Brake system for a motorcycle, and motorcycle incorporating same

A brake system for a motorcycle includes a pressure-regulating unit interposed between a fluid pressure-generating unit and a wheel brake. Operation of a pressure-regulating unit is managed and controlled by a control unit, based primarily on an applied force detected by an operating amount detector. The fluid pressure-generating unit is disposed between an engine body, mounted on a body frame, and an exhaust pipe which is connected to a front surface of a cylinder head of the engine body, and which extends downwardly from the cylinder head. The fluid pressure-generating unit is arranged on the body frame such that, during operation of the motorcycle, the fluid pressure-generating unit is substantially shielded and isolated from heat emitted by the engine body and the exhaust pipe.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority under 35 USC 119 based on Japanese patent application No. 2008-091949, filed on Mar. 31, 2008. The entire subject matter of this priority document, including specification claims and drawings, is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a brake system for a motorcycle, and to a motorcycle incorporating same. More particularly, the present invention relates a brake system for a motorcycle, including an operating amount detector for detecting an operating amount of a brake operating element, a fluid pressure-generating unit for generating a fluid pressure independent of an operation of the brake operating element, the fluid pressure-generating unit being disposed between an engine body and an exhaust pipe extending from the engine body, a pressure-regulating unit interposed between the fluid pressure-generating unit and a wheel brake for regulating an output fluid pressure of the fluid pressure-generating unit and for applying the regulated fluid pressure to the wheel brake, and a control unit for controlling the operation of the pressure-regulating unit based on a value detected by the operating amount detector.

2. Description of the Background Art

A configuration in which a fluid pressure-generating unit and a pressure-regulating unit are mounted to a body frame on the rear side of an engine mounted on a motorcycle has been known, as described in the Japanese Patent Publication Nos. Sho 63-17662 and Hei 7-88158.

In the configuration, as disclosed in the Japanese Patent Publication Nos. Sho 63-17662 and Hei 7-88158, the fluid pressure-generating unit is disposed on the rear side of the engine and is supported by the body frame. However, in order to contrive concentration of mass, it is desirable that the fluid pressure-generating unit and the like be laid out in the proximity of the engine body.

If the fluid pressure-generating unit is simply arranged close to the engine body from this point of view, the influence of the heat from the engine would be exerted on the fluid pressure-generating unit. Therefore, it is desirable to obviate the thermal influence on the fluid pressure-generating unit.

The present invention has been made in consideration of the above-mentioned circumstances. Accordingly, it is one of the objects of the present invention to provide a brake system for a motorcycle in which the influence of heat from an engine can be restrained from being exerted on the fluid pressure-generating unit, while disposing the fluid pressure-generating unit in the proximity of the engine body so as to contrive concentration of mass.

SUMMARY OF THE INVENTION

In order to achieve the above object, the present invention according to a first aspect thereof provides a brake system for a motorcycle. The brake system for a motorcycle includes an operating amount detector for detecting an operating amount of a brake operating element, a fluid pressure-generating unit operable to generate a fluid pressure independently from an operation of the brake operating element, a pressure-regulating unit interposed between the fluid pressure-generating unit and a wheel brake for regulating an output fluid pressure of the fluid pressure-generating unit and applying the regulated fluid pressure to the wheel brake, and a control unit for controlling the operation of the pressure-regulating unit based on a value detected by the operating amount detector.

The present invention according to the first aspect thereof is characterized in that the fluid pressure-generating unit is disposed between an engine body mounted on a body frame of the motorcycle, and an exhaust pipe which is connected to a front surface of a cylinder head of the engine body and which is extended downwards from the cylinder head.

The present invention according to a second aspect thereof, in addition to the first aspect, is characterized in that the fluid pressure-generating unit is attached, through a support member, to a frame member, which extends rearwardly downwards from a head pipe possessed by the body frame at its front end portion. The frame member constitutes a portion of the body frame.

The support member is configured in a frame form including a first support frame which is attached to the frame member and which extends in a left-right direction on a rear side of the fluid pressure-generating unit, and a second support frame which is attached to the first support frame in such a manner as to surround the fluid pressure-generating unit from the front side thereof.

The present invention according to a third aspect thereof, in addition to one of the first and second aspects, is characterized in that the fluid pressure-generating unit is disposed on a rear lower side of a radiator supported by the body frame on a front side of the engine.

