JP2025151687A - Engine lubrication system - Google Patents

Abstract

The present invention reduces the amount of oil returning to an oil pan without using a valve or a pump, lowering the oil level in the oil pan and preventing the amount of oil in the oil pan from becoming too low.
[Solution] The engine has an oil pan 2 located at the bottom of the engine body 1, and a reservoir tank 3 located at a position higher than the oil pan 2 and which receives some of the oil dripping from the engine body 1. The reservoir tank 3 has an inner tank 4 and a storage section 5 which covers the inner tank 4 with a gap formed between the inner tank 4, a first oil passage 6 which supplies oil from the engine body 1 into the inner tank 4, a second oil passage 7 located at the bottom of the inner tank 4 which discharges oil in the inner tank 4 to the storage section 5, and a third oil passage 8 which supplies oil in the storage section 5 to the oil pan 2. The cross-sectional area of the second oil passage 7 is smaller than the cross-sectional area of the first oil passage 6, and the cross-sectional area of the third oil passage 8 is the same size as the cross-sectional area of the first oil passage 6.
[Selected Figure] Figure 1

Description

This invention relates to a lubrication system for an engine mounted on a vehicle.

Generally, the lubrication system for engines installed in vehicles is designed so that oil introduced into the cylinder head above the engine passes through an oil trap in the cylinder block and falls into the oil pan located below the engine. The oil collected in the oil pan is then sucked up by an oil pump and introduced into the cylinder head. This process is repeated to circulate the oil.

In an engine's lubrication system, air pressure pulsations occur inside the crankcase due to the up and down movement of the pistons. These air pressure pulsations impede the up and down movement of the pistons and worsen the engine's fuel efficiency. For this reason, it is important to ensure sufficient ventilation area between the cylinders in the crankcase to suppress the occurrence of these air pressure pulsations. Generally, when the oil level in the oil pan rises, the ventilation area between the cylinders in the crankcase becomes smaller, which places restrictions on the upper oil amount limit. On the other hand, to ensure sufficient lubrication of the engine, it is necessary to ensure a large amount of oil in the oil pan.

Patent Document 1 describes an automatic oil pan supply device that addresses this upper oil limit restriction. In this device, a reserve tank is attached to the cylinder block via a supply pipe with a supply pump, and the actual oil level is calculated from the oil level in the oil pan, which is continuously detected by multiple oil level detection sensors. When the actual oil level is below the reference oil level, control is performed to supply new oil from the reserve tank to the oil pan, thereby controlling the amount of oil.

Patent document 2 also describes an engine oil supply device in which an auxiliary oil tank is attached to the oil pan via a supply pipe having a control valve, the internal space of the auxiliary oil tank is connected to the internal space of the engine via a communicating pipe having a control valve, and the amount of oil is controlled by controlling each control valve.

Patent Document 3 also describes an engine lubrication device that has an oil pan separator inside the oil pan, with a main chamber and an auxiliary chamber separated from the main chamber by a partition. In this device, the main chamber has an upper surface that opens toward the cylinder block and is equipped with a strainer suction port that supplies oil to the cylinder block, while the auxiliary chamber has an upper surface that opens toward the cylinder block. An outflow hole is provided at the bottom of the auxiliary chamber, allowing oil from the auxiliary chamber to flow into the main chamber. This outflow hole is set so that the amount of oil flowing from the auxiliary chamber into the main chamber is less than the amount of oil flowing from the cylinder block into the auxiliary chamber, and the amount of oil is adjusted by accumulating oil in the auxiliary chamber.

Japanese Patent Application Publication No. 06-323121 Japanese Patent Application Publication No. 05-240018 Japanese Patent Application Laid-Open No. 2014-105646

The automatic oil pan supply device described in Patent Document 1 and the engine oil supply device described in Patent Document 2 require valves and supply pumps to adjust the amount of oil supplied to the oil pan, making the devices complex.

Furthermore, with the oil pan separator described in Patent Document 3, the amount of oil that flows out from the auxiliary chamber to the main chamber returns to the oil pan, making it impossible to control the amount of oil returning to the oil pan.

The objective of this invention is to reduce the amount of oil returning to the oil pan without using a valve or pump, thereby lowering the oil level in the oil pan and preventing the amount of oil in the oil pan from becoming insufficient.

