Hydraulic clutch control device of vehicle power unit

A hydraulic clutch control device of a vehicle power unit in which the oil pressure control valve is prevented from being exposed above the oil level even when a vehicle body inclines frontward or rearward. A housing chamber housing an actuator is formed in a housing chamber forming body attached to an engine main body and an oil pressure control valve partially facing the housing chamber is supported by the housing chamber forming body. An oil return hole used to return excess hydraulic oil from the housing chamber into the engine main body is provided in the housing chamber forming body to communicate with an upper portion of the housing chamber at an end portion of the housing chamber on a side close to the oil pressure control valve.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hydraulic clutch control device of a vehicle power unit.

2. Description of Related Art

Japanese Patent Application Publication No. 2010-255840 discloses a structure including an oil pressure control valve to control an oil pressure of a hydraulic clutch inserted in a power transmission system of a power unit; and an actuator to drive the oil pressure control valve, the oil pressure control valve and the actuator being housed in a housing chamber filled with a hydraulic oil so as to prevent operating noise of the oil pressure control valve and the actuator from leaking to the outside.

In the structure disclosed in Japanese Patent Application Publication No. 2010-255840, the housing chamber is formed to be quite larger than the whole of the oil pressure control valve and the actuator, and the whole of the oil pressure control valve and the actuator is immersed deep in the hydraulic oil. This prevents the oil pressure control valve from being exposed above the oil level even when part of the housing chamber is not filled with the hydraulic oil, which flows out more than necessary from an oil return hole communicating with an upper portion of the housing chamber, because the vehicle body inclines frontward or rearward when the vehicle climbs or descends a slope while travelling. However, in order to provide such a large housing chamber in the engine main body, a relatively large space needs to be secured in the engine main body. This may not only restrict the disposing position but may also lead to increase in size of the engine main body.

SUMMARY OF THE INVENTION

The present invention has been made in view of the situations described above and an object is to provide a hydraulic clutch control device of a vehicle power unit which is capable of suppressing exposure of an oil pressure control valve above an oil level of a hydraulic oil even when a vehicle body inclines frontward or rearward, while avoiding an increase in size of an engine main body.

For the purpose of solving the above-mentioned problems, a first aspect of the present invention provides a hydraulic clutch control device of a vehicle power unit in which: a hydraulic clutch is inserted in a power transmission system of a power unit including an internal combustion engine having a engine main body mounted on a vehicle-body frame; an oil pressure control valve and an actuator are disposed in the engine main body, the oil pressure control valve being capable of controlling an oil pressure of the hydraulic clutch and arranged to have an operating direction extending in a front-rear direction of the vehicle-body frame, the actuator being serially connected to the oil pressure control valve in the operating direction to drive the oil pressure control valve; and at least the actuator out of the oil pressure control valve and the actuator is housed in a housing chamber filled with a hydraulic oil, wherein the housing chamber housing the actuator is formed in a housing chamber forming body attached to the engine main body and the oil pressure control valve partially facing the housing chamber is supported by the housing chamber forming body, and an oil return hole used to return an excessive portion of the hydraulic oil from the housing chamber into the engine main body is provided in the housing chamber forming body to communicate with an upper portion of the housing chamber at an end portion of the housing chamber on a side close to the oil pressure control valve.

According to the first aspect of the present invention, the actuator is housed in the housing chamber and the oil pressure control valve is arranged to have the operating direction extend in the front-rear direction of the vehicle-body frame. The actuator is serially arranged in the operating direction and connected to the oil pressure control valve to drive the oil pressure control valve. In addition, the oil return hole is disposed to communicate with the upper portion of the housing chamber at the end portion of the housing chamber on the side close to the oil pressure control valve. Accordingly, an oil level of the hydraulic oil is less likely to be low on the side close to the oil pressure control valve even when the vehicle body inclines frontward or rearward. Hence, exposure of the oil pressure control valve above the oil level can be suppressed without increasing the size of the housing chamber. Thus, an increase in size of the engine main body can be avoided.

A second aspect of the present invention is such that, in addition to the first aspect, the housing chamber forming body includes a supporting holder and a cover member. The supporting holder is attached to the engine main body with the oil pressure control valve fitted to and supported by the supporting holder. The cover member is attached to the supporting holder to form the housing chamber between the cover member and the supporting holder. Part of the supporting holder is cut away to form the oil return hole opening upward and laterally in an upper portion of the supporting holder.

According to the second aspect of the present invention, the housing chamber is formed between the supporting holder attached to the engine main body with the oil pressure control valve fitted to and supported by the supporting holder, and part of the supporting holder is cut away to form the oil return hole opening upward and laterally in an upper portion of the supporting holder. Accordingly, the oil return hole can be easily formed by machining or molding.

A third aspect of the present invention is such that, in addition to the second aspect, the oil pressure control valve includes a valve housing fitted and fixed to the supporting holder and a spool valve body slidably fitted to the valve housing and is thus configured to be a spool type. An oil passage is disposed above a center axis of the spool valve body, the oil passage being formed in the supporting holder and connecting the housing chamber and a damper chamber formed on an opposite side to the actuator, between the valve housing and the spool valve body.

According to the third aspect of the present invention, the oil pressure control valve is configured to be of a spool type and the oil passage is formed in the supporting holder to be disposed above the center axis of the spool valve body, the oil passage causing the damper chamber formed on the opposite side to the actuator, between the valve housing and the spool valve body, to communicate with the housing chamber. Accordingly, air from the damper chamber is more likely to be discharged to the outside from the oil return hole via the housing chamber.

A fourth aspect of the present invention is such that, in addition to the second or third aspect, an eaves portion covering the oil return hole from above protrudes integrally from the supporting holder.

According to the fourth aspect of the present invention, the oil return hole is covered from above with the eaves portion protruding integrally from the supporting holder. This prevents the oil falling from above the supporting holder from entering the oil return hole and thereby causing the discharge property of the hydraulic oil from the oil return hole to deteriorate.

A fifth aspect of the present invention is such that, in addition to the fourth aspect, paired ribs, which extend vertically with the oil return hole interposed therebetween in a front-rear direction, protrude integrally from the supporting holder with upper ends of the ribs being integrally continuous with the eaves portion.

