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(11) | EP 1 785 599 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Relief valve |
| (57) A relief valve (38) includes a cylindrical valve housing which is attached to an
engine body continuously with a relief passage (37), and which has an outlet (43)
provided in an axially intermediate portion thereof; a valve body (45) slidably fitted
to the valve housing (44) so as to allow the relief passage (37) to communicate with
the outlet as an oil pressure in the relief passage (37) becomes equal to, and exceeds
a predetermined oil pressure; and a skirt (46) which has an upper end portion fixed
to the valve housing (44) above the outlet in order to guide oil discharged from the
outlet (43) downward, and the relief valve (38) makes it possible to exert a sure
defoaming function in response to an increase of an amount of the oil discharged from
the outlet (43) and also to an increase of an ejection pressure thereof while avoiding
a size increase of a shape of the skirt (46). An annular recessed portion (54) is formed on an outer circumference of the intermediate portion of the valve housing (44) below the outlet (43). |
[0001] The present invention relates to a relief valve including: a cylindrical valve housing which is attached to an engine body so as to be longitudinally extended continuously with a relief passage communicating with an ejection port of an oil pump and provided in the engine body, and has an outlet provided in an axially intermediate portion thereof; a valve body slidably fitted to the valve housing so as to allow the relief passage to communicate with the outlet as an oil pressure in the relief passage becomes equal to, and exceeds a predetermined oil pressure; and a skirt which is formed in an umbrella shape so as to surround the valve housing and has an upper end portion fixed to the valve housing above the outlet in order to guide oil discharged from the outlet downward.
[0002] Such a relief valve is known, for example, in Patent Document 1 and the like, in which a valve housing is covered with an umbrella-like skirt below an outlet of the valve housing in order to prevent bubbles from being generated when oil discharged from the outlet is returned into an oil reservoir formed in a lower portion of an engine body.
Japanese Patent Application No. 2001-207818
[0003] Incidentally, since it is required that an internal combustion engine be more compact, it is not easy to change an inclination angle and size of the skirt so as to increase a flow passage area between the valve housing and the skirt in order to exert a sure defoaming function in response to an increase of an amount of the oil discharged from the outlet of the relief valve and also to an increase of an ejection pressure thereof.
[0004] The present invention has been made in consideration for such a circumstance as described above. It is an object of the present invention to provide a relief valve adapted to be capable of exerting the sure defoaming function in response to the increase of the amount of oil discharged from the outlet and also to the increase of the ejection pressure thereof while avoiding a size increase of the skirt shape.
[0005] In order to achieve the above-described object, an invention according to claim 1 is a relief valve including: a cylindrical valve housing which is attached to an engine body so as to be longitudinally extended continuously with a relief passage communicating with an ejection port of an oil pump and provided in the engine body, and has an outlet provided in an axially intermediate portion thereof; a valve body slidably fitted to the valve housing so as to allow the relief passage to communicate with the outlet in response to that an oil pressure in the relief passage becomes equal to, and exceeds a predetermined oil pressure; and a skirt which is formed in an umbrella shape so as to surround the valve housing and has an upper end portion fixed to the valve housing above the outlet in order to guide oil discharged from the outlet downward, characterized in that an annular recessed portion is formed on an outer circumference of the intermediate portion of the valve housing below the outlet.
[0006] Moreover, an invention according to claim 2 is, in addition to the construction of the invention according to claim 1, characterized in that a lower end of the skirt is disposed at a position corresponding to the intermediate portion of the annular recessed portion.
[0007] Furthermore, an invention according to claim 3 is, in addition to the construction of the invention according to any one of claims 1 and 2, characterized in that an upper end portion of the valve housing, the upper end portion forming an inlet, is fluid-tightly fitted to the relief passage, and a receiving portion which receives a lower end of the valve housing is provided in the engine body.
[0008] In accordance with the invention according to claim 1, the annular recessed portion is formed on the outer circumference of the intermediate portion of the valve housing. Thus, a size increase of the shape of the skirt can be avoided, a flow passage area between the valve housing and the skirt can be increased, and a sure defoaming function can be exerted in response to an increase of an amount of oil discharged from the outlet and also to an increase of an ejection pressure thereof.
In addition, the annular recessed portion is formed on the outer circumference of the intermediate portion of the valve housing below the outlet, and a high pressure on the relief passage side is not applied to the valve housing below the outlet. Accordingly, the forming of the annular recessed portion does not damage strength of the valve housing, thus making it possible to contribute to a weight reduction of the relief valve.
