Oil supply system and valve control device

Abstract

To provide an oil supply system and a valve control device capable of suppressing deterioration in exhaust gas purification performance and suppressing deterioration in fuel economy. The oil supply system cyclically supplies oil to a vehicle engine, and includes: an oil cooler that cools the oil; a bypass oil passage that bypasses the oil cooler; an oil thermostatic valve capable of switching between a first state in which oil having passed through the oil cooler is supplied to the engine and a second state in which oil having passed through the bypass oil passage is supplied to the engine; and a valve control device that controls the oil thermostatic valve to switch to the second state when the oil thermostatic valve is in the first state and the temperature of exhaust gas is in a decreasing trend.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of Japanese Patent Application No. 2025-048678, filed on Mar. 24, 2025, the contents of which are all incorporated by reference as if fully set forth herein in their entirety.TECHNICAL FIELD

[0002] The present disclosure relates to an oil supply system and a valve control device.BACKGROUND ART

[0003] An oil supply system that cyclically supplies engine oil (hereinafter, simply referred to as oil) to an engine of a vehicle has been known. For example, Patent Literature (hereinafter, referred to as PTL) 1 discloses an oil supply system including: an oil cooler that cools oil; a bypass oil passage that bypasses the oil cooler; and an oil thermostatic valve that switches a flow passage of the oil to any one of the oil cooler or the bypass oil passage according to the temperature of the oil.

[0004] In this oil supply system, when the temperature of the oil is low, the oil thermostatic valve is closed, so that the oil is led to the bypass oil passage and is supplied to the engine as it is. On the other hand, when the temperature of the oil is high, the oil thermostatic valve is opened, so that the oil is led to the oil cooler, and the oil cooled in the oil cooler is supplied to the engine.Citation ListPatent LiteraturePTL 1

[0005] Japanese Patent Application Laid-Open No. 2012-225238SUMMARY OF INVENTIONTechnical Problem

[0006] In the oil supply system described above, the following problems occur when the oil cooled by the oil cooler is supplied to the engine.

[0007] When the temperature of the oil supplied to the engine (e.g., piston or bore) is low, a temperature difference between the combustion gas and the oil becomes large. This increases the cooling loss transferred from the combustion gas to the oil via the piston, resulting in a decrease in exhaust gas temperature. As a result, the exhaust gas purification performance in the exhaust gas purification device decreases. However, measures to suppress the decrease in exhaust gas temperature, such as delaying the fuel injection timing, result in deteriorated fuel economy.

[0008] An object of one aspect of the present disclosure is to provide an oil supply system and a valve control device each capable of realizing suppression of deterioration of exhaust gas purification performance and suppression of deterioration of fuel economy.Solution to Problem

[0009] An oil supply system according to one aspect of the present disclosure is an oil supply system that cyclically supplies oil to an engine of a vehicle, and the oil supply system includes: an oil cooler that cools the oil; a bypass oil passage that bypasses the oil cooler; an oil thermostatic valve capable of switching between a first state in which the oil having passed through the oil cooler is supplied to the engine and a second state in which the oil having passed through the bypass oil passage is supplied to the engine; and a valve control device that controls the oil thermostatic valve to switch to the second state when the oil thermostatic valve is in the first state and a temperature of exhaust gas is in a decreasing trend.

[0010] A valve control device according to one aspect of the present disclosure is used in the above oil supply system according to one aspect of the present disclosure.Advantageous Effects of Invention

[0011] According to the present disclosure, it is possible to realize suppression of deterioration of exhaust gas purification performance and suppression of deterioration of fuel economy.BRIEF DESCRIPTION OF DRAWINGS

[0012] FIG. 1 is a schematic diagram illustrating a configuration example of an oil supply system according to an embodiment of the present disclosure;

[0013] FIG. 2 is a block diagram illustrating a configuration example of a valve control device according to the embodiment of the present disclosure;

[0014] FIG. 3 is a flowchart illustrating an operation example of the valve control device according to the embodiment of the present disclosure;

[0015] FIG. 4 is a graph illustrating changes in various parameters when an oil thermostatic valve according to the embodiment of the present disclosure is changed from a valve-open state to a valve-closed state; and

[0016] FIG. 5 is a flowchart illustrating an operation example of a valve control device according to a variation of the present disclosure.DESCRIPTION OF EMBODIMENTS

[0017] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals are assigned to the same components.

[0018] First, a configuration of oil supply system 10 according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic diagram illustrating a configuration example of oil supply system 10.

[0019] Oil supply system 10 is a system that is mounted on a vehicle (not shown) and that cyclically supplies oil to an engine (not shown) of the vehicle. The type of vehicle or engine is not particularly limited.

[0020] Oil supply system 10 includes oil pan 1, oil strainer 2, oil pump 3, main oil passage 4, oil cooler 5, bypass oil passage 6, oil thermostatic valve 7, and valve control device 100. Among these, since known technologies can be applied to the components other than valve control device 100, these components will be simply described below.

[0021] Oil pan 1 is installed below the engine and stores the oil discharged from the engine.

[0022] Oil strainer 2 captures and removes foreign matter contained in the oil.

[0023] Oil pump 3 suctions the oil in oil pan 1 through strainer 2 and discharges the oil to main oil passage 4 on a downstream side of oil pump 3.

