vehicle

Abstract

To avoid occurrence of embrittlement of an exhaust manifold using a metallic material that embrittles in a specific temperature region.SOLUTION: A vehicle V includes: an intake port and an exhaust port that are connected to a combustion chamber 2 of an engine 1; an exhaust manifold 30 connected to a downstream side of the exhaust port; an exhaust emission control device 15 provided in the exhaust passage 14 downstream of the exhaust manifold 30; and exhaust gas temperature control means 51 for controlling a temperature of exhaust gas discharged from the combustion chamber 2. The exhaust manifold 30 comprises a metallic material having a characteristic of embrittlement in a specific temperature region. When a member temperature of the exhaust manifold 30 is within the specific temperature range, the exhaust gas temperature control means 51 performs avoidance control for raising or lowering the temperature of the exhaust gas so as to cause the member temperature to deviate from the specific temperature region in accordance with an operating state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle equipped with an engine equipped with an exhaust manifold made of a metal material that becomes embrittled in a specific temperature range. [Background technology]

[0002] Generally, an engine has an intake port in a cylinder block and a cylinder head, which sends intake air into the combustion chamber, and an exhaust port leading from the combustion chamber. A fuel injection device is provided in the intake port or the combustion chamber, and the connection portions of the intake port and the exhaust port to the combustion chamber are opened and closed by valves, respectively.

[0003] An intake passage is connected to the upstream side of the intake port, and an exhaust passage is connected to the downstream side of the exhaust port. The exhaust passage is composed of an exhaust manifold (hereinafter referred to as the exhaust manifold) connected to the cylinder block, and various exhaust pipes such as a front pipe and a main pipe connected to the downstream end of the exhaust manifold. An exhaust purification device and a silencer are provided in the exhaust pipe depending on the type of engine and vehicle (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-150966 Summary of the Invention [Problem to be solved by the invention]

[0005] Exhaust manifolds are made of various metal materials with specific strengths and durability depending on the engine and vehicle specifications. Some of these metal materials become embrittled at certain temperatures. For example, ferritic stainless steel becomes embrittled at temperatures of 475°C ± 50°C.

[0006] Although exhaust manifolds made of such metallic materials have sufficient strength and durability, if the temperature of the components remains within a certain temperature range for a certain period of time, the material becomes susceptible to brittle fracture. Under such conditions, if excessive strain beyond what is normally expected occurs in the components, it may lead to the destruction of the parts.

[0007] Therefore, an object of the present invention is to prevent embrittlement of components in an exhaust manifold made of a metal material that becomes embrittled in a specific temperature range. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention employs a vehicle comprising an intake port and an exhaust port connected to a combustion chamber of an engine, an exhaust manifold connected downstream of the exhaust port, an exhaust purification device provided in an exhaust passage downstream of the exhaust manifold, and an exhaust gas temperature control means for controlling the temperature of exhaust gas discharged from the combustion chamber, wherein the exhaust manifold is made of a metal material that has the property of becoming embrittled in a specific temperature range, and when the temperature of a component of the exhaust manifold is within the specific temperature range, the exhaust gas temperature control means performs avoidance control to raise or lower the temperature of the exhaust gas depending on the driving state so that the component temperature deviates from the specific temperature range (Configuration 1).

[0009] In the configuration 1, the metallic material constituting the exhaust manifold may be, for example, ferritic stainless steel (configuration 2).

[0010] Further, in the configuration 1, the exhaust purification device is a diesel particulate filter, and the exhaust gas temperature control means performs regeneration control to restore the function of the diesel particulate filter, and if the avoidance control becomes necessary while the regeneration control is being performed, a configuration can be adopted in which the regeneration control is suppressed and control to lower the temperature of the exhaust gas is performed as the avoidance control (configuration 3).

[0011] Furthermore, a configuration in which both of the configurations 2 and 3 are added to the above configuration 1 may be adopted.

[0012] Furthermore, in each aspect consisting of any combination of the above, if the time elapsed since the temperature of the component entered the specific temperature range exceeds a predetermined time, a configuration can be adopted in which, if the vehicle speed is equal to or greater than the predetermined speed, control is performed to lower the temperature of the exhaust gas as the avoidance control, and if the vehicle speed is less than the predetermined speed, control is performed to raise the temperature of the exhaust gas as the avoidance control (Configuration 4).

