internal combustion engine

Abstract

An internal combustion engine comprises: a turbine of a supercharger, which is arranged in an exhaust passage through which exhaust gas generated from an internal combustion engine body flows; an EGR device, which is used to reflux a portion of the exhaust gas to the internal combustion engine body; a temperature sensor 55, which is arranged in the EGR device and detects the temperature of the refluxed exhaust gas; an action determination unit 123, which determines whether the EGR device is actuated; and an injection control unit 125, which controls the injection of fuel into the internal combustion engine body based on the temperature detected by the temperature sensor 55 when the EGR device is determined to be actuated, and controls the fuel injection in such a manner that the temperature of the exhaust gas flowing into the turbine does not exceed a predetermined threshold value when the EGR device is determined to be inactive.

Description

Technical Field

[0001] The present invention relates to internal combustion engines. Background Art

[0002] Some internal combustion engines include a supercharger that compresses intake air drawn into the engine body using the flow of exhaust gas. The supercharger includes, for example, a turbine disposed in an exhaust passage.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-31930. Summary of the Invention

[0006] Problems to be solved by the invention

[0007] However, the turbine easily becomes hot due to the heat of the exhaust gas flowing through the exhaust passage. Therefore, to prevent damage to the turbine, it is possible to suppress the exhaust gas from becoming hot by inhibiting the injection of fuel into the engine body.

[0008] On the other hand, it is difficult to accurately detect the temperature of the exhaust gas upstream of the turbine. Therefore, if fuel injection is suppressed in a state where the temperature cannot be accurately detected, the output of the internal combustion engine may be reduced.

[0009] Therefore, the present invention has been made in view of these problems, and an object of the present invention is to achieve high output of an internal combustion engine while suppressing the adverse effect of the heat of exhaust gas on a turbine.

[0010] Means of solving the problem

[0011] In one aspect of the present invention, an internal combustion engine is provided, comprising: a turbine of a supercharger, arranged in an exhaust passage through which exhaust gas generated from an internal combustion engine body flows; an EGR device, for causing a portion of the exhaust gas to flow back to the internal combustion engine body; a temperature sensor, arranged in the EGR device, for detecting the temperature of the refluxed exhaust gas; an action determination unit, for determining whether the EGR device is actuated; and an injection control unit, for controlling fuel injection into the internal combustion engine body based on the temperature detected by the temperature sensor, when the action determination unit determines that the EGR device is actuating, and for controlling fuel injection into the internal combustion engine body based on the temperature detected by the temperature sensor, when the action determination unit determines that the EGR device is actuating, and for controlling fuel injection in such a manner that the temperature of the exhaust gas flowing to the turbine does not exceed a predetermined threshold value, when the EGR device is determined to be not actuated.

[0012] In addition, the injection control unit may also control the fuel injection in a manner such that the temperature detected by the temperature sensor does not exceed a prescribed upper limit temperature when the EGR device is determined to be in operation, and may control the fuel injection in a manner such that the temperature does not exceed the threshold value which is a temperature lower than the upper limit temperature when the EGR device is determined to be inoperative.

[0013] In addition, a temperature acquisition unit may be provided, which estimates the temperature detected by the temperature sensor as the temperature of the exhaust gas upstream of the turbine in the exhaust passage and acquires the temperature detected by the temperature sensor. When the EGR device is determined to be in operation, the injection control unit may also control the fuel injection in such a manner that the temperature of the exhaust gas upstream of the turbine estimated by the temperature acquisition unit does not exceed the upper limit temperature.

[0014] Furthermore, the EGR device may include an EGR passage connecting an intake passage for intake air flowing to the engine body and the exhaust passage, wherein the temperature sensor is located closer to the exhaust passage than the intake passage in the EGR passage.

[0015] Furthermore, the distance between the temperature sensor and the engine body may be the same as the distance between the turbine and the engine body.

[0016] Furthermore, the internal combustion engine may further include a post-processing device provided in the exhaust passage to purify the exhaust gas, and the turbine may be located closer to the internal combustion engine body than the post-processing device in the exhaust passage.

