Lubrication system for internal combustion engines

Abstract

The purpose is to promote the evaporation of fuel in the oil, as well as to prevent oil degradation and maintain lubrication performance. [Solution] The lubrication system for an internal combustion engine includes an oil circulation path that includes an oil supply path that supplies oil stored in an oil reservoir to various oil supply sections in the internal combustion engine, and an oil recovery path that recovers the oil supplied to the various oil supply sections back into the oil reservoir, and a heat pump circuit that includes a compressor, a condenser, an expansion valve, and an evaporator in the refrigerant circulation path, wherein the evaporator cools the oil in the oil supply path and the condenser heats the oil in the oil recovery path.

Description

Technical Field

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[0001] The present invention relates to a lubrication device for an internal combustion engine.

Background Art

[0002] Conventionally, in order to suppress dilution of lubricating oil (hereinafter simply referred to as "oil") for an internal combustion engine due to mixing of water or fuel into the oil, it is known to heat the oil (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, recently, as a fuel for an internal combustion engine, a CN (carbon neutral) fuel such as a synthetic fuel called e-fuel may be used. The CN fuel has low volatility and tends to remain in the lubricating oil used in the internal combustion engine for a long time. Therefore, in an internal combustion engine using the CN fuel, the degree of requirement for raising the oil temperature is higher. However, on the other hand, in order to prevent deterioration of the oil and maintain lubrication performance, it is required to cool the oil. That is, there are conflicting requirements for the oil, namely, promoting the volatilization of the fuel by increasing the temperature while preventing deterioration of the oil and maintaining the lubrication performance by cooling. However, in Patent Document 1, only the temperature of the oil is raised to promote the volatilization of the fuel.

[0005] Therefore, an object of the present invention is to promote the volatilization of the fuel in the oil and to prevent deterioration of the oil and maintain lubrication performance.

Means for Solving the Problems

[0006] The above objective is achieved by a lubrication system for an internal combustion engine, comprising an oil circulation path including an oil supply path that supplies oil stored in an oil reservoir to various oil supply sections in the internal combustion engine, and an oil recovery path that recovers the oil supplied to the various oil supply sections back into the oil reservoir, and a heat pump circuit in the refrigerant circulation path that includes a compressor, a condenser, an expansion valve, and an evaporator, wherein the evaporator cools the oil in the oil supply path and the condenser heats the oil in the oil recovery path. [Effects of the Invention]

[0007] This promotes the evaporation of fuel in the oil, while also preventing oil degradation and maintaining lubrication performance. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing an internal combustion engine equipped with a lubrication device according to an embodiment. [Figure 2] Figure 2 is a magnified view of the area surrounding the heat pump circuit. [Modes for carrying out the invention]

[0009] (Embodiment) The internal combustion engine 1 shown in Figure 1 comprises a cylinder block 1a and a cylinder head 1b. An oil pan 10 is provided below the cylinder block 1a as an oil reservoir. An oil pump 12 and an oil strainer 13 are arranged inside the oil pan 10. The internal combustion engine 1 is equipped with a lubrication system 100. The lubrication system 100 includes an oil circulation path 11 and a heat pump circuit 20. The internal combustion engine 1 is equipped with a fuel injection system (not shown). CN fuel may be used as fuel in the internal combustion engine 1.

[0010] <Configuration of the oil circulation path> The oil circulation path 11 includes an oil supply path 11a, an oil supply section 11b1 inside the block, an oil supply section 11b2 inside the head, and an oil recovery path 11c.

[0011] The oil supply path 11a supplies oil stored in the oil pan 10 to the block oil supply section 11b1 and the head oil supply section 11b2. An oil strainer 13 is provided at the end of the oil supply path 11a. The oil strainer 13 collects debris and other contaminants in the oil. An oil pump 12 is provided downstream of the oil strainer 13 in the oil supply path 11a. When the oil pump 12 is driven, oil is drawn up from the oil pan 10. The oil pump 12 discharges the drawn-up oil towards the block oil supply section 11b1 and the head oil supply section 11b2. The oil pump 12 is driven by the crankshaft or camshaft (neither shown) of the internal combustion engine, but it may also be an electric type driven by a motor.

[0012] The oil supply section 11b1 within the block and the oil supply section 11b2 within the head are included in the oil supply sections. By supplying oil to the oil supply sections, the oil cools the oil supply sections and reduces friction in the oil supply sections.

[0013] The oil recovery path 11c recovers the oil supplied to the block oil supply section 11b1 and the head oil supply section 11b2 back into the oil pan 10. The oil recovered into the oil pan 10 may contain, for example, fuel injected into the cylinders of the internal combustion engine 1.