[0013] In the fourth aspect, the avoidance control can be performed by changing the fuel injection amount or fuel injection timing of a fuel injection device that injects fuel. [Effects of the Invention]

[0014] The present invention can prevent embrittlement from occurring in an exhaust manifold made of a metal material that becomes embrittled in a specific temperature range. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing an engine and an engine control device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view showing an exhaust manifold according to the embodiment; [Figure 3] 3 is a flowchart showing an example of control according to the present invention. [Figure 4] 1 is an overall schematic diagram of a vehicle equipped with an engine and an engine control device according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will now be described with reference to the drawings. An engine 1 in this embodiment is a diesel engine for an automobile. Fig. 1 shows the engine 1 and a control device for the engine 1 in this embodiment, and Fig. 2 shows an exhaust manifold 30 provided in the engine 1. Fig. 3 shows an example of control of a vehicle V equipped with these, and Fig. 4 is a schematic diagram conceptually showing the configuration of the vehicle V.

[0017] The engine 1 of this embodiment is a diesel engine for an automobile. As shown in Fig. 1, the engine 1 is configured to include a combustion chamber 2 formed of a cylindrical space in which an air-fuel mixture is burned, an intake port for sending intake air into the combustion chamber 2, and an exhaust port drawn out from the combustion chamber 2, all of which are located within an engine body 6 equipped with a cylinder block and a cylinder head. The engine 1 also includes a fuel injection device for injecting fuel into the intake port or the combustion chamber 2. The intake port and the exhaust port are each opened and closed by a valve.

[0018] In this embodiment, a four-cylinder engine 1 having four cylinders is assumed, but the present invention is applicable regardless of the number of cylinders or the arrangement of the cylinders.

[0019] An intake passage 4, which introduces intake air into the combustion chamber 2, is drawn out through an intake port by an intake manifold 7 (hereinafter referred to as the intake manifold 7). The intake passage 4 is made up of a passage 3 inside the intake manifold 7, which is fixed to the cylinder block, and various intake pipes connected to the upstream end of the intake manifold 7. Along the intake pipe, from upstream to downstream, there are provided, in this order, an air cleaner, an air flow sensor that detects the amount of intake air to achieve a predetermined air-fuel ratio, a throttle valve 5 that controls the flow rate of intake air by changing the cross-sectional area of ​​the passage, and a surge tank that reduces the flow rate by temporarily storing excess intake air (the air cleaner, air flow sensor, surge tank, etc. are not shown).

[0020] An exhaust passage 14, which discharges exhaust gas from the combustion chamber 2, is drawn out through an exhaust port by an exhaust manifold 30 (hereinafter referred to as the exhaust manifold 30). The exhaust passage 14 is made up of a passage 31 inside the exhaust manifold 30, which is fixed to the cylinder block, and various exhaust pipes such as a front pipe and a main pipe connected to the downstream end of the exhaust manifold 30. An exhaust purification device 15, a silencer (muffler) 16, etc. are provided in the exhaust pipe.

[0021] The engine 1 of this embodiment also includes a turbocharger 10. As shown in Fig. 1, the turbocharger 10 is composed of a compressor 11 that is disposed in the intake passage 4 and that supercharges the intake air introduced into the combustion chamber, and an exhaust turbine 12 that is disposed in the exhaust passage 14. When the exhaust turbine 12 is rotated by the exhaust gas flowing through the exhaust passage 14, the rotation is transmitted to the compressor 11 in the intake passage 4. The rotation of the compressor 11 supercharges the intake air flowing through the intake passage 4. The intake passage 4 may also be provided with an intercooler (not shown) that cools the intake air.

[0022] The exhaust purification device 15 is provided for the purpose of purifying exhaust gas emitted from an engine of an automobile or the like before it is released into the atmosphere. The exhaust purification device in this embodiment is a diesel particulate filter installed to remove particulate matter (PM), which is a harmful substance contained in exhaust gas produced by burning diesel oil. In addition to the diesel particulate filter, the exhaust purification device 15 also includes a device for removing nitrogen oxides (NOX), which are harmful substances contained in exhaust gas.

[0023] These exhaust gas purification devices 15 are activated when the device reaches a certain temperature or higher, and perform the specified exhaust gas purification function. For this reason, it is desirable to increase the temperature of the exhaust gas as soon as possible after the engine starts, so that the exhaust gas purification device can be activated as early as possible.