[0017] In addition, the EGR device may also have an openable and closable EGR valve, which is used to adjust the flow rate of the reflowed exhaust gas. The action determination unit may also determine that the EGR device is operating when the EGR valve is in an open state, and determine that the EGR device is not operating when the EGR valve is in a closed state.

[0018] Effects of the Invention

[0019] According to the present invention, there is an effect of achieving high output of the internal combustion engine while suppressing the adverse effect of the heat of the exhaust gas on the turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram for explaining the structure of the internal combustion engine 1 according to one embodiment.

[0021] Figure 2 It is a schematic diagram for explaining the detailed structure of the control device 100 .

[0022] Figure 3 This is a flowchart for explaining an example of the operation of the internal combustion engine 1 . DETAILED DESCRIPTION

[0023] <Structure of internal combustion engine>

[0024] Reference Figure 1 The structure of an internal combustion engine according to one embodiment of the present invention will be described.

[0025] Figure 1 Schematic diagram for explaining the structure of an internal combustion engine 1 according to one embodiment. The internal combustion engine 1 is, for example, a multi-cylinder engine mounted on a vehicle such as a truck. The internal combustion engine 1 is a diesel engine, but is not limited thereto and may be, for example, a gasoline engine. Figure 1 As shown, the internal combustion engine 1 includes an engine body 10 , a fuel injection device 15 , an intake passage 20 , an exhaust passage 30 , a turbocharger 40 , an EGR device 50 , and a control device 100 .

[0026] Here, the engine body 10 includes four cylinders 12, but the present invention is not limited thereto. Each cylinder 12 is provided with movable parts such as a piston and a crankshaft.

[0027] The fuel injection device 15 is an injection device that injects fuel into the combustion chamber in the engine body 10. Here, the fuel injection device 15 is a common rail type fuel injection device, which includes injectors 16 and a common rail 17. The injectors 16 inject fuel into the combustion chamber in each cylinder 12. The common rail 17 stores the fuel injected from the injectors 16 in a high-pressure state.

[0028] The intake passage 20 is a passage through which intake air drawn into the engine body 10 flows. The intake passage 20 includes an intake manifold 22 connected to the engine body 10 and an intake pipe 23 connected to the upstream end of the intake manifold 22. The intake manifold 22 distributes the intake air sent from the intake pipe 23 to the intake ports of each cylinder. The intake pipe 23 is equipped with an air filter 24, an air flow meter 25, the compressor 42C of the turbocharger 40, an intercooler 27, and an intake throttle valve 28. The air flow meter 25 detects the amount of air taken into the internal combustion engine 1 per unit time, i.e., the intake air flow rate.

[0029] The exhaust passage 30 is a passage through which exhaust gas generated by the engine main body 10 flows. The exhaust passage 30 includes an exhaust manifold 32 connected to the engine main body 10 and an exhaust pipe 33 connected to the downstream end of the exhaust manifold 32. The exhaust manifold 32 collects exhaust gas sent from the exhaust ports of each cylinder. The exhaust pipe 33 is provided with a turbine 42T of the turbocharger 40 and a post-processing device 35. The post-processing device 35 is a device for purifying exhaust gas and includes, for example, an oxidation catalyst, a DPF, an SCR, and an ammonia oxidation catalyst.

[0030] The turbocharger 40 is a supercharger that compresses intake air flowing through the intake passage 20 by utilizing the flow of exhaust gas flowing through the exhaust passage 30. The turbocharger 40 includes a turbine 42T provided in the exhaust passage 30 and a compressor 42C provided in the intake passage 20. The turbine 42T is located in the exhaust passage 30 closer to the engine body 10 than the aftertreatment device 35.

[0031] The EGR device 50 recirculates a portion of the exhaust gas to the engine body 10. Specifically, the EGR device 50 recirculates a portion of the exhaust gas (hereinafter referred to as EGR gas) within the exhaust passage 30 (herein, within the exhaust manifold 32) into the intake passage 20 (herein, within the intake manifold 22). The EGR device 50 includes an EGR passage 52, an EGR cooler 53, an EGR valve 54, and a temperature sensor 55.

