This application claims the benefit of Japanese Patent Application JP 2015-210360, filed Oct. 27, 2015, the entire content of which is hereby incorporated by reference, the same as if set forth at length.
The present invention relates to a lubrication structure of an engine having a turbocharger and a motorcycle having the lubrication structure.
Motorcycles having a turbocharger are known in which exhaust gas of the engine is used as a drive source of the turbocharger. In these motorcycles, an exhaust manifold is attached to an exhaust port formed in a cylinder head and the turbocharger is attached to the exhaust manifold.
In turbochargers, usually, proper lubrication is done in such a manner that part of oil that circulates through an engine is supplied to a drive unit of the turbocharger (refer to JP-UM-B-60-36758, for example). JP-UM-B-60-36758 discloses a turbocharger lubrication structure in which oil that is pumped up from an oil pan by a pump is supplied to a turbocharger via an oil supply passage and then returned to the oil pan via an oil return passage.
Incidentally, in JP-UM-B-60-36758, the turbocharger is disposed below an oil surface of the oil pan. As a result, a separate oil pump or a check valve needs to be installed to return oil that has been used for lubrication of the inside of the turbocharger to the oil pan. This results in increase in the number of components and hence is a factor in causing cost increase.
The present invention has been made in the above circumstances, and an object of the invention is therefore to provide an engine lubrication structure that enables lubrication of a turbocharger and returning of oil from it by means of an inexpensive structure, as well as a motorcycle having such an engine lubrication structure.
An engine lubrication structure according to the present invention supplies oil stored in an oil pan disposed under a crank case to individual components in the crank case, and comprises: a turbocharger which compresses intake air using exhaust gas of an engine; an oil passage which supplies oil to the turbocharger; and an oil return passage which returns oil from the turbocharger to the oil pan, wherein the crank case is provided with a connection port of the oil return passage, and the connection port is disposed below an oil surface that occurs during operation of the engine and above an oil surface that occurs when a side stand is used.
In this configuration, while the engine is in operation, since the connection port of the oil return passage is located below the oil surface, oil that has been used for lubrication of the turbocharger is returned to the oil pan so as to directly join the oil existing there. This prevents generation of bubbles through stirring of the oil surface and lowering of the lubrication performance. Furthermore, when the side stand is used after a stop of the engine, since the outlet port of the oil return passage is located above the oil surface, oil is returned to the oil pan so as to enter it from a position that is higher than the oil surface. Thus, oil can be discharged smoothly from the turbocharger. In summary, it is not necessary to return oil that has been used for lubrication of the turbocharger to the oil pan using a separate pump and hence lubrication of the turbocharger and returning of oil from it can be realized by an inexpensive structure.
Further, in the engine lubrication structure according to the present invention, it is preferable: that the turbocharger is disposed above the oil pan; and that the connection port is disposed at a front surface of the crank case on the opposite side to the side stand in the left-right direction. With this configuration, when the side stand is used, oil can be returned to the oil pan utilizing its own weight, which means increase in oil dischargeability.
Further, in the engine lubrication structure according to the present invention, it is preferable that the oil return passage is larger in sectional area than the oil passage. With this configuration, the resistance of the oil return passage against returning oil can be reduced, which means increase in oil dischargeability.
Further, a motorcycle according to the present invention comprises the engine lubrication structure.
The invention can realize lubrication of the turbocharger and returning of oil from it by means of an inexpensive structure because the position of the connection port of the oil return passage with respect to the oil surface when the engine is in operation is made different from that when the engine is stopped.
1: Engine
2: Turbocharger
24
a: Inlet pipe (oil passage)
24
b: Outlet pipe (oil return passage)
4: Crank case
40
a: Connection port (oil passage)
41
a: Connection port (oil return passage)
5: Oil pan
L1, L2: Oil surface
An embodiment of the present invention will be hereinafter described in detail with reference to the accompanying drawings. The embodiment is such that the lubrication structure of an engine having a turbocharger according to the invention is applied to a motorcycle. However, the invention is not limited to this case and can also be applied to other kinds of vehicles such as other types of motorcycles, buggy-type motor tricycles, and automobiles. As for the directions relating to the vehicle, the forward, rearward, leftward, and rightward directions will be indicated by arrows FR, RE, L, and R, respectively. It is also noted that in each drawing part of the components and members are omitted for convenience of description.