[0024] Temperature detection means g for detecting the temperature of exhaust purification device 15 (temperature of exhaust gas) is provided in exhaust purification device 15 or in exhaust passage 14 before and after it. In FIG. 1, a temperature sensor that measures the temperature of exhaust and components near the inlet of exhaust purification device 15 is used as temperature detection means g, but the present invention is not limited to this form, and for example, the temperature sensor may be placed inside exhaust purification device 15 or near the outlet. The temperature of exhaust purification device 15 obtained by temperature detection means g is equivalent to the temperature of exhaust gas, and this temperature information is transmitted via a cable to electronic control unit 50 that controls engine 1.

[0025] Furthermore, various sensors such as an air-fuel ratio sensor (not shown) that detects the ratio of fuel to air in the exhaust gas are provided as needed in the exhaust passage 14 before and after the exhaust purification device 15. Information obtained by these sensors is also transmitted to the electronic control unit 50.

[0026] The exhaust passage 14 upstream of the exhaust purification device 15 and the space within the intake passage 4 are connected by an exhaust gas recirculation passage 21. The exhaust gas recirculation passage 21 is opened and closed by an exhaust gas recirculation valve, and a portion of the exhaust gas is recirculated into the intake passage 4 as recirculated gas. The exhaust gas recirculation passage 21, the exhaust gas recirculation valve, and other components constitute an exhaust gas recirculation device 20. Control of the exhaust gas recirculation device 20, including the opening and closing of the exhaust gas recirculation valve, is performed by control means 52 of the electronic control unit 50.

[0027] Generally, the oxygen content in exhaust gas is low or zero, so mixing this exhaust gas with intake air reduces the oxygen concentration in the intake air. This makes the intake air less oxygen-rich than the atmosphere, lowering the combustion temperature and suppressing the generation of nitrogen oxides. Furthermore, lowering the combustion temperature reduces the dissipation of heat energy from the walls of the combustion chamber 2 and the surface of the piston, which is said to contribute to reducing heat loss and suppressing knocking.

[0028] Furthermore, the control means 52 of the electronic control unit 50 determines the operating state of the vehicle V, in particular the operating state of the engine 1. The control means 52 acquires information such as the coolant temperature information, engine 1 rotation speed, engine 1 load, and vehicle V speed from the engine 1, and utilizes this information for the overall control of the engine 1. The intake valves, exhaust valves, fuel injection devices, and other devices necessary for engine operation are controlled by the control means 52.

[0029] Furthermore, the electronic control unit 50 is provided with exhaust gas temperature control means 51 that controls the temperature of the exhaust gas discharged from the combustion chamber 2. The exhaust gas temperature control means 51 functions in cooperation with the control means 52, and can perform control to increase the temperature of the exhaust gas (hereinafter referred to as temperature increase control) or control to decrease the temperature of the exhaust gas (hereinafter referred to as temperature decrease control) based on predetermined conditions.

[0030] Typical temperature rise control is performed when the engine is cold as described above. In order to quickly raise the temperature of the exhaust gas immediately after starting the engine 1, control is performed to increase the amount of fuel and air and retard the fuel injection timing. Information on whether the engine 1 is cold or has warmed up can be determined by obtaining the coolant temperature and the elapsed time since the engine 1 was started using a timer.

[0031] The engine 1 also uses an exhaust manifold 30 made of a material that becomes embrittled in a specific temperature range. In this embodiment, the exhaust manifold 30 is made of ferritic stainless steel. Ferritic stainless steel has the property of becoming embrittled in a temperature range of around 50°C around 475°C, so the specific temperature range is between 425°C and 525°C. Here, embrittlement refers to a material losing its ductility and toughness, becoming brittle and easily broken. For this reason, it is not desirable for the temperature of the components of the exhaust manifold 30 to remain within this specific temperature range for a long period of time.

[0032] Therefore, when the component temperature of the exhaust manifold 30 (the component temperature is considered to be equivalent to the exhaust temperature) is within a specific temperature range, the exhaust gas temperature control means 51 performs temperature increase control or temperature decrease control depending on the operating state to raise or lower the temperature of the exhaust manifold 30 and perform control to avoid the specific temperature range (hereinafter referred to as avoidance control) (Configuration 1). That is, in this embodiment, avoidance control is performed so that the component temperature falls outside the temperature range of 425°C or higher and lower than 525°C (Configuration 2).

