engine speed and load, making it more suitable for safer DPF regeneration. Therefore, by working backward from the grain discharge operation, SCR urea injection is stopped and SCR ammonia consumption control is initiated when the amount of grain in the grain tank exceeds a certain level, allowing DPF regeneration to start smoothly when the next grain discharge operation begins.

[0048] Figure 8 is a flowchart of another embodiment.

[0049] In agricultural machinery equipped with a DPF and SCR system, when the load factor remains below a certain level, urea injection to the SCR is stopped and ammonia consumption control is initiated before the soot accumulation in the DPF reaches the regeneration threshold. When the soot accumulation amount Y exceeds B, urea injection is stopped, but B is set to a predetermined value smaller than the DPF regeneration threshold.

[0050] When the engine is running at a relatively low load for an extended period, stopping urea injection and switching to ammonia consumption control can cause the ammonia in the SCR to take too long to be consumed, potentially leading to an excessive buildup of soot in the DPF. Therefore, by switching to ammonia consumption control early, before the soot level reaches the regeneration threshold, and performing DPF regeneration as soon as the control is complete (for example, after a predetermined time has elapsed), it becomes possible to prevent excessive soot buildup that could cause DPF regeneration to be missed. As a result, the engine will no longer be forced to switch to manual regeneration or have its output limited, improving work efficiency.

[0051] Figure 9 is a flowchart showing another embodiment.

[0052] In agricultural machinery equipped with DPF and SCR systems, during manual DPF regeneration, SCR urea injection is stopped during the heating process after the manual regeneration rotation transition, and ammonia consumption control is initiated. After ammonia consumption is confirmed, post-injection is started, and the SCR also returns to normal urea injection control.

[0053] In areas where manual regeneration is required, power output is often limited to protect the engine, making it difficult to initiate control that consumes ammonia in the SCR catalyst before DPF regeneration during normal operation. In such cases, the manual regeneration process is executed as is, maintaining the temperature rise stroke before the post-injection process, where the exhaust temperature rises rapidly, for an extended period. Then, urea injection stop control is applied at this point, and after ammonia consumption is confirmed, the system transitions to post-injection control. This allows for smooth manual DPF regeneration while protecting the SCR system.

[0054] Figure 10 is a flowchart of another embodiment.

[0055] In agricultural machinery equipped with DPF and SCR systems, during automatic DPF regeneration, SCR urea injection is stopped during the heating process, and ammonia consumption control is initiated. When the actual stop time reaches a preset stop time corresponding to the average load rate during urea injection stop, the urea injection stop is released, and the process of restarting post-injection begins, and the SCR also returns to normal urea injection control.

[0056] In other words, in areas with relatively low engine load, even when urea injection stop control is activated and the ammonia consumption process begins, consumption may not progress smoothly. In such cases, to enter normal regeneration control, when the stop time reaches a set time corresponding to the average load during urea stop, the urea injection stop is released and the system switches to post-injection control for DPF regeneration. As a result, a small amount of ammonia slip is tolerated, protecting the DPF regeneration system and preventing regeneration problems.

[0057] To explain the relationship between the heating process and post-injection during the automatic DPF regeneration described above, in low-load operation, the exhaust temperature may not reach the minimum required for post-injection. In such cases, the intake throttle is first restricted (heating process), and once the exhaust temperature rises above a certain level, post-injection is initiated. This is because if the exhaust temperature is too low, the catalyst will not be activated, and post-injection will not raise the temperature. Normally, during the intake throttle restriction process, the injection timing and duration are simultaneously changed to facilitate raising the exhaust temperature.

[0058] Therefore, even when entering regeneration mode, post-injection may not occur immediately. In such cases, the above invention is effective.

[0059] Figure 11 is a flowchart of another embodiment.