First, a general configuration of a motorcycle according to the embodiment will be described with reference to
As shown in
The crank case 4 is configured so as to be dividable in the vertical direction and has a top case 40 and a bottom case 41. A space for containing various shafts is formed in the crank case 4 by combining the top case 40 and the bottom case 41 together. A top-front portion of the top case 40 has an opening, and the cylinder block 10 is attached to the top case 40 so as to close the opening. The bottom case 41 is formed with an opening at the bottom, and an oil pan 5 is attached to the bottom case 41 so as to close the opening.
As shown in
The crank case 4 is formed with respective openings on the left side and the right side. A magneto cover 16 (not shown in
Being a water-cooling engine, the engine 1 according to the embodiment is equipped with a water pump 18 for feeding cooling water to it. The right side surface of the crank case 4 is provided with a water pump 18 in front of the clutch cover 17. Although not shown in any drawings, a side stand for supporting a vehicle body (engine 1) is disposed on the bottom-left of the crank case 4.
As shown in
The housing portion 22 is shaped like a cylinder whose axis extends in the vehicle width direction (left-right direction) and houses a turbine (not shown) inside. The manifold portion 21 is connected to a top portion of the cylindrical housing portion 22. The manifold portion 21 has a connection portion that is connected to the housing portion 22 and a pair of branch pipes 21a which extends upward from the connection portion. Tip portions of the branch pipes 21a are connected to the two respective front exhaust ports of the cylinder head 11.
An exhaust pipe (not shown) is connected to a right end portion of the housing portion 22. A bearing housing 24 which houses a bearing (not shown) of a turbo shaft (not shown) is disposed on the left of the housing portion 22. A compressor housing 25 which houses a compressor (not shown) is disposed on the left of the bearing housing 24.
One end of an inlet pipe 24a for supplying oil from the crank case 4 to the turbocharger 2 is connected to a top portion of the bearing housing 24, and the other end of the inlet pipe 24a is connected to the top case 40. More specifically, the top case 40 is formed with, at a front-right position, a connection port 40a for the inlet pipe 24a. As shown in
The inlet pipe 24a extends leftward from the connection port 40a alongside the sub-gallery 48 and is then bent downward so as to go around the housing portion 22 (goes under it). The inlet pipe 24a goes under an operation shaft 28 of a waste gate valve 26 (described later) so as not to pass through a movable range of the operation shaft 28. Then the inlet pipe 24a extends upward alongside the housing portion 22 and is connected to a top end portion of the bearing housing 24.
One end of an outlet pipe 24b for returning oil that has been used for lubrication of the inside of the turbocharger 2 is connected to a bottom portion of the bearing housing 24, and the other end of the outlet pipe 24b is connected to the bottom case 41. More specifically, the bottom case 41 is formed with, at a front-right position, a connection port 41a for the outlet pipe 24b. The connection port 41a is formed on the front surface below the turbocharger 2.
A turbine is fixed to one (right) end portion of the turbo shaft which extends in the vehicle width direction between the housing portion 22 and the compressor housing 25, and the compressor is fixed to the other (left) end portion of the turbo shaft. Thus, the turbine and the compressor can rotate together on the turbo shaft.
The waste gate valve 26 is disposed below the compressor housing 25. The waste gate valve 26 has a role of adjusting the rate of inflow of exhaust gas into the turbine (housing portion 22). The waste gate valve 26 has a main body unit 27 for adjusting the flow rate of exhaust gas inside the housing portion 22 by detecting the pressure in the compressor housing 25. The main body unit 27 is disposed below the compressor housing 25, and the operation shaft 28 which extends toward the housing portion 22 is attached to the main body unit 27.
