Chain pulley cover for the oil pump of an internal combustion engine

Abstract

The invention relates to a sprocket cover for an internal combustion engine oil pump. In order to reduce the number of screws required for connecting an oil pump (20) connected to a crankcase (8), to reduce weight and labor, and to ensure low cost, one side of the sprocket cover (34) of the oil pump (20) is fixed to the crankcase (8), and the other side of the sprocket cover (34) of the oil pump (20) is fixed to the oil pump (20). à

Description

The invention relates to a sprocket cover for an oil pump of an internal combustion engine. In particular, the invention relates to a sprocket cover for an oil pump which serves, on the one hand, as a cover for an oil pump sprocket and, on the other hand, as a mounting member (bracket) for holding the oil pump. The invention also relates to a sprocket cover for an oil pump of an internal combustion engine, and in particular to a sprocket cover for an oil pump which reduces the mixing of oil flowing in the gap between the sprocket cover of the oil pump and the oil pump with air. The invention also relates to a sprocket cover for an internal combustion engine oil pump, and in particular to a sprocket cover for an oil pump which reduces the velocity of the oil near the outlet of the sprocket cover of the oil pump and reduces oil mist and mixing of the oil with air. Internal combustion engines are equipped with an oil pump that draws oil from the oil pan and delivers it under pressure to lubricate and cool engine components. This means that in the internal combustion engine installed in the vehicle, the oil pump circulates oil to lubricate and cool the engine components. The oil is stored in the oil pan under the internal combustion engine, flows to the engine components, and returns to the oil pan after lubricating and cooling the engine components. For example, as shown in FIGS. 17 and 18 , in the internal combustion engine 102 , a cylinder head 106 is mounted on a cylinder block 104 and a crankcase 110 in cooperation with the cylinder block 104 rotatably supports a crankshaft 108 . An oil pump 112 is secured below the crankcase 110 by a plurality of pump attachment bolts (not shown) and the crankshaft 108 is provided with an oil pump drive sprocket 114 . The oil pump sprocket 118 is on the pump shaft 116 of the oil pump 112 . An oil pump drive chain 120 is passed around the oil pump drive sprocket 114 and the oil pump sprocket 118 . The oil pump sprocket 118 is covered by the oil pump sprocket cover 122. The oil pump sprocket cover 122 is attached to the oil pump 112 by cover attachment bolts 124, as shown in FIG. 18 . As shown in Figure 19, the oil pump sprocket cover 122 is sometimes attached to the bottom of the crankcase 110 by cover attachment bolts 124. A sprocket cover of this type for oil pumps of internal combustion engines is disclosed in Japanese Patent Publication No. 63-16569 (No. 16569 / 1988). The sprocket cover described in this publication is connected to a flange formed on a sprocket-side side wall of an oil pump housing so as to surround a sprocket connected to a drive shaft protruding from the oil pump housing. The upper edge of the sprocket cover is at least above the highest oil level and a plurality of elongated holes formed along an imaginary circle. The elongated holes are arranged in the circumferential direction of the imaginary circle. A wall portion connected to the end side of the flange by screws in the elongated holes and a guide portion extending from the sprocket along the drive chain and disposed on the sprocket-driving side of the drive chain wrapped around the sprocket are integrally formed. The guide part is equipped with a wear-resistant elastic material to constantly contact the drive chain and tension the drive chain.Therefore, the drive sprocket of the oil pump, which is placed in the oil, does not stir or stir the oil or ripple the surface of the oil while rotating, and the tension of the drive chain around the sprocket is also prevented from loosening. Japanese Provisional Patent Publication No. 5-332113 (No. 332113 / 1993) discloses another type of sprocket cover for an oil pump. In the oil pump coupling structure described in this publication, an oil pump is disposed in an oil sump, and a cover surrounding a portion of the oil pump sprocket is disposed near the pump sprocket to prevent oil from mixing in the oil sump when the oil pump is operating. This prevents poor oil suction at low temperatures, and also prevents the pump sprocket and the pump drive chain from mixing the oil. However, the traditional sprocket cover for oil pumps only serves one function: it serves as a