According to the fifth aspect of the present invention, the paired ribs disposed in front and rear of the oil return hole with the oil return hole interposed therebetween extend vertically and protrude integrally from the supporting holder with the upper ends of the ribs being integrally continuous with the eaves portion. Accordingly, the supporting holder can be reinforced in a portion where the oil return hole is disposed. In addition, the hydraulic oil from the oil return hole can be led downward and discharged in an excellent manner.

A sixth aspect of the present invention is such that, in addition to the fifth aspect, paired oil pressure control valves individually corresponding to paired hydraulic clutches inserted in the power transmission system are arranged parallel to each other in the supporting holder, and at least one of the paired ribs protrudes integrally from the supporting holder to extend over both of the oil pressure control valves.

According to the sixth aspect of the present invention, at least one of the paired ribs protrudes integrally from the supporting holder to extend over the paired oil pressure control valves disposed parallel to each other in the supporting holder. Accordingly, the supporting holder can be reinforced in a portion where the paired oil pressure control valves are disposed.

A seventh aspect of the present invention is such that, in addition to any of the first to sixth aspects, the actuator, having a coupler that protrudes laterally and to which an electric wire is connected is connected to the oil pressure control valve such that the coupler is disposed on an oblique lower side or an oblique upper side of the actuator in a view in an operation axis direction of the oil pressure control valve.

According to the seventh aspect of the present invention, the actuator is connected to the oil pressure control valve such that the coupler is disposed on an oblique lower side or an oblique upper side of the actuator in the view in an operation axis direction of the oil pressure control valve. Accordingly, it is possible to prevent the coupler from largely protruding from the actuator in the up-down direction and in the right-left direction and to effectively use a dead space in the housing chamber to dispose the coupler.

An eighth aspect of the present invention is such that, in addition to the seventh aspect, paired actuators individually connected to paired oil pressure control valves, which are disposed parallel to each other in the supporting holder and which individually correspond to paired hydraulic clutches inserted in the power transmission system are connected respectively to the oil pressure control valves with the couplers of the actuators arranged in the same direction.

According to the eighth aspect of the present invention, the couplers of the paired actuators are arranged in the same direction. Accordingly, the paired actuators are housed in the housing chamber in a space efficient manner while interference between the couplers is avoided.

A ninth aspect of the present invention is such that, in addition to the second aspect, a recessed portion forming an electric wire lead-out hole between the supporting holder and the recessed portion is provided in the cover member, the electric wire lead-out hole being used to lead the electric wire connected to the actuator to the outside.

According to the ninth aspect of the present invention, the electric wire lead-out hole used to lead the electric wire connected to the actuator to the outside is formed between the supporting holder and the recessed portion provided in the cover member. Accordingly, deterioration in stiffness of the supporting holder can be suppressed compared to the case where the electric wire lead-out hole is provided in the supporting holder, in addition to the oil return hole.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention is described with reference toFIGS. 1 to 15. Note that front, rear, up, down, right, and left in the description below refer to directions viewed by a rider riding on a motorcycle.

First, as shown inFIG. 1, a vehicle-body frame F of the motorcycle includes: a head pipe12steerably supporting a front fork11supporting a front wheel WF about an axis; right and left main frames13extending downward toward the rear from the head pipe12; right and left down frames14extending downward toward the rear at an angle steeper than that of the main frames13; right and left center frames15extending downward respectively from rear ends of the main frames13; right and left seat rails16extending upward toward the rear respectively from upper portions of the center frames15; and rear frames17connecting intermediate portions of the center frames15and rear portions of the seat rails16with each other.

A power unit P is disposed in a region surrounded by the main frames13, the down frames14, and the center frames15to be supported by the vehicle-body frame F. The power unit P includes an internal combustion engine E that has multiple cylinders, for example two cylinders, and a transmission M (seeFIG. 3), which is partially built into an engine main body18of the internal combustion engine E. A front end portion of a swing arm19is supported by the center frames15so as to be swingable upward and downward. A rear wheel WR is supported about an axis at a rear end portion of the swing arm19. The rear wheel WR is driven by a power generated by the power unit P. A storage box20is mounted on the main frames13, above the internal combustion engine E. A rider seat21of a tandem type is disposed behind the storage box20to be supported by the seat rails16. A fuel tank22is disposed under the rider seat21.

As shown inFIG. 2, the engine main body18of the internal combustion engine E is mounted on the vehicle-body frame F and includes: a crankcase26rotatably supporting a crankshaft25having an axial line extending in a vehicle width direction; a cylinder block27joined to an upper end of a front portion of the crankcase26and having a cylinder axial line C inclining frontward; a cylinder head28joined to an upper end of the cylinder block27; a head cover29joined to an upper end of the cylinder head28; and a oil pan30joined to a lower portion of the crankcase26.

Referring also toFIG. 3, the crankcase26is formed by joining an upper case half body31and a lower case half body32that can be divided from each other into upper and lower portions at a dividing surface extending along a horizontal plane passing through the axial line of the crankshaft25. The cylinder block27is formed integrally with the upper case half body31.

The cylinder block27has multiple, for example two, cylinder bores33,33serially arranged in the vehicle width direction. Pistons34are slidably fitted to the cylinder bores33, respectively. The pistons34are connected to the crankshaft25, which is rotatably supported by the crankcase26and which extends in the vehicle width direction, i.e. the arrangement direction of the cylinder bores33.

An electricity generator cover35forming an electricity generator chamber36between the electricity generator cover35and the crankcase26is joined to a left face of the crankcase26. A rotor38of an electricity generator37housed in the electricity generator chamber36is fixed to an end portion of the crankshaft25protruding into the electricity generator chamber36. A stator39of the electricity generator37is fixed to the electricity generator cover35to be surrounded by the rotor38.

As shown inFIG. 2, a starter motor40is fixedly disposed in an upper portion of the crankcase26. A driven gear42forming part of a reduction gear train41transmitting power from the starter motor40is connected to the rotor38via a one-way clutch43.

A clutch cover45forming part of the engine main body18is joined to a right face of the crankcase26to form a clutch chamber46between the clutch cover45and the crankcase26. The transmission M, which is housed in the crankcase26, includes gear trains, for example a first speed gear train G1to a sixth speed gear train G6, capable of selectively establishing multiple speeds between a counter shaft49and each of first and second main shafts47,48which have axes parallel to the crankshaft25and which are rotatably supported by the crankcase26.