In order to solve the above problems, the present invention can employ the following configurations 1 to 4.
[Configuration 1]
The engine has an oil pan provided at the bottom of the engine body, and a reservoir tank provided at a higher position than the oil pan to receive some of the oil dripping from the engine body.
The reservoir tank has a tank body and a storage section that covers the tank body with a gap formed between the tank body and the storage section, a first oil passage that supplies oil from the engine body into the tank body, a second oil passage that discharges oil in the tank body to the storage section, and a third oil passage that supplies oil in the storage section to the oil pan,
A lubrication device for an engine, wherein the second oil passage has a cross-sectional area smaller than that of the first oil passage, and the third oil passage has a cross-sectional area equal to that of the first oil passage.

[Configuration 2]
2. The engine lubrication device according to claim 1, wherein the reservoir tank is provided so as to contact a side surface of the engine body.
[Configuration 3]
The first oil passage extends in a direction intersecting the vertical direction and is connected to the engine body, the engine body is provided with an oil drop hole that opens in the vertical direction, the opening of the first oil passage in the engine body and the oil drop hole face each other horizontally, and the upper end of the opening of the first oil passage is positioned higher than the oil drop hole.
[Configuration 4]
a supply passage for returning oil in the oil pan to an upper portion of the engine body via a pump;
the upper end of the tank body is provided such that a first portion located on one side of the entire circumference in a direction perpendicular to the up-down direction is lower than a second portion located on the other side opposite to the one side,
4. The lubrication device for an engine according to claim 3, wherein the intake port of the supply passage is located on the other side of the center of the oil pan in a direction perpendicular to the up-down direction of the oil pan.

According to this invention, the cross-sectional area of the second oil passage is smaller than the cross-sectional area of the first oil passage. Therefore, the amount of oil discharged from the tank body through the second oil passage to the storage section is less than the amount of oil supplied from the engine body through the first oil passage into the tank body. This allows oil to accumulate within the tank body, lowering the oil level in the oil pan. Furthermore, because the cross-sectional area of the third oil passage is approximately the same as the cross-sectional area of the first oil passage, if oil in the oil pan is supplied to the tank body to the point that it overflows from the tank body, the amount of oil that overflows from the tank body and is supplied to the oil pan through the third oil passage will be greater than the amount of oil supplied from the engine body through the first oil passage into the tank body, preventing the oil level in the oil pan from dropping excessively.

FIG. 1 is a front view illustrating a lubrication device for an engine according to a first embodiment of the present invention; FIG. 1 is an enlarged front view of a reservoir tank of the engine lubrication device; FIG. 1 is an enlarged front view of the engine lubrication device in a tilted state; FIG. 10 is an enlarged front view illustrating a reservoir tank of a lubrication device for an engine according to a second embodiment of the present invention. FIG. 10 is a front view illustrating a state in which the lubrication device of the engine is tilted toward the first direction. 1 is an enlarged front view of the engine lubrication device showing the reservoir tank tilted toward the first direction.

An engine lubrication device according to a first embodiment of the present invention will be described with reference to Figures 1 to 3. This invention is a lubrication device that introduces and circulates oil into an engine primarily mounted on a vehicle.

As shown in FIG. 1, the engine lubrication system of this embodiment includes an oil pan 2 located below the engine body 1, a reservoir tank 3 located higher than the oil pan 2 and configured to receive a portion of the oil dripping from the engine body 1, and a supply passage 9 that supplies oil from the oil pan 2 to the top of the engine body 1. The reservoir tank 3 includes a tank body 4 (inner tank 4), a storage section 5 that covers the inner tank 4, a first oil passage 6 that supplies a portion of the oil dripping from the engine body 1 into the inner tank 4, a second oil passage 7 that discharges oil from the inner tank 4 to the storage section 5, and a third oil passage 8 that supplies oil from the storage section 5 to the oil pan 2.

The engine body 1 comprises a cylinder block 10, a crankcase 11 integrally formed with the lower part of the cylinder block 10, and a cylinder head 12 integrally connected to the upper part of the cylinder block 10. The engine body 1 is mounted on the vehicle tilted at a predetermined angle. An oil pan 2 is connected to the lower part of the cylinder block 10. The supply path 9 consists of a passage 13 formed inside the cylinder block 10 and cylinder head 12, and a suction pipe 14 connected to the oil pan 2 side of the passage 13.