A valve plug (not shown) is attached to the housing-portion-22-side tip of the operation shaft 28. The valve plug causes opening of closure as the operation shaft 28 is operated by the main body unit 27, whereby the flow rate of exhaust gas inside the housing portion 22 is adjusted. For example, when the turbo pressure has risen rapidly, the main body unit 27 operates the operation shaft 28 so that the valve plug causes opening, whereby the rate of inflow of exhaust gas into the housing portion 22 is lowered.
A compressor pipe (not shown) for introducing, into the turbocharger 2, air that has passed through an air cleaner (not shown). An intake pipe (not shown) for introducing, into the engine 1, air that has been compressed in the compressor housing 25 is connected to a top portion of the compressor housing 25.
In the motorcycle which is equipped with the thus-configured turbocharger 2, whereas exhaust gas of the engine 1 is introduced into the housing portion 22 via the manifold portion 21 according to a throttle manipulation of a rider, external air is introduced into the compressor housing 25 via the air cleaner and the compressor pipe.
In the housing portion 22, the turbine is rotated at high speed by a flow of exhaust gas. And the exhaust gas is discharged to the outside via the exhaust pipe. In the compressor housing 25, the compressor is rotated according to the rotation of the turbine, whereby air is compressed there. The compressed air is introduced into the engine 1 via the intake pipe.
By compressing air by the turbocharger 2 in the above manner, an air-fuel mixture exceeding a total displacement of the engine 1 can be fed to the engine 1 to increase its output power.
Part of oil that circulates through the engine 1 is supplied from the sub-gallery 48 to the turbocharger 2 (bearing housing 24) via the inlet pipe 24a, whereby the turbo shaft and the bearing are lubricated. After being used for lubrication of the turbocharger 2, the oil is returned to the crank case 4 (oil pan 5) via the outlet pipe 24b. The sectional area of the outlet pipe 24b is larger than that of the inlet pipe 24a. Thus, the resistance of the oil return flow passage is reduced and hence the returning of oil from the turbocharger 2 can be performed smoothly.
Incidentally, in conventional motorcycles that are equipped with a turbocharger which compresses intake air using exhaust gas of an engine, the turbocharger is disposed in front of an oil pan. In this case, if the drive shaft (turbo shaft) of the turbocharger is disposed below an oil surface of the oil pan, oil that has been used for lubrication of the inside of the turbocharger is not returned to the oil pan easily. To solve this problem, an oil return passage of the turbocharger is provided with a separate (dedicated) oil pump (scavenging pump) which forcibly returns oil that has been used for lubrication of the turbocharger to the oil pan.
In particular, since the turbocharger is a component that heats to a very high temperature (e.g., higher than 800° C.), if oil remains inside the turbocharger after a stop of the engine, not only is deterioration of the oil accelerated by heat, but also the bearing may seize up. It is therefore desirable to discharge oil from the turbocharger as soon as the engine is stopped.
In view of the above, in the embodiment, the sub-gallery 48 for supplying oil to the shafts in the engine 1 is provided with the oil passage (connection port 40a and inlet pipe 24a) to the turbocharger 2. With this measure, not only can oil be supplied to the shafts at a sufficiently high pressure, but also oil can be supplied to the turbocharger 2. Furthermore, since the connection port 41a of the outlet pipe 24b is disposed below the turbocharger 2, oil can be discharged from the turbocharger 2 smoothly utilizing its own weight.
In particular, in the embodiment, the position of the connection port 41a of the oil return passage (outlet pipe 24b) with respect to the oil surface when the engine 1 is in operation is made different from that when the engine 1 is stopped. With this measure, while the engine 1 is in operation, the connection port 41a is lower than an oil surface L1 (see
Next, referring to
First, the arrangement of the shafts will be described. As shown in
A counter shaft 31 is disposed in the top-rear of the crank shaft 30. The right end of the counter shaft 31 is provided with the clutch (not shown). A drive shaft 32 is disposed in the bottom-rear of the counter shaft 31. The drive shaft 32 is provided with various shift gears. Plural (in the embodiment, two) balancer shafts 33 for preventing rotation-induced vibration of the engine 1 are disposed around the crank shaft 30.