The first and second main shafts47,48are coaxially disposed. The first main shaft47rotatably penetrates a right wall of the crankcase26and is rotatably supported by the clutch cover45. The other end of the first main shaft47is rotatably supported by a left wall of the crankcase26via a ball bearing50. The second main shaft48coaxially surrounds the first main shaft47and rotatably penetrates the right wall of the crankcase26. A ball bearing51is interposed between the right wall of the crankcase26and the second main shaft48and multiple needle bearings52,52are interposed between the first and second main shafts47,48.

One end portion of the counter shaft49protrudes from a rear portion of the left wall of the crankcase26with a ball bearing53and an annular sealing member54interposed between the counter shaft49and the left wall of the crankcase26. The other end portion of the counter shaft49is rotatably supported by the right wall of the crankcase26with a needle bearing55interposed therebetween.

The first speed gear train G1, the third speed gear train G3, and the fifth speed gear train G5are provided between the first main shaft47and the counter shaft49. The second speed gear train G2, the fourth speed gear train G4, and the sixth speed gear train G6are provided between the second main shaft48and the counter shaft49.

A driving sprocket56is fixed to the one end portion of the counter shaft49protruding from the left wall of the crankcase26and a rotational power outputted from the transmission M is transmitted to the rear wheel WR by use of an endless chain (not shown) wound around the driving sprocket56.

A power transmission system, which transmits the rotational power outputted from the crankshaft25of the internal combustion engine E to the rear wheel WR, is configured to include a primary reduction device60transmitting the power from the crankshaft25, a first hydraulic clutch61, a second hydraulic clutch62, the transmission M, the driving sprocket56, and the chain. The primary reduction device60, the first hydraulic clutch61interposed between the primary reduction device60and the first main shaft47, and the second hydraulic clutch62interposed between the primary reduction device60and the second main shaft48are housed in the clutch chamber46.

A pulsar63is fixedly attached to an end portion of the crankshaft25in the clutch chamber46. A rotational speed sensor64disposed in the clutch chamber46to face an outer periphery of the pulsar63is fixed to the clutch cover45.

InFIG. 4, a hollow power transmission tube shaft65is fitted to an intermediate portion of the first main shaft47, which is located closer to the other end of the first main shaft47, to be adjacent to the second main shaft48in an axial direction and to be capable of rotating relative to the first main shaft47. A large-diameter portion65aand a flange portion65bare integrally provided in the power transmission tube shaft65, the large-diameter portion65abulging to protrude outward in a radial direction in an intermediate portion of the power transmission tube shaft65in the axial direction, the flange portion65bprotruding outward in the radial direction from an outer periphery of the large-diameter portion65a. The first hydraulic clutch61is provided on the power transmission tube shaft65and the first main shaft47to be capable of performing switching of disconnection and connection of power between the power transmission tube shaft65and the first main shaft47. The second hydraulic clutch62is provided on the power transmission tube shaft65and the second main shaft48to be capable of performing switching of disconnection and connection of power between the power transmission tube shaft65and the second main shaft48.

The primary reduction device60includes: a primary driving gear67which, rotates together with the crankshaft25; a primary driven gear68, which is supported to be capable of moving in the axial direction and rotating relative to the large-diameter portion65aof the power transmission tube shaft65such that the primary driven gear68rotates when the rotational power is transmitted thereto from the crankshaft25via the primary driving gear67; multiple damper springs69, which are interposed between the power transmission tube shaft65and the primary driven gear68; friction springs70, which bias the primary driven gear68toward the flange portion65bto generate a friction force between the primary driven gear68and the flange portion65bof the power transmission tube shaft65and thereby suppress relative rotation between the power transmission tube shaft65and the primary driven gear68.

The primary driven gear68integrally has: a cylindrical boss portion68a, which coaxially surrounds the large-diameter portion65aof the power transmission tube shaft65; and a circular plate portion68b, which protrudes outward from the boss portion68ain the radial direction and in which multiple teeth72,72meshing with the primary driving gear67are provided in an outer periphery. The circular plate portion68bis provided continuously and integrally with an end portion of the boss portion68aon a side close to the flange portion65b. An annular washer71is interposed between the flange portion65band an inner peripheral portion of the primary driven gear68on the side close to the flange portion65b.

The damper springs69are coil springs and are housed in multiple housing holes74provided in the circular plate portion68bof the primary driven gear68at equal intervals in a circumferential direction. The circular plate portion68bis interposed between a first side plate75facing a side surface of the circular plate portion68bon a side close to the flange portion65band a second side plate76facing a side surface of the circular plate portion68bon the opposite side to the flange portion65b, and the damper springs69are held in the housing holes74by the side plates75,76. Moreover, cylindrical collars77are interposed between the first and second side plates75,76and are disposed respectively at multiple positions, at equal intervals in a circumferential direction of the first and second side plates75,76. The first and second side plates75,76are connected to each other by rivets78that extend through the collars77. The first and second side plates75,76are thus fixed to the power transmission tube shaft65and rotate together with the power transmission tube shaft65.

When the primary driven gear68is not rotating relative to the first side plate75, the second side plate76, and the power transmission tube shaft65, both ends of each of the damper springs69are in contact with the primary driven gear68and with the first and second side plates75,76. When the primary driven gear68rotates relative to the first side plate75and the second side plate76, the damper springs69are compressed between the first driving gear68and the first and second side plates75,76, and an abrupt change in torque, which is caused by a spring force exerted by the damper springs69is buffered.

Moreover, multiple restriction holes79in which the collars77are respectively inserted are provided in the circular plate portion68bof the primary driven gear68and are each formed to have a long hole shape elongated in a circumferential direction of the power transmission tube shaft65. Hence, the rotation of the primary driven gear68relative to the first and second side plates75,76, i.e. the power transmission tube shaft65is restricted within a range in which the collars77move in the restriction holes79.

The friction springs70are disc springs inclining to be farther away from the flange portion65btoward an outer side in the radial direction. Two friction springs70,70overlapping each other are interposed between the second side plate76and the circular plate portion68bsuch that smaller diameter ends of the friction springs70,70on the inner peripheral sides are brought into contact with the side surface of the circular plate portion68bof the primary driven gear68on the opposite side to the flange portion65b.

