Wastegate valve control device for a supercharged internal combustion engine with a positive crankcase ventilation valve

Abstract

To provide a wastegate valve control device of an internal combustion engine with a supercharger having a positive crankcase ventilation valve which can reduce a malfunction for blocking a path caused by the dew condensation and the freezing of a water component in a blowby gas even if a sensor for measuring an intake air temperature is failed.SOLUTION: A wastegate valve control device 112 of an internal combustion engine with a supercharger having a positive crankcase ventilation valve comprises an input part 201 for accepting an intake air temperature which is measured by an intake air temperature sensor of the internal combustion engine, and a controller 204 for performing control to prohibit the closure of a wastegate valve 109 when a temperature sensor 104 is failed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a wastegate valve control device for a supercharged internal combustion engine having a positive crankcase ventilation valve. [Background technology]

[0002] A turbocharged internal combustion engine uses the exhaust flow to drive a compressor, increasing the density of the air drawn into the engine, allowing more oxygen to be sent to the combustion chamber and resulting in higher combustion energy.

[0003] On the other hand, in a turbocharged internal combustion engine, the pressure inside the combustion chamber is high, and unburned gases and the air-fuel mixture tend to leak into the crankcase through the gap between the engine's cylinder and piston. This gas is called blow-by gas.

[0004] Patent Document 1 describes a turbocharged internal combustion engine equipped with a blow-by gas treatment device, in which when the load on the internal combustion engine is low, the wastegate valve is controlled to be fully open so that the exhaust turbine is driven with minimum driving efficiency, and the amount of blow-by gas returned by the ejector 11 is kept to a minimum, thereby suppressing a decrease in ventilation efficiency of the blow-by gas due to the backflow of outside air. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-98814 Summary of the Invention [Problem to be solved by the invention]

[0006] In a supercharged engine equipped with a WGV, closing the WGV beforehand in a range where supercharging is not required (Natural Aspiration (NA) range) can improve supercharging response and is expected to result in improved acceleration performance. When the pressure inside the intake manifold becomes positive, blow-by gas flows back into the atmosphere side of the PCV in the blow-by gas treatment device. Under low intake air temperature conditions, the hose on the atmosphere side of the PCV cools, causing the moisture in the blow-by gas to condense and freeze, which could block the path. In particular, when driving steadily at high speeds and in high gears, the engine load is high and the pressure inside the intake manifold remains positive, increasing the risk of freezing.

[0007] For example, if the sensor that measures intake air temperature fails and normal temperature is set as the failsafe value, the wastegate valve may close, causing the pressure in the intake manifold to rise. As a result, if blow-by gas flows back in a low-temperature environment, the moisture in the blow-by gas may condense and freeze, blocking the passage. [Means for solving the problem]

[0008] The wastegate valve control device for a supercharged internal combustion engine having a positive crankcase ventilation valve according to the present disclosure is configured to perform control to prohibit the wastegate valve from closing if a temperature sensor fails. [Effects of the Invention]

[0009] According to the wastegate valve control device for a turbocharged internal combustion engine having a positive crankcase ventilation valve disclosed herein, even if the sensor that measures the intake air temperature fails, the problem of moisture in the blow-by gas condensing and freezing, causing the passage to become blocked, can be reduced. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing an example of an internal combustion engine system according to an embodiment of the present invention; [Figure 2]2 is a block diagram showing an example of the internal configuration of an ECU 112 according to the present embodiment. FIG. [Figure 3] 4 is a flowchart showing an example of the operation of the ECU 112 according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] This embodiment Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram showing an example of an internal combustion engine system according to this embodiment. In Fig. 1, the internal combustion engine system 10 includes an engine 100, an intake passage 101, an exhaust passage 102, an air flow meter 103, an intake temperature sensor 104, a turbocharger 105, a throttle valve 106, a throttle position sensor 107, an exhaust bypass passage 108, a WGV (WASTE GATE VALVE) 109, a blow-by gas passage 110, a PCV (Positive Crankcase Ventilation) valve 111, and an ECU (Engine Control Unit) 112.