The present invention according to a fourth aspect thereof, in addition to the first aspect, is characterized in that the engine body includes a crankcase, a cylinder block rising at a forwardly upward inclination from the crankcase, and the cylinder head connected to an upper portion of the cylinder block; that the exhaust pipe has an inclined portion extending forwardly downwards from a front surface of the cylinder head, and a curved portion curved from a lower portion of the inclined portion toward a lower side of the engine body so that a substantially triangular-shaped space (a space having substantial triangular shape), when viewed in side view, is formed between the exhaust pipe and a front surface of the engine body; and the fluid pressure-generating unit is disposed in the substantially triangular-shaped space.

As discussed in the detailed description of illustrative embodiments of the present invention, a brake lever corresponds to the brake operating element, a front wheel fluid pressure-generating unit corresponds to the fluid pressure-generating unit, a front pressure-regulating unit corresponds to the pressure-regulating unit, a first pressure sensor corresponds to the operating amount detector, a main frame corresponds to the frame member, and a front wheel brake corresponds to the wheel brake.

EFFECTS OF THE INVENTION

According to the first aspect of the present invention, the fluid pressure-generating unit is laid out by effectively utilizing a vacant space on the front side of the engine body and below the exhaust pipe, thereby contriving concentration of mass.

Moreover, although the heat from the exhaust pipe reaches the fluid pressure-generating unit, the temperature of the fluid pressure-generating unit can be prevented from being raised excessively, since the running airflow generated by during running of the motorcycle, comes into contact with the fluid pressure-generating unit.

According to the second aspect of the present invention, the fluid pressure-generating unit is attached, through the support member, to the frame member extending rearwardly downwards from the head pipe and which constitutes a portion of the body frame. The support member is configured in a frame form having the first support frame which is attached to the frame member and which extends in a left-right direction on the rear side of the fluid pressure-generating unit, and the second support frame which is attached to the first support frame in such a manner as to surround the fluid pressure-generating unit from the front side thereof. Therefore, the fluid pressure-generating unit can be supported in such a manner that the fluid pressure-generating unit is easily exposed to the running airflow.

According to the third aspect of the present invention, the fluid pressure-generating unit can be protected by the radiator and the exhaust pipe against foreign matter such as flying stones coming from the front side.

According to the fourth aspect of the present invention, the cylinder head is connected to the upper portion of the cylinder block rising at a forwardly upward inclination from the crankcase. The exhaust pipe connected to the front surface of the cylinder head has the inclined portion which extends forwardly downwards from the front surface of the cylinder head and the curved portion curved from a lower portion of the inclined portion toward the lower side of the engine body so that a substantially triangular-shaped space, when viewed in side view, is formed between the exhaust pipe and the front surface of the engine body, and the fluid pressure-generating unit is disposed in the substantially triangular-shaped space.

Therefore, a comparatively large space can be secured between the exhaust pipe and the front surface of the engine body. Accordingly, during operation of the motorcycle, it is easier for the running airflow to pass through the surroundings of the fluid pressure-generating unit disposed in the space. Also, it is possible to effectively prevent the temperature of the fluid pressure-generating unit from rising excessively.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

An embodiment of the present invention will now be described, with reference to the drawings. Throughout this description, relative terms like “upper”, “lower”, “above”, “below”, “front”, “back”, and the like are used in reference to a vantage point of an operator of the vehicle, seated on the driver's seat and facing forward. It should be understood that these terms are used for purposes of illustration, and are not intended to limit the invention.

Now, a mode of carrying out the present invention is described below, based on one illustrative embodiment of the invention shown in the attached drawings.

FIGS. 1 to 25illustrate one illustrative embodiment of the present invention.FIG. 1is a diagram showing a configuration of a brake system for a motorcycle.FIG. 2is a left side view of the motorcycle having the brake system according to the present invention.FIG. 3is an exploded perspective view of a support structure for a front pressure-regulating unit.FIG. 4is a perspective view showing the front pressure-regulating unit is supported by the support member.FIG. 5is a side view showing the condition of support of the front pressure-regulating unit on a body frame.

FIG. 6is a plan view taken along arrow6ofFIG. 5.FIG. 7is a sectional view taken along line7-7ofFIG. 6.FIG. 8is a partially cut-away front view of the body frame, an engine body and front fluid pressure-generating unit, as viewed along line8-8ofFIG. 2.FIG. 9is a sectional view taken along line9-9ofFIG. 8.FIG. 10is a sectional view taken along line10-10ofFIG. 8.FIG. 11is a sectional view taken along line11-11ofFIG. 9.FIG. 12is an enlarged sectional view taken along line12-12ofFIG. 9.FIG. 13is an enlarged sectional view taken along line13-13ofFIG. 9.FIG. 14is a view from the rear side of a rear pressure-regulating unit and the body frame.FIG. 15is a sectional view taken along line15-15ofFIG. 14.FIG. 16is a sectional view taken along line16-16ofFIG. 14.