A pump P is connected to the suction pipe 14, and multiple discharge ports 13a are connected to the cylinder head 12 side of the passage 13. When the pump P is driven, oil in the oil pan 2 is sucked through the suction port 14a of the suction pipe 14 and supplied from the multiple discharge ports 13a to various engine sliding parts located in the cam chamber 12a of the cylinder head 12.

An oil drop hole 15 is provided on the bottom surface of the cam chamber 12a of the cylinder head 12. The oil drop hole 15 is located on one side (the lowest side in the vertical direction) within the range of the bottom surface of the cam chamber 12a. The oil drop hole 15 penetrates the cylinder block 10 and the cylinder head 12. The oil drop hole 15 is supplied with oil from multiple discharge ports 13a, and returns a portion of the oil that accumulates on the bottom surface of the cam chamber 12a to the oil pan 2. In this embodiment, multiple oil return holes with a structure similar to the oil drop hole 15 are provided on the other side of the range of the bottom surface of the cam chamber 12a from the oil drop hole 15.

The cylinder head 12 is provided with a first oil passage 6 that connects to the cam chamber 12a. The first oil passage 6 is provided on one side of the bottom surface of the cam chamber 12a relative to the cylinder head 12. The first oil passage 6 also extends horizontally from the cylinder head 12, with the end opposite the cylinder head 12 facing downward above the inner tank 4 of the reservoir tank 3.

The opening 6a of the first oil passage 6 and the oil drop hole 15 face each other horizontally. That is, the opening 6a of the first oil passage 6, or in other words the connection portion of the first oil passage 6 with the engine body 1, opens in a direction perpendicular to the vertical direction, and the opening 6a of the first oil passage 6 and the oil drop hole 15 are approximately the same height in the vertical direction. The lower end of the opening 6a of the first oil passage 6 and one end of the bottom surface of the cam chamber 12a are aligned in the vertical direction. The upper end of the opening 6a of the first oil passage 6 is located higher than the opening of the oil drop hole 15 on the cam chamber 12a side.

The inner tank 4 of the reservoir tank 3 is mounted on the side of the engine body 1 with a gap between it and the side of the engine body 1. The inner tank 4 has a cylindrical portion 4a that is open at the top and a bottom portion 4b that closes the bottom of the cylindrical portion 4a. The upper end of the cylindrical portion 4a is formed at the same height around its entire circumference. A second oil passage 7 is connected to the bottom portion 4b. The second oil passage 7 is made of a tube with a constant oil passage cross-sectional area A2, which is set smaller than the oil passage cross-sectional area A1 of the first oil passage 6. Note that the oil passage cross-sectional area refers to the smallest oil passage cross-sectional area from the upstream to downstream side of the oil passage.

The accommodation section 5 surrounds the outer periphery of the cylindrical section 4a of the inner tank 4 and is disposed in contact with the engine body 1. The accommodation section 5 has a side section 5a disposed on the engine body 1, an upper section 5b located above the inner tank 4, and a bottom section 5c located below the bottom section 4b of the inner tank 4. The side section 5a is formed, for example, from a strip-shaped member bent so that both longitudinal ends face each other. Both longitudinal ends of the side section 5a (the ends on the engine body 1 side) are fixed across the cylinder block 10 and cylinder head 12 of the engine body 1, respectively. The upper section 5b closes the upper end opening formed by the periphery of the side section 5a and the engine body 1. The first oil passage 6 is connected to the upper section 5b. The bottom section 5c closes the lower end opening formed by the periphery of the side section 5a and the engine body 1. The bottom section 5c slopes downward toward the engine body 1. A third oil passage 8 is provided at the lower end of the housing portion 5, connecting to the space formed by the housing portion 5 and the engine body 1.

The third oil passage 8 penetrates the cylinder block 10, with its tip located inside the crankcase 11. The cross-sectional area A3 of the third oil passage 8 is set to be the same as the cross-sectional area A1 of the first oil passage 6. Note that "the same size" does not have to be exactly the same, and can be, for example, 0.8 to 1.2 times. The inner tank 4 is covered by the accommodation section 5 and the engine body 1. A gap is provided between the cylindrical section 4a of the inner tank 4 and the side section 5a of the accommodation section 5 and the engine body 1. Because this gap also functions as an oil passage, it will be referred to as the fourth oil passage below.