The first hydraulic clutch61is disposed to the right of the primary reduction device60and includes: a first clutch outer80, a first clutch inner81, multiple first driving friction plates82,82, multiple first driven friction plates83,83, a ring-shaped first pressure receiving plate84, a first retaining ring85, a first piston86, and a first clutch spring88. The first clutch outer80is formed in a bowl shape opened to the opposite side to the primary reduction device60and is joined to the power transmission tube shaft65to be incapable of rotating relative thereto. The first clutch inner81is joined to the first main shaft47to be incapable of rotating relative thereto. The first driving friction plates82,82are engaged with the first clutch outer80to be capable of performing a relative movement in the axial direction. The first driven friction plates83,83are disposed alternately with the first driving friction plates82,82and are engaged with the first clutch inner81to be capable of performing a relative movement in the axial direction. The first pressure receiving plate84faces the outermost one of the multiple first driving friction plates82,82and the multiple first driven friction plates83,83, which are disposed alternately. The first retaining ring85is attached to the first clutch outer80to be capable of engaging with the first pressure receiving plate84from the opposite side to the first driving friction plates82,82and the first driven friction plates83,83. The first piston86has a pushing portion86ain an outer circumferential portion and the first driving friction plates82,82and the first driven friction plates83,83are interposed between the pushing portion86aand the first pressure receiving plate84. Moreover, the first piston86is slidably fitted to the first clutch outer80in a liquid tight manner and forms a first oil pressure chamber87between the first piston86and the first clutch outer80. The first clutch spring88biases the first piston86in such a direction that the capacity of the first oil pressure chamber87becomes smaller. A ball bearing89is interposed between the first clutch inner81and the clutch cover45. In other words, the other end portion of the first main shaft47is rotatably supported by the clutch cover45via the first clutch inner81.

When the hydraulic pressure is not acting on the first oil pressure chamber87, the first hydraulic clutch61as described above is in a clutch off state where the power transmission is cut off. When the oil pressure is acting on the first oil pressure chamber87, the first hydraulic clutch61is in a clutch on state where the rotational power transmitted from the crankshaft25to the first clutch outer80via the primary reduction device60, the damper springs69, and the power transmission tube shaft65is transmitted to the first main shaft47.

The second hydraulic clutch62disposed closer to the crankcase26than the first hydraulic clutch61with the primary reduction device60interposed between the second hydraulic clutch62and the first hydraulic clutch61. The second hydraulic clutch62includes a second clutch outer90, a second clutch inner91, multiple driving friction plates92,92, multiple second driven friction plates93,93, a ring-shaped second pressure receiving plate94, a second retaining ring95, a second piston96, and a second clutch spring98. The second clutch outer90is formed in a tubular shape opened toward the crankcase26and is joined to the power transmission tube shaft65to be incapable of rotating relative thereto with the primary driven gear68interposed between the second clutch outer90and the first clutch outer80. The second clutch inner91is joined to the second main shaft48to be incapable of rotating relative thereto. The second driving friction plates92,92are engaged with the second clutch outer90to be capable of performing a relative movement in the axial direction. The second driven friction plates93,93are disposed alternately with the second driving friction plates92,92and are engaged with the second clutch inner91to be capable of performing a relative movement in an axial direction. The second pressure receiving plate94faces the outermost one of the multiple second driving friction plates92,92and the multiple second driven friction plates93,93, which are disposed alternately. The second retaining ring95is attached to the second clutch outer90to be capable of engaging with the second pressure receiving plate94from the opposite side to the second driving friction plates92,92and the second driven friction plates93,93. The second piston96has a pushing portion96ain an outer circumferential portion and the second driving friction plates92,92and the second driven friction plates93,93are interposed between the pushing portion96aand the second pressure receiving plate94. Moreover, the second piston96is slidably fitted to the second clutch outer90in a liquid tight manner and forms a second oil pressure chamber97between the second piston96and the second clutch outer90. The second clutch spring98biases the second piston96in such a direction that the capacity of the second oil pressure chamber97becomes smaller.

When the hydraulic pressure is not acting on the second oil pressure chamber97, the second hydraulic clutch62, as described above, is in a clutch off state where the power transmission is cut off. When the oil pressure is acting on the second oil pressure chamber97, the second hydraulic clutch62is in a clutch on state where the rotational power transmitted from the crankshaft25to the second clutch outer90via the primary reduction device60, the damper springs69, and the power transmission tube shaft65is transmitted to the second main shaft48.

A first oil passage100communicating with the first oil pressure chamber87is provided in the first clutch outer80of the first hydraulic clutch61and the power transmission tube shaft65. A first annular recessed portion101communicating with the first oil passage100is provided in an outer periphery of the first main shaft47. Moreover, a second oil passage102communicating with the second oil pressure chamber97is provided in the second clutch outer90of the second hydraulic clutch62and the power transmission tube shaft65. A second annular recessed portion103communicating with the second oil passage102is provided in an outer periphery of the first main shaft47.

First and second axial direction oil passages104,105parallel to each other are provided in an end portion of the first main shaft47on a side close to the clutch cover45to have inner ends thereof closed and extend in the axial direction. The first axial direction oil passage104communicates with the first oil pressure chamber87via the first annular recessed portion101and the first oil passage100. The second axial direction oil passage105communicates with the second oil pressure chamber97via the second annular recessed portion103and the second oil passage102. Moreover, an outer end opening portion of the first axial direction oil passage104is closed with a plug member106and an outer end of the second axial direction oil passage105is left open.

The end portion of the first main shaft47on the side close to the clutch cover45is fitted to a tube member107fitted and fixed to the clutch cover45. A communication passage110causing the first axial direction oil passage104to communicate with an annular first oil chamber108formed between an outer periphery of the tube member107and the clutch cover45is provided in the first main shaft47and the tube member107. Moreover, a second oil chamber109communicating with the second axial direction oil passage105is formed between the clutch cover45and a group of the first main shaft47and the tube member107.

Referring toFIG. 2, a first oil filter111is provided in a lower portion of the clutch cover45. A level gauge insertion tube224located behind the first oil filter111is provided in the clutch cover45to extend upward from the lower portion of the clutch cover45. Moreover, oil for control is supplied to the first oil filter111, after being discharged from a first oil pump (not illustrated) built in the engine main body18such that oil in the oil pan30is pumped up. An oil pressure control device113for controlling the pressure of the oil cleaned by the first oil filter111for each of the first hydraulic clutch61and the second hydraulic clutch62is disposed on an inner face side of the clutch cover45to partially overlap the level gauge insertion tube224in a side view. Furthermore, an oil filter oil pressure sensor114, which detects the pressure of the oil to be supplied to the first oil filter111, is attached to the first oil filter111. First and second oil pressure sensors115,116individually detecting the oil pressures of the first and second hydraulic clutches61,62controlled by the oil pressure control device113are disposed in the clutch cover45.