FIG. 17is an enlarged view, of a portion ofFIG. 2, showing the rear fluid pressure-generating unit and the surroundings thereof.FIG. 18is a view taken along arrow18ofFIG. 17.FIG. 19is a perspective view taken along arrow19ofFIG. 17.FIG. 20is a perspective view taken along arrow20ofFIG. 17.FIG. 21is a sectional view taken along line21-21ofFIG. 18.FIG. 22is an enlarged view of that portion ofFIG. 2which shows a control unit and the vicinity thereof.FIG. 23is a view, corresponding toFIG. 22, showing the condition where a front cowl is removed.FIG. 24is a view showing the condition where the control unit is removed from the condition shown inFIG. 23.FIG. 25is a sectional view taken along line25-25ofFIG. 22.

First, as shown inFIG. 1, a front wheel brake BF provided in a motorcycle is provided with a front pressure-regulating unit18F by which a fluid pressure outputted from a front master cylinder MF according to an operation of a brake lever15serving as a brake operating element can be exerted and by which a fluid pressure outputted from front fluid pressure-generating unit17F can also be exerted.

The front pressure-regulating unit18F is interposed between the front master cylinder MF and the front fluid pressure-generating unit17F, and the front wheel brake BF.

In addition, the rear wheel brake BR is provided with rear pressure regulating unit17R by which a fluid pressure outputted from a rear master cylinder MR according to an operation of a brake pedal16serving as a brake operating element can be exerted and by which a fluid pressure outputted from rear fluid pressure-generating unit17R can also be exerted. The rear pressure regulating unit18R is interposed between the rear master cylinder MR and the rear fluid pressure-generating unit17R, and the rear wheel brake BR.

The front fluid pressure-generating unit17F, which generates a fluid pressure by operation of an electric motor19, includes the electric motor19, a piston22slidably fitted in a cylinder body20while forming a fluid pressure chamber21between itself and the cylinder body20; a return spring23composedly disposed between the cylinder body20and the piston22so as to urge the piston22to the side for increasing the internal volume of the fluid pressure chamber21; a pushing shaft24coaxially linked to the piston22from the side opposite to the fluid pressure chamber21; and a gear mechanism26which has a gear25coaxially screw engaged with the pushing shaft24through a ball screw (not shown) and which is connected to an output shaft of the electric motor19.

The front fluid pressure-generating unit17F can output, from the fluid pressure chamber21, a fluid pressure varying according to the operation of the electric motor19.

The rear fluid pressure-generating unit17R is configured in the same fashion as the front fluid pressure-generating unit17F above. Therefore, it is only shown in the figure with its parts corresponding to those of the front fluid pressure-generating unit17F being denoted by the same reference symbols, as used above, and detailed description thereof is omitted.

The front pressure-regulating unit18F includes a first solenoid-operated on-off valve28for switching the communication/cutoff between the front master cylinder MF and the front wheel brake BF; a second solenoid-operated on-off valve29for switching the communication/cutoff between the front fluid pressure-generating unit17F and the front wheel brake BF; a stroke simulator30for exerting a dummy reaction force according to the operating amount of the brake lever15on the front master cylinder MF when the first solenoid-operated on-off valve28is closed; a third solenoid-operated on-off valve31for switching the communication/cutoff between the stroke simulator30and the front master cylinder MF; a first one-way valve32connected in parallel to the second solenoid-operated on-off valve29for permitting the flow of a brake fluid from the front fluid pressure-generating unit17F to the side of the front wheel brake BF; and a second one-way valve33connected in parallel to the third solenoid-operated on-off valve31for permitting the flow of the brake fluid from the stroke simulator30to the side of the front wheel brake BF.

The pressure in the stroke simulator30is detected by a first pressure sensor34serving as operating amount detector, the output fluid pressure of the front master cylinder MF is detected by a second pressure sensor35, and the output fluid pressure of the front fluid pressure-generating unit17F is detected by a third pressure sensor36.

The first pressure sensor34obtains the operating amount of the brake lever15by detecting the output fluid pressure of the front master cylinder MF when the first solenoid-operated on-off valve28is closed.

The second pressure sensor35is provided for fail-safe diagnosis, and a judgment that an abnormal state is present can be made when a difference of not less than a predetermined value is generated between the pressure detected by the second pressure sensor35and the value detected by the first pressure sensor34.