[0024] Main oil passage 4 is an oil passage through which the oil discharged from oil pump 3 flows. Oil cooler 5 and oil thermostatic valve 7 are provided in series in main oil passage 4 in this order from the upstream side.

[0025] Oil cooler 5 cools the oil.

[0026] Bypass oil passage 6 is provided in parallel to oil cooler 5 and is an oil passage that bypasses oil cooler 5. An upstream end of bypass oil passage 6 is connected to main oil passage 4 on the upstream side of oil cooler 5, and a downstream end of bypass oil passage 6 is connected to oil thermostatic valve 7.

[0027] Oil thermostatic valve 7 is provided in main oil passage 4 on the downstream side of oil cooler 5.

[0028] Oil thermostatic valve 7 includes first inlet 7a, second inlet 7b, and outlet 7c. First inlet 7a is connected to main oil passage 4 on the downstream side of oil cooler 5. Second inlet 7b is connected to the downstream end of bypass oil passage 6. Outlet 7c is connected to main oil passage 4 on the downstream side of oil thermostatic valve 7. First inlet 7a and second inlet 7b are opened or blocked, but outlet 7c is always open.

[0029] Oil thermostatic valve 7 can be switched between a valve-open state (example of first state) and a valve-closed state (example of second state).

[0030] The valve-open state is a state in which first inlet 7a is open and second inlet 7b is blocked. Accordingly, the oil that has passed through oil cooler 5 flows into oil thermostatic valve 7 from first inlet 7a, flows out from outlet 7c, and is supplied to the engine. Thus, the valve-open state may also be described as a state in which the oil that has passed through oil cooler 5 is supplied to the engine.

[0031] The valve-closed state is a state in which first inlet 7a is blocked and second inlet 7b is open. Accordingly, the oil that has passed through bypass oil passage 6 flows into oil thermostatic valve 7 from second inlet 7b, flows out from outlet 7c, and is supplied to the engine. Thus, the valve-closed state may also be described as a state in which the oil that has passed through bypass oil passage 6 is supplied to the engine.

[0032] Oil thermostatic valve 7 is electrically connected to valve control device 100 and is controlled to be in any one of the valve-open state or the valve-closed state by valve control device 100 (details will be described later).

[0033] The oil that has flowed out from oil thermostatic valve 7 flows through main oil passage 4 on the downstream side and is supplied to each part (not shown) of the engine.

[0034] Examples of the parts of the engine include intake and exhaust valves of a cylinder head and a crankshaft of a cylinder block, but the present disclosure is not limited thereto, and other components may be used. In addition, the oil supply destination may include components other than the engine (e.g., turbocharger, oil jet that jets oil to a piston, or the like).

[0035] The configuration of oil supply system 10 has been described above.

[0036] Next, the configuration of valve control device 100 will be described with reference to FIG. 2. FIG. 2 is a block diagram illustrating a configuration example of valve control device 100.

[0037] Valve control device 100 is realized by, for example, an electronic control unit (ECU). Therefore, valve control device 100 includes, as hardware, for example, a central processing unit (CPU), read only memory (ROM) that stores computer programs, random access memory (RAM) that serves as working memory, and the like. The operation of each section described below is realized by the CPU executing computer programs read from the ROM in the RAM.

[0038] Valve control device 100 includes acquisition section 110, determination section 120, and control section 130.

[0039] Acquisition section 110 acquires the temperature of exhaust gas.

[0040] The temperature of the exhaust gas to be acquired is, for example, a value detected by a known exhaust gas temperature sensor (not shown) provided on the upstream side of an exhaust gas purification device (not shown). The exhaust gas temperature sensor continuously detects the temperature of the exhaust gas at predetermined time intervals and outputs the detected temperature to valve control device 100.

[0041] Examples of the exhaust gas purification device include an oxidation catalyst, a selective reduction catalyst, an NOx adsorption catalyst, a three-way catalyst, and a particulate filter, but the present disclosure is not limited thereto.

[0042] In addition, acquisition section 110 acquires the temperature of the oil flowing through oil thermostatic valve 7.

[0043] The temperature of the oil to be acquired is, for example, a value detected by a known oil temperature sensor (not shown) provided near outlet 7c of oil thermostatic valve 7. The oil temperature sensor continuously detects the temperature of the oil at predetermined time intervals and outputs the detected temperature to valve control device 100.

[0044] Determination section 120 determines whether the temperature of the exhaust gas acquired by acquisition section 110 is in a decreasing trend, when oil thermostatic valve 7 is in the valve-open state.

[0045] For example, when the time derivative of the change in the temperature of the exhaust gas acquired in time series is a negative value, determination section 120 determines that the temperature of the exhaust gas is in a decreasing trend. Note that the determination method is not limited thereto, and another known method may be used.

[0046] Examples of a case where the temperature of the exhaust gas is in a decreasing trend include a case where the fuel injection amount decreases during deceleration of the vehicle and a case where the vehicle changes from acceleration operation to constant speed operation. Thus, determination section 120 may determine that the temperature of the exhaust gas is in a decreasing trend when the fuel injection amount decreases during deceleration of the vehicle. In addition, determination section 120 may determine that the temperature of the exhaust gas is in a decreasing trend when the vehicle transitions from an acceleration state to a constant speed state.