[0012] Each cylinder of the engine 100 is connected to an intake passage 101 and an exhaust passage 102. The turbocharger 105 includes a compressor 151 and a turbine 152. The blow-by gas passage 110 includes a light load blow-by gas passage 113 and a high load blow-by gas passage 114.

[0013] The engine 100 is an internal combustion engine that burns fuel such as gasoline in a cylinder and obtains power using the combustion gases generated thereby.

[0014] The intake passage 101 is a passage through which air is introduced into the engine 100. Near the inlet of the intake passage 101, an air flow meter 103 and an intake air temperature sensor 104 are provided.

[0015] The exhaust passage 102 is a passage through which exhaust gas emitted from the engine 100 is released into the atmosphere. An exhaust bypass passage 108 that bypasses the turbine 152 is connected to the exhaust passage 102.

[0016] The air flow meter 103 outputs a signal to the ECU 112 according to the flow rate of air taken into the intake passage 101 .

[0017] The intake air temperature sensor 104 outputs to the ECU 112 a signal corresponding to the temperature of the air taken into the intake passage 101 (the intake air temperature or the outside air temperature). A compressor 151 of a turbocharger 105 is installed downstream of the air flow meter 103 and the intake air temperature sensor 104 .

[0018] The turbocharger 105 is a supercharger that uses the flow of exhaust gas to increase the density of the air that is taken in by the internal combustion engine. The turbocharger 105 includes a compressor 151, a turbine 152, and a connecting shaft 153.

[0019] The compressor 151 is integrally connected to a turbine 152 disposed in the exhaust passage 102 via a connecting shaft 153. The compressor 151 increases the density of the air that is taken in by the power transmitted from the turbine 152. A throttle valve 106 is provided downstream of the compressor 151 to adjust the amount of air taken in by the engine 100.

[0020] The turbine 152 rotates using the flow of exhaust gas, and transmits the power generated by the rotation to the compressor 151 via a connecting shaft 153.

[0021] The throttle valve 106 is an electronically controlled valve that is driven by a throttle motor (not shown) based on the accelerator opening. A throttle position sensor 107 is disposed near the throttle valve 106.

[0022] The throttle position sensor 107 is a sensor that detects the throttle opening and outputs a signal corresponding to the detected throttle opening to the ECU 112.

[0023] The exhaust bypass passage 108 is a passage that releases the exhaust gas into the atmosphere, bypassing the turbine 152. A WGV 109 is provided midway along the exhaust bypass passage 108.

[0024] The WGV 109 is a valve that opens and closes the exhaust bypass passage 108. Specifically, the WGV 109 is connected to the inside of the crankcase of the engine 100, and opens to allow ventilation in only one direction when the internal pressure of the intake manifold is lower than that of the crankcase. Here, the WGV 109 is configured so that it can be adjusted to any opening degree by a pressure-regulating or electric actuator (not shown).

[0025] The blow-by gas passage 110 is a passage 110 that connects the engine 100 and the intake passage 101 in order to process blow-by gas generated inside the engine 100. More specifically, the blow-by gas passage 110, one end of which is connected to the engine 100, branches into a light load blow-by gas passage 113 and a heavy load blow-by gas passage 114 midway.

[0026] Here, the passage that is connected to the intake passage 101 downstream of the throttle valve 106 after branching is referred to as a light load blow-by gas passage 113. Also, the passage that is connected to the intake passage 101 upstream of the compressor 151 after branching is referred to as a high load blow-by gas passage 114.

[0027] The PCV valve 111 is a valve that operates in response to intake negative pressure. The PCV valve 111 is installed in the middle of a light-load blow-by gas passage 113. Under a light load, the PCV valve 111 opens, and blow-by gas in an amount corresponding to the intake manifold negative pressure downstream of the throttle valve 106 is introduced into the intake passage 101 downstream of the throttle valve 106 via the light-load blow-by gas passage 113. On the other hand, under a high load (supercharging), the PCV valve 111 closes, and the blow-by gas is introduced into the intake passage 101 upstream of the compressor 151 via a high-load blow-by gas passage 114.