[0060] In agricultural machinery equipped with DPF and SCR systems, when SCR urea injection is stopped during the heating process of automatic DPF regeneration and ammonia consumption control is initiated, but urea injection is restarted by a timer, the rate of increase in the post-injection amount at the start of post-injection is reduced compared to normal conditions (when automatic DPF regeneration is not performed), thereby reducing ammonia slip.

[0061] In other words, when the DPF regeneration process begins and ammonia consumption control is initiated by stopping urea injection, consumption does not progress quickly. When the timer restarts urea injection and starts post-injection, the initial increase gradient of post-injection is made smaller than usual, as shown in Figure 12, which slows down the rise in DPF temperature. This makes it more difficult for the ammonia accumulated in the SCR catalyst to be released all at once, thus eliminating the problem of ammonia odor coming from the muffler.

[0062] Figure 13 is a flowchart of another embodiment.

[0063] In agricultural machinery equipped with a DPF and SCR system, when the DPF deposit soot reaches the regeneration threshold and the regeneration process begins, urea injection into the SCR is stopped, and the current target temperature is slowly increased relative to the final DPF target temperature to ensure sufficient ammonia consumption. After that, urea injection is resumed.

[0064] In other words, by setting a low target temperature at the start of DPF regeneration and allowing it to rise slowly, it is possible to gain time for ammonia consumption within the SCR. This relatively simple control prevents ammonia from being released into the atmosphere all at once.

[0065] Figure 14 is a flowchart of another embodiment.

[0066] In agricultural machinery equipped with a DPF and SCR system, when the DPF accumulated soot reaches the regeneration threshold and the regeneration process begins, urea injection to the SCR is stopped, and post-injection is used to maintain the DPF regeneration temperature at 350°C to 400°C and consume ammonia. When it is determined that sufficient ammonia has been consumed, the system returns to normal regeneration and resumes urea injection.

[0067] By intentionally performing post-injection to maintain a temperature conducive to SCR activation before normal DPF regeneration, the ammonia in the SCR can be consumed more quickly. As a result, normal regeneration can be returned to normal sooner, reducing the likelihood of excessively long regeneration times. Furthermore, this type of control prevents a large amount of ammonia from being released into the atmosphere all at once.

[0068] Figure 15 shows yet another embodiment.

[0069] In agricultural machinery equipped with a DPF and SCR system, when the DPF deposit soot reaches the manual regeneration threshold and regeneration begins, the intake throttle is narrowed more than usual to activate the SCR and consume the ammonia adsorbed by the SCR. After it is determined that the ammonia has been consumed, the regeneration control returns to normal.

[0070] Manual DPF regeneration is often performed first thing in the morning or during breaks in other work, meaning the SCR itself is usually cold. Since ammonia is normally adsorbed in the SCR, it needs to be consumed before regeneration. By narrowing the intake throttle opening more than during normal regeneration, the exhaust gas temperature rises, which in turn raises the temperature of the gas flowing through the SCR. This activates the SCR and accelerates the reaction between ammonia and NOx. As a result, it is possible to return to normal regeneration more quickly, reducing the problem of excessively long regeneration times. Furthermore, this type of control prevents a large amount of ammonia from being released into the atmosphere all at once.

[0071] Next, we will describe an invention relating to the prevention of HC poisoning in a urea SCR system.

[0072] (1) Figure 16 shows an embodiment of this, and is a diagram of the DPF system and urea SCR system configuration.

[0073] In engines equipped with an SCR system for exhaust gas regulations, DPF regeneration is performed to remove HC deposits from the SCR catalyst in order to prevent HC poisoning of the SCR system. This solves the following problems.

[0074] HC poisoning refers to the reduction in catalytic performance due to HC adsorption by unburned HC, etc. In SCR catalysts, this is due to N3 adsorption by ammonia (NH3). OX The N2 conversion performance deteriorates. Also, under HC poisoning conditions, the N2 in the exhaust gas OX The concentration is higher than the standard value and is discharged.

[0075] This method prevents HC poisoning of the SCR catalyst.