cover to cover the sprocket of the oil pump. Therefore, the oil pump must be fixed with a predetermined number of pump connection bolts. The disadvantages of this are greater weight, greater assembly labor, and higher cost. As described above and shown in FIG. 19 , in a conventional internal combustion engine, an oil pan 132 is mounted on the lower portion of the crankcase 110 of the internal combustion engine 102 , and the oil pump 112 is located in this oil pan 132 . The oil pump chain 120 is wrapped around the oil pump sprocket 118 of the oil pump 112, and the oil pump 112 is driven by the driving force of the crankshaft 108 through the oil pump chain 120. The oil pump sprocket cover 122, which is mounted to the crankcase 110, is located near the oil pump sprocket 118, and there is a gap 126 between the oil pump sprocket cover 122 and the oil pump 112. The oil in the sprocket cover 122 of the oil pump flows directly into the oil sump 132 through this gap 126. As a result, the oil in the oil pump sprocket cover, which is heavily mixed with air, flows directly into the oil sump, and as a result, the oil sucked in through the coarse oil filter in the oil sump will contain more air. This can result in poor suction of the oil filter. This has the disadvantage that the lubricating capacity of the oil pump, which transports the sucked-in oil under pressure, is reduced, and the reliability of the internal combustion engine is impaired. If the lubricating capacity of the oil pump decreases, the wear of the parts that need to be lubricated will increase. As a result, the service life of the parts will be shorter, which will lead to more frequent replacement of the parts. HU 221 284 Bl increases. This results in increased costs and is therefore economically disadvantageous. In addition, the sprocket cover 122 surrounding a portion of the sprocket wheel of the oil pump 118 is positioned such that the first clearance S1 between the sprocket cover 122 of the oil pump and the chain 120 of the oil pump on the inlet side, where the chain 120 forming the drive chain of the oil pump enters the sprocket cover, is approximately equal to the second clearance S2 between the sprocket cover 122 of the oil pump and the chain 120 of the oil pump, which is formed on the outlet side, where the chain 120 of the oil pump leaves the sprocket cover. As a result, the outlet side inner surface of the oil pump sprocket cover 122 is close to the oil pump chain 120, so that the outlet side inner surface acts as a guide member, a kind of "ejector member" for the oil in the oil pump sprocket cover 122, so that a large amount of oil mist is generated in the crankcase 110. Therefore, the capacity of the not shown breathing chamber in the cylinder head cover 128 must be increased. As a result, the engine becomes larger, which is disadvantageous in practical use. The oil drawn from the bottom of the oil pump sprocket cover 122 by the chain of the oil pump 120 is directly acted upon by the chain of the oil pump 120 near the second gap S2, so that the oil flows out through the second gap S2 without a decrease in speed. As a result, the amount of oil mist in the crankcase 110 increases and the mixing of air into the oil also increases.Therefore, in the oil sucked in by the oil filter, the mixing of air into the oil increases, resulting in a decrease in lubricity and engine reliability. The aim of our invention is to eliminate the above disadvantages. This object is achieved according to the invention by providing that in an internal combustion engine for which the oil pump sprocket cover according to the invention can be used, the crankcase, in cooperation with the cylinder block, rotatably supports the crankshaft. The oil pump is located under the crankcase. The oil pump drive sprocket is on the crankshaft, the oil pump sprocket is on the oil pump. The oil pump drive chain is passed around the oil pump drive sprocket and the oil pump sprocket. The sprocket cover covers the oil pump sprocket. One side of the oil pump sprocket cover is fixed to the crankcase, the other side to the oil pump. The oil pump sprocket cover according to the invention serves as a cover for the oil pump sprocket and as a fixing member (brace) for holding the oil pump. This reduces the number of screws required to connect the oil pump, resulting in less weight, reduced assembly labor, and lower cost. According to the invention, one side of the oil pump sprocket cover is fixed to the crankcase, and the other side of the oil pump sprocket cover is fixed to the oil pump. Therefore, the oil pump sprocket cover serves as both the oil pump sprocket cover and the fixing member (brace) to support the oil pump. This