[0009] Moreover, in accordance with the invention according to claim 2, the discharged oil which flows between the valve housing and the skirt can be guided by a lower end of the annular recessed portion, and can be discharged so as to spread radially, and a defoaming effect can be enhanced.
[0010] Furthermore, in accordance with the invention according to claim 3, the valve housing is thrust downward by a liquid pressure of the relief passage. Moreover, the annular recessed portion is formed on the intermediate portion of the valve housing, and accordingly, a seated area of the lower end of the valve housing on the receiving portion provided in the engine body can be set relatively large while increasing a flow passage area between the valve housing and the skirt, a large load can be avoided from being concentratedly applied to the lower end of the valve housing, and the valve housing can be surely attached to the engine body.
[0011]
FIG. 1 is a side view of an internal combustion engine.
FIG. 2 is an enlarged longitudinal cross-sectional side view of main portions of FIG. 1.
FIG. 3 is a cross-sectional view along a line 3-3 of FIG. 2.
[0012] A description will be made below of a mode for carrying out the present invention based on an embodiment of the present invention, which is shown in the accompanying drawings.
[0013] FIG. 1 to FIG. 3 show the embodiment of the present invention: FIG. 1 is a side view of an internal combustion engine; FIG. 2 is an enlarged longitudinal cross-sectional side view of main portions of FIG. 1; and FIG. 3 is a cross-sectional view along a line 3-3 of FIG. 2.
[0014] First in FIG. 1, an engine body 5 having a cylinder axis inclined upward to the front is mounted on a vehicle body frame of a motorcycle. The engine body 5 includes: a cylinder block 8 integrally having a cylinder barrel 6 and an upper case 7 continuous with a lower portion of the cylinder barrel 6; a lower case 9 coupled to a lower portion of the cylinder block 8 so as to construct a crankcase 10 in cooperation with the upper case 7; an oil pan 11 coupled to a lower portion of the lower case 9, that is, to a lower portion of the crankcase 10; a cylinder head 12 coupled to an upper portion of the cylinder block 8; and a head cover 13 coupled to an upper portion of the cylinder head 12. A coupling surface 14 between the upper case 7 and the lower case 9 is set so as to be inclined downward to the front in a state where the engine 5 is mounted on the motorcycle.
[0015] Between the upper case 7 and the lower case 9, which construct the crankcase 10, a crankshaft 15 having an axis along a vehicle width direction of the motorcycle is supported rotatably. To the crankshaft 15, rotational power from a starter motor 16 attached to the upper case 7 is inputted through a starter gear transmission mechanism 17.
[0016] Moreover, an output of the crankshaft 15 is shifted by a gear transmission 18 and is transmitted to a rear wheel as a driving wheel. The transmission 18 is composed by providing gear trains between a main shaft 19 and a counter shaft 20. The gear trains are capable of selectively establishing a plurality of speeds. The main shaft 19 has an axis parallel to the crank shaft 15, and is rotatably supported between the upper case 7 and the lower case 9. The counter shaft 20 has an axis parallel to the main shaft 19, and is rotatably supported by the lower case 9.
[0017] Onto one end of the main shaft 19, a starting clutch 21 interposed between the crankshaft 15 and the main shaft 19 is attached. When the starting clutch 21 turns to an engaged state in response to a shifting operation of a rider, power from the crankshaft 15 is transmitted to the main shaft 19.
[0018] Between the cylinder head 12 and the head cover 13, a valve mechanism 24 including an intake camshaft 22 and an exhaust camshaft 23 is housed. To the intake camshaft 22 and the exhaust camshaft 23, which are supported rotatably by the cylinder head 12, the rotational power of the crankshaft 15, which is reduced by half in speed by timing transmission means 26 including a timing chain 25, is transmitted thereby.
[0019] Referring to FIG. 2 in combination, to the lower case 9 in the crankcase 10, an oil pump 28 having a rotation axis parallel to the crankshaft 15 is attached. An endless chain 32 is wound around a drive sprocket 31 fixed to the main shaft 19 of the gear transmission 18, and around a driven sprocket 30 fixed to a rotation shaft 29 of the oil pump 28.
[0020] Oil reserved in an oil reservoir 33 formed in the oil pan 11 is drawn up by the oil pump 28 through an oil strainer 34. Moreover, in the lower case 9, an ejection passage 35 extended parallel to the coupling surface 14 between the upper case 7 and the lower case 9 is provided so as to communicate with an ejection port 36 of the oil pump 28, and the oil from the oil pump 28 is ejected to the ejection passage 35. In addition, a relief passage 37 which is perpendicularly branched from the ejection passage 35 and is extended downward so as to allow an upper end portion thereof to communicate with the ejection passage 35 is provided in the lower case 9. By a function of a relief valve 38 connected to the relief passage 37, a pressure of the oil in the ejection passage 35 is maintained to be constant.