[0014] <Configuration of the Heat Pump Circuit> The heat pump circuit 20 can simultaneously cool one area and heat another. The heat pump circuit 20 is equipped with a refrigerant circulation path 21. The refrigerant circulation path 21 is filled with refrigerant. In this embodiment, the refrigerant is water, but conventionally known refrigerants can be used as appropriate. The refrigerant circulation path 21 is provided with a compressor 22, a condenser 23, an expansion valve 24, and an evaporator 25. In this embodiment, the direction of refrigerant flow in the refrigerant circulation path 21 is clockwise in each figure.

[0015] The compressor 22 compresses the refrigerant circulating in the refrigerant circulation path 21. The compressor 22 is coaxially connected to the oil pump 12 via a drive member 22a, but the drive mechanism of the compressor 22 is not limited to this. By driving the compressor 22 coaxially with the oil pump 12, the drive system of the compressor 22 can be made compact.

[0016] The condenser 23 is positioned downstream of the compressor 22 in the refrigerant flow direction in the refrigerant circulation path 21. This causes the temperature of the refrigerant in the condenser 23 to rise. The condenser 23 is positioned in contact with the oil recovery path 11c. Here, the part of the oil recovery path 11c upstream of the condenser 23 is designated as the upstream part of the recovery path 11c1, and the part downstream of the condenser 23 is designated as the downstream part of the recovery path 11c2. The heat from the condenser 23 moves as indicated by the arrows in Figure 2, and the oil in the oil recovery path 11c is heated by the condenser 23. As a result, the temperature of the oil flowing in the downstream part of the recovery path 11c2 becomes higher than the temperature of the oil flowing in the upstream part of the recovery path 11c1. Consequently, the temperature of the oil recovered in the oil pan 10 rises, and the volatilization of fuel mixed in the oil is promoted.

[0017] The expansion valve 24 is located downstream of the condenser 23 in the refrigerant flow direction in the refrigerant circulation path 21. The refrigerant pressure upstream of the expansion valve 24 is increased by the compressor 22. The expansion valve 24 reduces the refrigerant pressure by opening.

[0018] The evaporator 25 is arranged on the downstream side of the refrigerant flow direction in the refrigerant circulation path 21 with respect to the expansion valve 24. Thereby, the refrigerant vaporizes in the evaporator 25 and the temperature of the refrigerant decreases. The evaporator 25 is provided so as to contact the oil supply path 11a. Here, the upstream side of the oil supply path 11a with respect to the evaporator 25 is defined as the upstream part 11a1 of the supply path, and the downstream side of the evaporator 25 is defined as the downstream part 11a2 of the supply path. The heat of the oil supply path 23a moves as indicated by the arrow in FIG. 2, and the oil in the oil supply path 11a is cooled by the evaporator 25. Thereby, the temperature of the oil flowing in the downstream part 11a2 of the supply path becomes lower than the temperature of the oil flowing in the upstream part 11a1 of the supply path. As a result, the temperature of the oil supplied to the in-block oil supply part 11b1 and the head-in oil supply part 11b2 decreases, deterioration of the oil is prevented, and lubricating performance is maintained. In the present embodiment, the oil can be cooled by the evaporator 25. For this reason, a special device for cooling oil such as an oil cooler can be omitted.

[0019] [Effect] The lubricating device 100 of the embodiment can cool the oil in the oil supply path 11a by the evaporator 25. Thereby, it is possible to prevent deterioration of the oil and maintain lubricating performance. Further, the lubricating device 100 of the embodiment can heat the oil in the oil recovery path 11c by the condenser 23. Thereby, the volatilization of the fuel in the oil can be promoted.

[0020] As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of reference numerals

[0021] 1...Internal combustion engine, 1a...Cylinder block, 1b...Cylinder head, 10...Oil pan (oil reservoir), 11...Oil circulation path, 11a...Oil supply path, 11b1...Oil supply section inside the block, 11b2...Oil supply section inside the head, 11c...Oil recovery path, 20...Heat pump circuit, 21...Refrigerant circulation path, 22...Compressor, 22a...Drive component, 23...Condenser, 24...Expansion valve, 25...Evaporator, 100...Lubrication device

Claims

[Claim 1] A lubrication system for an internal combustion engine, An oil circulation path includes an oil supply path that supplies oil stored in an oil reservoir to various oil supply sections in the internal combustion engine, and an oil recovery path that recovers the oil supplied to the various oil supply sections back into the oil reservoir. A heat pump circuit comprising a compressor, condenser, expansion valve, and evaporator in the refrigerant circulation path, Equipped with, The evaporator cools the oil in the oil supply path, and the condenser heats the oil in the oil recovery path. Lubrication system for internal combustion engines.

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