[0032] The EGR passage 52 is a passage through which EGR gas flows. The EGR passage 52 connects the intake passage 20 (herein, the intake manifold 22) and the exhaust passage 30 (herein, the exhaust manifold 32). The EGR cooler 53 is provided in the EGR passage 52 to cool the EGR gas.

[0033] The EGR valve 54 is an openable and closable valve provided downstream of the EGR cooler 53 to adjust the flow rate of the EGR gas. When the EGR valve 54 is closed, the EGR gas does not flow through the EGR passage 52.

[0034] The temperature sensor 55 detects the temperature of the EGR gas flowing through the EGR passage 52. The temperature sensor 55 is provided upstream of the EGR cooler 53 and is located closer to the exhaust passage 30 than the intake passage 20 in the EGR passage 52.

[0035] The control device 100 controls the overall operation of the internal combustion engine 1. In this embodiment, the control device 100 controls fuel injection from the fuel injection device 15 based on the temperature of the exhaust gas flowing through the exhaust passage 30, as described in detail later. This suppresses the adverse effects of exhaust gas heat on the turbine 42T while achieving high output from the internal combustion engine 1.

[0036] <Detailed Structure of Control Device>

[0037] Reference Figure 2 The detailed structure of the control device 100 will be described.

[0038] Figure 2 1 is a schematic diagram for explaining the detailed configuration of the control device 100. The control device 100 includes a storage unit 110 and a control unit 120.

[0039] The storage unit 110 includes, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory) and stores programs and various data for execution by the control unit 120 .

[0040] The control unit 120 is, for example, a CPU (Central Processing Unit). The control unit 120 controls the operation of the internal combustion engine 1 by executing a program stored in the storage unit 110. In this embodiment, the control unit 120 functions as a valve control unit 122, an operation determination unit 123, a temperature acquisition unit 124, and an injection control unit 125.

[0041] The valve control unit 122 controls the opening and closing of the EGR valve 54. When the valve control unit 122 opens the EGR valve 54, a portion of the exhaust gas flows as EGR gas within the EGR passage 52. On the other hand, when the valve control unit 122 closes the EGR valve 54, EGR gas does not flow within the EGR passage 52. The valve control unit 122 outputs information indicating the open / closed state of the EGR valve 54 to the actuation determination unit 123.

[0042] The operation determination unit 123 determines whether the EGR device 50 is operating. For example, the operation determination unit 123 determines whether the EGR device 50 is operating based on the open / closed state of the EGR valve 54 controlled by the valve control unit 122. Specifically, the operation determination unit 123 determines that the EGR device 50 is operating when the EGR valve 54 is open, and determines that the EGR device 50 is not operating when the EGR valve 54 is closed.

[0043] The temperature acquisition unit 124 acquires the temperature of the EGR gas detected by the temperature sensor 55 of the EGR device 50. Here, the temperature acquisition unit 124 estimates the temperature detected by the temperature sensor 55 as the temperature of the exhaust gas upstream of the turbine 42T in the exhaust passage 30 (hereinafter referred to as the turbine upstream temperature) and acquires the temperature detected by the temperature sensor 55. Specifically, when the EGR device 50 is operating, the temperature acquisition unit 124 estimates the temperature detected by the temperature sensor 55 of the EGR device 50 as the turbine upstream temperature and acquires the temperature detected by the temperature sensor 55 of the EGR device 50.

[0044] In this embodiment, no temperature sensor for detecting the temperature of the exhaust gas is provided between the exhaust manifold 32 and the turbine 42T in the exhaust passage 30. Therefore, the temperature sensor 55 provided in the EGR passage 52 is the temperature sensor located upstream and closest to the turbine 42T. In addition, the distance between the temperature sensor 55 and the engine body 10 is approximately the same as the distance between the turbine 42T and the engine body 10. As an example, Figure 1 In FIG, the distance between the temperature sensor 55 and the engine main body 10 is the same as the distance between the turbine 42T and the engine main body 10. Therefore, the temperature of the EGR gas detected by the temperature sensor 55 is substantially the same as the turbine upstream temperature.

[0045] The injection control unit 125 controls the fuel injection from the fuel injection device 15 to the engine body 10. For example, the injection control unit 125 sets the injection amount of the fuel and injects the fuel at an injection timing corresponding to the set injection amount.