The value detected by the third pressure sensor36is used in a fluid pressure feedback control for controlling the output fluid pressure of the front fluid pressure-generating unit17F based on the value detected by the first pressure sensor34.

The first solenoid-operated on-off valve28is a normally open type solenoid valve, while the second and third solenoid-operated on-off valves29,31are normally closed type solenoid on-off valves. The opening/closing operations of the first to third solenoid-operated on-off valves28,29,31and the operations of the electric motor19in the front fluid pressure-generating unit17F are controlled by a control unit39connected with a battery38.

The control unit39is supplied as inputs with a value detected by a front speed sensor40F and the values detected by the first to third pressure sensors34,35,36. The control unit39controls the opening/closing operations of the first to third solenoid-operated on-off valves28,29,31and the operation of the electric motor19based on the value detected by the front speed sensor40F and the values detected by the first to third pressure sensors34to36. In addition, an alarm lamp41is connected to the control unit39.

At the ignition-ON state of the motorcycle, the first solenoid-operated on-off valve28is in the open state, whereas the second and third solenoid-operated on-off valves29,31are in the closed state, the electric motor19is in the non-operative state, and the alarm lamp41is in the ON state. When the brake lever15is operated to cause a fluid pressure to be outputted from the front master cylinder MF under this condition, the fluid pressure is exerted on the front wheel brake BF through the first solenoid-operated on-off valve28.

When running of the motorcycle is started, the control unit39performs an initial diagnosis, and turns OFF the alarm lamp41if the system is judged to be in normal condition. After the start of the running of the motorcycle, the system is put into a stand-by state, the third solenoid-operated on-off valve31is opened, and the front master cylinder MF is put into the state of communicating with the stroke simulator30.

In response to the detection by the first pressure sensor34of a fluid pressure of not less than a predetermined value due to an operation of the brake lever15during the stand-by condition, the control unit39closes the first solenoid-operated on-off valve28and opens the second solenoid-operated on-off valve29.

Further, the control unit39operates the electric motor19of the front fluid pressure-generating unit17F, to control the output fluid pressure of the front fluid pressure-generating unit17F, which is detected by the third pressure sensor36, in such a manner that the output fluid pressure of the front fluid pressure-generating unit17F is brought to a pressure according to the value detected by the first pressure sensor34. This ensures that the front wheel brake BF is supplied with the fluid pressure outputted from the front fluid pressure-generating unit17F according to the operational load on the brake lever15.

The rear pressure-regulating unit18R is configured in the same fashion as the front pressure-regulating unit18F, as discussed above. Therefore, it is only shown in the figure with its parts corresponding to those of the front pressure regulating unit18F being denoted by the same reference symbols as used above, and with detailed description thereof omitted. Incidentally, in the fluid pressure control by the rear pressure-regulating unit18R, the control unit39uses the value detected by the rear speed sensor40R in place of the value detected by the front speed sensor40F which is used in the fluid pressure control by the front pressure-regulating unit18F.

In addition, by performing the fluid pressure control by the rear pressure-regulating unit18R together with the fluid pressure control by the front pressure-regulating unit18F according to the operation of the brake lever15, the control unit39can carry out a rear braking force distribution control by which the front and rear wheel brakes BF, BR are operated so as to exert distributed braking forces on the front wheel and the rear wheel.

Besides, on the contrary, by performing the fluid pressure control by the front pressure-regulating unit18F together with the fluid pressure control by the rear pressure-regulating unit18R in response to the operation of the brake pedal16, the control unit39can carry out a rear braking force distribution control by which the front and rear wheel brakes BF, BR are operated so as to apply distributed braking forces to the front wheel and the rear wheel.

As shown inFIG. 2, the body frame F of the motorcycle includes a head pipe45on which a front fork43rotatably bearing the front wheel WF equipped with the front wheel brake BF and a steering handle44connected to the front fork43are steerably borne; a left-right pair of main frames46. . . extending rearwardly downwards from the head pipe45; center frames47. . . connected respectively to rear parts of both the main frames46. . . ; pivot plates48. . . integrally connected to the center frames47. . . and extending downwards; and a left-right pair of seat rails49. . . connected to rear parts of the center frames4. . . and extending rearwardly upwards.

The main frames46. . . are integrally provided with engine hangers50. . . extending downwards. An engine body51of an engine E of the in-line four-cylinder type, for example, is supported by lower portions of the engine hangers50. . . , the center frames47. . . and the pivot plates48. . . , in such an attitude that the cylinder axis thereof is inclined forwardly upwards.