[0028] The ECU 112 is a control device that controls the internal combustion engine system 10. The ECU 112 also functions as a wastegate valve control device for a supercharged internal combustion engine having a positive crankcase ventilation valve.

[0029] The ECU 112 then checks whether an abnormality has occurred in the intake air temperature sensor 104. If an abnormality has occurred in the intake air temperature sensor 104, the ECU 112 prohibits the WGV 109 from closing. For example, if the output of the intake air temperature sensor 104 indicates a value outside a predetermined temperature range, the ECU 112 determines that an abnormality has occurred in the intake air temperature sensor 104. The ECU 112 then sets the intake air temperature to a fail-safe value and performs control. The ECU 112 sets the fail-safe value, which is a control that prohibits the WGV 109 from closing. For example, the ECU 112 sets the fail-safe value to -40°C. Note that for control other than the WGV 109, the ECU 112 may set the fail-safe value to room temperature (for example, 20°C).

[0030] Note that a description of engine control other than that of the WGV 109 will be omitted. Also, various sensors for detecting the operating state of the engine 100, such as the air flow meter 103, intake air temperature sensor 104, and throttle position sensor 107, are connected to an input section of the ECU 112. Also, various actuators for controlling the operating state of the engine 100, such as the throttle valve 106 and WGV 109, as well as fuel injection valves that supply fuel to the engine 100, are connected to an output section of the ECU 112.

[0031] Next, details of the ECU 112 will be described. Fig. 2 is a block diagram showing an example of the internal configuration of the ECU 112 of this embodiment. In Fig. 2, the ECU 112 includes an input unit 201, a temperature sensor check unit 202, a fail-safe value setting unit 203, a WGV control unit 204, and an output unit 205.

[0032] Various sensors for detecting the operating state of the engine 100, such as the air flow meter 103, the intake air temperature sensor 104, and the throttle position sensor 107, are connected to the input unit 201. The input unit 201 receives outputs from these sensors.

[0033] The temperature sensor check unit 202 checks the output value of a temperature sensor that detects the intake air temperature and determines whether the output value of the temperature sensor is abnormal. If the temperature sensor check unit 202 detects that the output value of the temperature sensor is abnormal, it notifies the fail-safe value setting unit 203 to that effect.

[0034] If the output value of the temperature sensor is abnormal, fail-safe value setting unit 203 sets the detected value of the intake air temperature to a reference temperature (for example, −40° C.) or lower that prohibits control of closing the wastegate valve. Then, fail-safe value setting unit 203 outputs the set fail-safe value as the output value of the temperature sensor to WGV control unit 204. On the other hand, if the output value of the temperature sensor is normal, fail-safe value setting unit 203 outputs the output value of the temperature sensor to WGV control unit 204.

[0035] The WGV control unit 204 is a controller that controls the opening and closing of the wastegate valve. For example, when the intake air temperature is higher than a predetermined reference value, the WGV control unit 204 controls the opening of the WGV 109 in accordance with the throttle opening detected by the throttle position sensor 107. When the intake air temperature is equal to or lower than the predetermined reference value, the WGV control unit 204 prohibits the WGV 109 from closing.

[0036] To the output section 205, in addition to the throttle valve 106 and WGV 109, various actuators for controlling the operating state of the engine 100, such as a fuel injection valve that supplies fuel to the engine 100, are connected.

[0037] Next, a description will be given of the operation of the ECU 112. Fig. 3 is a flowchart showing an example of the operation of the ECU 112 according to this embodiment.

[0038] First, in step S301, the intake air temperature sensor 104 measures the temperature of the intake air taken into the intake passage 101. Then, the intake air temperature sensor 104 outputs a signal according to the intake air temperature to the ECU 112. Then, the process proceeds to step S302.

