Oil pump for motorcycle engine

Abstract

The present invention provides an oil pump for a motorcycle engine, belonging to the technical field of engines. It solves the problem that the existing engine oil pump occupies a large installation space. The engine includes a housing and an oil pan arranged at the bottom of the housing, a mounting hole is opened in the inner wall of the housing, the oil pump includes a pump body inserted and fixed in the mounting hole, a main pump cavity is formed between the inner end of the pump body and the hole wall of the inner end of the mounting hole, a rotatable pump shaft is passed through the pump body and the inner end of the pump shaft extends into the main pump cavity, the pump shaft outer sleeve located in the main pump cavity is provided with a main rotor capable of pressing the oil in the oil pan toward the oil circuit of the housing, the cavity inside the pump body is an auxiliary pump cavity, and the pump shaft outer sleeve located in the auxiliary pump cavity is provided with an auxiliary rotor capable of pressing the oil in the housing toward the oil pan. The oil pump of the motorcycle engine has the advantages of occupying a small installation space and good stability.

Description

Technical Field

[0001] The invention belongs to the technical field of engines and relates to an oil pump for a motorcycle engine. Background Art

[0002] The motorcycle engine includes a crankcase and an oil pan fixed at the bottom of the crankcase. An oil pump is also installed in the engine. When the engine is working, the oil pump pumps up the oil in the oil pan to lubricate and cool the various parts on the engine body. The oil on the various parts flows back or drips into the crankcase, and then flows back from the crankcase to the oil pan. However, due to the high oil pumping efficiency of the oil pump, the speed at which the oil in the crankcase flows back to the oil pan is slow, which leads to the problem of insufficient oil supply in the oil pan. The oil pump will inhale air or even run idle during the oil pumping process, which makes the oil pump easy to be damaged, and also affects the lubrication and cooling of various parts of the engine.

[0003] In response to the above problems, people have made various improvements, and some have even applied for patents. For example, Chinese patent literature discloses a lubrication structure of a motorcycle engine [application number: 202011393550.6; application publication number: CN112412572A], which includes an oil pan, a crankcase and an auxiliary oil pump. The crankcase has a crankshaft cavity and a shift shaft cavity. The lubrication structure also includes an oil pump mounting shell positioned between the oil pan and the crankcase. The auxiliary oil pump is arranged in the oil pump mounting shell. The oil pump mounting shell has an oil collecting cavity. The bottom of the crankshaft cavity and the bottom of the shift shaft cavity are both provided with through holes connecting the oil collecting cavity. The oil inlet of the auxiliary oil pump is connected to the oil collecting cavity, and the oil outlet of the auxiliary oil pump is connected to the inner cavity of the oil pan.

[0004] The lubrication structure of this structure includes an auxiliary oil pump and a main oil pump. The auxiliary oil pump allows the oil in the oil pan to flow better to the various oil circuits in the engine body, and the main oil pump allows the oil to flow back to the oil pan better. However, the lubrication structure of this structure requires an oil pump mounting shell to be installed between the crankcase and the oil pan. The auxiliary oil pump and the main oil pump are respectively installed at both ends of the oil pump mounting shell, which makes the length of the oil pump mounting shell longer; at the same time, the edge of the oil pump mounting shell also extends outward to form an oil collecting chamber for collecting oil, which results in a larger volume of the oil pump mounting shell and requires a larger installation space. However, the space inside the engine body is limited, which brings inconvenience to the arrangement of other components; and the oil pump mounting shell and the crankcase are independent, and there is a problem of asynchronous vibration. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems in the prior art and to propose an oil pump for a motorcycle engine. The technical problem to be solved is how to make the installation space occupied by the oil pump small and the stability good.

[0006] The objectives of the present invention can be achieved through the following technical solutions: an oil pump for a motorcycle engine, the engine comprising a casing and an oil pan arranged at the bottom of the casing, characterized in that a mounting hole is opened in the inner wall of the casing, the oil pump comprises a pump body inserted and fixed in the mounting hole, a main pump cavity is formed between the inner end of the pump body and the hole wall of the inner end of the mounting hole, a rotatable pump shaft is passed through the pump body and the inner end of the pump shaft extends into the main pump cavity, a pump shaft jacket located in the main pump cavity is provided with a main rotor capable of pressing the oil in the oil pan toward the casing oil circuit, the cavity inside the pump body is an auxiliary pump cavity, and a pump shaft jacket located in the auxiliary pump cavity is provided with an auxiliary rotor capable of pressing the oil in the casing toward the oil pan.