[0047] Furthermore, determination section 120 determines whether the temperature of the oil acquired by acquisition section 110 exceeds a predetermined value, when oil thermostatic valve 7 is in a valve-closed state. The predetermined value is a temperature at which the oil needs to be cooled, and is set in advance based on results of experiments, simulations, or the like.

[0048] Control section 130 controls oil thermostatic valve 7 to switch from the valve-open state to the valve-closed state in a case where oil thermostatic valve 7 is in the valve-open state and determination section 120 determines that the temperature of the exhaust gas is in a decreasing trend.

[0049] Specifically, control section 130 outputs a control signal for instructing oil thermostatic valve 7 to block first inlet 7a and open second inlet 7b. Oil thermostatic valve 7 blocks first inlet 7a and opens second inlet 7b based on the control signal.

[0050] After oil thermostatic valve 7 is switched to the valve-closed state, control section 130 continues to control oil thermostatic valve 7 to be in the valve-closed state until the temperature of the oil exceeds the predetermined value as long as the engine does not malfunction.

[0051] Control section 130 controls oil thermostatic valve 7 to switch from the valve-closed state to the valve-open state in a case where oil thermostatic valve 7 is in the valve-closed state and determination section 120 determines that the temperature of the oil exceeds the predetermined value.

[0052] Specifically, control section 130 outputs a control signal for instructing oil thermostatic valve 7 to open first inlet 7a and block second inlet 7b. Oil thermostatic valve 7 opens first inlet 7a and blocks second inlet 7b based on the control signal.

[0053] The configuration of valve control device 100 has been described above.

[0054] Next, the operation of valve control device 100 will be described with reference to FIG. 3. FIG. 3 is a flowchart illustrating an operation example of valve control device 100. The flowchart in FIG. 3 is started when oil thermostatic valve 7 enters the valve-open state (in other words, when the supply of the oil cooled by oil cooler 5 to each part of the engine is started).

[0055] First, acquisition section 110 acquires the temperature of the exhaust gas (step S11).

[0056] Next, determination section 120 determines whether the temperature of the exhaust gas is in a decreasing trend (step S12).

[0057] When the temperature of the exhaust gas is not in a decreasing trend (Step S12: NO), the process returns to Step S11.

[0058] When the temperature of the exhaust gas is in a decreasing trend (Step S12: YES), control section 130 controls oil thermostatic valve 7 to be in the valve-closed state (Step S13).

[0059] The operation of valve control device 100 has been described above.

[0060] FIG. 4 shows changes in various parameters when oil thermostatic valve 7 is controlled from the valve-open state to the valve-closed state by the above-described operation. As illustrated in FIG. 4, the temperatures of the oil, the exhaust gas, and the piston and the purification rate of the exhaust gas purification device increase. On the other hand, the oil pressure (discharge pressure of the oil pump) and the heat loss (cooling loss transferred from the combustion gas to the oil via the piston) decrease.

[0061] As described in detail above, oil supply system 10 according to the present embodiment is an oil supply system that cyclically supplies oil to an engine of a vehicle, and oil supply system 10 includes: oil cooler 5 that cools the oil; bypass passage 6 that bypasses oil cooler 5; oil thermostatic valve 7 that can switch between an valve-open state (example of first state) in which the oil having passed through oil cooler 5 is supplied to the engine and a valve-closed state (example of second state) in which the oil having passed through bypass oil passage 6 is supplied to the engine; and valve control device 100 that controls oil thermostatic valve 7 to switch to the valve-closed state when oil thermostatic valve 7 is in the valve-open state and the temperature of the exhaust gas is in a decreasing trend.

[0062] Therefore, in oil supply system 10 according to the present embodiment, the decrease in the temperature of the exhaust gas can be suppressed, and thus the deterioration of exhaust gas purification performance can be suppressed. In addition, since control (e.g., delaying fuel injection timing) for suppressing the decrease in the temperature of the exhaust gas is not required, the deterioration of fuel economy can also be suppressed.

[0063] In addition, generally, when the oil flows through oil cooler 5, the fuel economy deteriorates due to an increase in the driving force of oil pump 3 (which is caused by an increase in the discharge oil pressure of oil pump 3 or a decrease in the viscosity) or an increase in the heat loss. In contrast, in the present embodiment, when no malfunction occurs in the engine, oil thermostatic valve 7 is controlled to be in the valve-closed state. As a result, the oil bypasses oil cooler 5 and is supplied to each part of the engine, thereby suppressing deterioration in fuel economy due to the increase in the driving force of oil pump 3 or the increase in the heat loss.

[0064] The present disclosure is not limited to the description of the above embodiment, and various modifications can be made within the scope not departing from the concept of the present disclosure. In the following, variations will be described.Variation 1

[0065] In the embodiment, the case has been described where the condition for switching oil thermostatic valve 7 in the valve-open state to the valve-closed state is a case where the temperature of the exhaust gas is in a decreasing trend as an example, but the condition may be further added.

[0066] Hereinafter, the flow of the operation in the present variation will be described with reference to a flowchart in FIG. 5. The flowchart in FIG. 5 is started when oil thermostatic valve 7 is in the valve-open state (in other words, when the supply of the oil cooled by oil cooler 5 to each part of the engine is started), as in the flowchart in FIG. 3.