Moreover, a second oil pump (not illustrated) different from the first oil pump is built in the engine main body18to discharge a lubrication oil. The oil discharged from the second oil pump is cleaned by a second oil filter119attached to a lower portion of a front wall of the crankcase26in the engine main body18. A lubrication oil pressure sensor120, which detects a supplying oil pressure of the lubrication oil, is attached to a front face of the crankcase26.

Referring toFIGS. 3 and 4, a lubrication oil passage123is provided in the first main shaft47. The lubrication oil passage123allows the lubrication oil cleaned by the second oil filter119to be supplied to portions to be lubricated around the first main shaft47.

The lubrication oil is supplied to the lubrication oil passage123from the end portion of the first main shaft47on the opposite side to the clutch cover45. The lubrication oil passage123is formed of an upstream oil passage123aprovided coaxially with the first main shaft47and a downstream oil passage123bformed to have a diameter smaller than the upstream oil passage123aand extending parallel to the axis of the first main shaft47. The downstream oil passage123bis preferably formed to have the same diameter as those of the first and second axial direction oil passages104,105.

The upstream oil passage123ais bored in the first main shaft47such that the first main shaft47is opened at an outer end in the end portion on the opposite side to the clutch cover45. An inner end of the upstream oil passage123ais arranged at a position overlapping, in the side view, the second hydraulic clutch62out of the first and second hydraulic clutches61,62arranged side by side in the direction along the axis of the first main shaft47. Meanwhile, the downstream oil passage123bis bored in the first main shaft47from the end portion close to the clutch cover45to communicate with the inner end of the upstream oil passage123a. An outer end of the down stream oil passage123bis closed by a plug124.

Oil holes125,125for supplying the lubrication oil to multiple portions of the transmission M and a portion between the first and second main shafts47,48are provided at multiple locations in the first main shaft47with intervals in the axial direction, in such a way that inner ends of the oil holes125,125communicate with the upstream oil passage123aof the lubrication oil passage123.

Moreover, multiple communication passages126, whose inner ends communicate with the downstream oil passage123bof the lubrication oil passage123, are provided in the first main shaft47such that outer ends of the communication passages126communicate with an annular groove127provided in an inner periphery of the power transmission tube shaft65at a position corresponding to an intermediate portion of the large diameter portion65aof the power transmission tube shaft65in the axial direction. Multiple supply oil holes128, which each have one end opened at the inner periphery of the power transmission tube shaft65to communicate with the annular groove127, are provided in the large diameter portion65aof the power transmission tube shaft65to extend in the radial direction of the power transmission tube shaft65. The other ends of the supply oil holes128are opened at the outer periphery of the large diameter portion65aof the power transmission tube shaft65while at least partially facing an inner peripheral surface of the boss portion68ain the primary driven gear68on the side close to the flange portion65b.

An annular groove130allowing the lubrication oil to be supplied from the supply oil holes128is provided in the inner periphery of the boss portion68a. Multiple boss portion oil holes129, whose one ends are opened at the inner periphery of the boss portion68ato communicate with the annular groove130, are provided in the boss portion68a. The other ends of the boss portion oil holes129are each opened at the outer periphery of the boss portion68aat such a position that the circular plate portion68bof the primary driven gear68is disposed between the other end of the boss portion oil hole129and the flange portion65b. Furthermore, the boss portion oil holes129are formed to incline to be away from the flange portion65btoward the outer periphery of the boss portion68a.

The opening portions of the boss portion oil holes129at the outer periphery of the boss portion68aare disposed at positions corresponding to the friction springs70in contact with the side surface of the circular plate portion68bof the primary driven gear68on the opposite side to the flange portion65b. The friction springs70are disc springs inclining to be farther away from the flange portion65btoward the outer side in the radial direction and the smaller diameter ends of the friction springs70on the inner peripheral sides are in contact with the side surface of the circular plate portion68bon the opposite side to the flange portion65b. Hence, the opening portions of the boss portion oil holes129at the outer periphery of the boss portion68aare located at the positions corresponding to the contact portions of the smaller diameter ends of the friction springs70to the circular plate portion68b.

InFIG. 5, a filter case132of the first oil filter111has a cylindrical shape and is formed of a bottomed cylindrical case main portion133formed integrally with the clutch cover45and a lid member134joined to the case main portion133with a pair of bolts135. A filtering material136formed in a ring shape is inserted and held in the filter case132. An uncleaned oil chamber137is formed between an outer periphery of the filtering material136and the filter case132while a cleaned oil chamber138is formed in the filtering material136.

An inlet passage139communicating with the uncleaned oil chamber137is provided in a side wall of the case main portion133. A connection passage140into which a hydraulic oil discharged from the first oil pump is introduced communicates with the inlet passage139via a connection pipe141and the hydraulic oil discharged from the first oil pump is supplied to the uncleaned oil chamber137.

The oil filter oil pressure sensor114is attached to the case main portion133such that the axis of the oil filter oil pressure sensor114is perpendicular to the axis of the filter case132and such that a front end of the oil filter oil pressure sensor114faces the inlet passage139. Moreover, an outlet passage142communicating with the cleaned oil chamber138is provided in the clutch cover45and a filter143is attached to the outlet passage142.

Referring also toFIGS. 6 to 8, the oil pressure control device113is formed of: a first oil pressure control valve144that controls the oil pressure of the first hydraulic clutch61; a first solenoid145that is an actuator connected to the first oil pressure control valve144to drive the first oil pressure control valve144; a second oil pressure control valve146that controls the oil pressure of the second hydraulic clutch62; a second solenoid147that is an actuator connected to the second oil pressure control valve146to drive the second oil pressure control valve146. The oil pressure control device113is disposed on the inner face side of the clutch cover45.

The first and second oil pressure control valves144,146include valve housings148,149and spool valve bodies150,151housed in the valve housings148,149and are thus configured to be of a spool-type. The first and second oil pressure control valves144,146are disposed on the inner face side of the clutch cover45forming part of the engine main body18in such a posture that the operating directions thereof extend in a front-rear direction of the vehicle-body frame F.

A housing chamber forming body152is attached the inner face of the clutch cover45and a housing chamber153, which houses the first and second solenoids145,147, is formed in the housing chamber forming body152. The first and second oil pressure control valves144,146are supported by the housing chamber forming body152to partially face the housing chamber153.