[0076] (2) The invention described in (1) above, which concerns the prevention of HC poisoning in the SCR system, is further enhanced by the addition of a trigger. The level of HC deposition is calculated from the post-DPF temperature, and if the threshold per unit time falls below a certain value, DPF regeneration is requested.

[0077] (3) Figure 17 shows the invention described in (1) above, which includes a trigger for preventing HC poisoning in the SCR system. Specifically, when the NOx purification rate of the SCR catalyst falls below a certain value, it is determined that the system is in an HC poisoned state and DPF regeneration is requested.

[0078] (4) Figure 18 shows the invention described in (2) above regarding the prevention of HC poisoning in an SCR system, wherein the method for removing HC deposits is carried out by means other than DPF regeneration. That is, after recognizing that the system is in an HC poisoning state, a program is added that restricts the intake throttle valve to raise the exhaust temperature and remove the accumulated HC. Since flowing high-temperature exhaust gas is an effective means of preventing HC poisoning, restricting the intake throttle valve raises the exhaust temperature and removes the HC.

[0079] (5) Regarding the above (3) concerning the prevention of HC poisoning in the SCR system, the method for removing HC deposits will be carried out by means other than DPF regeneration. Specifically, after recognizing that the system is in an HC poisoning state, a program will be added that restricts the intake throttle valve to raise the exhaust temperature and remove the accumulated HC. Since flowing high-temperature exhaust gas is an effective means of preventing HC poisoning, restricting the intake throttle valve will raise the exhaust temperature and remove the HC.

[0080] (6) Figure 19 shows the method for removing HC deposits other than DPF regeneration, as described in (2) above regarding the prevention of HC poisoning in the SCR system. Specifically, after recognizing that the system is in an HC poisoning state, a program is added to increase the engine speed to the Hi idle speed, increase the exhaust gas flow rate, and blow away the HC adsorbed on the catalyst. Since HC poisoning occurs due to the adsorption of HC such as unburned HC, it is prevented by adding a process to blow it away under certain conditions.

[0081] (7) Regarding the above (3) concerning the prevention of HC poisoning in the SCR system, the method for removing HC deposits will be carried out by means other than DPF regeneration. Specifically, after recognizing that the system is in an HC poisoning state, a program will be added that increases the engine speed to the Hi idle speed, increases the exhaust gas flow rate, and blows away the HC adsorbed on the catalyst. Since HC poisoning occurs due to the adsorption of HC such as unburned HC, it will be prevented by adding a process to blow it away under certain conditions.

[0082] (8) Figure 20 shows pressure sensors installed before and after the SCR catalyst. A threshold is set for the differential pressure of the sensor values, and when it exceeds a certain value, it is determined that HC poisoning has occurred and a lamp is turned on.

[0083] (9) Figure 21 shows the above (8) regarding the prevention of HC poisoning in the SCR system, with the addition of an HC removal method. After the lamp lights up, the DPF is regenerated to remove HC, and the SCR catalyst is raised to a high temperature to remove HC. Once the differential pressure is eliminated, the system is returned to normal operation.

[0084] (10) Figure 22 shows the above (8) regarding the prevention of HC poisoning in the SCR system, with the addition of an HC removal method. After the lamp lights up, a program is added to increase the engine speed to the Hi idle speed to remove HC, increase the exhaust gas flow rate, and blow away the HC adsorbed on the catalyst.

[0085] (11) Figure 23 shows the above (8) regarding the prevention of HC poisoning in the SCR system, with the addition of an HC removal method. After the lamp lights up, a program is added to restrict the engine's intake throttle valve to remove HC, increase the exhaust gas temperature, and remove the HC adsorbed on the catalyst.

[0086] (12) Figures 24(A) and (B) show a method for preventing HC poisoning in an SCR system, as described in (11) above, which involves calculating the differential pressure value from a pressure sensor, adjusting the throttling amount of the intake throttle valve according to the differential pressure, and controlling the exhaust gas temperature to remove HC before it is adsorbed to a certain extent by the SCR catalyst.