[0046] The injection control unit 125 controls fuel injection based on whether the EGR device 50 is operating. For example, if the operation determination unit 123 determines that the EGR device 50 is operating, the injection control unit 125 controls fuel injection into the engine body 10 based on the temperature detected by the temperature sensor 55. Specifically, the injection control unit 125 controls fuel injection into the engine body 10 based on the temperature upstream of the turbine. For example, the injection control unit 125 controls fuel injection into the engine body 10 so that the temperature detected by the temperature sensor 55 does not exceed an upper limit temperature. In this context, the upper limit temperature is a temperature at which the turbine 42T is not damaged by the heat of the exhaust gas, for example, 150°C.

[0047] On the other hand, when it is determined that the EGR device 50 is not operating, the injection control unit 125 controls the fuel injection in such a way that the temperature of the exhaust gas flowing to the turbine does not exceed a predetermined threshold value. That is, the injection control unit 125 limits the amount of fuel injected in such a way that the temperature of the exhaust gas does not exceed the threshold value. The temperature of the exhaust gas can be detected, for example, by a temperature sensor provided in the after-treatment device 35. The threshold value is a temperature lower than the above-mentioned upper limit temperature, for example, 140°C. In this way, the temperature of the exhaust gas can be suppressed from becoming high, so that damage to the turbine 42T due to the heat of the exhaust gas can be prevented. In addition, the upper limit temperature and the threshold value are stored in the storage unit 110, for example.

[0048] In this embodiment, when the EGR device 50 is operating, the turbine upstream temperature is accurately estimated using the detection results of the temperature sensor 55. Fuel is injected so that the temperature does not exceed the upper limit. This prevents excessive restriction of the fuel injection amount, thereby achieving high output for the internal combustion engine 1. Furthermore, when the EGR device 50 is not operating, EGR gas does not flow through the EGR passage 52, so the temperature detected by the temperature sensor 55 may deviate from the actual turbine upstream temperature. Therefore, by not using the detection results of the temperature sensor 55 when the EGR device 50 is not operating, erroneous control of the injection amount can be prevented.

[0049] <Operation Example of Internal Combustion Engine>

[0050] Reference Figure 3 An operation example of the internal combustion engine 1 will be described.

[0051] Figure 3 This is a flowchart for explaining an example of the operation of the internal combustion engine 1. This flowchart starts when the internal combustion engine 1 is operating. At the same time, exhaust gas generated from the engine body 10 is flowing through the exhaust passage 30.

[0052] First, the operation determination unit 123 of the control device 100 determines whether the EGR valve 54 is open (step S102 ). For example, the operation determination unit 123 determines whether the EGR valve 54 is open based on the control state of the EGR valve 54 by the valve control unit 122 .

[0053] If it is determined in step S102 that the EGR valve 54 is open (Yes), the operation determination unit 123 determines that the EGR device 50 is operating (step S104 ). That is, the operation determination unit 123 determines that the EGR gas is flowing in the EGR passage 52 .

[0054] Next, the temperature acquisition unit 124 acquires the temperature of the EGR gas flowing in the EGR passage 52 as the exhaust gas temperature upstream of the turbine 42T, ie, the turbine upstream temperature (step S106). For example, the temperature acquisition unit 124 acquires the turbine upstream temperature at predetermined intervals.

[0055] Next, the injection control unit 125 causes the fuel injection device 15 to inject fuel so that the turbine upstream temperature acquired by the temperature acquisition unit 124 does not exceed the upper limit temperature (step S108). That is, when the EGR device 50 is operating, the injection control unit 125 causes the fuel injection device 15 to inject fuel so that the upper limit temperature is not exceeded to prevent damage to the turbine 42T.

[0056] On the other hand, if it is determined in step S102 that the EGR valve 54 is closed (No), the operation determination unit 123 determines that the EGR device 50 is not operating (step S110 ).

[0057] Next, the injection control unit 125 causes the fuel injection device 15 to inject fuel so that the exhaust gas temperature does not exceed a threshold value (step S112). That is, when the EGR device 50 is not operating, the injection control unit 125 causes the fuel injection device 15 to inject fuel so that the exhaust gas temperature does not exceed a threshold value lower than the upper limit temperature.