Referring also toFIG. 9, the housing chamber forming body152is formed of a supporting holder154and a cover member155. The supporting holder154is attached to the clutch cover45with the first and second oil pressure control valves144,146fitted to and supported by the supporting holder154. The cover member155is attached to the supporting holder154to form the housing chamber153between the cover member155and the supporting holder154.

The supporting holder154integrally has a holder main portion154aand a tube portion154b, which is formed to have a tubular shape opened rearward and extends rearward from a rear end of the holder main portion154a. The cover member155is formed to have a bottomed tubular shape opened frontward and is joined to the rear end of the tube portion154bwith multiple, for example two bolts156,156to close a rear-end opening portion of the tube portion154b. The supporting holder154and the cover member155thus form the housing chamber153.

Referring also toFIG. 10, the holder main portion154aof the supporting holder154is provided such that a pair of bottomed attachment holes157,158extend parallel to each other. Each of the attachment holes157,158has a circular lateral cross section, and has a front end closed and a rear end opened to the housing chamber153. The valve housing148of the first oil pressure control valve144is formed to have a cylindrical shape with one end thereof closed with a lid member159and is fitted into the lower attachment hole157out of the attachment holes157,158from a side close to the lid member159. Moreover, the valve housing149of the second oil pressure control valve146is formed to have a cylindrical shape with one end thereof closed with a lid member160and is fitted into the upper attachment hole158out of the attachment holes157,158from a side close to the lid member160. An attachment plate161is engaged with the other end portions of the valve housings148,149of the first and second oil pressure control valves144,146, which protrude from the holder main portion154a. The attachment plate161is fastened to holder main portion154awith a bolt162and is thus fixedly supported by the supporting holder154with both of the valve housings148,149fitted respectively to the attachment holes157,158.

A damper chamber163is formed between the lid member159and the spool valve body150in the valve housing148of the first oil pressure control valve144. A return spring164biasing the spool valve body150toward the first solenoid145is housed in the damper chamber163. Moreover, a damper chamber165is formed between the lid member160and the spool valve body151in the valve housing149of the second oil pressure control valve146. A return spring166biasing the spool valve body151toward the second solenoid147is housed in the damper chamber165.

The first and second solenoids145,147have plungers167,168, which coaxially come into contact with end portions of the spool valve bodies150,151on the opposite side to the damper chambers163,165. The first and second solenoids145,147are connected to the other end portions of the valve housings148,149, which protrude from the holder main portion154a, so as to be connected serially to the first and second oil pressure control valves144,146in the operating direction. Connection portions of the plungers167,168to the spool valve bodies150,151are housed in plunger chambers169,170formed between the first and second solenoids145,147and the valve housings148,149of the first and second oil pressure control valves144,146. The plunger chambers169,170communicate with the housing chamber153.

The supporting holder154is attached to the inner face of the clutch cover45with multiple, for example five bolts174,174, with a flat-plate-shaped partition member173interposed between the supporting holder154and the inner face of the clutch cover45. In a state where the supporting holder154is attached to the clutch cover45, a center axis C1of the first oil pressure control valve144and a center axis C2of the second oil pressure control valve146extend in a front-rear direction of the vehicle-body frame F and are substantially horizontal.

The first and second solenoids145,147have couplers145a,147athat protrude laterally with electric wires175,176connected thereto. The first and second solenoids145,147are connected to the first and second oil pressure control valves144,146such that the couplers145a,147aare disposed on oblique lower or upper sides of the first and second solenoids145,147in a view in the operating direction of the first and second oil pressure control valves144,146, i.e. a direction of the center axes C1, C2. In the embodiment, the first and second solenoids145,147are connected to the first and second oil pressure control valves144,146with the couplers145a,147abeing disposed at positions such that the couplers145a,147aprotrude obliquely downward from the first and second solenoids145,147in the view in the direction of the center axes C1, C2.

Moreover, the first and second solenoids145,147are connected to the first and second oil pressure control valves144,146with the couplers145a,147aaligned in the same direction.

A recessed portion178forming a electric wire lead-out hole177between the recessed portion178and the supporting holder154is provided in an upper portion of the cover member155. The electric wire lead-out hole177is used to lead the electric wires175,176, which are connected to the couplers145a,147aof the first and second solenoids145,147, to the outside. The electric wires175,176penetrate a grommet179, which is attached to the electric wire lead-out hole177, in a liquid tight manner and are thus led outside.

Referring toFIG. 6, a drain port181, an output port182, an input port183, and a feed-back port184are provided in the valve housing148of the first oil pressure control valve144with intervals, in this order from a side close to the plunger chamber169to a side close to the damper chamber163. The drain port181communicates with the housing chamber153, the feed-back port184is provided with a restriction portion185, and the output port182communicates with feed-back port184. A resultant force of the spring force of the return spring164and the oil pressure force generated by an oil outputted from the output port182and restricted by the restriction portion185acts on the spool valve body150of the first oil pressure control valve144in such a direction that the output port182communicates with the drain port181while being disconnected from the input port183. Moreover, a driving force from the plunger167generated when electricity is supplied to the first solenoid145acts in such a direction that the output port182communicates with the input port183while being disconnected from the drain port181. Hence, the hydraulic oil is outputted from the output port182at an oil pressure corresponding to the amount of electricity supplied to the first solenoid145and the hydraulic oil is discharged to the housing chamber153from the drain port181, according to the operation of the first oil pressure control valve144.

Moreover, an oil passage186connecting the damper chamber163of the first oil pressure control valve144and the housing chamber153to each other is formed in the supporting holder154. The oil passage186is disposed above the center axis C1of the first oil pressure control valve144.

Referring toFIG. 7, a drain port188, an output port189, an input port190, and a feed-back port191are provided in the valve housing149of the second oil pressure control valve146with intervals, in this order from a side close to the plunger chamber170to a side close to the damper chamber165. The drain port188communicates with the housing chamber153, the feed-back port191is provided with a restriction portion192, and the output port189communicates with feed-back port191. A resultant force of the spring force of the return spring166and the oil pressure force generated by an oil outputted from the output port189and restricted by the restriction portion192acts on the spool valve body151of the second oil pressure control valve146in such a direction that the output port189communicates with the drain port188while being disconnected from the input port190. Moreover, a driving force from the plunger168generated when electricity is supplied to the second solenoid147acts in such a direction that the output port189communicates with the input port190while being disconnected from the drain port188. Hence, the hydraulic oil is outputted from the output port189at an oil pressure corresponding to the amount of electricity supplied to the second solenoid147and the hydraulic oil is discharged to the housing chamber153from the drain port188, according to the operation of the second oil pressure control valve146.