[0007] The pump shaft drives the main rotor to rotate, so that the oil in the oil pan flows to the oil circuit in the housing, and the pump shaft drives the auxiliary rotor to rotate, so that the oil in the housing flows back to the oil pan, speeding up the flow rate of the oil in the engine, thereby improving the lubrication and cooling effects. When the housing is cast, the mounting hole is integrally formed with the housing, and the housing mold is slightly changed. The oil pump is inserted and fixed in the mounting hole, that is, the oil pump is installed in the inner wall of the housing, and the space of the inner wall of the housing is reasonably used, and the space inside the housing is not too much occupied, so that the installation space occupied by the oil pump is small; at the same time, because the oil pump is directly fixed in the inner wall of the housing, it vibrates synchronously with the housing and has good stability. Moreover, the oil pump forms a main pump cavity through the inner end of the pump body and the hole wall of the inner end of the mounting hole, which is used to install the main rotor, and the space of the mounting hole is reasonably used, and the space inside the housing is not too much occupied, so that the installation space occupied by the oil pump is small.

[0008] In the above-mentioned oil pump of a motorcycle engine, a first oil inlet channel and a first oil outlet channel are provided in the inner wall of the housing, the oil inlet end of the first oil inlet channel is connected to the inner cavity of the oil pan, the oil outlet end of the first oil inlet channel is connected to the main pump cavity, the oil inlet end of the first oil outlet channel is connected to the main pump cavity, and the oil outlet end of the first oil outlet channel is connected to the oil path in the housing. When the pump shaft drives the main rotor to rotate, the negative pressure generated by the rotation of the main rotor allows the oil in the oil pan to enter the main pump cavity more quickly through the first oil inlet channel, and at the same time, the rotation of the main rotor presses the oil in the main pump cavity to the oil path in the housing better through the first oil outlet channel, thereby achieving rapid flow of the oil and improving the lubrication and cooling effects of the oil.

[0009] In the above-mentioned oil pump of a motorcycle engine, a first protruding portion is provided on the cavity wall at the inner end of the main pump cavity, and a first axial hole is provided in the first protruding portion for the inner end of the pump shaft to be inserted, and the first protruding portion separates the oil outlet end of the first oil inlet channel from the oil inlet end of the first oil outlet channel. The provision of the first protruding portion and the first axial hole plays a role in stabilizing the pump shaft, so that the pump shaft will not shake when rotating rapidly, thereby improving stability; the first protruding portion separates the oil outlet end of the first oil inlet channel from the oil inlet end of the first oil outlet channel, so that the oil can pass through the main pump cavity faster, realizing rapid flow of the oil, and improving the lubrication and cooling effects of the oil.

[0010] In the above-mentioned oil pump of a motorcycle engine, the inner end of the pump body has a first abutment portion that is protruding, the main rotor is located between the first abutment portion and the first protrusion, the first abutment portion cooperates with the first protrusion to position the main rotor axially in the main pump cavity, and the oil outlet end of the first oil inlet channel and the oil inlet end of the first oil outlet channel are located on the inner side of the main rotor. This structure improves the stability of the main rotor, thereby improving the stability of the oil pump; the oil outlet end of the first oil inlet channel and the oil inlet end of the first oil outlet channel are located on the inner side of the main rotor, that is, on the same side of the main rotor, relative to being located on both sides of the main rotor, the length of the mounting hole can be shortened, thereby reducing the installation space occupied by the oil pump.

[0011] In the above-mentioned oil pump of a motorcycle engine, a first lubricating oil groove is recessed on the circumferential inner side wall of the mounting hole, a second lubricating oil groove is recessed on the side of the first abutting portion close to the main rotor, one end of the second lubricating oil groove passes through the circumferential side wall of the first abutting portion, one end of the first lubricating oil groove is connected to the oil outlet end of the first oil inlet channel, and the other end is connected to one end of the second lubricating oil groove. The provision of the first lubricating oil groove and the second lubricating oil groove allows the oil to flow better around the main rotor, so that the lubrication effect of the main rotor is good when it rotates, and the stability of the main rotor is improved, thereby improving the stability of the oil pump.