[0058] <Effects of this embodiment>

[0059] When it is determined that the EGR device 50 is operating, the control device 100 of the internal combustion engine 1 in the above-described embodiment controls fuel injection into the engine body 10 based on the temperature detected by the temperature sensor 55 provided in the EGR device 50. On the other hand, when it is determined that the EGR device 50 is not operating, the internal combustion engine 1 controls fuel injection so that the temperature of the exhaust gas flowing into the turbine 42T does not exceed a predetermined threshold value.

[0060] Thus, when the EGR device 50 is operating, the exhaust gas temperature upstream of the turbine 42T (turbine upstream temperature) can be estimated with high accuracy based on the temperature of the EGR gas detected by the temperature sensor 55 of the EGR device 50. This allows the internal combustion engine 1 to achieve high output while suppressing damage to the turbine 42T. On the other hand, when the EGR device 50 is not operating, fuel is injected so that the exhaust gas temperature does not exceed a predetermined threshold value, without using the temperature detected by the temperature sensor 55. This prevents erroneous control of fuel injection caused by erroneous estimation of the turbine upstream temperature.

[0061] While the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and alterations can be made within the scope of its main purpose. For example, all or part of the device can be functionally or physically dispersed or combined in arbitrary units. In addition, new embodiments generated by any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments generated by the combination have the effects of the original embodiments.

[0062] Reference numerals

[0063] 1 Internal combustion engine

[0064] 10 Engine body

[0065] 15 Fuel injection device

[0066] 20 Intake passage

[0067] 30 Exhaust passage

[0068] 35 Post-processing device

[0069] 42T turbine

[0070] 50 EGR device

[0071] 52 EGR passage

[0072] 54 EGR valve

[0073] 55 Temperature Sensor

[0074] 123 Action Determination Unit

[0075] 125 Injection Control Unit

Claims

1. An internal combustion engine comprising: The turbine of the supercharger is provided in an exhaust passage through which exhaust gas generated from the internal combustion engine body flows; An EGR device for returning a portion of the exhaust gas to the internal combustion engine body; a temperature sensor, disposed in the EGR device, for detecting the temperature of the reflowing exhaust gas; an operation determination unit for determining whether the EGR device is in operation; an injection control unit that controls fuel injection into the internal combustion engine body based on the temperature detected by the temperature sensor when the operation determination unit determines that the EGR device is operating, and controls fuel injection so that the temperature of the exhaust gas toward the turbine does not exceed a predetermined threshold value when the EGR device is determined not to be operating; as well as a temperature acquisition unit that estimates and acquires the temperature detected by the temperature sensor as the temperature of the exhaust gas upstream of the turbine in the exhaust passage, When the EGR device is determined to be operating, the injection control unit controls the fuel injection so that the temperature of the exhaust gas upstream of the turbine estimated by the temperature acquisition unit does not exceed a predetermined upper limit temperature.

2. The internal combustion engine according to claim 1, wherein The injection control unit: When the EGR device is determined to be inoperative, the fuel injection is controlled so as not to exceed the threshold value, which is a temperature lower than the upper limit temperature.

3. The internal combustion engine according to claim 1 or 2, wherein: The EGR device includes an EGR passage connecting an intake passage through which intake air flows toward the engine body and the exhaust passage. The temperature sensor is positioned closer to the exhaust passage than to the intake passage in the EGR passage.

4. The internal combustion engine according to claim 3, wherein: The temperature sensor is located at the same distance from the engine body as the turbine is located from the engine body.

5. The internal combustion engine according to claim 1, wherein A post-processing device is further provided, the post-processing device being provided in the exhaust passage and being used for purifying the exhaust gas. The turbine is positioned closer to the internal combustion engine body than to the after-treatment device in the exhaust passage.

6. The internal combustion engine according to claim 1, wherein The EGR device includes an openable and closable EGR valve for adjusting the flow rate of the recirculated exhaust gas. The operation determination unit determines that the EGR device is operating when the EGR valve is in an open state, and determines that the EGR device is not operating when the EGR valve is in a closed state.

Images