The balancer shafts 33 include a first balancer shaft 34 which is disposed in front of the crank shaft 30 and a second balancer shaft 35 which is disposed (right) under the crank shaft 30. The first balancer shaft 34 and the second balancer shaft 35 extend parallel with the axis of the crank shaft 30, and are arranged in such a manner that the straight line connecting the first balancer shaft 34 and the crank shaft 30 and that connecting the second balancer shaft 35 and the crank shaft 30 form approximately a right angle.
As shown in
Now, a description will be made of the oil paths in the crank case 4. As shown in
Oil passages 44 and 45 for supplying oil from the main gallery 43 to the crank shaft 30 and the first balancer shaft 34 and an oil passage 46 for supplying oil from the crank shaft 30 to the main gallery 43 are formed in the bottom case 41. An oil passage 47 for supplying oil to the drive shaft 32 is connected to the oil passage 46. The oil passages 44 and 47 are formed so as to penetrate through the plural through-holes 42 obliquely. With this measure, the through-holes 42 for the fastening bolts 7 can be utilized as parts of the oil passages.
On the other hand, in the top case 40, the sub-gallery 48 is formed above the first balancer shaft 34 so as to extend in the left-right direction. An oil passage 49 for supplying oil from the main gallery 43 to the sub-gallery 48 via the first balancer shaft 34 is formed in the top case 40.
In the embodiment, oil that is stored in the oil pan 5 is pumped up by an oil pump and supplied to the main gallery 43. The oil that has been supplied to the main gallery 43 is supplied to the shafts and the bearings while being kept at a sufficiently high pressure. Part of the oil, that is oil supplied to the first balancer shaft 34, is then supplied to the sub-gallery 48 via an oil passage 49.
The oil that has been supplied to the sub-gallery 48 is then supplied to the turbocharger 2 (see
In the embodiment, the shafts are arranged in the above-described manner and the main gallery 43 and the sub-gallery 48 are formed in free regions located in the vicinities of the two balancer shafts 33. That is, the first balancer shaft 34 is disposed below the sub-gallery 48 and the main gallery 43 is formed below the first balancer shaft 34. This structure makes it possible to form the oil passages to the shafts (bearings) in the form of straight through-holes. Thus, the oil passages can be formed by simple boring and the number of machining steps can be reduced.
In particular, since the oil passage 45 from the main gallery 43 to the first balancer shaft 34 and the oil passage 49 from the first balancer shaft 34 to the sub-gallery 48 can be straight ones, the oil passages 45 and 49 can be made short, leading to suppression of reduction in oil pressure.
Since the crank shaft 30 and the second balancer shaft 35 are adjacent to each other in the bottom case 41, the oil passage 46 between the crank shaft 30 and the second balancer shaft 35 can be formed easily by boring. Thus, the crank case 4 can be made lighter than in a structure that a separate (independent) oil passage is formed utilizing unused portions of the crank case 4.
As shown in
Since the piston jets 50 have open ends, when the engine 1 stopped and the driving of the oil pump is stopped, air inside the crank case 4 is sucked by the piston jets 50 and introduced to the turbocharger 2 (see
Furthermore, since the sub-gallery 48 is located above the oil surface in the crank case 4, the connection port 40a (see
Next, the height of the oil surface in the engine 1 will be described with reference to
As described above, in the engine 1, a prescribed amount of oil is stored in the oil pan 5 which is located under the crank case 4. When the engine 1 is driven, oil in the oil pan 5 is pumped up by the oil pump (not shown) and supplied to the individual components of the engine 1. Oil that has been used for lubrication of the individual components of the engine 1 is returned to the oil pan 5.
As shown in
On the other hand, when the side stand is used after a stop of the engine 1, the engine 1 is inclined as the vehicle body leans toward the side of the side stand (i.e., leftward). At this time, if the oil surface L2 indicated by a two-dot chain line is regarded as a horizontal surface, it is located below the connection port 41a of the outlet pipe 24b. That is, the inside of the connection port 41a is located above the oil surface L2 and is in contact with the air. Furthermore, since the main body of the turbocharger 2 is located higher than the connection port 41a, oil is discharged from the turbocharger 2 to the bottom case 4 going down the outlet pipe 24b because of its own weight.