[0012] In the above-mentioned oil pump of a motorcycle engine, a second oil inlet channel is provided in the housing, a second oil outlet channel and a first circulation channel are provided in the pump body, the oil inlet end of the second oil inlet channel is connected to the inner cavity of the housing, the oil outlet end of the second oil inlet channel is connected to the auxiliary pump cavity through the first circulation channel, the oil inlet end of the second oil outlet channel is connected to the auxiliary pump cavity, and the oil outlet end of the second oil outlet channel is connected to the inner cavity of the oil pan. When the pump shaft drives the auxiliary rotor to rotate, the rotation of the auxiliary rotor generates negative pressure so that the oil in the inner cavity of the housing can enter the auxiliary pump cavity faster through the second oil inlet channel, and at the same time, the rotation of the auxiliary rotor presses the oil in the auxiliary pump cavity to the oil pan better through the second oil outlet channel, so as to realize the rapid flow of the oil, prevent the problem of lack of oil in the oil pan, and improve the lubrication and cooling effect of the oil.

[0013] In the above-mentioned oil pump for a motorcycle engine, the pump body includes a cylindrical main body and a pump cover fixedly connected to the outer end of the main body, the outer end of the main body has a retaining edge protruding in the circumferential direction, the contour of the retaining edge is adapted to the contour of the pump cover and the retaining edge is arranged in close contact with the pump cover, the retaining edge has a second circulation channel running through it, the second oil outlet channel is located in the pump cover, and the oil outlet end of the second oil outlet channel is connected to the inner cavity of the oil pan through the second circulation channel. The arrangement of the pump cover and the arrangement of the second oil outlet channel in the pump cover can reduce the number of holes to be drilled in the box body and improve the strength of the box body mounting hole.

[0014] In the above-mentioned oil pump for a motorcycle engine, the oil outlet end of the second oil inlet channel and the oil inlet end of the second oil outlet channel are respectively located at the inner and outer sides of the auxiliary rotor. Since the pump cover is located outside the mounting hole and the second oil outlet channel is located in the pump cover, the arrangement of the second oil inlet channel and the second oil outlet channel is reasonable.

[0015] In the above-mentioned oil pump of a motorcycle engine, a second protruding portion is provided on the cavity wall at the inner end of the pump body, a second axial hole is provided in the second protruding portion for the pump shaft to pass through, a third lubricating oil groove is provided on the side of the second protruding portion close to the auxiliary rotor, a fourth lubricating oil groove is provided on the circumferential cavity wall of the auxiliary pump cavity, and the third lubricating oil groove and the fourth lubricating oil groove are both connected to the oil outlet end of the second oil inlet channel. The provision of the second protruding portion and the second axial hole improves the stability of the pump shaft, thereby improving the stability of the oil pump; the provision of the third lubricating oil groove and the fourth lubricating oil groove improves the lubrication effect of the auxiliary rotor, improves the stability of the auxiliary rotor, and thereby improves the stability of the oil pump.

[0016] In the above-mentioned oil pump for a motorcycle engine, the inner cavity of the box body has a plurality of protruding partition protrusions, and the mounting hole is located at the connection of the plurality of partition protrusions. The arrangement of the partition protrusions can divide the cavity inside the box body into a plurality of small cavities, and the thickness of the connection of the partition protrusions is generally thicker, and the mounting hole is located therein to better utilize the space of the inner wall of the box body.

[0017] Compared with the prior art, the oil pump for a motorcycle engine provided by the present invention has the following advantages:

[0018] 1. The oil pump of this machine is directly installed in the mounting hole of the inner wall of the box body, which makes rational use of the space of the inner wall of the box body. At the same time, a main pump cavity is formed between the inner end of the pump body and the hole wall of the inner end of the mounting hole, so that the overall length of the oil pump of this machine can be relatively short, without occupying too much space inside the box body, so that the installation space occupied by the oil pump is small.

[0019] 2. The oil pump of this machine is directly installed in the mounting hole on the inner wall of the box. The oil pump and the box vibrate synchronously and have good stability.

[0020] 3. This oil pump sets the main rotor and the auxiliary rotor so that the oil in the oil pan can flow to the oil circuit in the case better, and at the same time, the oil in the case can flow back to the oil pan better, preventing the problem of insufficient oil in the oil pan, increasing the speed of oil circulation in the engine, and improving the lubrication and cooling effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a sectional view of the overall structure of the motorcycle engine oil pump.

[0022] Figure 2 It is a structural diagram of the oil pump installation position of this machine.