[0067] First, acquisition section 110 acquires the temperature of the exhaust gas, the temperature of the oil, and the temperature of the piston (Step S21).

[0068] The temperature of the exhaust gas and the temperature of the oil to be acquired are as described in the embodiment. The temperature of the piston (not shown) to be acquired is, for example, a value detected by a known piston temperature sensor (not shown). The piston temperature sensor continuously detects the temperature of the piston at predetermined time intervals and outputs the detected temperature to valve control device 100. The temperature of the piston may be acquired by a known method other than the method of detecting the temperature by the piston temperature sensor (e.g., method for estimating the temperature based on the driving condition (rotation speed or fuel flow rate) of the engine).

[0069] Next, determination section 120 determines whether the temperature of the exhaust gas is in a decreasing trend (Step S22).

[0070] When the temperature of the exhaust gas is not in a decreasing trend (Step S22: NO), the process returns to Step S21.

[0071] When the temperature of the exhaust gas is in a decreasing trend (Step S22: YES), determination section 120 determines whether the temperature of the oil is less than a first predetermined value (Step S23).

[0072] The first predetermined value is, for example, a temperature at which the oil deteriorates (which may be referred to as oxidation). For example, the first predetermined value is set in advance based on results of experiments, simulations, or the like.

[0073] When the temperature of the oil is not less than the first predetermined value (Step S23: NO), the process returns to step S21.

[0074] When the temperature of the oil is less than the first predetermined value (Step S23: YES), determination section 120 determines whether the temperature of the piston is less than a second predetermined value (Step S24).

[0075] The second predetermined value is, for example, a temperature at which the piston seizes. For example, the second predetermined value is set in advance based on results of experiments, simulations, or the like.

[0076] When the temperature of the piston is not less than the second predetermined value (Step S24: NO), the process returns to Step S21.

[0077] When the temperature of the piston is less than the second predetermined value (Step S24: YES), control section 130 controls oil thermostatic valve 7 to be in the valve-closed state (Step S25).

[0078] The operation of the present variation has been described above.

[0079] The present variation is characterized in that oil thermostatic valve 7 is switched to the valve-closed state when the temperature of the exhaust gas is in a decreasing trend, the oil does not deteriorate, and the piston does not seize. Therefore, when controlling oil thermostatic valve 7 to be in the closed state, the safety of the engine can be ensured (specifically, that no malfunctions have occurred due to oil deterioration and that no piston seizure has occurred).

[0080] Note that, in FIG. 5, Steps S22 to S24 may be performed in a different order. In addition, only one of Step S23 or Step S24 may be performed.Variation 2

[0081] In the embodiment and Variation 1, the case where oil thermostatic valve 7 is provided on the downstream side of oil cooler 5 has been described as an example, but the oil thermostatic valve may be provided on the upstream side of oil cooler 5. In this case, the oil thermostatic valve includes one inlet through which the oil pressurized by oil pump 3 flows in, a first outlet through which the oil flows out to the oil cooler, and a second outlet through which the oil flows out to bypass oil passage 6.

[0082] In the valve-open state, the first outlet is opened, and the second outlet is blocked (example of first state). In the valve-closed state, the first outlet is blocked, and the second outlet is opened (example of second state). The opening and blocking of the outlets are controlled by valve control device 100. Note that the inlet is always open.Industrial Applicability

[0083] The oil supply system and the valve control device of the present disclosure are useful for a technique of cyclically supplying fluid to a supply target part.REFERENCE SIGNS LIST

[0084] 1 Oil pan

[0085] 2 Strainer

[0086] 3 Oil pump

[0087] 4 Main oil passage

[0088] 5 Oil cooler

[0089] 6 Bypass oil passage

[0090] 7 Oil thermostatic valve

[0091] 7a First inlet

[0092] 7b Second inlet

[0093] 7c Outlet

[0094] 10 Oil supply system

[0095] 100 Valve control device

[0096] 110 Acquisition section

[0097] 120 Determination section

[0098] 130 Control section

Examples

Embodiment Construction

[0017]Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals are assigned to the same components.

[0018]First, a configuration of oil supply system 10 according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic diagram illustrating a configuration example of oil supply system 10.

[0019]Oil supply system 10 is a system that is mounted on a vehicle (not shown) and that cyclically supplies oil to an engine (not shown) of the vehicle. The type of vehicle or engine is not particularly limited.

[0020]Oil supply system 10 includes oil pan 1, oil strainer 2, oil pump 3, main oil passage 4, oil cooler 5, bypass oil passage 6, oil thermostatic valve 7, and valve control device 100. Among these, since known technologies can be applied to the components other than valve control device 100, these components will be simply described below.

[0021]Oil pan 1 is installed...

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of Japanese Patent Application No. 2025-048678, filed on Mar. 24, 2025, the contents of which are all incorporated by reference as if fully set forth herein in their entirety.TECHNICAL FIELD

[0002] The present disclosure relates to an oil supply system and a valve control device.BACKGROUND ART

[0003] An oil supply system that cyclically supplies engine oil (hereinafter, simply referred to as oil) to an engine of a vehicle has been known. For example, Patent Literature (hereinafter, referred to as PTL) 1 discloses an oil supply system including: an oil cooler that cools oil; a bypass oil passage that bypasses the oil cooler; and an oil thermostatic valve that switches a flow passage of the oil to any one of the oil cooler or the bypass oil passage according to the temperature of the oil.