[0087] (13) The above invention relating to the prevention of HC poisoning in an SCR system is made known to the user by displaying the respective alarms and execution lamps on the meter panel. By making the user aware of these, the user can recognize which operating patterns are likely to cause HC poisoning and take preventative measures.

[0088] Next, we will explain how DPF regeneration can resolve SCR poisoning.

[0089] Figures 25(A) and (B) show an agricultural machine equipped with a DPF and SCR system, which includes a system for estimating the amount of HC accumulated in the SCR, and a mechanism for forcing regeneration when the amount of HC exceeds a certain level. The system converts the amount of HC into a soot value and displays the DPF soot value and the MAX selected value to the operator.

[0090] In other words, if a large amount of HC deposits inside the SCR catalyst, the catalyst efficiency decreases, and N2 is not produced properly. Ox It is known that reduction reactions cannot be carried out, and that it is necessary to periodically raise the exhaust temperature to remove HC. However, if operators are suddenly asked to perform DPF regeneration, for example, they may not be able to grasp the situation and become confused. The above method can prevent such confusion.

[0091] Therefore, by converting the amount of HC accumulated in the SCR into a suit value and allowing the operator to select between the DPF suit and MAX, the operator can make decisions using the same unit of suit, making it simple and easy to understand. With a machine that can display the accumulated suit, even if a DPF regeneration request is issued, there is always a visual process of the suit increasing beforehand, so the operator will not get confused.

[0092] Figure 26 shows that in agricultural machinery equipped with a DPF and SCR system, the amount of HC accumulated in the SCR is estimated, and the DPF soot accumulation threshold for initiating DPF regeneration is changed according to the amount of HC accumulated in the SCR and the amount of soot accumulated in the DPF.

[0093] In other words, if a large amount of HC deposits inside the SCR catalyst, the catalyst efficiency decreases, and N2 is not produced properly. Ox It is known that reduction reactions cannot be performed, and that it is necessary to periodically raise the exhaust temperature to remove HC. However, by doing as described above, instead of determining the timing of DPF regeneration by looking at the amount of HC accumulated in the SCR and the amount of soot in the DPF separately, the timing can be determined based on both values. This allows for the determination of the regeneration timing, taking into account risks such as those that increase only when both amounts are present. In this way, it is possible to avoid causing major problems in the engine.

[0094] Figure 27 shows that in agricultural machinery equipped with a DPF and SCR system, when the engine speed is continuously below a certain level and the load factor is also continuously below a certain level, the remaining time until manual regeneration is calculated by working backward from the amount of HC accumulated in the SCR, and the remaining time is also calculated by working backward from the amount of DPF accumulation. The operator is then allowed to select the minimum time from either of these options, and the selected remaining time is displayed to the operator.

[0095] In other words, if a large amount of HC deposits inside the SCR catalyst, the catalyst efficiency decreases, and N2 is not produced properly. OxIt is known that reduction reactions cannot be initiated, and that it is necessary to periodically raise the exhaust temperature to remove HC. However, when the engine speed is low and the load is low, automatic regeneration cannot be initiated, so manual regeneration must be forced in the middle of the operation. To make it easier to avoid this, the time Ta until the amount of HC accumulated in the SCR reaches a threshold and the time Tb until the DPF accumulated suit reaches a threshold are selected as minimum values, and the remaining time Tfinal that was finally selected is displayed to the operator, making it easier for the operator to consider when to initiate manual regeneration. As a result, forced interruptions to the operation are eliminated, and work efficiency can be increased.

[0096] Next, an invention relating to the prevention of urea precipitation will be described.

[0097] Figure 28 shows that in agricultural machinery equipped with a DPF and SCR system, when the engine speed is continuously operating at low idle or slightly above idle, and the load factor remains below a certain level, and when the cumulative low-speed operation exceeds a predetermined time (hr), the equivalent ratio of urea solution injected is reduced to prevent urea deposition.