The engine body51includes a crankcase53; a cylinder block54rising at a forwardly upward inclination from the crankcase53; and a cylinder head52connected to an upper portion of the cylinder block54.

A fuel tank55is mounted on both the main frames46. . . on the upper side of the engine body51. In addition, an upwardly extending intake system57is connected to a rear surface of the cylinder head52of the engine body51, and an air cleaner56that the intake system57has at its upstream end is so disposed as to be covered with the fuel tank55.

On the other hand, an exhaust system58connected to a front surface of the cylinder head52includes: a plurality of exhaust pipes59. . . which are connected to the front surface of the cylinder head52in the manner of corresponding respectively to the cylinders and which extend downwards from the cylinder head52; and an exhaust muffler60disposed between rear parts of both the seat rails49. . . in the state of being connected to the exhaust pipes59. . . . Moreover, the exhaust pipes59. . . have inclined portions59aextending forwardly downwards from the front surface of the cylinder head52, and curved portions59bcurved from lower portions of the inclined portions59a. . . toward the lower side of the engine body51, so that a substantially triangular-shaped space (space in a triangular shape), when viewed in side view is formed between the exhaust pipes59and the front surface of the engine body51. Furthermore, on the front side of the engine body51, a radiator61is fixedly disposed so as to be located on the skew upper side of the exhaust pipes59. . . .

On the pivot plates4. . . of the body frame F, a front end portion of a swing arm62rotatably supporting the rear wheel WR (which is equipped with the rear wheel brake BR) on its rear end portions is vertically swingably borne. A link mechanism63is provided between a front-end-side lower portion of the swing arm62and lower portions of the pivot plates48, and a lower end portion of a shock absorber (cushion unit)65connected at its upper end portion to the swing arm62and extending vertically is connected to a link member64constituting a part of the link mechanism63.

Further, an output from a transmission (not shown) incorporated in the crankcase53possessed by the engine body51is transmitted to the rear wheel WR through chain-type power transmission unit67having an endless chain66.

A riders' seat68is provided on the seat rails49. . . so as to be disposed on a rear side of the fuel tank55. The riders' seat68includes a front seat69for a driver or operator of the motorcycle, and a rear seat70for a passenger. The rear seat70is spaced to the rear side from the front seat69. Pillion steps71are arranged on outside surfaces of intermediate portions of the seat rails49. . . . The pillion steps71are used as feet rest for a passenger seating on the rear seat70.

A portion of the body frame F and the engine E are covered with a front cowl72formed from a synthetic resin. The front cowl72includes a front cover73for covering the head pipe45on the front side, and side covers74. . . which are in connection with the front cover73and which cover the engine body51, the exhaust pipes59. . . of the exhaust system58, and the radiator61on both lateral sides.

In the motorcycle, as discussed above, the front fluid pressure-generating unit17F, the front pressure regulating unit18F, the rear fluid pressure-generating unit17R, the rear pressure-regulating unit18R and the control unit39are disposed in the proximity of the engine E, i.e., in the vicinity of the center of the vehicle body.

Now, a structure for arrangement of the front fluid pressure-generating unit17F, the front pressure-regulating unit18F, the rear fluid pressure-generating unit17R, the rear pressure-regulating unit18R, and the control unit39in the motorcycle, and the operations and effects of the structure, are sequentially described below.

An arrangement structure of the front pressure-regulating unit18F is described referring toFIGS. 3 to 7.

First, as shown inFIG. 3, the first solenoid-operated on-off valve28, the second solenoid-operated on-off valve29, the stroke simulator30, the third solenoid-operated on-off valve31, the first one-way valve32, and the second one-way valve33which constitute the front pressure-regulating unit18F are arranged on a base77formed in a rectangular parallelopiped shape by casting of a light metal such as an aluminum alloy.

Projecting portions of the first solenoid-operated on-off valve28, the second solenoid-operated on-off valve29, the third solenoid-operated on-off valve31, the first one-way valve32and the second one-way valve33which are projecting from the base77are covered by a synthetic resin-made cover78integrally provided with a coupler part78a. The first to third pressure sensors34to36are also arranged on the base77. The projecting portions of the first to third pressure sensors34to36which are projecting from the base77are also covered with the cover78.

Referring toFIGS. 4 to 7, the front pressure-regulating unit18F is arranged in a position which is on the rear side of the intake system57being connected to the cylinder head52of the engine body51mounted on the body frame F and being extended upwards from the cylinder head52and which is between the engine body51and the fuel tank55disposed on the upper side of the engine body51. The front pressure-regulating unit18F is flexibly supported, through an elastic case79covering the pressure-regulating unit18F, on support member83supported on the body frame F.