[0004] In this oil supply system, when the temperature of the oil is low, the oil thermostatic valve is closed, so that the oil is led to the bypass oil passage and is supplied to the engine as it is. On the other hand, when the temperature of the oil is high, the oil thermostatic valve is opened, so that the oil is led to the oil cooler, and the oil cooled in the oil cooler is supplied to the engine.Citation ListPatent LiteraturePTL 1

[0005] Japanese Patent Application Laid-Open No. 2012-225238SUMMARY OF INVENTIONTechnical Problem

[0006] In the oil supply system described above, the following problems occur when the oil cooled by the oil cooler is supplied to the engine.

[0007] When the temperature of the oil supplied to the engine (e.g., piston or bore) is low, a temperature difference between the combustion gas and the oil becomes large. This increases the cooling loss transferred from the combustion gas to the oil via the piston, resulting in a decrease in exhaust gas temperature. As a result, the exhaust gas purification performance in the exhaust gas purification device decreases. However, measures to suppress the decrease in exhaust gas temperature, such as delaying the fuel injection timing, result in deteriorated fuel economy.

[0008] An object of one aspect of the present disclosure is to provide an oil supply system and a valve control device each capable of realizing suppression of deterioration of exhaust gas purification performance and suppression of deterioration of fuel economy.Solution to Problem

[0009] An oil supply system according to one aspect of the present disclosure is an oil supply system that cyclically supplies oil to an engine of a vehicle, and the oil supply system includes: an oil cooler that cools the oil; a bypass oil passage that bypasses the oil cooler; an oil thermostatic valve capable of switching between a first state in which the oil having passed through the oil cooler is supplied to the engine and a second state in which the oil having passed through the bypass oil passage is supplied to the engine; and a valve control device that controls the oil thermostatic valve to switch to the second state when the oil thermostatic valve is in the first state and a temperature of exhaust gas is in a decreasing trend.

[0010] A valve control device according to one aspect of the present disclosure is used in the above oil supply system according to one aspect of the present disclosure.Advantageous Effects of Invention

[0011] According to the present disclosure, it is possible to realize suppression of deterioration of exhaust gas purification performance and suppression of deterioration of fuel economy.BRIEF DESCRIPTION OF DRAWINGS

[0012] FIG. 1 is a schematic diagram illustrating a configuration example of an oil supply system according to an embodiment of the present disclosure;

[0013] FIG. 2 is a block diagram illustrating a configuration example of a valve control device according to the embodiment of the present disclosure;

[0014] FIG. 3 is a flowchart illustrating an operation example of the valve control device according to the embodiment of the present disclosure;

[0015] FIG. 4 is a graph illustrating changes in various parameters when an oil thermostatic valve according to the embodiment of the present disclosure is changed from a valve-open state to a valve-closed state; and

[0016] FIG. 5 is a flowchart illustrating an operation example of a valve control device according to a variation of the present disclosure.DESCRIPTION OF EMBODIMENTS

[0017] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals are assigned to the same components.

[0018] First, a configuration of oil supply system 10 according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic diagram illustrating a configuration example of oil supply system 10.

[0019] Oil supply system 10 is a system that is mounted on a vehicle (not shown) and that cyclically supplies oil to an engine (not shown) of the vehicle. The type of vehicle or engine is not particularly limited.

[0020] Oil supply system 10 includes oil pan 1, oil strainer 2, oil pump 3, main oil passage 4, oil cooler 5, bypass oil passage 6, oil thermostatic valve 7, and valve control device 100. Among these, since known technologies can be applied to the components other than valve control device 100, these components will be simply described below.

[0021] Oil pan 1 is installed below the engine and stores the oil discharged from the engine.

[0022] Oil strainer 2 captures and removes foreign matter contained in the oil.

[0023] Oil pump 3 suctions the oil in oil pan 1 through strainer 2 and discharges the oil to main oil passage 4 on a downstream side of oil pump 3.

[0024] Main oil passage 4 is an oil passage through which the oil discharged from oil pump 3 flows. Oil cooler 5 and oil thermostatic valve 7 are provided in series in main oil passage 4 in this order from the upstream side.

[0025] Oil cooler 5 cools the oil.

[0026] Bypass oil passage 6 is provided in parallel to oil cooler 5 and is an oil passage that bypasses oil cooler 5. An upstream end of bypass oil passage 6 is connected to main oil passage 4 on the upstream side of oil cooler 5, and a downstream end of bypass oil passage 6 is connected to oil thermostatic valve 7.

[0027] Oil thermostatic valve 7 is provided in main oil passage 4 on the downstream side of oil cooler 5.

[0028] Oil thermostatic valve 7 includes first inlet 7a, second inlet 7b, and outlet 7c. First inlet 7a is connected to main oil passage 4 on the downstream side of oil cooler 5. Second inlet 7b is connected to the downstream end of bypass oil passage 6. Outlet 7c is connected to main oil passage 4 on the downstream side of oil thermostatic valve 7. First inlet 7a and second inlet 7b are opened or blocked, but outlet 7c is always open.