reduces the number of bolts required to connect the oil pump, thus reducing the weight, reducing the assembly labor, and ensuring low cost. In order to overcome the above-described disadvantages, in another preferred embodiment of the invention, a sprocket cover for an oil pump of an internal combustion engine encloses a drive chain connecting the oil pump sprocket with the oil pump drive sprocket fixed to the end of the crankshaft. The oil pump is driven by the rotational force of the crankshaft. The sprocket cover surrounds the oil pump sprocket. A bracket is disposed with a gap between the oil pump sprocket cover and the oil pump, which secures the oil pump sprocket cover to the oil pump, catches the oil flowing out through the gap, and, after the air mixing into the oil has been reduced, directs the oil to an oil sump. According to the invention, if oil leaks through the gap between the oil pump sprocket cover and the oil pump as described above, the bracket catches the oil and, after the air mixing into the oil has decreased, it causes the oil to flow into the oil sump. According to the invention, a sprocket cover for an oil pump of an internal combustion engine encloses a drive chain that connects the sprocket of the oil pump to the oil pump drive sprocket fixed to the end of the crankshaft. The oil pump is driven by the rotational force of the crankshaft. The sprocket cover surrounds the sprocket of the oil pump. A bracket is disposed with a gap between the sprocket cover of the oil pump and the oil pump, which fixes the sprocket cover of the oil pump to the oil pump, receives oil flowing through the gap, and after the air mixing in the oil is reduced, causes the oil to flow into an oil sump. Therefore, the bracket can perform a function of connecting the sprocket cover of the oil pump to the oil pump and another function of temporarily blocking the flow of oil flowing through the gap. This is advantageous in practical application.The oil flowing out through the gap between the oil pump and the oil pump sprocket cover is caught by the bracket and, after the air mixing into the oil is reduced, is allowed to flow into the oil pan. Thus, the air mixing into the oil can be reduced when the oil is absorbed through the oil filter, so that the lubrication conditions of the entire internal combustion engine are improved. This contributes to the improvement of reliability. In addition, since the air mixing into the oil is reduced, the lubricity of the oil pump can be improved. This prevents wear of the parts to be lubricated, so that the service life of the parts can be extended. As a result, the frequency of replacement of parts is reduced, thereby reducing the cost. This is also economically advantageous. To overcome the above-described disadvantages, in a further preferred embodiment of the invention, a sprocket cover for an oil pump of internal combustion engines covers the drive chain connecting the oil pump sprocket to the oil pump drive sprocket fixed to the end of the crankshaft. The oil pump HU 221 284 Β1 is driven by the rotational force of the crankshaft. The sprocket cover surrounds the oil pump sprocket. A first gap is formed between the oil pump sprocket cover and the drive chain on the inlet side where the drive chain enters the oil pump sprocket cover and a second gap is formed between the oil pump sprocket cover and the drive chain on the outlet side where the drive chain leaves the oil pump sprocket cover. The second gap is larger than the first gap so that the amount of oil mist and air mixing into the oil is reduced by reducing the flow rate of the oil near the outlet of the oil pump sprocket cover. According to the invention, as described above, when the crankshaft rotates, the rotating force of the oil pump drive sprocket rotates the oil pump sprocket through the pump drive chain, and this drives the oil pump. When the oil pump is driven, the second gap formed to be larger reduces the speed of the oil near the outlet of the oil pump sprocket cover, so that the amount of oil mist and air mixing into the oil are reduced. According to the invention, a sprocket cover for an oil pump of an internal combustion engine encloses a drive chain connecting the oil pump sprocket to an oil pump drive sprocket fixed to the end of a crankshaft. The oil pump is driven by the rotational force of the crankshaft. The sprocket cover surrounds the oil pump sprocket. A first gap is formed between the oil pump sprocket cover and the drive chain on the inlet side where the drive chain enters the oil pump sprocket cover, and a second gap is formed between the oil pump sprocket cover and the drive chain on the outlet side where the drive chain leaves