[0021] Incidentally, to lubricated portions of the engine body 5, such as between crank journal walls 39... and the crankshaft 15, which the crankcase 10 includes, the oil is supplied from a main gallery 40 provided in the lower case 9 of the crankcase 10. The main gallery 40 is connected to the ejection passage 35 through an oil filter 41 and an oil cooler 42.
[0022] Specifically, the oil ejected from the oil pump 28 is pressure-regulated by the relief valve 38, and as shown by arrows in FIG. 2, is cleaned by the oil filter 41, is then cooled by the oil cooler 42, and is guided to the main gallery 40.
[0023] Referring to FIG. 3 in combination, the relief valve 38 is the one composed according to the present invention. The relief valve 38 includes: a cylindrical valve housing 44 which is attached between the lower case 9 and oil pan 11 of the engine body 5 so as to be longitudinally extended continuously with the relief passage 37 and has outlets 43... provided in axially intermediate portions thereof; a valve body 45 slidably fitted to the valve housing 44 so as to allow the relief passage 37 to communicate with the outlets 43...as an oil pressure in the relief passage 37 becomes equal to, and exceeds a predetermined oil pressure; and a skirt 46 which is formed in an umbrella shape in a portion surrounding the outlets 43... and has an upper end portion fixed to the valve housing 44 above the outlets 43... in order to guide the oil discharged from the outlets 43... downward.
[0024] The relief passage 37 is provided in the lower case 9 so as to be longitudinally extended so that a lower end thereof opens to the oil reservoir 33 side. An upper end portion of the valve housing 44, which forms an inlet 47, is fluid-tightly fitted to the lower end portion of the relief passage 37 so as to allow the inlet 47 to communicate with the relief passage 37. Specifically, an O-ring 48 is attached to an outer circumference of the valve housing 44 in a fitted portion of the valve housing 44 to the relief passage 37.
[0025] Meanwhile, in the oil pan 11 in the engine body 5, a receiving portion 49 which receives a lower end of the valve housing 44 is protruded. The receiving portion 49 is formed into a cylindrical shape so as to be longitudinally extended. Then, since the coupling surface 14 between the upper case 7 and the lower case 9 is inclined downward to the front, and the valve housing 44 coaxially continues with the relief passage 37 perpendicularly branched from the ejection passage 35 extended parallel to the coupling surface 14, an upper end surface of the receiving portion 49 is formed in an inclined manner so as to perpendicularly abut on the lower end of the valve housing 44. In addition, a notch 55 is provided in a part along a circumferential direction of the receiving portion 49.
[0026] The outlets 43... are provided on the axially intermediate portions of the valve housing 44 so as to be located below the lower case 9 when the upper end portion of the valve housing 44 is fluid-tightly fitted to the lower case 9 so as to coaxially continue with the relief valve 37. The valve body 45 slidably fitted to the valve housing 44 so as to switch the communication/shutoff between the inlet 47 and the outlets 43... is formed into a closed-end cylindrical shape in which an upper end is closed.
[0027] In addition, above the outlets 43..., into the valve housing 44, a stopper pin 50 having an axis along one diameter line thereof is inserted. An upper limit position of the valve body 45 is regulated in such a manner that the upper-end closed portion thereof abuts on the stopper pin 50, and the valve body 45 located at the upper limit position makes the shutoff between the inlet 47 and the outlets 43....
[0028] Moreover, a disk-like retainer 52 is inserted into a lower portion of the valve housing 44 so that a downward movement thereof can be regulated by a snap ring 51 attached to an inner surface of the lower end of the valve housing 44. A valve spring 53 which urges the valve body 45 upward is compressed between the retainer 52 and the valve body 45. Then, when force in a valve opening direction, which presses the valve body 45 downward by the oil pressure in the inlet 47 communicating with the relief passage 37, exceeds force in a valve closing direction, which urges the valve body 45 upward by the valve spring 53, the valve body 45 moves downward so as to allow the inlet 47 to communicate with the outlets 43.... Specifically, the oil pressures in the relief passage 37 and the ejection passage 35 are maintained to be constant by the function of the relief valve 38.