[0098] In other words, when the engine operates at a low idle speed or close to it and is running at a low load for an extended period, precipitation may occur around the inside of the pipe injecting urea solution. If this precipitation is left untreated, it can clog the pipe, causing problems such as a sudden increase in exhaust pressure. However, with the above configuration, when the low-speed, low-load operation condition persists for a certain period of time or longer, the amount of urea solution injected is reduced, and N Ox By shifting the control system from prioritizing the amount of purification to prioritizing the reliable reaction of the urea solution, it is possible to prevent the urea solution from precipitating.

[0099] Figures 29 and 30 show that exhaust gas flow rate and SCR temperature are monitored in agricultural machinery equipped with a DPF and SCR system. A map is created with the x-axis representing exhaust gas flow rate, the y-axis representing SCR temperature, and the z-axis representing cumulative time (hr). When the cumulative time is reached, the system is forced to switch to manual DPF regeneration.

[0100] In other words, the lower the exhaust gas flow rate and the lower the SCR temperature, the greater the tendency for urea solution to precipitate in the pipe. This is mapped, and when a cumulative time threshold is reached, the system switches to DPF regeneration. By doing so, the precipitates can be eliminated by the flow of high-temperature exhaust gas, thus preventing problems caused by precipitate clogging.

[0101] In Figures 31 and 32, agricultural machinery equipped with a DPF and SCR system monitors the pre-SCR pressure, and when the pre-SCR pressure begins to rise, it forcibly switches to manual DPF regeneration.

[0102] In other words, as urea deposits accumulate in the SCR pipe, the exhaust pressure increases. By detecting this pressure increase, the system switches to DPF regeneration, which allows high-temperature exhaust gas to flow through and eliminate the deposits. This prevents excessive buildup of deposits that could lead to blockage problems.

[0103] Furthermore, we will provide a further explanation regarding the prevention of urea solution crystallization, partially overlapping with the above explanation.

[0104] (1) Urea solution crystallization refers to the accumulation of crystallized urea solution around the urea solution injection nozzle when the vehicle is continuously operated under low exhaust gas flow rate and exhaust temperature conditions such as low rotation speed and low load. This degrades the reaction in the SCR catalyst and increases the amount of nitrogen in the exhaust gas. OX The concentration may exceed the standard value and be discharged (see Figure 33).

[0105] Therefore, DPF regeneration is performed to remove the crystallized urea.

[0106] (2) Regarding the above (1) concerning the prevention of urea solution crystallization in the SCR system, a trigger is provided, and the level of accumulation of crystallized urea solution is calculated from the post-DPF temperature and urea solution injection amount, and if the threshold per hour exceeds a certain value, DPF regeneration is requested (see Figure 34).

[0107] (3) As shown in Figure 35, in the above (1) concerning the prevention of urea water crystallization in the SCR system, a trigger is provided for the N of the SCR catalyst. ox When the purification rate falls below a certain value, the system determines whether crystallized deposits of urea solution have accumulated and requests DPF regeneration.

[0108] (4) As shown in Figure 36, regarding the above (2) concerning the prevention of urea solution crystallization in the SCR system, the method for removing crystallized deposits is to be carried out by means other than DPF regeneration. That is, after recognizing that crystallized urea solution has accumulated, a program is added that restricts the intake throttle valve to raise the exhaust temperature and remove the accumulated urea solution crystals. Since flowing high-temperature exhaust gas is an effective means of crystallizing urea solution, restricting the intake throttle valve raises the exhaust temperature and removes the deposits.

[0109] (5) In relation to preventing urea solution crystallization in the SCR system, as described in (3) above, the method for removing urea solution crystal deposits is to be other than DPF regeneration. After recognizing that crystallized urea solution has accumulated, a program is added that restricts the intake throttle valve to raise the exhaust temperature and remove the accumulated urea solution crystals. Since flowing high-temperature exhaust gas is an effective means of preventing urea solution crystallization, restricting the intake throttle valve raises the exhaust temperature and removes the deposits.