Moreover, an oil passage193connecting the damper chamber165of the second oil pressure control valve146and the housing chamber153to each other is formed in the supporting holder154. The oil passage193is disposed above the center axis C2of the second oil pressure control valve146.

The first and second oil pressure control valves144,146are individually connected to the first and second hydraulic clutches61,62by first and second control oil supply oil passages196,197. First and second cover-side supply oil passages196a,197aforming part of the first and second control oil supply oil passages196,197are provided in the clutch cover45to extend to a side of the first main shaft60from the oil pressure control device113while inclining upward toward the rear. A downstream end of the first cover-side supply oil passage196acommunicates with the first oil chamber108communicating with the first oil pressure chamber87of the first hydraulic clutch61. A downstream end of the second cover-side supply oil passage197acommunicates with the second oil chamber109communicating with the second oil pressure chamber97of the second hydraulic clutch62.

Referring also toFIG. 11, first and second control-valve-side supply oil passages196b,197bindividually communicating with the first and second cover-side supply oil passages196a,197aare formed on both faces of the partition member173, i.e. a face of the partition member173on a side close to the clutch cover45and a face of the partition member173on a side close to the supporting holder154, to form the first and second control oil supply oil passages196,197together with the first and second cover-side supply oil passages196a,197a. Moreover, a supply oil passage198(seeFIG. 5) extending from the first oil filter111to the first and second oil pressure control valves144,146is formed.

InFIG. 12, the holder main portion154aof the supporting holder154is provided with an outlet hole201, an inlet hole202, and a feed-back hole203respectively communicating with the output port182, the input port183, and the feed-back port184of the first oil pressure control valve144, as well as with an outlet hole204, an inlet hole205, and a feed-back hole206respectively communicating with the output port189, the input port190, and the feed-back port191of the second oil pressure control valve146. Moreover, a groove207connecting the outlet hole201and the feed-back hole203to each other and a groove208connecting the outlet hole204and the feed-back hole206to each other are provided in the face of the supporting holder154which faces the partition member173.

Meanwhile, as shown inFIG. 13, through holes209,210corresponding to the outlet hole201and the inlet hole202provided in the supporting holder154on the side close to first oil pressure control valve144are provided in the partition board173to communicate with the outlet hole201and the inlet hole202as indicated by densely-hatched areas inFIG. 12, when the partition member173is interposed between the supporting holder154and the clutch cover45. Moreover, through holes211,212corresponding to the outlet hole204and the inlet hole205provided in the supporting holder154on the side close to second oil pressure control valve146are provided in the partition board173to communicate with the outlet hole204and the inlet hole205, as indicated by densely-hatched areas inFIG. 12, when the partition member173is interposed between the supporting holder154and the clutch cover45.

Furthermore, the partition member173is provided with a through hole213communicating with the outlet passage142of the first oil filter111and a through hole215communicating with a groove214provided in the face of the supporting holder154facing the partition member173, the groove214provided in such a manner that the one end communicates with the through hole213and the other end communicates with the through hole215. As shown inFIGS. 5 and 11, a groove216, curved such that the through hole215communicates with the through holes210,212, is provided in the face of the clutch cover45facing the partition member173.

Accordingly, the supply oil passage198from the first oil filter111to the first and second oil pressure control valves144,146is formed of the through hole213of the partition member173, the groove214of the supporting holder154, the through hole215of the partition member173, the groove216of the clutch cover45, the through holes210,212of the partition member173, and the inlet holes202,205of the supporting holder154.

A groove217communicating with the outlet hole201of the supporting holder154via the through hole209of the partition member173is provided in the face of the clutch cover45facing the partition member173. The groove217communicates with a through hole219provided in the partition member173. Moreover, a groove220, whose one end communicates with the through hole219, is provided in the face of the supporting holder154facing the partition member173. A through hole221communicating with the other end of the groove220is provided in the partition member173. The through hole221communicates with the first cover-side supply oil passage196a. In other words, the first control-valve-side supply oil passage196bis formed of the through hole209of the partition member173, the groove217of the clutch cover45, the through hole219of the partition member173, the groove220of the supporting holder154, and the through hole221of the partition member173, and the first control-valve-side supply oil passage196bis formed between one surface of the partition member173and the face of the supporting holder154facing the partition member173as well as between the other surface of the partition member173and the face of the clutch cover45facing the partition member173.

Moreover, a groove218, whose one end communicates with the outlet hole204of the supporting holder154via the through hole211of the partition member173, is provided in the face of the clutch cover45facing the partition member173. A through hole222communicating with the other end of the groove218is provided in the partition member173. The through hole222communicates with the second cover-side supply oil passage197a. In other words, the second control-valve-side supply oil passage197bis formed of the through hole211of the partition member173, the groove218of the clutch cover45, and the through hole222of the partition member173, and the second control-valve-side supply oil passage197bis formed between the face of the clutch cover45facing the partition member173and the face of the partition member173facing the clutch cover45.

The partition member173is provided with through holes230,231communicating with the grooves207,208provided in the supporting holder154. The clutch cover45is provided with a first detection oil passage232communicating with the groove207, i.e. the output port182of the first oil pressure control valve144via the through hole230and a second detection oil passage233communicating with the output port189of the second oil pressure control valve146via the through hole231. The first oil pressure sensor115, which detects the oil pressure of the first detection oil passage232, and the second oil pressure116, which detects the oil pressure of the second detection oil passage233, are disposed on the clutch cover45.

Referring also toFIGS. 14 and 15, an oil return hole225for retuning excessive hydraulic oil from the housing chamber153into the engine main body18is provided in the housing chamber forming body152to communicate with an upper portion of the housing chamber153at an end portion of the housing chamber153on a side close to the first and second oil pressure control valves144,146, the housing chamber forming body152attached to the inner face side of the clutch cover45in the engine main body18.

The oil return hole225is formed to open upward and laterally in an upper portion of the supporting holder154forming the housing chamber forming body152together with the cover member155. The oil return hole225is formed by cutting away part of the supporting holder154.