The elastic case79includes lower and upper case members80,81provided as bisected lower and upper portions so as to clamp the front pressure-regulating unit18F in such an attitude as to have the base77located on the upper side. Both the case members80,81are formed of an elastic material, for example, a rubber.

The lower case member80is formed in a box-like shape open to the upper side so that the cover78of the front pressure-regulating unit18F can be fitted therein, and the upper case member81is formed in a box-like shape open to the lower side so that the base77of the front pressure-regulating unit18F can be fitted therein.

Moreover, the upper case member81is provided with a cutout82for permitting the coupler78aof the cover78to project therethrough. In addition, of both the case members80and81, at least the lower case member80is integrally and projectingly provided at its inner surface, in this embodiment, both the case members80and81are integrally and projectingly provided at their inner surface, with a plurality of projections80a. . . ,81a. . . put into the pressure-regulating unit18F.

The support member83is composed in a frame form by use of a lower frame body84which is attached to the body frame F so as to cover substantially the whole perimeter of a lower portion of the front pressure-regulating unit18F and to support the front pressure-regulating unit18F on the lower side of the latter, and an upper frame body85which is fastened to the lower frame body84.

The lower frame body84has a plurality of bent, small-width metallic plate materials connected to each other. Specifically, the lower frame body84includes: a frame part84asurrounding substantially the whole perimeter of the lower portion of the front pressure-regulating unit18F; two support plate parts84b,84cconnected to the frame part84aso as to support the front pressure-regulating unit18F on the lower side of the latter; three support arm portions84d,84e,84fextending outwardly sideways from the frame body84a; and two attaching projected parts84g,84hprojected from the frame body84aso as to fasten the upper frame body85thereto.

The front pressure-regulating unit18F, together with the lower case member80fitted in a lower portion thereof, is fitted into and supported by the frame part84aand both the support plate parts84b,84cof the lower frame body84.

The support arm portions84d,84e,84fare extended to the side of the left-side main frame46and the left-side center frame47, of both the main frames46. . . and both the center frames47. . . of the body frame F. The support arm portion84dis fastened to the engine hanger50integral with the main frame46by a bolt86, the support arm portion84eis fastened to the main frame46on the rear side relative to the engine hanger50by a bolt87, and the support arm portion84fis fastened to the center frame47by a bolt88.

The upper frame body85is brought from above into contact with the upper case member81fitted from above into an upper portion, or the base77, of the front pressure-regulating unit18F, and is fastened to both the attaching projected parts84g,84hof the lower frame body84. The upper frame body85integrally includes a presser part85aput into contact with the upper case member81from above; and a pair of attaching leg parts85b,85cextended from the presser part85atoward the sides of both the attaching projected parts84g,84h.

On the other hand, weld nuts89. . . are firmly attached to the lower surfaces of both the attaching projected parts84g,84hof the lower frame body84. Bolts90,90passed through tip parts of both the attaching leg parts85b,85cand through both the attaching projected parts84g,84hare screw engaged with the weld nuts89. . . and tightened, whereby the upper frame body85is fastened to the lower frame body84.

As a result, the support member83is composed in a frame form by use of the lower frame body84which is attached to the body frame F so as to cover substantially the whole perimeter of the lower portion of the front pressure-regulating unit18F and to support the front pressure-regulating unit18F on the lower side of the latter, and the upper frame body85fastened to the lower frame body84.

In addition, the front pressure-regulating unit18F is clamped between the lower frame body84and the upper frame body85, with the lower case member80and the upper case member81(which are formed of an elastic material) interposed therebetween.

Moreover, the front pressure-regulating unit18F is disposed on the upper side of and in proximity to a cooling pipe (not shown) constituting portion of a cooling water circulation circuit provided for the engine E. In view of this, the lower case member80is provided in its lower surface with a recessed portion80bwhich is curved to the upper side in order to obviate interference with the cooling water pipe, whereby a cooling effect on the front pressure-regulating unit18F owing to the arrangement of the unit in proximity to the cooling water pipe can be obtained.

According to the arrangement structure of the front pressure-regulating unit18F as above, the front pressure-regulating unit18F is covered by the elastic case79, so that the influence of the heat from the engine E can be prevented from being exerted on the front pressure-regulating unit18F. In addition, since the front pressure-regulating unit18F is flexibly supported through the elastic case79on the support member83supported on the body frame F, transmission of vibrations from the engine E to the front pressure-regulating unit18F can be suppressed.