The combined cross-sectional area A5, which is the sum of the cross-sectional area A4 of the fourth oil passage and the cross-sectional area A2 of the second oil passage 7, is set to be more than twice the cross-sectional area A3 of the third oil passage 8. With this setting, for example, if the engine body 1 tilts significantly due to vehicle tilt, causing oil to leak from the inner tank 4 through the fourth oil passage, which occupies approximately half of the fourth oil passage on the tilted side of the engine body 1, the total amount of oil leaking from the inner tank 4 and the amount of oil discharged from the second oil passage 7 to the storage section 5 will be approximately the same as the amount of oil supplied from the third oil passage 8 to the oil pan 2. When the engine body 1 tilts significantly, as in this case, the oil leaking from the inner tank 4 due to the tilt can be supplied to the oil pan 2, thereby preventing the oil in the oil pan 2 from becoming unevenly distributed due to the engine body 1 tilting significantly and reducing the amount of oil in part of the oil pan 2.

In this embodiment of the engine lubrication system, engine operation drives the pump in the supply passage 9, drawing oil from the oil pan 2 through the suction port 14a of the suction pipe 14 of the supply passage 9. The drawn oil passes through the passage 13 of the supply passage 9 and is supplied to various engine sliding parts located within the cam chamber 12a from the discharge port 13a. Some of the supplied oil flows to one side along the bottom of the cam chamber 12a, passes through the oil drop hole 15, passes through the crankcase 11, and returns to the oil pan 2. Meanwhile, the remaining oil passes from the cam chamber 12a through the opening 6a, passes through the first oil passage 6, and is supplied to the inner tank 4. The oil in the inner tank 4 is discharged through the second oil passage 7 to the storage section 5. Here, because the cross-sectional area A2 of the second oil passage 7 is smaller than the cross-sectional area A1 of the first oil passage 6, oil accumulates within the inner tank 4.

The oil then drains from the second oil passage 7 into the storage section 5, passes through the third oil passage 8, and returns to the oil pan 2 via the crankcase 11. The oil in the oil pan 2 is then sucked in by the pump in the supply passage 9. This process is repeated to circulate the oil.

As described above, this engine lubrication system allows oil supplied from the first oil passage 6 to be stored in the inner tank 4 while the engine is running. By storing oil up to the capacity of the inner tank 4 while the engine is running, the amount of oil circulating within the engine is ensured while the amount of oil that accumulates in the oil pan 2 is reduced, making it possible to lower the oil level within the oil pan 2. By lowering the oil level within the oil pan 2, the ventilation area between the cylinders in the crankcase 11 is expanded, making it possible to suppress the generation of air pressure pulsations associated with the up and down movement of the pistons described above.

Furthermore, if oil is supplied from the first oil passage 6 when the inner tank 4 is filled to capacity, the oil will overflow from the inner tank 4. The overflowing oil is supplied to the oil pan 2 via the fourth oil passage formed between the storage section 5 and the inner tank 4 and the third oil passage 8. Because the inner tank 4 does not store oil beyond its capacity, it is possible to prevent the amount of oil in the oil pan 2 from decreasing drastically.

Furthermore, as shown in Figure 3, when the vehicle is in operation, the engine body 1 may tilt as the vehicle tilts. In this case, the angle of the oil level in the oil pan 2 changes. In this engine lubrication system, the inner tank 4 tilts in accordance with the angle at which the engine body 1 tilts, and oil in the inner tank 4 overflows from the tilted upper end of the inner tank 4 by a volume α shown in Figure 3.

The oil that overflows by the volume α shown in Figure 3 is supplied to the oil pan 2 through the fourth oil passage formed between the storage section 5 and the inner tank 4 and the third oil passage 8, thereby raising the oil level in the oil pan 2. On the other hand, when the vehicle is not tilted (normal state), the inner tank 4 does not tilt, and oil is stored up to the capacity of the inner tank 4, including the volume α shown in Figure 3, and in this case, the oil level in the oil pan 2 can be lowered.

As described above, the engine lubrication system stores oil up to the capacity of the inner tank 4, and any oil supplied above that capacity is supplied to the oil pan 2 via the third oil passage 8. This makes it possible to control the amount of oil supplied to the oil pan 2 without installing valves or pumps in the first oil passage 6, second oil passage 7, and third oil passage 8.

Furthermore, the storage section 5 is located so that it contacts the side of the engine body 1. This allows the oil in the storage section 5 to be heated quickly by the heat generated when the engine is running. This allows the oil viscosity to be reduced early after the engine starts, reducing friction during the warm-up process.