the oil pump sprocket cover. The second gap is larger than the first gap to reduce the amount of oil mist and air mixing into the oil, thereby reducing the oil flow rate near the outlet of the oil pump sprocket cover.Therefore, the second gap can reduce the speed of the oil near the outlet of the oil pump sprocket cover, so that the amount of oil mist and air mixing into the oil can be reduced. Reducing the amount of oil mist allows the breathing chamber in the cylinder head cover to be compact. This is advantageous in terms of practical application. In addition, since the air mixing into the oil can be reduced, the lubricity of the entire internal combustion engine is improved, which contributes to improving reliability. Our invention is described in more detail with reference to its exemplary embodiments with the help of our drawings, of which the Figure 1 is a bottom view of the crankcase after the oil pump sprocket cover according to one embodiment of the invention is attached, the Figure 2 is a front view of the oil pump sprocket cover of Figure 1, Figure 3 is a top view of the oil pump sprocket cover of Figure 1, Figure 4 is a bottom view of the oil pump sprocket cover of Figure 1, Figure 5 is a rear view of the oil pump sprocket cover of Figure 1, Figure 6 is a section taken along line VI-VI of Figure 2, Figure 7 is a section of Figure 6 taken along section line VII-VII, Figure 8 is a section of Figure 6 taken along the section line VIII—VIII, Figure 9 is a side view of Figure 5 in the direction of arrow IX, Figure 10 shows the bottom view of the crankcase after the oil pump sprocket cover has been attached, Figure 11 is a cross-section of the internal combustion engine, Figure 12. Front view of the internal combustion engine, Figure 13 is a schematic, enlarged, vertical section of an oil pump sprocket cover and an oil pump according to another embodiment of the invention, the Figure 14 is a schematic, enlarged, horizontal section of the oil pump sprocket cover and oil pump according to Figure 13, Figure 15 is a partially broken away, schematic front view of an internal combustion engine with another embodiment of the invention, the Figure 16 is a schematic cross-section of the internal combustion engine according to Figure 15, Figure 17 is a partial view-section of a conventional internal combustion engine, Figure 18 is a partial cross-sectional view of the oil pump sprocket in a conventional internal combustion engine, Figure 19 is an enlarged partial cross-sectional view of another sprocket in a conventional internal combustion engine, and Figure 20 is a partially broken away, schematic front view of the prior art internal combustion engine. 1-12. An embodiment of the invention is shown in Fig. 11. and 12. The internal combustion engine 2, the cylinder block 4, the cylinder head 6, the crankcase 8 and the oil sump 10 are shown in Fig. 12. The crankshaft 12 is rotatably supported in the lower part of the cylinder block 4 in cooperation with the upper part of the crankcase 8. The intake camshaft 14 and the exhaust camshaft 16 are rotatably arranged in the cylinder head 6. The oil pump 20 is secured to the lower part of the crankcase 8 by three pump connecting bolts 18. The bolts 18 are arranged in a predetermined manner, as shown in Figure 1. This oil pump 20 sucks the oil in the oil sump 10 through the suction pipe 26 and delivers it under pressure to the components of the internal combustion engine 2 by rotation of the pump shaft 24 rotatably fixed in the pump body 22. The oil pump sprocket 28 is secured to the pump shaft 24. At the end of the crankshaft 12, an oil pump drive sprocket 30 is fixed in a position corresponding to the oil pump sprocket 28. HU 221 284 B1 The oil pump chain 32 is routed around the oil pump drive sprocket 30 and the oil pump sprocket 28. To cover the oil pump sprocket 28, a sprocket cover 34 is attached to the lower part of the crankcase 8 and the lower part of the oil pump 20. As shown in Fig. 2-9, the oil pump sprocket cover 34 has a crankcase connector cover 36 on one side, an oil pump connector cover 38 on the other side, and a cover 40 that connects the crankcase connector cover 36 to the oil pump connector cover 38 and covers the oil pump sprocket 28. The crankcase connecting cover 36 is provided with crankcase-side holes 44 into which the crankcase-side fixing bolts 42 are inserted. As shown in Figure 10, the crankcase-side fixing bolts 42 connect the crankcase connecting cover 36 to the bottom of the crankcase 8 by being threaded into the crankcase-side threaded holes 46 formed in the bottom of the crankcase 8. The oil pump connection cover 38 has pump-side holes 50 formed for the pump-side