[0033] In this embodiment, a diesel particulate filter is provided as the exhaust purification device 15. The diesel particulate filter has a filter therein that removes particulate matter, and traps the particulates to prevent them from being released into the atmosphere. However, if too many particulates accumulate in the filter, the filter will become clogged. Therefore, by raising the temperature of the exhaust gas (for example, to about 600°C to 700°C) under certain operating conditions, the accumulated particulates are burned and removed, and the function of the diesel particulate filter is restored. This control for removing the particulates will be referred to as regeneration control hereinafter. The regeneration control is controlled by exhaust gas temperature control means 51.

[0034] If regeneration control becomes necessary while regeneration control is being performed, the exhaust gas temperature control means 51 performs control to lower the temperature of the exhaust gas as avoidance control (Configuration 3).

[0035] In this regard, during regeneration control, feedback control of the exhaust gas temperature is in operation, and the temperature can be raised by increasing the post-addition amount, or lowered by decreasing it. Here, the post-addition amount refers to the amount of fuel injected in the post-injection that is performed after the main injection to raise the exhaust temperature. During regeneration control, the post-addition amount is often already set to maximize the combustion speed. For this reason, if, during regeneration control, the component temperature falls within the temperature range of 425°C or higher but lower than 525°C and avoidance control becomes necessary, it is more effective to control the exhaust gas temperature to lower it rather than to control it to further raise it.

[0036] From the above viewpoint, if avoidance control becomes necessary during regeneration control, the exhaust gas temperature control means 51 can temporarily suspend the regeneration control and perform avoidance control (Configuration 4). Then, after the avoidance control is completed and the component temperature leaves the temperature range of 425°C or higher and lower than 525°C, the regeneration control can be resumed.

[0037] It is known that embrittlement of components due to the above temperature conditions can be repaired by raising the component temperature above a specific temperature (600°C or higher in the case of ferritic stainless steel). However, in vehicles equipped with diesel engines, there are cases where driving conditions without high load operation continue for long periods of time, particularly depending on the driver's skill and the vehicle's use. If driving conditions without high load operation continue for long periods of time, a situation may arise where the temperature around 475°C becomes the normal operating range of the engine 1. For this reason, under such driving conditions, it is also effective to perform embrittlement repair control as an avoidance control by further raising the component temperature to above a specific temperature. However, it is desirable to avoid performing avoidance control (embrittlement repair control) in such a high temperature range for long periods of time, as it can lead to melting and damage to the diesel particulate filter.

[0038] Furthermore, the exhaust gas temperature control means 51 can perform avoidance control by lowering the temperature of the exhaust gas when the time that has elapsed since the temperature of the component entered a specific temperature range is equal to or less than a predetermined time (Configuration 5).

[0039] Furthermore, when the time elapsed since the component temperature entered a specific temperature range exceeds a predetermined time, if the speed of the vehicle V is equal to or greater than a predetermined speed, the exhaust gas temperature control means 51 performs avoidance control by controlling to lower the temperature of the exhaust gas, and if the speed of the vehicle V is less than the predetermined speed, performs avoidance control by controlling to raise the temperature of the exhaust gas (Configuration 6). Note that information on the speed of the vehicle V is detected by a speed sensor f (see FIG. 4).

[0040] In this regard, even if the component temperature enters a specific temperature range, embrittlement of the component does not occur immediately, so it is important to determine when to start avoidance control. Therefore, as a criterion for determining when to start avoidance control, it is effective to distinguish between cases where the elapsed time is equal to or less than a predetermined time (Configuration 5) and where the elapsed time exceeds the predetermined time (Configuration 6) based on the elapsed time since the component temperature entered the specific temperature range. Here, the elapsed time can be detected by a timer provided in the electronic control unit 50. The predetermined time can be, for example, 10 minutes (600 seconds). The predetermined time can be shorter during idling or low speed than during high speed, for example, 5 minutes (300 seconds). When avoidance control is started, the timer is reset.

[0041] Specifically, in the case of configuration 5, it is considered that the temperature of the exhaust gas is not yet very high because the elapsed time is not yet that long. Therefore, the avoidance control is performed by controlling the temperature of the exhaust gas to decrease it.

[0042] Furthermore, specifically, in the case of configuration 6, since the elapsed time is relatively long, when the speed of the vehicle V is equal to or greater than a predetermined speed, the effect of air cooling on the engine 1 and the radiator is high, making it an environment in which temperature rise is relatively difficult. For this reason, it is effective to select control that lowers the temperature of the exhaust gas as the avoidance control. Furthermore, when the speed of the vehicle V is less than a predetermined speed, the effect of air cooling on the engine 1 and the radiator is low, making it an environment in which temperature rise is relatively easy. For this reason, it is effective to select control that raises the temperature of the exhaust gas as the avoidance control.