Next, an engine lubrication device according to a second embodiment of the present invention will be described with reference to Figures 4 to 6. The engine lubrication device of this embodiment differs from the first embodiment described above in that the portion of the upper end of the cylindrical portion 4a of the inner tank 4 that is located on the first direction side (described below) is lower than the portion that is located on the second direction side, which is opposite the first direction, and the suction port 14a of the suction pipe 14 is positioned closer to the second direction side in the oil pan 2. Other structural elements that are the same as those in the first embodiment are designated by the same reference numerals as in the first embodiment, and their description will be omitted.

In this embodiment of the engine lubrication system, when the vehicle tilts while in operation, the tilt of the oil level in the oil pan 2 changes in accordance with the tilt of the vehicle. For example, when the vehicle tilts in the first direction (to one side in a direction intersecting the vertical direction), as shown in FIG. 5, the suction port 14a of the suction pipe 14 may momentarily or intermittently approach the oil level in the oil pan 2 (part of the suction port 14a may appear to be about to move upward from the oil level). In this embodiment, the suction port 14a is located on the other side of the center of the oil pan 2 in the direction intersecting the vertical direction, i.e., the second direction. Therefore, when the vehicle tilts in the first direction, the amount of oil in the oil pan 2 on the first direction side increases and the amount of oil on the second direction side, i.e., the suction port 14a side, decreases. In this state, there is a risk of poor suction of oil in the oil pan 2 from the suction pipe 14.

In this engine lubrication system, the upper end of the cylindrical portion 4a of the inner tank 4, located on the first direction side, is positioned lower than the portion located on the second direction side, which is opposite the first direction. Therefore, when the vehicle tilts toward the first direction and the suction port of the suction pipe 14 moves partially or completely away from the oil level in the oil pan 2, oil is more likely to leak from the upper end of the inner tank 4 on the first direction side and be supplied to the oil pan 2 through the third oil passage 8, raising the oil level in the oil pan 2. As a result, the suction port 14a of the suction pipe 14 is positioned lower than the oil level in the oil pan 2, preventing poor oil suction. On the other hand, when the vehicle tilts toward the second direction, the suction port of the suction pipe 14 is less likely to move away from the oil level in the oil pan 2, making it easier for oil to accumulate in the inner tank 4 and reducing the amount of oil in the oil pan 2.

1 Engine body 1a Reinforcement rib 2 Oil pan 3 Reservoir tank 4 Inner tank 4a Cylindrical portion 4b Bottom surface portion 5 Storage portion 5a Side surface portion 5b Top surface portion 5c Bottom surface portion 6 First oil passage 6a Opening 7 Second oil passage 8 Third oil passage 9 Supply passage 10 Cylinder block 11 Crankcase 12 Cylinder head 12a Cam chamber 13 Passage 13a Discharge port 14 Suction pipe 14a Suction port 15 Oil drop hole P Pump

Claims (4)

The engine has an oil pan provided at the bottom of the engine body, and a reservoir tank provided at a higher position than the oil pan to receive some of the oil dripping from the engine body.
The reservoir tank has a tank body and a storage section that covers the tank body with a gap formed between the tank body and the storage section, a first oil passage that supplies oil from the engine body into the tank body, a second oil passage that discharges oil in the tank body to the storage section, and a third oil passage that supplies oil in the storage section to the oil pan,
A lubrication device for an engine, wherein the second oil passage has a cross-sectional area smaller than that of the first oil passage, and the third oil passage has a cross-sectional area equal to that of the first oil passage. The engine lubrication device according to claim 1, wherein the reservoir tank is provided so as to contact the side surface of the engine body. An engine lubrication device as described in claim 1 or claim 2, wherein the first oil passage extends in a direction intersecting the vertical direction and is connected to the engine body, the engine body is provided with an oil drop hole that opens in the vertical direction, the opening of the first oil passage in the engine body and the oil drop hole face each other horizontally, and the upper end of the opening of the first oil passage is positioned higher than the oil drop hole. a supply passage for returning oil in the oil pan to an upper portion of the engine body via a pump;
the upper end of the tank body is provided such that a first portion located on one side of the entire circumference in a direction perpendicular to the up-down direction is lower than a second portion located on the other side opposite to the one side,
4. The lubrication device for an engine according to claim 3, wherein the intake port of the supply passage is located on the other side of the center of the oil pan in a direction perpendicular to the up-down direction of the oil pan.