[0029] Oil thermostatic valve 7 can be switched between a valve-open state (example of first state) and a valve-closed state (example of second state).

[0030] The valve-open state is a state in which first inlet 7a is open and second inlet 7b is blocked. Accordingly, the oil that has passed through oil cooler 5 flows into oil thermostatic valve 7 from first inlet 7a, flows out from outlet 7c, and is supplied to the engine. Thus, the valve-open state may also be described as a state in which the oil that has passed through oil cooler 5 is supplied to the engine.

[0031] The valve-closed state is a state in which first inlet 7a is blocked and second inlet 7b is open. Accordingly, the oil that has passed through bypass oil passage 6 flows into oil thermostatic valve 7 from second inlet 7b, flows out from outlet 7c, and is supplied to the engine. Thus, the valve-closed state may also be described as a state in which the oil that has passed through bypass oil passage 6 is supplied to the engine.

[0032] Oil thermostatic valve 7 is electrically connected to valve control device 100 and is controlled to be in any one of the valve-open state or the valve-closed state by valve control device 100 (details will be described later).

[0033] The oil that has flowed out from oil thermostatic valve 7 flows through main oil passage 4 on the downstream side and is supplied to each part (not shown) of the engine.

[0034] Examples of the parts of the engine include intake and exhaust valves of a cylinder head and a crankshaft of a cylinder block, but the present disclosure is not limited thereto, and other components may be used. In addition, the oil supply destination may include components other than the engine (e.g., turbocharger, oil jet that jets oil to a piston, or the like).

[0035] The configuration of oil supply system 10 has been described above.

[0036] Next, the configuration of valve control device 100 will be described with reference to FIG. 2. FIG. 2 is a block diagram illustrating a configuration example of valve control device 100.

[0037] Valve control device 100 is realized by, for example, an electronic control unit (ECU). Therefore, valve control device 100 includes, as hardware, for example, a central processing unit (CPU), read only memory (ROM) that stores computer programs, random access memory (RAM) that serves as working memory, and the like. The operation of each section described below is realized by the CPU executing computer programs read from the ROM in the RAM.

[0038] Valve control device 100 includes acquisition section 110, determination section 120, and control section 130.

[0039] Acquisition section 110 acquires the temperature of exhaust gas.

[0040] The temperature of the exhaust gas to be acquired is, for example, a value detected by a known exhaust gas temperature sensor (not shown) provided on the upstream side of an exhaust gas purification device (not shown). The exhaust gas temperature sensor continuously detects the temperature of the exhaust gas at predetermined time intervals and outputs the detected temperature to valve control device 100.

[0041] Examples of the exhaust gas purification device include an oxidation catalyst, a selective reduction catalyst, an NOx adsorption catalyst, a three-way catalyst, and a particulate filter, but the present disclosure is not limited thereto.

[0042] In addition, acquisition section 110 acquires the temperature of the oil flowing through oil thermostatic valve 7.

[0043] The temperature of the oil to be acquired is, for example, a value detected by a known oil temperature sensor (not shown) provided near outlet 7c of oil thermostatic valve 7. The oil temperature sensor continuously detects the temperature of the oil at predetermined time intervals and outputs the detected temperature to valve control device 100.

[0044] Determination section 120 determines whether the temperature of the exhaust gas acquired by acquisition section 110 is in a decreasing trend, when oil thermostatic valve 7 is in the valve-open state.

[0045] For example, when the time derivative of the change in the temperature of the exhaust gas acquired in time series is a negative value, determination section 120 determines that the temperature of the exhaust gas is in a decreasing trend. Note that the determination method is not limited thereto, and another known method may be used.

[0046] Examples of a case where the temperature of the exhaust gas is in a decreasing trend include a case where the fuel injection amount decreases during deceleration of the vehicle and a case where the vehicle changes from acceleration operation to constant speed operation. Thus, determination section 120 may determine that the temperature of the exhaust gas is in a decreasing trend when the fuel injection amount decreases during deceleration of the vehicle. In addition, determination section 120 may determine that the temperature of the exhaust gas is in a decreasing trend when the vehicle transitions from an acceleration state to a constant speed state.

[0047] Furthermore, determination section 120 determines whether the temperature of the oil acquired by acquisition section 110 exceeds a predetermined value, when oil thermostatic valve 7 is in a valve-closed state. The predetermined value is a temperature at which the oil needs to be cooled, and is set in advance based on results of experiments, simulations, or the like.

[0048] Control section 130 controls oil thermostatic valve 7 to switch from the valve-open state to the valve-closed state in a case where oil thermostatic valve 7 is in the valve-open state and determination section 120 determines that the temperature of the exhaust gas is in a decreasing trend.

[0049] Specifically, control section 130 outputs a control signal for instructing oil thermostatic valve 7 to block first inlet 7a and open second inlet 7b. Oil thermostatic valve 7 blocks first inlet 7a and opens second inlet 7b based on the control signal.

[0050] After oil thermostatic valve 7 is switched to the valve-closed state, control section 130 continues to control oil thermostatic valve 7 to be in the valve-closed state until the temperature of the oil exceeds the predetermined value as long as the engine does not malfunction.

