JP-2026075235-A - Dry sump engine

JP2026075235AJP 2026075235 AJP2026075235 AJP 2026075235AJP-2026075235-A

Abstract

[Problem] To reliably prevent or suppress the rise in internal pressure of the oil tank with a simple structure. [Solution] The system includes an on/off valve 15 provided between the oil tank 3 and a gas receiving section 10 that receives blow-by gas without leaking it to the outside, and a controller 19 that controls the on/off valve 15. The controller 19 includes a low-pressure determination unit that determines that the pressure inside the oil tank 3 is lower than a predetermined first reference pressure, a determination unit that determines that a predetermined condition other than the pressure inside the oil tank being lower than the first reference pressure has been met, and an opening control unit that opens the on/off valve 15 when the low-pressure determination unit determines that the pressure inside the oil tank is lower than the first reference pressure, or when the determination unit determines that a predetermined condition has been met. [Selection Diagram] Figure 1

Inventors

東雄大
堀井裕也
弓削元宏
竹内寛貴

Assignees

トヨタ自動車株式会社

Dates

Publication Date: 20260508
Application Date: 20241022

Claims (6)

A dry sump engine comprising: an oil tank for receiving lubricating oil and blow-by gas sent from the crankcase or oil pan by a pump; a pipeline for sending the blow-by gas from the oil tank to the intake side; and a PCV valve provided in the pipeline that opens when the pressure in the oil tank is higher than the pressure on the intake side, An on/off valve is provided between the oil tank and a gas receiving section that receives the blow-by gas without leaking it to the outside, The system includes a controller for controlling the on/off valve, The aforementioned controller, A low-pressure determination unit that determines whether the pressure inside the oil tank is lower than a predetermined first reference pressure, A determination unit that determines whether predetermined conditions are met, except that the pressure inside the oil tank is lower than the first reference pressure, A dry sump engine characterized by having an opening control unit that opens the on/off valve when the low-pressure determination unit determines that the pressure inside the oil tank is lower than the first reference pressure, or when the determination unit determines that the predetermined conditions have been met.
A dry sump engine according to claim 1, A dry-sump engine characterized in that the predetermined condition is that it is presumed that the PCV valve will freeze.
A dry sump engine according to claim 2, The controller is characterized in that it makes it possible to estimate that the PCV valve will freeze when the engine water temperature is below a predetermined reference temperature.
A dry sump engine according to claim 1, The aforementioned predetermined condition is a dry sump engine characterized in that the pressure inside the oil tank is equal to or greater than a predetermined second reference pressure.
A dry sump engine according to any one of claims 1 to 4, The supercharger further comprises a compressor for pressurizing the intake air, A dry-sump engine characterized in that the gas receiving section is the compressor.
A dry sump engine according to any one of claims 1 to 4, A dry-sump engine characterized in that the on/off valve is an electromagnetic valve that is electrically controlled to open and close.

Description

This invention relates to a dry-sump engine, and more particularly to a dry-sump engine configured to control the internal pressure of the oil tank. A dry-sump engine has an oil tank and scavenging pump located outside the engine. The scavenging pump draws oil from the crankcase into the oil tank, separating blow-by gases. This separated oil is then recirculated back into the crankcase. A PCV (Positive Crankcase Ventilation) valve is provided to regulate the internal pressure of the oil tank. The PCV valve is located between the oil tank and the intake manifold, or between the oil tank and the turbocharger's compressor. It opens when the internal pressure of the oil tank becomes high, recirculating blow-by gases from the oil tank to the engine's intake side. When the engine is running, the temperature inside the crankcase is high, and therefore, the moisture contained in gases such as blow-by gas sent from the crankcase to the oil tank is in the form of water vapor. However, the piping that circulates blow-by gas from the oil tank to the engine's intake side is exposed to the atmosphere and can become cold. Therefore, when the outside temperature is low, the water vapor sent to the engine's intake side along with the blow-by gas may condense and freeze along the piping, including the PCV valve. If the moisture freezes at the PCV valve, the PCV valve will not open due to the pressure inside the oil tank. This can lead to excessively high pressure inside the oil tank, potentially causing seal damage or deterioration, oil leaks, and even damage to the oil tank itself. Patent documents 1 and 2 describe dry-sump engines configured to prevent freezing of the blow-by gas pipeline. In the dry-sump engine described in Patent Document 1, the PCV valve is positioned to exchange heat with the oil passage that carries lubricating oil from the crankcase to the oil tank. By heating the PCV valve with the heat of the lubricating oil, freezing of the PCV valve is suppressed. Patent Document 2 describes an anti-freezing structure having a heat-receiving passage inside the cylinder head cover that warms the blow-by gas. In this anti-freezing structure, the blow-by gas sent from the external oil separator to the intake system passage is heated by the heat inside the cylinder head, thereby preventing the blow-by gas pipe from freezing. Japanese Patent Publication No. 2008-038839Japanese Patent Publication No. 2016-135996 Figure 1 is a schematic diagram illustrating an embodiment of the present invention, and mainly shows the flow system of lubricating oil and blow-by gas.Figure 2 is a block diagram showing the functional configuration of the controller.Figure 3 is a flowchart illustrating the control performed by that controller. Next, embodiments of this invention will be described with reference to the attached drawings. Note that the embodiments described below are merely examples of how this invention can be implemented and do not limit the invention. The engine 1 in the embodiment of this invention shown in Figure 1 is a dry-sump type engine in which the oil tank 3 is provided separately from the engine body 2. The engine body 2, like conventionally known gasoline engines, is mainly composed of a cylinder block with multiple cylinders, a crankcase with an integrated oil pan, and a cylinder head. Furthermore, the engine body 2 is configured to be cooled to a predetermined temperature or lower by coolant. A scavenging pump 4 is provided on the underside of the engine body 2 to pump lubricating oil from the crankcase and send it to the oil tank 3. Since blow-by gas is dissolved in the lubricating oil in the crankcase, the blow-by gas is separated from the temporarily stored lubricating oil in the oil tank 3. Therefore, the oil tank 3 also functions as a gas-liquid separator. Furthermore, an oil pump 5 is connected to the oil tank 3 to supply an amount of lubricating oil to the engine 1 according to its operating state. The engine 1 shown in Figure 1 is equipped with a supercharger 6 that pressurizes the intake air. An example of a supercharger 6 is a turbocharger driven by exhaust gas from the engine 1. The supercharger 6 includes a turbine 8 driven by exhaust gas discharged from the exhaust manifold 7, and a compressor 10 that rotates in conjunction with the turbine 8 to pressurize air and supply it to the intake manifold 9. The blow-by gas needs to be recirculated to the intake side of the engine 1. To this end, a first recirculation passage 11 guides the blow-by gas, separated from the lubricating oil inside the oil tank 3, to the intake manifold 9 or its upstream side, and a second recirculation passage 12 guides it to the intake side of the compressor 10. Therefore, each recirculation passage 11 and 12 corresponds to a pipeline in this embodiment of the invention, and the intake manifold 9 and compressor 10 correspond to gas receiving sections in this embodiment of the invention. Each of the first and second return passa