Moreover, the front pressure-regulating unit18F is arranged in a position which is on the rear side of the intake system57being connected to the cylinder head52of the engine body51mounted on the body frame F and being extended upwards from the cylinder head52and which is between the engine body51and the fuel tank55disposed on the upper side of the engine body51.

Such arrangement of the front pressure-regulating unit18F ensures that the front pressure-regulating unit18F is disposed at such a position as to be less liable to be exposed to the radiant heat from the exhaust system58of the engine E, whereby the influence of the heat from the engine E upon the front pressure-regulating unit18F can be effectively restrained. In addition, the front pressure-regulating unit18F is laid out in a comparatively large vacant space on the rear side of the intake system57, whereby the influence of the front pressure-regulating unit18F upon the layout of other component parts can be minimized.

Also, the elastic case79is composed of the elastic material-made lower and upper case members80,81provided as bisected lower and upper portions so as to clamp the front pressure-regulating unit18F from the lower and upper sides, and at least the lower case member80of both the case members80and81, or as shown the illustrative embodiment, both of the case members80and81are integrally and projectingly provided at their inner surfaces with the plurality of projected parts80a. . . ,81a. . . put into contact with the front pressure-regulating unit18F.

Therefore, the front pressure-regulating unit18F can be flexibly (flexibly) supported assuredly while facilitating the operation of containing the front pressure-regulating unit18F into the elastic case79.

Further, the front pressure-regulating unit18F is flexibly supported, through the lower and upper case members80and81of the elastic case79, on the support member83mounted to the body frame F. Besides, the support member83is composed in a frame form by use of the lower frame body84which is attached to the body frame F so as to cover substantially the whole perimeter of the lower portion of the front pressure-regulating unit18F and to support the front pressure-regulating unit18F on the lower side of the latter, and the upper frame body85which is fastened to the lower frame body84.

Moreover, the front pressure-regulating unit18F is clamped between the lower frame body84and the upper frame body85, with the lower and upper case members80and81therebetween. Therefore, by a simple process in which the front pressure-regulating unit18F is mounted to the lower frame body84attached to the body frame F through the lower case member80and then the upper frame body85with the upper case member81interposed between itself and the front pressure-regulating unit18F is attached to the lower frame body84, the front pressure-regulating unit18F can be flexibly (flexibly) supported on the support member83mounted to the body frame F. Thus, the mounting operation is facilitated.

An arrangement structure of the front fluid pressure-generating unit17F is described referring toFIGS. 8 to 13.

First, as shown inFIG. 2, the front fluid pressure-generating unit17F is arranged between the engine body51and the exhaust pipes59. . . extended downwards from the front surface of the cylinder head52in the engine body51.

Moreover, the exhaust pipes59. . . include the inclined portions59a. . . which extends forwardly downwards from the front surface of the cylinder head52, and the curved portions59bwhich are curved from the lower portions of the inclined portions59a. . . toward the lower side of the engine body51, in such a manner that a space rectangular in shape in side view is formed between themselves and the front surface of the engine body51, with the front fluid pressure-generating unit17F being arranged in the space. Furthermore, the front fluid pressure-generating unit17F is arranged on the rear lower side of the radiator61which is supported on the body frame F on the front side of the engine body51.

As shown inFIG. 8, the front fluid pressure-generating unit17F is supported, through support member93, on the engine hangers50. . . provided to be integral with the left-right pair of main frames46which extend rearwardly downwards from the head pipe45and which constitute a part of the body frame F.

The support member93is composed in a frame form by use of a first support frame94which is attached to the engine hangers50. . . and which extends in the left-right direction on the rear side of the front fluid pressure-generating unit17F, and a second support frame95which is attached to the first support frame94in such a manner as to surround the front fluid pressure-generating unit17F from the front side of the latter.

Referring toFIG. 9, a weld nut96is securely attached to the rear surface of an intermediate portion in the width direction of the first support frame94, and a weld nut97is secured to the rear surface of a tip portion of a support arm portion94abranched skewly downward from a left-side end portion (inFIG. 8, a right-side end portion) of the first support frame94as viewed from a person facing in the running (forward) direction of the motorcycle.

One end portion of the second support frame95is fastened to the intermediate portion in the width direction of the first support frame94by a bolt98screw engaged with the weld nut96, and the other end portion of the second support frame95is firmly attached to the tip part of the support arm portion94aof the first support frame94by a bolt99screw engaged with the weld nut97.