[0051] Control section 130 controls oil thermostatic valve 7 to switch from the valve-closed state to the valve-open state in a case where oil thermostatic valve 7 is in the valve-closed state and determination section 120 determines that the temperature of the oil exceeds the predetermined value.

[0052] Specifically, control section 130 outputs a control signal for instructing oil thermostatic valve 7 to open first inlet 7a and block second inlet 7b. Oil thermostatic valve 7 opens first inlet 7a and blocks second inlet 7b based on the control signal.

[0053] The configuration of valve control device 100 has been described above.

[0054] Next, the operation of valve control device 100 will be described with reference to FIG. 3. FIG. 3 is a flowchart illustrating an operation example of valve control device 100. The flowchart in FIG. 3 is started when oil thermostatic valve 7 enters the valve-open state (in other words, when the supply of the oil cooled by oil cooler 5 to each part of the engine is started).

[0055] First, acquisition section 110 acquires the temperature of the exhaust gas (step S11).

[0056] Next, determination section 120 determines whether the temperature of the exhaust gas is in a decreasing trend (step S12).

[0057] When the temperature of the exhaust gas is not in a decreasing trend (Step S12: NO), the process returns to Step S11.

[0058] When the temperature of the exhaust gas is in a decreasing trend (Step S12: YES), control section 130 controls oil thermostatic valve 7 to be in the valve-closed state (Step S13).

[0059] The operation of valve control device 100 has been described above.

[0060] FIG. 4 shows changes in various parameters when oil thermostatic valve 7 is controlled from the valve-open state to the valve-closed state by the above-described operation. As illustrated in FIG. 4, the temperatures of the oil, the exhaust gas, and the piston and the purification rate of the exhaust gas purification device increase. On the other hand, the oil pressure (discharge pressure of the oil pump) and the heat loss (cooling loss transferred from the combustion gas to the oil via the piston) decrease.

[0061] As described in detail above, oil supply system 10 according to the present embodiment is an oil supply system that cyclically supplies oil to an engine of a vehicle, and oil supply system 10 includes: oil cooler 5 that cools the oil; bypass passage 6 that bypasses oil cooler 5; oil thermostatic valve 7 that can switch between an valve-open state (example of first state) in which the oil having passed through oil cooler 5 is supplied to the engine and a valve-closed state (example of second state) in which the oil having passed through bypass oil passage 6 is supplied to the engine; and valve control device 100 that controls oil thermostatic valve 7 to switch to the valve-closed state when oil thermostatic valve 7 is in the valve-open state and the temperature of the exhaust gas is in a decreasing trend.

[0062] Therefore, in oil supply system 10 according to the present embodiment, the decrease in the temperature of the exhaust gas can be suppressed, and thus the deterioration of exhaust gas purification performance can be suppressed. In addition, since control (e.g., delaying fuel injection timing) for suppressing the decrease in the temperature of the exhaust gas is not required, the deterioration of fuel economy can also be suppressed.

[0063] In addition, generally, when the oil flows through oil cooler 5, the fuel economy deteriorates due to an increase in the driving force of oil pump 3 (which is caused by an increase in the discharge oil pressure of oil pump 3 or a decrease in the viscosity) or an increase in the heat loss. In contrast, in the present embodiment, when no malfunction occurs in the engine, oil thermostatic valve 7 is controlled to be in the valve-closed state. As a result, the oil bypasses oil cooler 5 and is supplied to each part of the engine, thereby suppressing deterioration in fuel economy due to the increase in the driving force of oil pump 3 or the increase in the heat loss.

[0064] The present disclosure is not limited to the description of the above embodiment, and various modifications can be made within the scope not departing from the concept of the present disclosure. In the following, variations will be described.Variation 1

[0065] In the embodiment, the case has been described where the condition for switching oil thermostatic valve 7 in the valve-open state to the valve-closed state is a case where the temperature of the exhaust gas is in a decreasing trend as an example, but the condition may be further added.

[0066] Hereinafter, the flow of the operation in the present variation will be described with reference to a flowchart in FIG. 5. The flowchart in FIG. 5 is started when oil thermostatic valve 7 is in the valve-open state (in other words, when the supply of the oil cooled by oil cooler 5 to each part of the engine is started), as in the flowchart in FIG. 3.

[0067] First, acquisition section 110 acquires the temperature of the exhaust gas, the temperature of the oil, and the temperature of the piston (Step S21).

[0068] The temperature of the exhaust gas and the temperature of the oil to be acquired are as described in the embodiment. The temperature of the piston (not shown) to be acquired is, for example, a value detected by a known piston temperature sensor (not shown). The piston temperature sensor continuously detects the temperature of the piston at predetermined time intervals and outputs the detected temperature to valve control device 100. The temperature of the piston may be acquired by a known method other than the method of detecting the temperature by the piston temperature sensor (e.g., method for estimating the temperature based on the driving condition (rotation speed or fuel flow rate) of the engine).

[0069] Next, determination section 120 determines whether the temperature of the exhaust gas is in a decreasing trend (Step S22).

[0070] When the temperature of the exhaust gas is not in a decreasing trend (Step S22: NO), the process returns to Step S21.