[0043] First, when the speed of the vehicle V is equal to or greater than a predetermined speed (for example, 20 km / h), the wind speed hitting the vehicle V is high, and the engine 1 is required to have a certain level of output performance. Furthermore, because the speed of the vehicle V is high, a certain degree of increase in noise inside the vehicle can be tolerated. For this reason, it is possible to adopt a means for lowering the temperature of the exhaust gas, such as by advancing the injection timing. Furthermore, if split injection (fuel injection in multiple divided injections during one cycle) is being performed at that time, it is also possible to control the engine 1 to reduce the number of split injections. Furthermore, if split injection is being performed in three or more stages, it is also effective to reduce the number of split injections in stages to reduce the number of split injections.

[0044] Conversely, when the speed of the vehicle V is less than a predetermined speed (for example, 20 km / h), the wind speed hitting the vehicle V is low, and the output performance of the engine 1 is not required to be as high. However, since the speed is low, the situation is such that the increase in noise inside the vehicle is unacceptable. For this reason, when performing temperature increase control as avoidance control, it is effective to perform the aforementioned embrittlement recovery control by, for example, retarding the injection timing.

[0045] The exhaust manifold 30 is provided with a temperature detection means h that detects the temperature of components of the exhaust manifold 30. In FIG. 2, a temperature sensor that measures the temperature of the exhaust gas and components near the fourth cylinder is used as the temperature detection means h. Providing the temperature detection means h in the exhaust manifold 30 is preferable because it improves the accuracy of the temperature conditions when performing embrittlement recovery control. It is particularly effective to provide the temperature detection means h at the point when the temperature conditions are the worst or at the point where distortion is most likely to occur. However, this is not limiting, and for example, the temperature sensor may be installed in a location other than near the fourth cylinder. Furthermore, information from a temperature detection means g installed near the exhaust purification device 15 may be used, or temperature information estimated and calculated from various operating conditions may be utilized.

[0046] Furthermore, in a so-called longitudinally mounted engine in which multiple cylinders (combustion chambers 2) are arranged in parallel in the longitudinal direction of the vehicle, the frontmost cylinder tends to cool most easily, and the rearmost cylinder tends to cool least. For this reason, when a temperature detection means h is provided in the exhaust manifold 30, it is desirable to provide the temperature detection means h near the rearmost cylinder, which has the worst cooling conditions. In FIG. 2, the fourth cylinder (corresponding to reference numeral 13a in FIG. 2) in which the temperature detection means h is provided is the rearmost cylinder, and corresponds to a cylinder that is more difficult to cool than the other first to third cylinders (corresponding to reference numerals 13d to 13b in FIG. 2) located in front of it. Note that reference numeral 22 in FIGS. 1 and 2 denotes a passage that constitutes a part of the exhaust recirculation passage 21.

[0047] An example of the control of the present invention will be described with reference to the flowchart of FIG.

[0048] Control is started in step S1, and the exhaust manifold surface temperature (temperature of components of the exhaust manifold 30) is acquired in step S2. In the following step S3, it is determined whether the exhaust manifold surface temperature is in a specific temperature range (a range of 425°C or higher and lower than 525°C). If the exhaust manifold surface temperature is in the specific temperature range, the process proceeds to step S4, where the accumulation of the elapsed time since the exhaust manifold surface temperature entered the specific temperature range is started, and then the process proceeds to step S5. On the other hand, if the exhaust manifold surface temperature is not in the specific temperature range, the process proceeds to step S13, and the control ends.

[0049] In step S5, it is determined whether POST fuel addition is in progress, i.e., whether post injection, which is performed after the main injection, is being performed. Post injection is also a form of divided injection that is performed during regeneration control of the diesel particulate filter. If POST fuel addition is in progress, the process proceeds to step S6, and if POST fuel addition is not in progress, the process proceeds to step S8.

[0050] In step S6, the exhaust target temperature is lowered, i.e., exhaust gas temperature is controlled to fall outside a specific temperature range. Here, POST reduction is performed (the amount of fuel injected by post injection is reduced), regeneration control is temporarily suspended, and avoidance control (temperature reduction control) is prioritized. Next, the process proceeds to step S12, and if there is a change in the gear position or required torque of the transmission mechanism, the process proceeds to step S13 and the avoidance control is terminated. If there is no change in the gear position or required torque of the transmission mechanism, the process returns to step S5 and the control is repeated.