fixing bolts 48. As shown in FIG. 10, the pump-side fixing bolts 48 connect the oil pump connection cover 38 to the oil pump 20 by being threaded into the pump-side threaded holes 52. The pump-side threaded holes 52, as shown in FIG. 10, are formed in the lower part at locations where there are no pump connection bolts 18, i.e. in the lower part of the pump body 22. As shown in FIG. 6 , the cover portion 40 has a side member 54 that is in contact with the crankcase connector cover portion 36 on one side, and another side member 56 that is connected to the side member 54 and the crankcase connector cover portion 36 on the oil pump connector cover portion 38 side. The overlapping portion of the side member 54 and the crankcase connector cover portion 36 is formed at approximately right angles and maintains a predetermined strength by using a reinforcing member 58, as shown in FIG. 6 . The operation of this embodiment will be described below. One side of the oil pump sprocket cover 34, the crankcase connecting cover portion 36, is secured to the lower portion of the crankcase 8 and the other side, the oil pump connecting cover portion 38, is secured to the lower portion of the oil pump 20 at locations where there is no pump connecting bolt 18. The cover portion 40 is positioned to cover the oil pump sprocket 28 and to connect the crankcase 8 to the pump body 22. Then, the oil pump sprocket cover 34 not only has the function of covering the oil pump sprocket 28, but also serves as a fixing member (brace) that supports the oil pump 20 to the crankcase 8. The oil pump 20 can therefore be secured to the crankcase 8 by the oil pump sprocket cover 34. Therefore, the number of pump connection bolts 18 directly connecting the oil pump 20 to the crankcase 8 can be reduced to three. This reduces the weight of the oil pump 20, reducing labor and cost. 13 and 14 show another embodiment of the invention. In this embodiment of the invention, like parts are designated by like reference numerals. In Fig. 11, an internal combustion engine 2 and a cylinder block 4 are shown. In the internal combustion engine 2, a cylinder head 6 and a cylinder head cover 68 are mounted on the upper side of the cylinder block 4. The upper surface of the crankcase 8 is connected to the lower surface of the cylinder block 4. An oil pan 10 is connected to the lower rim of the crankcase 8. A crankshaft 12 is rotatably disposed between the lower surface of the cylinder block 4 and the upper surface of the crankcase 8. This crankshaft 12 extends from one end (left in the figure) of the internal combustion engine 2 to the other end (right in the figure). An oil pump drive sprocket 30 is mounted on one end (left in the figure) of the crankshaft 12. An oil pump 20 is disposed in the oil sump 10. An oil pump chain 32 is passed around the sprocket 28 of the oil pump 20. A sprocket cover 34 surrounding a portion of the sprocket 28 of the oil pump 20 is provided near the sprocket 28 of the oil pump to prevent the oil in the oil sump from being mixed when the oil pump 20 is driven by the driving force of the crankshaft 12 via the oil pump chain 32. A gap 66 is formed between the oil pump sprocket cover 34 and the oil pump 20. Below the gap 66 is a bracket 78 which secures the oil pump sprocket cover 34 to the oil pump 20, receives the oil flowing through the gap 66 and, after the air mixing into the oil has been reduced, drains the oil into the oil sump 10. This bracket 78 corresponds to the oil pump connecting cover part 38 in the previous embodiment of the invention. In more detail, as shown in Figure 13, one end of the bracket 78 is attached to the lower part of the sprocket cover 34 of the oil pump, the other end extends from the curved end piece 70 forming the gap 66 of the sprocket cover 34 of the oil pump to the oil pump 20 and is attached to the lower part of the oil pump 20 by the fastening screws 48. The cross-section of the oil pump sprocket cover 34 is U-shaped, so that it surrounds a part of the oil pump sprocket 28 and one end is fixed to the crankcase 8. One end of the bracket 78 is fixed to the lower surface of the oil pump sprocket cover 34. Therefore, the bracket 78 functions as a support member that fixes the oil pump sprocket cover 34 to the oil pump 20. Also visible are the coarse oil filter 64 located in the oil sump 10, the suction pipe 26 connecting the oil filter 64 to the oil pump 20, and the oil suction opening 59. The operation is described below. When the crankshaft 12 rotates, the oil pump drive 30 chain attached to the crankshaft 12 is HU 221 284 Wheel Β1 rotates and the rotational force of this oil pump drive sprocket 30 drives the oil pump 20 via the oil pump