[0029] The skirt 46 integrally includes, in order from an upper end thereof: a small-diameter cylindrical portion 46a press-fitted to the valve housing 44; a tapered portion 46b which allows a small-diameter end thereof to coaxially continue with a lower end of the small-diameter cylindrical portion 46a and is formed to be larger in diameter as going downward; and a large-diameter cylindrical portion 46c which coaxially continues with a lower end, that is, a large-diameter end of the tapered portion 46b. The small-diameter cylindrical portion 46a is fixed to the valve housing 44 by press fitting and the like so as to cover both ends of the stopper pin 50 in order to inhibit the stopper pin 50 from separating from the valve housing 44. Then, the valve housing 44 is surrounded by the tapered portion 46b and large-diameter cylindrical portion 46c of the skirt 46, and the tapered portion 46b and the large-diameter cylindrical portion 46c form the umbrella shape surrounding the valve housing 44.
[0030] In addition, an annular recessed portion 54 is formed on an outer circumference of the intermediate portion of the valve housing 44 below the outlets 43.... A lower end of the skirt 46, that is, a lower end of the large-diameter cylindrical portion 46c is disposed at a position corresponding to the intermediate portion of the annular recessed portion 54.
[0031] Next, a description will be made of functions of this embodiment. In order to prevent bubbles from being generated when the oil discharged from the outlets 43... provided in the valve housing 44 of the relief valve 38 is returned into the oil reservoir 33 in the oil pan 11, the upper end portion of the skirt 46 formed into the umbrella shape so as to surround the outlets 43... is fixed to the valve housing 44 above the outlets 43.... Moreover, the annular recessed portion 54 is formed on the outer circumference of the intermediate portion of the valve housing 44 below the outlets 43.... Therefore, it is possible to avoid a size increase of the shape of the skirt 46 and to increase a flow passage area between the outlets 43... and the skirt 46, and a sure defoaming function can be exerted in response to an increase of an amount of the oil discharged from the outlets 43... and also to an increase of an ejection pressure thereof. In addition, the annular recessed portion 54 is formed on the outer circumference of the intermediate portion of the valve housing 44 below the outlets 43..., and a high pressure on the relief passage 37 side is not applied to the valve housing 44 below the outlets 43.... Accordingly, the forming of the annular recessed portion 54 does not damage strength of the valve housing 44, thus making it possible to contribute to a weight reduction of the relief valve 38.
[0032] Moreover, the lower end of the skirt 46 is disposed at the position corresponding to the intermediate portion of the annular recessed portion 54, and accordingly, the discharged oil which flows between the valve housing 44 and the skirt 46 can be guided by the lower end of the annular recessed portion 54, and can be discharged so as to spread radially, and a defoaming effect can be enhanced.
[0033] Moreover, the upper end portion of the valve housing 44, which forms the inlet 47, is fluid-tightly fitted to the relief passage 37, the receiving portion 49 which receives the lower end of the valve housing 44 is provided in the oil pan 11, and the valve housing 44 is thrust on the receiving portion 49 side by the liquid pressure of the relief passage 37. Furthermore, the annular recessed portion 54 is formed on the intermediate portion of the valve housing 44, and accordingly, a seated area of the lower end of the valve housing 49 on the receiving portion 49 can be set relatively large while increasing a flow passage area between the valve housing 44 and the skirt 46, a large load can be avoided from being concentratedly applied to the lower end of the valve housing 44, and the valve housing 44 can be surely attached to the engine body 5.
1. A relief valve including: a cylindrical valve housing (44) attached to an engine body
(5) to be longitudinally extended continuously with a relief passage (37) which communicates
with an ejection port (36) of an oil pump (28), and which is provided in the engine
body (5), and the valve housing (44) being provided with an outlet (43) in an axially
intermediate portion thereof; a valve body (45) slidably fitted to the valve housing
(44) to allow the relief passage (37) to communicate with the outlet (43) as an oil
pressure in the relief passage (37) becomes equal to, and exceeds a predetermined
oil pressure; and a skirt (46) which is formed in an umbrella shape to surround the
valve housing (44), an upper end portion of the skirt (46) being fixed to the valve
housing (44) above the outlet (43) in order to guide oil discharged from the outlet
(43) downward, the relief valve wherein an annular recessed portion (54) is formed
on an outer circumference of the intermediate portion of the valve housing (44) below
the outlet (43).
2. The relief valve according to claim 1, wherein a lower end of the skirt (46) is disposed
at a position corresponding to an intermediate portion of the annular recessed portion
(54).
3. The relief valve according to any one of claims 1 and 2, wherein an upper end portion
of the valve housing (44), the upper end portion forming an inlet (47), is fluid-tightly
fitted to the relief passage (37), and a receiving portion (49) which receives a lower
end of the valve housing (44) is provided in the engine body (5).
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description