[0051] In step S8, it is determined whether the cumulative time A (cumulative value of elapsed time) since entering the specific temperature range exceeds a predetermined time T. If the cumulative time A exceeds the predetermined time T, the process proceeds to step S9. If the cumulative time A does not exceed the predetermined time T, the process proceeds to step S11.

[0052] Next, in step S9, it is determined whether the vehicle speed (speed of the vehicle V) is less than a predetermined speed V. If the vehicle speed is less than the predetermined speed V, the process proceeds to step S10. If the vehicle speed is not less than the predetermined speed V, the process proceeds to step S11.

[0053] If the process proceeds to step S10, avoidance control accompanied by embrittlement recovery (embrittlement recovery control (temperature increase control)) is performed by, for example, retarding the fuel injection timing. If the process proceeds to step S11, avoidance control not accompanied by embrittlement recovery (temperature decrease control) is performed by, for example, advancing the fuel injection timing. Next, the process proceeds to step S12, and if there is a change in the gear position or required torque of the transmission mechanism, the process proceeds to step S13, where the avoidance control ends. If there is no change in the gear position or required torque of the transmission mechanism, the process returns to step S5, and the control is repeated.

[0054] In this embodiment, the metal material constituting the exhaust manifold 30 is ferritic stainless steel, but the metal material from which the exhaust manifold 30 is made is not limited to this embodiment and may be other metal materials that have the property of becoming embrittled in a specific temperature range.

[0055] Furthermore, in this embodiment, the present invention has been described using an automobile diesel engine as an example of the engine 1, but the present invention can also be applied to engines of other types than diesel engines.

[0056] In this embodiment, a diesel particulate filter that removes particulate matter, which is a harmful substance, is used as the exhaust purification device 15. However, the exhaust purification device 15 may also be a purification device that requires a certain degree of temperature rise in order to perform other functions. For example, the exhaust purification device 15 may be a purification device that removes hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO), which are harmful substances contained in exhaust gas. X The avoidance control may be a three-way catalyst or other purification device that removes pollutants such as pollutants. Furthermore, although the avoidance control is performed by controlling the fuel injection amount and fuel injection timing of the fuel injection device, it may also be a heating means or cooling means that can directly raise or lower the temperature of the exhaust manifold, such as an electric heater attached to the exhaust manifold and controlled to be on / off, or a cooling device attached to the exhaust manifold and controlled to control the amount of water. [Explanation of symbols]

[0057] 1 engine 2. Combustion chamber 4 Intake passage 6 Engine body 7. Intake manifold 14 Exhaust passage 15 Exhaust purification device 30 Exhaust manifold 50 Electronic Control Unit 51 Exhaust gas temperature control means V vehicle

Claims

1. an intake port and an exhaust port connected to a combustion chamber of the engine; an exhaust manifold connected to the downstream side of the exhaust port; an exhaust purification device provided in an exhaust passage downstream of the exhaust manifold; an exhaust gas temperature control means for controlling the temperature of exhaust gas discharged from the combustion chamber; Equipped with Exhaust manifolds are made of metal materials that become brittle in certain temperature ranges. A vehicle in which, when the component temperature of the exhaust manifold is within the specific temperature range, the exhaust gas temperature control means performs avoidance control to raise or lower the temperature of the exhaust gas so that the component temperature falls outside the specific temperature range, depending on the driving state.

2. The metal material constituting the exhaust manifold is ferritic stainless steel. The vehicle of claim 1 .

3. the exhaust purification device is a diesel particulate filter, the exhaust gas temperature control means performs regeneration control to restore the function of the diesel particulate filter, 2. The vehicle according to claim 1, wherein, when the avoidance control becomes necessary while the regeneration control is being performed, the regeneration control is suppressed and the avoidance control is performed by controlling the temperature of the exhaust gas to decrease.

4. A vehicle as described in any one of claims 1 to 3, wherein, when the elapsed time since the component temperature entered the specific temperature range exceeds a predetermined time, if the vehicle speed is equal to or greater than the predetermined speed, the avoidance control is to control the temperature of the exhaust gas to decrease, and if the vehicle speed is less than the predetermined speed, the avoidance control is to control the temperature of the exhaust gas to increase.

5. 5. The vehicle according to claim 4, wherein the avoidance control is performed by changing a fuel injection amount or a fuel injection timing of a fuel injection device that injects fuel.

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