chain 32. At this time, mixing of the oil in the oil sump 10 caused by the oil pump sprocket 28 and the oil pump chain 32 is prevented because the oil pump sprocket cover 34 covers a portion of the oil pump sprocket 28. The oil entering the oil pump sprocket cover 34 flows out of the oil pump sprocket cover 34 through the gap 66 and reaches the inside of the bracket 78 due to the rotation of the oil pump chain 32 and the oil pump sprocket 28. The bracket 78 temporarily receives the oil flowing through the gap 66, after a short interval it drains the oil, allowing it to drain into the oil sump 10 after the entrainment of air into the oil in the bracket 78 has been reduced. The function of the bracket 78 is, on the one hand, to connect the sprocket cover 34 of the oil pump to the oil pump 20, and on the other hand, to temporarily stop the flow of oil through the gap 66. This is advantageous in practical application. The oil flowing out through the gap 66 between the oil pump 20 and the oil pump sprocket cover 34 is received by a bracket 78, and after the air mixing into the oil in the bracket 78 is reduced, it is allowed to flow into the oil sump 10. This can reduce the air mixing into the oil when the oil is sucked into the oil filter 64. Thus, the lubrication conditions of the entire internal combustion engine are improved. This contributes to the improvement of reliability. In addition, since the mixing of air into the oil is reduced, the lubricating ability of the oil pump can be improved. This prevents wear of the parts to be lubricated, so that the service life of the parts can be extended. As a result, the frequency of replacement of parts is reduced, thereby reducing the cost. This is also economically advantageous. The invention is not limited to the above embodiment and may have various modifications. In this embodiment of the invention, for example, when forming the bracket, one end thereof is fixed to the lower surface of the sprocket cover of the oil pump formed into a U-shaped cross section, and the other end thereof is fixed to the lower part of the oil pump by using fixing bolts. However, the design of the bracket is arbitrary. The point is that the bracket is placed under the gap between the sprocket cover of the oil pump and the oil pump, and can receive the oil flowing through the gap. The design of the connecting part and the connection at both ends of the bracket can be changed as desired. A further embodiment of the invention is shown in Figures 15 and 16. In this embodiment of the invention, the same parts are designated by the same reference numerals. In the internal combustion engine 2 shown in Figures 15 and 16, the crankshaft 12 is connected to one end (left in Figure 16) of the crankshaft, one after the other, from one end inward, with the crank sprocket 76 and the oil pump drive sprocket 30. A first drive chain 84 is passed around the crank sprocket 76 and the large diameter sprocket 82 mounted on the countershaft 80. A second drive chain 96 is passed around the small diameter sprocket 86 mounted on the countershaft 80, the first sprocket 92 mounted on the first camshaft 16, and the second sprocket 92 mounted on the second camshaft 14. The oil pump 20 is located in the oil sump 10 and the oil pump chain 32 - the third drive chain - is passed around the oil pump 20 sprocket 28 and the oil pump drive sprocket 30 of the crankshaft 12. An oil pump sprocket cover 34 surrounding a portion of the oil pump sprocket 28 is provided near the oil pump sprocket 28 to prevent the oil in the oil sump 10 from being mixed when the oil pump 20 is driven by the driving force of the crankshaft 12 via the oil pump chain 32. On this sprocket cover 34 of the oil pump, a first gap S1 is formed between the sprocket cover 34 of the oil pump and the oil pump chain 32 on the inlet side where the oil pump chain 32 enters the cover, and a second gap S2 is formed between the sprocket cover 34 of the oil pump and the oil pump chain 32 on the outlet side where the oil pump chain 32 leaves the cover. The second gap S2 is formed to be larger than the first gap S1 and thus reduces the amount of oil mist and air mixing into the oil by reducing the flow rate of the oil near the outlet opening of the sprocket cover 34 of the oil pump. In more detail, as shown in Fig. 15, the second gap S2 gradually increases from the lower part of the oil pump sprocket cover 34 toward the outlet, so that the size of the second gap S2 near the outlet is about twice the size of the first gap S1. The oil pump sprocket cover 34 is connected to the oil pump 20 by the bracket 78. The operation is described below. When the crankshaft 12 rotates, the oil pump drive sprocket 30 