[0023] Figure 3 This is a schematic diagram of the location of the oil inlet and outlet channels of the oil pump of this machine.

[0024] Figure 4 This is a schematic diagram of the structure inside the oil pump mounting hole of this machine.

[0025] Figure 5 It is a schematic diagram of the overall structure of the oil pump of this machine.

[0026] Figure 6 It is a schematic diagram of the internal structure of the oil pump body of this machine.

[0027] Figure 7 This is an exploded view of the oil pump body and pump cover of this machine.

[0028] In the figure, 1, casing; 2, oil pan; 3, mounting hole; 4, pump body; 41, main body; 42, pump cover; 43, retaining edge; 5, main pump chamber; 6, pump shaft; 7, main rotor; 8, auxiliary pump chamber; 9, auxiliary rotor; 10, first oil inlet channel; 11, first oil outlet channel; 12, first protrusion; 13, first axial hole; 14, first abutment; 15, first lubricating oil groove; 16, second lubricating oil groove; 17, second oil inlet channel; 18, second oil outlet channel; 19, first circulation channel; 20, second circulation channel; 21, second protrusion; 22, second axial hole; 23, third lubricating oil groove; 24, fourth lubricating oil groove; 25, partition protrusion. DETAILED DESCRIPTION

[0029] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0030] like Figure 1 , Figure 2 , Figure 3As shown, the engine includes a housing 1, an oil pan 2 and an oil pump. The housing 1 includes a crankcase, the oil pan 2 is fixedly connected to the bottom of the crankcase, and the oil pump includes a pump body 4, a pump shaft 6, a main rotor 7 and an auxiliary rotor 9.

[0031] In this embodiment, the inner cavity of the box body 1 has three protruding partition protrusions 25, and the inner wall of the box body 1 has a mounting hole 3, which is located at the connection of the three partition protrusions 25. In actual production, the number of the partition protrusions 25 can be four or five.

[0032] The pump body 4 includes a cylindrical main body 41 and a pump cover 42. The outer end of the main body 41 has a retaining edge 43 protruding in the circumferential direction. The contour of the retaining edge 43 is adapted to the contour of the pump cover 42 and the retaining edge 43 and the pump cover 42 are arranged in a close fit. The main body 41 is inserted into the mounting hole 3, and the retaining edge 43 abuts against the casing 1. The oil pump is fixedly connected to the casing 1 by bolts passing through the pump cover 42 and the retaining edge 43 and penetrating into the casing 1.

[0033] like Figure 4 As shown, a main pump chamber 5 is formed between the inner end of the pump body 4 and the hole wall of the inner end of the mounting hole 3, and a first protruding portion 12 is provided on the cavity wall of the inner end of the main pump chamber 5, and a first axial hole 13 is provided in the first protruding portion 12. A first oil inlet channel 10 and a first oil outlet channel 11 are provided in the inner wall of the housing 1, and the oil inlet end of the first oil inlet channel 10 is connected to the inner cavity of the oil pan 2, and the oil outlet end of the first oil inlet channel 10 is connected to the main pump chamber 5, and the oil inlet end of the first oil outlet channel 11 is connected to the main pump chamber 5, and the oil outlet end of the first oil outlet channel 11 is connected to the oil circuit in the housing 1. The inner end of the pump body 4 has a protruding first abutment portion 14, and the main rotor 7 is located between the first abutment portion 14 and the first protrusion 12. The first abutment portion 14 cooperates with the first protrusion 12 to axially position the main rotor 7 in the main pump chamber 5. The first protrusion 12 separates the oil outlet end of the first oil inlet channel 10 from the oil inlet end of the first oil outlet channel 11. The oil outlet end of the first oil inlet channel 10 and the oil inlet end of the first oil outlet channel 11 are located on the inner side of the main rotor 7.

[0034] A first lubricating oil groove 15 is recessed on the circumferential inner side wall of the mounting hole 3, and a second lubricating oil groove 16 is recessed on the side of the first abutment portion 14 close to the main rotor 7. One end of the second lubricating oil groove 16 passes through the circumferential side wall of the first abutment portion 14, and one end of the first lubricating oil groove 15 is connected to the oil outlet end of the first oil inlet channel 10, and the other end is connected to one end of the second lubricating oil groove 16.