In particular, in the embodiment, the turbocharger 2 is located above the oil pan 5 and the connection port 41a is disposed on the front surface of the crank case 4, that is, on the side (right side) opposite to the side stand. As a result, when the side stand is used, oil can be returned to the oil pan 5 utilizing its own weight which means further increase in oil dischargeability.
As described above, oil can be discharged properly from the turbocharger 2 even after a stop of the engine 1, of course during operation of the engine 1. This makes it to possible to prevent oil deterioration due to heat generated in the turbocharger 2 and seizing-up of, for example, the bearing of the turbo shaft.
As described above, according to the embodiment, while the engine 1 is in operation, since the connection port 41a of the outlet pipe 24b is located below the oil surface L1, oil that has been used for lubrication of the turbocharger 2 is returned to the oil pan 5 so as to directly join the oil existing there. This prevents generation of bubbles through stirring of the oil surface L1 and lowering of the lubrication performance.
Furthermore, when the side stand is used after a stop of the engine 1, since the outlet port 41a of the outlet pipe 24b is located above the oil surface L2, oil is returned to the oil pan 5 so as to enter it from a position that is higher than the oil surface L2. Thus, oil can be discharged smoothly from the turbocharger 2.
In summary, it is not necessary to return oil that has been used for lubrication of the turbocharger 2 to the oil pan 5 using a separate pump and hence lubrication of the turbocharger 2 and returning of oil from it can be realized by an inexpensive structure.
The invention is not limited to the above embodiment and can be practiced by modifying it in various manners. The invention is not limited to the sizes, shapes, etc. shown in the drawings and they can be modified as appropriate within the confines that the advantages of the invention can be obtained. Other modifications can also be made as appropriate as long as the object of the invention is attained.
For example, although the above embodiment is directed to the 2-cylinder engine 1, the invention is not limited to that case; the invention can also be applied to single-cylinder engines and engines having three or more cylinders.
Although the above embodiment is directed to the water-cooling engine 1, the invention is not limited to that case; the invention can also be applied to air-cooling engines and other types of engines.
Although in the embodiment the sub-gallery 48 is disposed in front of the crank shaft 30, the invention is not limited to that case; the sub-gallery 48 may be disposed in the rear of the crank shaft 30.
Although in the embodiment oil is supplied from the sub-gallery 48 to only the turbocharger 2 and the piston jets 50, the invention is not limited to that case; oil may also be supplied from the sub-gallery 48 to the cylinder head 11 etc.
Although in the embodiment oil is supplied from the main gallery 43 to the sub-gallery 48 via the bearing of the first balancer shaft 34, the invention is not limited to that case; oil may be supplied directly to the sub-gallery 48 from the main gallery 43.
Although in the embodiment connection port 41a of the outlet pipe 24b is disposed at a front position of the engine 1, the invention is not limited to that case; the outlet pipe 24b may be disposed at a side position or a rear position of the engine 1.
Although in the embodiment the side stand is disposed on the left of the engine 1, the invention is not limited to that case; the side stand may be disposed on the right of the engine 1. In this case, it is preferable that the connection port 41a be disposed on the side (left side) opposite to the side stand.
Although in the embodiment the inlet pipe 24a and the connection port 40a (oil passage) and the outlet pipe 24b and the connection port 41a (oil return passage) have circular cross sections, the invention is not limited to that case; these oil passage and oil return passage may have proper shapes other than a circle in cross section.
Providing the above-described advantage that lubrication of the turbocharger and returning of oil from it can be realized by an inexpensive structure, the invention is particularly useful when applied to lubrication structures of engines having a turbocharger and motorcycles having such a lubrication structure.
Number | Date | Country | Kind |
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2015-210360 | Oct 2015 | JP | national |