fixed to the crankshaft 12 rotates, and the rotational force of this oil pump drive sprocket 30 drives the oil pump 20 via the oil pump chain 32. At this time, mixing of the oil in the oil sump 10 caused by the oil pump sprocket 28 and the oil pump chain 32 is prevented because the oil pump sprocket cover 34 covers the lower half of the oil pump sprocket 28. The oil entering the oil pump sprocket cover 34 is discharged through the second gap S2, which is the outlet of the oil pump sprocket cover 34, due to the rotation of the oil pump chain 32 and the oil pump sprocket 28. The oil passes through the second gap S2, which gradually increases from the lower part of the oil pump sprocket cover 34 towards the outlet, so that the size of the second gap S2 near the outlet is about twice the size of the first gap S1, so that the flow rate of the oil in the second gap S2 decreases. HU 221 284 Bl This means that the second gap S2 can reduce the speed of the oil near the outlet. This can reduce the amount of oil mist emitted from the outlet and the mixing of air into the oil. Reducing the amount of oil mist allows the breathing chamber in the cylinder head cover to be compact. This is advantageous from a practical application perspective. In addition, since air mixing into the oil can be reduced, the lubricity of the entire internal combustion engine is improved, contributing to improved reliability. Furthermore, the second gap S2 gradually increases from the lower part of the oil pump sprocket cover toward the outlet, so that the size of the second gap S2 near the outlet is about twice the size of the first gap S1. Thus, the flow rate of the drawn oil toward the outlet can be gradually reduced. Thus, the amount of oil mist discharged from the outlet and the mixing of air into the oil can be effectively reduced. The invention is not limited to the above embodiment and may have various modifications. In this embodiment of the invention, for example, the second gap is designed to be twice as large as the first gap. However, the second gap can also be designed to be larger than twice the size of the first gap. The larger size of the second gap reliably reduces the oil flow rate.

Claims

PATENT CLAIMS 1. A sprocket cover for an oil pump of an internal combustion engine, wherein in an internal combustion engine (2), a crankcase (8) cooperates with a cylinder block (4) to rotatably support a crankshaft (12); an oil pump (20) is located under the crankcase (8); the oil pump drive sprocket (30) is located on the crankshaft (12), and the oil pump sprocket (28) is located on the oil pump (20); the oil pump chain (32) is passed around the oil pump drive sprocket (30) and the oil pump sprocket (28) and the sprocket cover (34) covers the oil pump sprocket (28), characterized in that one side of the sprocket cover (34) of the oil pump (20) is fixed to the crankcase (8), and the other side of the sprocket cover (34) of the oil pump (20) is fixed to the oil pump (20).

2. A sprocket cover for an oil pump of an internal combustion engine, the internal combustion engine (2) comprising an oil pump chain (32) connecting an oil pump sprocket (28) to an oil pump drive sprocket (30) attached to the end of a crankshaft (12), the oil pump (20) being driven by the crankshaft (12) and the sprocket cover (34) surrounding the sprocket (28) of the oil pump (20), characterised in that a bracket (78) is disposed below the gap (66) between the sprocket cover of the oil pump (20) and the oil pump (20), which secures the sprocket cover (34) of the oil pump (20) to the oil pump (20), receives oil flowing through the gap (66) and directs it to an oil sump (10).

3. A sprocket cover for an oil pump of an internal combustion engine, the internal combustion engine (2) comprising a drive chain connecting an oil pump sprocket (28) to an oil pump drive sprocket (30) secured to the end of a crankshaft (12); the oil pump (20) is driven by the crankshaft (12) and the sprocket cover (34) surrounds the sprocket (28) of the oil pump (20), characterized in that a first gap (S1) is formed between the sprocket cover (34) of the oil pump (20) and the oil pump chain (32) on the inlet side where the oil pump chain (32) enters the sprocket cover (34) of the oil pump (20), and a second gap (S2) is formed between the sprocket cover (34) of the oil pump (20) and the oil pump chain (32) on the outlet side where the oil pump chain (32) leaves the sprocket cover (34) of the oil pump (20);the second gap (S2) is larger than the first gap (S1), so that the amount of oil mist and air mixing into the oil are reduced by reducing the flow rate of the oil near the outlet of the sprocket cover (34) of the oil pump (20);