[0035] like Figure 5 , Figure 6 , Figure 7As shown, the pump body 4 has a secondary pump cavity 8 inside, a second oil inlet channel 17 is provided in the housing 1, a first circulation channel 19 is provided in the main body 41, a second oil outlet channel 18 is provided in the pump cover 42, and a second circulation channel 20 is provided through the retaining edge 43. The oil inlet end of the second oil inlet channel 17 is connected to the inner cavity of the housing 1, the oil outlet end of the second oil inlet channel 17 is connected to the secondary pump cavity 8 through the first circulation channel 19, the oil inlet end of the second oil outlet channel 18 is connected to the secondary pump cavity 8, and the oil outlet end of the second oil outlet channel 18 is connected to the inner cavity of the oil pan 2 through the second circulation channel 20. The oil outlet end of the second oil inlet channel 17 and the oil inlet end of the second oil outlet channel 18 are respectively located on the inner and outer sides of the secondary rotor 9.

[0036] A second protruding portion 21 is protruded on the cavity wall at the inner end of the pump body 4, and a second axial hole 22 is provided in the second protruding portion 21. A third lubricating oil groove 23 is recessed on the side of the second protruding portion 21 close to the auxiliary rotor 9. A fourth lubricating oil groove 24 is recessed on the circumferential cavity wall of the auxiliary pump cavity 8. Both the third lubricating oil groove 23 and the fourth lubricating oil groove 24 are connected to the oil outlet end of the second oil inlet channel 17.

[0037] A rotatable pump shaft 6 is passed through the pump body 4, the inner end of the pump shaft 6 extends into the main pump chamber 5, and the inner end of the pump shaft 6 is embedded in the first shaft hole 13, the middle of the pump shaft 6 is passed through the second shaft hole 22, and the outer end of the pump shaft 6 passes through the pump cover 42, and the outer end of the pump shaft 6 is used to fix the sprocket. The pump shaft 6 located in the main pump chamber 5 is covered with a main rotor 7, and the pump shaft 6 located in the auxiliary pump chamber 8 is covered with an auxiliary rotor 9.

[0038] During operation, the pump shaft 6 drives the main rotor 7 and the auxiliary rotor 9 to rotate. The rotation of the main rotor 7 generates negative pressure, causing the oil in the oil pan 2 to enter the main pump chamber 5 through the first oil inlet passage 10. At the same time, the main rotor 7 rotates to press the oil in the main pump chamber 5 toward the oil path in the housing 1 through the first oil outlet passage 11, causing the oil in the oil pan 2 to flow toward the oil path in the housing 1. At the same time, the rotation of the auxiliary rotor 9 generates negative pressure, causing the oil in the inner cavity of the housing 1 to enter the auxiliary pump chamber 8 through the second oil inlet passage 17. At the same time, the rotation of the auxiliary rotor 9 presses the oil in the auxiliary pump chamber 8 toward the oil pan 2 through the second oil outlet passage 18, causing the oil in the housing 1 to flow back into the oil pan 2.

[0039] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0040] Although the present invention uses more terms such as housing 1, oil pan 2, mounting hole 3, pump body 4, main body 41, pump cover 42, retaining edge 43, main pump chamber 5, pump shaft 6, main rotor 7, auxiliary pump chamber 8, auxiliary rotor 9, first oil inlet passage 10, first oil outlet passage 11, first protrusion 12, first shaft hole 13, first abutment 14, first lubricating oil groove 15, second lubricating oil groove 16, second oil inlet passage 17, second oil outlet passage 18, first circulation passage 19, second circulation passage 20, second protrusion 21, second shaft hole 22, third lubricating oil groove 23, fourth lubricating oil groove 24, and partition protrusion 25, the possibility of using other terms is not excluded. The use of these terms is only for the purpose of more conveniently describing and explaining the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. An oil pump for a motorcycle engine, the engine comprising a housing (1) and an oil pan (2) arranged at the bottom of the housing (1), characterized in that The housing (1) has an installation hole (3) formed in its inner wall. The oil pump comprises a pump body (4) inserted and fixed in the installation hole (3). A main pump chamber (5) is formed between the inner end of the pump body (4) and the hole wall of the inner end of the installation hole (3). A rotatable pump shaft (6) is passed through the pump body (4) and the inner end of the pump shaft (6) extends into the main pump chamber (5). The pump shaft (6) located in the main pump chamber (5) is covered with a sleeve that can press the oil in the oil pan (2) toward the oil path of the housing (1). The pump body (4) comprises a main rotor (7), the cavity inside the pump body (4) being an auxiliary pump cavity (8), the pump shaft (6) located in the auxiliary pump cavity (8) being provided with an auxiliary rotor (9) capable of pressing the engine oil in the housing (1) toward the oil pan (2), the housing (1) being provided with a first oil inlet passage (10) and a first oil outlet passage (11), the oil inlet end of the first oil inlet passage (10) being connected to the inner cavity of the oil pan (2), and the oil outlet end of the first oil inlet passage (10) being connected to the main pump cavity (5). The first oil outlet passage (11) is connected to the main pump chamber (5), the oil outlet end of the first oil outlet passage (11) is connected to the oil path in the casing (1), the inner end of the main pump chamber (5) has a first protruding portion (12) on the cavity wall, the first protruding portion (12) has a first axial hole (13) for inserting the inner end of the pump shaft (6), the first protruding portion (12) connects the oil outlet end of the first oil inlet passage (10) and the first oil outlet end of the first oil outlet passage (11). The pump body (4) is separated from the oil inlet end of an oil outlet passage (11), the inner end of the pump body (4) has a protruding first abutment portion (14), the main rotor (7) is located between the first abutment portion (14) and the first protrusion (12), the first abutment portion (14) cooperates with the first protrusion (12) to axially position the main rotor (7) in the main pump chamber (5), and the oil outlet end of the first oil inlet passage (10) and the oil inlet end of the first oil outlet passage (11) are located on the inner side of the main rotor (7).