[0110] (6) In Figure 37, in (2) above, regarding the prevention of urea solution crystallization in the SCR system, the method for removing urea solution crystal deposits is performed by means other than DPF regeneration. After recognizing that crystallized urea solution has accumulated, a program is added to increase the engine speed to the Hi idle speed, increase the exhaust gas flow rate, and blow away the crystallized deposits adsorbed around the urea solution injection nozzle. Since urea solution crystallized deposits occur around the nozzle, crystallization is prevented by adding a blowing step under certain conditions.

[0111] The engine system of the present invention described above is applicable not only to various agricultural vehicles but also to other vehicles. [Industrial applicability]

[0112] This invention provides an engine system that allows for a space-saving configuration of the airflow sensor and blow-by gas recirculation point, and prevents blow-by gas from flowing back to the airflow sensor side, making it ideal for tractors, combine harvesters, rice transplanters, and the like. [Explanation of Symbols]

[0113] 1 Engine 2. Intake piping 2a part 3. Air flow sensor 4. Blow-by gas hose 4a Reduction points 5. Aperture section 6 Rectifier plate 7. Air cleaner 7a Outlet pipe 8. Connecting hoses 9 EGR cooler 9a EGR valve 10 Valve bracket 11 Urea water tank 12 Solenoid valve 13 Alternator bracket 14 DPF 15 SCR

Claims

1. An engine system having an air cleaner, a turbo unit, and an air flow sensor, A restrictor is provided in the middle of the intake piping connected to the outlet of the aforementioned air cleaner. An engine system characterized in that the air flow sensor is provided upstream of the restricted portion of the intake pipe, and a blow-by gas recirculation point is provided downstream of the restricted portion of the intake pipe.

2. The engine system according to claim 1, characterized in that a portion of the intake piping upstream of the air flow sensor is inserted inside the outlet pipe connected to the outlet of the air cleaner, and the outlet pipe and the portion of the upstream intake piping are connected from the outside by a connecting hose.

3. The engine system according to claim 2, characterized in that a rectifier plate is placed near the upstream side of the air flow sensor.

4. Equipped with a urea SCR system having a urea water tank, Exhaust gas from an EGR system having an EGR cooler flows into the aforementioned intake piping. The coolant that flows out of the engine cooling radiator cools the engine and then flows into the EGR cooler, and the coolant that flows out of the EGR cooler flows into the engine cooling radiator. The engine system according to claim 3, wherein a portion of the coolant flowing into the EGR cooler is diverted, warms the urea water tank, and then merges with the coolant flowing out of the EGR cooler.

5. The engine system according to claim 4, wherein a solenoid valve that controls the flow of cooling water into the urea water tank is fixed to the bracket of the alternator.

6. Equipped with a DPF system, When the load factor (X) of the engine falls below a predetermined value (A), and the amount of accumulated soot in the DPF reaches a predetermined value (B) or more, the urea injection of the urea SCR system is stopped, ammonia consumption control is initiated, and after a predetermined time has elapsed, DPF regeneration is performed. The engine system according to claim 5, wherein the predetermined value (B) is smaller by a predetermined amount than the DPF regeneration threshold.

7. Equipped with a DPF system, The engine system according to claim 5, wherein, during the temperature rise process caused by the start of automatic DPF regeneration, the urea injection of the urea SCR system is stopped, and when the actual time reaches a predetermined stop time corresponding to the average load rate during the urea injection stop, the stop of urea injection is released and post-injection is started.

8. The engine system according to claim 7, wherein the degree of increase in the post-injection amount during a predetermined time from the start of post-injection is controlled to be less than the degree of increase in the post-injection amount when DPF automatic regeneration is not performed.

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