[0071] When the temperature of the exhaust gas is in a decreasing trend (Step S22: YES), determination section 120 determines whether the temperature of the oil is less than a first predetermined value (Step S23).

[0072] The first predetermined value is, for example, a temperature at which the oil deteriorates (which may be referred to as oxidation). For example, the first predetermined value is set in advance based on results of experiments, simulations, or the like.

[0073] When the temperature of the oil is not less than the first predetermined value (Step S23: NO), the process returns to step S21.

[0074] When the temperature of the oil is less than the first predetermined value (Step S23: YES), determination section 120 determines whether the temperature of the piston is less than a second predetermined value (Step S24).

[0075] The second predetermined value is, for example, a temperature at which the piston seizes. For example, the second predetermined value is set in advance based on results of experiments, simulations, or the like.

[0076] When the temperature of the piston is not less than the second predetermined value (Step S24: NO), the process returns to Step S21.

[0077] When the temperature of the piston is less than the second predetermined value (Step S24: YES), control section 130 controls oil thermostatic valve 7 to be in the valve-closed state (Step S25).

[0078] The operation of the present variation has been described above.

[0079] The present variation is characterized in that oil thermostatic valve 7 is switched to the valve-closed state when the temperature of the exhaust gas is in a decreasing trend, the oil does not deteriorate, and the piston does not seize. Therefore, when controlling oil thermostatic valve 7 to be in the closed state, the safety of the engine can be ensured (specifically, that no malfunctions have occurred due to oil deterioration and that no piston seizure has occurred).

[0080] Note that, in FIG. 5, Steps S22 to S24 may be performed in a different order. In addition, only one of Step S23 or Step S24 may be performed.Variation 2

[0081] In the embodiment and Variation 1, the case where oil thermostatic valve 7 is provided on the downstream side of oil cooler 5 has been described as an example, but the oil thermostatic valve may be provided on the upstream side of oil cooler 5. In this case, the oil thermostatic valve includes one inlet through which the oil pressurized by oil pump 3 flows in, a first outlet through which the oil flows out to the oil cooler, and a second outlet through which the oil flows out to bypass oil passage 6.

[0082] In the valve-open state, the first outlet is opened, and the second outlet is blocked (example of first state). In the valve-closed state, the first outlet is blocked, and the second outlet is opened (example of second state). The opening and blocking of the outlets are controlled by valve control device 100. Note that the inlet is always open.Industrial Applicability

[0083] The oil supply system and the valve control device of the present disclosure are useful for a technique of cyclically supplying fluid to a supply target part.REFERENCE SIGNS LIST

[0084] 1 Oil pan

[0085] 2 Strainer

[0086] 3 Oil pump

[0087] 4 Main oil passage

[0088] 5 Oil cooler

[0089] 6 Bypass oil passage

[0090] 7 Oil thermostatic valve

[0091] 7a First inlet

[0092] 7b Second inlet

[0093] 7c Outlet

[0094] 10 Oil supply system

[0095] 100 Valve control device

[0096] 110 Acquisition section

[0097] 120 Determination section

[0098] 130 Control section

Examples

Embodiment Construction

[0017]Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals are assigned to the same components.

[0018]First, a configuration of oil supply system 10 according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic diagram illustrating a configuration example of oil supply system 10.

[0019]Oil supply system 10 is a system that is mounted on a vehicle (not shown) and that cyclically supplies oil to an engine (not shown) of the vehicle. The type of vehicle or engine is not particularly limited.

[0020]Oil supply system 10 includes oil pan 1, oil strainer 2, oil pump 3, main oil passage 4, oil cooler 5, bypass oil passage 6, oil thermostatic valve 7, and valve control device 100. Among these, since known technologies can be applied to the components other than valve control device 100, these components will be simply described below.

[0021]Oil pan 1 is installed...

Claims

1. An oil supply system that cyclically supplies oil to an engine of a vehicle, the oil supply system comprising:an oil cooler that cools the oil;a bypass oil passage that bypasses the oil cooler;an oil thermostatic valve capable of switching between a first state in which the oil having passed through the oil cooler is supplied to the engine and a second state in which the oil having passed through the bypass oil passage is supplied to the engine; anda valve control device that controls the oil thermostatic valve to switch to the second state when the oil thermostatic valve is in the first state and a temperature of exhaust gas is in a decreasing trend.

2. The oil supply system according to claim 1, whereinthe valve control device controls the oil thermostatic valve to switch from the first state to the second state, when the temperature of the exhaust gas is in a decreasing trend and a temperature of the oil is less than a first predetermined value set as a temperature at which the oil deteriorates.

3. The oil supply system according to claim 1, whereinthe valve control device controls the oil thermostatic valve to switch from the first state to the second state, when the temperature of the exhaust gas is in a decreasing trend and a temperature of a piston is less than a second predetermined value set as a temperature at which the piston seizes.

4. The oil supply system according to claim 1, whereinthe valve control device controls the oil thermostatic valve to be in the second state when a malfunction has not occurred in the engine.

5. The oil supply system according to claim 1, whereinthe valve control device determines that the temperature of the exhaust gas is in a decreasing trend, when a fuel injection amount decreases during deceleration of the vehicle or when the vehicle transitions from an acceleration state to a constant speed state.

6. A valve control device used in the oil supply system according to any one of claim 1 to 5.

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