2. The oil pump for a motorcycle engine according to claim 1, characterized in that: A first lubricating oil groove (15) is recessed on the circumferential inner side wall of the mounting hole (3); a second lubricating oil groove (16) is recessed on the side of the first abutting portion (14) close to the main rotor (7); one end of the second lubricating oil groove (16) passes through the circumferential side wall of the first abutting portion (14); one end of the first lubricating oil groove (15) is connected to the oil outlet end of the first oil inlet channel (10); and the other end is connected to one end of the second lubricating oil groove (16).

3. An oil pump for a motorcycle engine according to claim 1 or 2, characterized in that: The housing (1) is provided with a second oil inlet passage (17), and the pump body (4) is provided with a second oil outlet passage (18) and a first circulation passage (19); the oil inlet end of the second oil inlet passage (17) is connected to the inner cavity of the housing (1); the oil outlet end of the second oil inlet passage (17) is connected to the auxiliary pump cavity (8) through the first circulation passage (19); the oil inlet end of the second oil outlet passage (18) is connected to the auxiliary pump cavity (8); and the oil outlet end of the second oil outlet passage (18) is connected to the inner cavity of the oil pan (2).

4. The oil pump for a motorcycle engine according to claim 3, characterized in that: The pump body (4) comprises a cylindrical main body (41) and a pump cover (42) fixedly connected to the outer end of the main body (41); the outer end of the main body (41) has a retaining edge (43) protruding in the circumferential direction; the contour of the retaining edge (43) matches the contour of the pump cover (42) and the retaining edge (43) and the pump cover (42) are arranged in close contact; the retaining edge (43) has a second circulation channel (20) running through it; the second oil outlet channel (18) is located in the pump cover (42); and the oil outlet end of the second oil outlet channel (18) is connected to the inner cavity of the oil pan (2) through the second circulation channel (20).

5. The oil pump for a motorcycle engine according to claim 3, characterized in that: The oil outlet end of the second oil inlet channel (17) and the oil inlet end of the second oil outlet channel (18) are respectively located on the inner and outer sides of the auxiliary rotor (9).

6. The oil pump for a motorcycle engine according to claim 3, characterized in that: The inner end of the pump body (4) has a second protruding portion (21) on the cavity wall, the second protruding portion (21) has a second axial hole (22) for the pump shaft (6) to pass through, the second protruding portion (21) has a third lubricating oil groove (23) on the side close to the auxiliary rotor (9), the circumferential cavity wall of the auxiliary pump cavity (8) has a fourth lubricating oil groove (24) on the circumferential cavity wall, the third lubricating oil groove (23) and the fourth lubricating oil groove (24) are both connected to the oil outlet end of the second oil inlet channel (17).

7. An oil pump for a motorcycle engine according to claim 1 or 2, characterized in that: The inner cavity of the box body (1) is provided with a plurality of protruding partition protrusions (25), and the mounting hole (3) is located at the connection between the plurality of partition protrusions (25).

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