An eaves portion226covering the oil return hole225from above protrudes integrally from the supporting holder154. A pair of ribs227,228extending vertically with the oil return hole225interposed therebetween in a front rear direction protrude integrally from the supporting holder154with the upper ends thereof being integrally continuous with the eaves portion226.

The first and second oil pressure control valves144,146individually corresponding to the first and second hydraulic clutches61,62are disposed parallel to each other in the supporting holder154in a direction along the front-rear direction of the vehicle-body frame F. At least one of the pair of ribs227,228(the rib228in the embodiment) protrudes integrally from the supporting holder154to extend over both of the oil pressure control valves144,146.

Next, operations of the embodiment are described. The housing chamber153housing the first and second solenoids145,147is formed in the housing chamber forming body152attached to the inner face side of the clutch cover45forming part of the engine main body18, the first and second oil pressure control valves144,146partially facing the housing chamber153are supported by the housing chamber forming body152, and the oil return hole225for returning excessive hydraulic oil from the housing chamber153into the engine main body18is provided in the housing chamber forming body152to communicate with the upper portion of the housing chamber153at the end portion of the housing chamber153on the side close to the first and second oil pressure control valves144,146. Accordingly, an oil level of the hydraulic oil is less likely to be low on the side close to the first and second oil pressure control valves144,146even when the vehicle body inclines frontward or rearward. Hence, the exposure of the first and second oil pressure control valves144,146above the oil level can be suppressed without increasing the size of the housing chamber153. Thus, the increase in size of the engine main body18can be avoided.

Here, with reference toFIG. 8, assume a case where the vehicle body inclines upward toward the front while climbing a slope or the like. When the oil level of the hydraulic oil in the housing chamber153is at a position shown by a chain line LF ofFIG. 8, there is a possibility of outside air entering the plunger chamber170of the second oil pressure control valve146from the oil return hole225. However, the position shown by the chain line LF is a state where the vehicle body inclines upward toward the front at 70°, for example, and such a state does not occur in normal travelling. Accordingly, the exposure of the first and second oil pressure control valves144,146above the oil level can be suppressed. Moreover, assume a case where the vehicle body inclines upward toward the rear while descending a slope or the like. When the oil level of the hydraulic oil in the housing chamber153is at a position shown by a chain line LR ofFIG. 8, there is a possibility of outside air entering the plunger chamber170of the second oil pressure control valve146from the oil return hole225. However, the position shown by the chain line LR is a state where the vehicle body inclines upward toward the rear at 54°, for example, and such a state does not occur in normal travelling. Accordingly, the exposure of the first and second oil pressure control valves144,146above the oil level can be suppressed.

Moreover, the housing chamber forming body152is formed of: the supporting holder154attached to the clutch cover45with the first and second oil pressure control valves144fitted to and supported by the clutch cover45; and the cover member155attached to the supporting holder154to form the housing chamber153between the cover member155and the supporting holder154, and the part of the supporting holder154is cut away to form the oil return hole225opening upward and laterally in the upper portion of the supporting holder154. Accordingly, the oil return hole225can be easily formed by machining or molding.

Furthermore, the first and second oil pressure control valves144,146include the valve housings148,149fitted and fixed to the supporting holder154and the spool valve bodies150,151slidably fitted to the valve housings148,149and are thus configured to be of a spool-type. In addition, the oil passage186,193are disposed above the center axes C1, C2of the first and second oil pressure control valves144,146, the oil passages186,193formed in the supporting holder154and connecting the housing chamber153and the damper chambers163,165formed on the opposite side to the first and second solenoids145,147driving the first and second oil pressure control valves144,146, between the valve housings148,149and the spool valve bodies150,151. Accordingly, air from the damper chambers163,165is more likely to be discharged to the outside from oil return hole225via the housing chamber153.

Moreover, the eaves portion226covering the oil return hole225from above protrudes integrally from the supporting holder154. This prevents the oil falling from above the supporting holder154from entering the oil return hole225and thereby causing the discharge property of the hydraulic oil from the oil return hole to deteriorate.

In addition, the pair of ribs227,228extend vertically with the oil return hole225interposed therebetween in a front rear direction protrude integrally from the supporting holder154with the upper ends thereof being integrally continuous with the eaves portion226. Accordingly, the supporting holder154can be reinforced in a portion where the oil return hole225is disposed. In addition, the hydraulic oil from the oil return hole225can be led downward and discharged in an excellent manner.

Furthermore, the first and second oil pressure control valves144,146individually corresponding to the first and second hydraulic clutches61,62are disposed parallel to each other in the supporting holder154and at least one of the pair of ribs227,228(the rib228in the embodiment) protrudes integrally from the supporting holder154to extend both of the oil pressure control valves144,146. Accordingly, the supporting holder154can be reinforced in a portion where the pair of the oil pressure control valves144,146are disposed.

Moreover, the first and second solenoids145,147having the couplers145a,147a, which protrude laterally with the electric wires175,176connected thereto, are connected to the first and second oil pressure control valves144,146such that the couplers145a,147aare disposed on the oblique lower or upper sides of the first and second solenoids145,147in the view in the operation axis direction of the first and second oil pressure control valves144,146. Accordingly, it is possible to prevent the couplers145a,147afrom largely protruding from the first and second solenoids145,147in the up-down direction and in the right-left direction and to effectively use a dead space in the housing chamber153to dispose the couplers145a,147a.

Furthermore, the first and second solenoids145,147individually connected to the first and second oil pressure control valves144,146are connected to the first and second oil pressure control valves144,146with the couplers145a,147aaligned in the same direction. Accordingly, the first and second solenoids145,147are housed in the housing chamber153in a space efficient manner while interference between the couplers145a,147ais avoided.

Moreover, the recessed portion178forming the electric wire lead-out hole177between the recessed portion178and the supporting holder154is provided in the cover member155forming the housing chamber forming body152together with the supporting holder154, the electric wire lead-out hole177used to lead the electric wires175,176connected to the first and second solenoids145,147to the outside. Accordingly, deterioration in stiffness of the supporting holder154can be suppressed compared to the case where the electric wire lead-out hole is provided in the supporting holder154, in addition to the oil return hole225.

The embodiment of the present invention has been described above. However, the present invention is not limited to the embodiment described above and various design changes can be made without departing from the present invention described in the scope of claims.

EXPLANATION OF THE REFERENCE NUMERALS