[0039] In step S302, the temperature sensor check unit 202 of the ECU 112 determines whether or not there is an abnormality in the output value of the intake air temperature sensor 104. If there is an abnormality in the output value, the process proceeds to step S303. If there is no abnormality in the output value, the process proceeds to step S304.

[0040] In step S303, the fail-safe value setting unit 203 sets the detected value of the intake air temperature to a reference temperature or lower that prohibits the wastegate valve from being closed, and then the process proceeds to step S304.

[0041] In step S304, throttle position sensor 107 detects the throttle opening, and outputs a signal corresponding to the detected throttle opening to ECU 112. Then, the process proceeds to step S305.

[0042] In step S305, WGV control unit 204 determines whether the intake air temperature is equal to or lower than a predetermined reference value or higher than the reference value. If the intake air temperature is equal to or lower than the predetermined reference value, the process proceeds to step S306. If the intake air temperature is higher than the predetermined reference value, the process proceeds to step S307.

[0043] In step S306, the WGV control unit 204 prohibits the WGV 109 from closing, and then ends the process.

[0044] In step S307, the WGV control unit 204 controls the opening of the WGV 109 in accordance with the throttle opening detected by the throttle position sensor 107. Then, the process ends.

[0045] The series of processes in FIG. 3 may be repeated periodically as necessary.

[0046] In this way, the wastegate valve control device of this embodiment prohibits the WGV from closing if the temperature sensor fails, thereby preventing a pressure increase in the intake manifold due to the valve closure. As a result, backflow of blow-by gas in low-temperature environments is suppressed, reducing problems such as path blockage caused by condensation or freezing of moisture in the blow-by gas.

[0047] Furthermore, when the intake air temperature sensor fails, even if the fail-safe value is set to room temperature (for example, 20°C), the WGV control will set the detected value to a low temperature value, preventing the valve from being closed erroneously.

[0048] The present invention is not limited to the above-described embodiment, and modifications can be made as appropriate without departing from the spirit of the present invention. For example, the conditions for prohibiting closure of WGV 109 may be, in addition to when the intake air temperature is equal to or lower than a predetermined reference value, when at least one of the following conditions is satisfied: vehicle speed is higher than a predetermined speed; or the transmission gear ratio is high (i.e., the engine load is high). Furthermore, the operation for prohibiting control to close WGV 109 may be controlled by setting a prohibition flag. [Explanation of symbols]

[0049] 10 Internal combustion engine system 100 Engine 101 Intake passage 102 Exhaust passage 103 Air flow meter 104 Intake air temperature sensor 105 Turbocharger 106 Throttle valve 107 Throttle position sensor 108 Exhaust bypass passage 110 Blow-by gas passage 111 PCV valve 113 Blow-by gas passage under light load 114 Blow-by gas passage under high load 151 Compressor 152 Turbine 153 Connecting shaft 201 Input section 202 Temperature sensor check section 203 Fail-safe value setting section 204 Control Unit 205 Output section

Claims

[Claim 1] an input unit that receives an intake air temperature measured by an intake air temperature sensor of the internal combustion engine; a controller that performs control to prohibit closing of the wastegate valve when the intake air temperature sensor fails. A wastegate valve control device for a supercharged internal combustion engine having a positive crankcase ventilation valve, comprising: The controller uses a detected value of the intake air temperature for control when the intake air temperature sensor is not malfunctioning, When the intake air temperature sensor fails, the controller sets a detected value of the intake air temperature used to control the wastegate valve to a reference temperature or lower that prohibits control of the wastegate valve to close, and sets a detected value of the intake air temperature used to control valves other than the wastegate valve to room temperature; The reference temperature is lower than room temperature, The wastegate valve control device for a turbocharged internal combustion engine having a positive crankcase ventilation valve, wherein the controller performs control to prohibit the wastegate valve from closing when the detected value of the intake air temperature is equal to or lower than a predetermined reference value.

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