Referring toFIG. 10, while the brackets53a. . . provided at the crankcase53of the engine body51are fastened to the engine hangers50. . . provided to be integral with the main frames46. . . through bolts105, attaching members102. . . clamped between the brackets53a. . . and the engine hangers50. . . are co-fastened to the engine hangers50. . . together with the brackets53a. . . by the bolts105.

On the other hand, both end portions of the first support frame94are fitted with rubber bushings100,100. Collars101. . . provided at their one-side ends with flange portions101a. . . projecting outwards are inserted in the rubber bushings100. . . , and the flange portions101a. . . are put in abutment on the attaching members102. . . .

In addition, washers103. . . are put in contact with the other-side ends of the collars101. . . so that the collars101. . . are clamped between the washers10. . . and the attaching members102. . . , and bolts10. . . passed through the washer10. . . and the collars10. . . are screw engaged with the attaching members102. . . . Thus, both left and right end portions of the first support frame94of the support member93are fastened to the engine hangers50. . . of the left-right pair of main frames46. . . , by co-fastening thereof together with the brackets53a. . . of the crankcase53in the engine body51.

Referring toFIG. 11, an attaching arm106extending upwards is securely attached to an intermediate portion in the left-right direction of the first support frame94. A rubber bushing107is mounted to an upper end portion of the attaching arm106, and a collar108provided at its one end with a flange portion108aprojecting outwards is passed through the rubber bushing107. On the other hand, the cylinder block54of the engine body51is provided with a support boss part54afor contact with the flange portion108a. A washer109is put in contact with the other end of the collar108so as to clamp the collar108between itself and the support boss part54a, and a bolt110passed through the washer109and the collar108is screw engaged with the support boss part54a.

Referring toFIG. 12, a support bar111extending downwards is secured to an intermediate portion in the left-right direction of the first support frame94. The support bar111is fitted in a rubber bushing112mounted to the crankcase53of the engine body51.

Thus, both the left and right end portions of the first support frame94of the support member93are supported on the engine hangers50. . . of the main frames4. . . through the rubber bushings100, and the intermediate portion in the left-right direction of the first support frame94is supported on the engine body51through the rubber bushings107,112.

The front fluid pressure-generating unit17F is elastically supported by the support member93, and a support plate116opposed from the front side to a bracket115provided at a left side part of the front fluid pressure-generating unit17F is firmly attached to the first support frame94of the support member93.

As shown inFIG. 13, a rubber bushing117is mounted to the support plate116, and a collar118provided at its one end with a flange portion118aprojecting outwards is passed through the rubber bushing117so that the flange portion118amakes contact with the bracket115. In addition, a washer119is put in contact with the other end of the collar118so as to clamp the collar118between itself and the bracket115, and a bolt120passed through the washer119and the collar118is screw engaged with the bracket115.

Besides, the second support frame95is provided with a support plate part121which is opposed to the front fluid pressure-generating unit17F from the lower side, and a support plate122which is opposed to the front fluid pressure-generating unit17F from the left side. Rubber bushings123,124mounted to the support plate parts121,122are attached to the front fluid pressure-generating unit17F through bolts125,126by use of the same structure as that shown inFIG. 13.

In other words, the front fluid pressure-generating unit17F is supported on the support member93through the rubber bushings117,123, and124.

According to the arrangement structure of the front fluid pressure-generating unit17F, as discussed above, the front fluid pressure-generating unit17F is arranged between the engine body51and the exhaust pipes59. . . extended downwards from the cylinder head52. Therefore, the front fluid pressure-generating unit17F can be laid out by utilizing effectively the vacant space which is on the front side of the engine body51and on the lower side of the exhaust pipes59. . . , whereby concentration of mass can be contrived.

Moreover, although the heat from the exhaust pipes59. . . reaches the front fluid pressure-generating unit17F, the running airflow generated by the running of the motorcycle comes into contact with the front fluid pressure-generating unit17F, so that the temperature of the front fluid pressure-generating unit17F can be prevented from rising excessively.

In addition, since the support member93for supporting the front fluid pressure-generating unit17F is supported through the rubber bushings100. . . ,107,112on the engine body51and the engine hangers50. . . of the main frames46. . . constituting a part of the body frame F, transmission of vibrations from the engine E to the front fluid pressure-generating unit17F can also be restrained.

Further, the cylinder head52is connected to an upper portion of the cylinder block54rising at a forwardly upward inclination from the crankcase53. The exhaust pipes59. . . connected to the front surface of the cylinder head52have the inclined surfaces59a. . . extending forwardly downwards from the front surface of the cylinder head52, and the curved portions59b. . . curved from the lower portions of the inclined portions59a. . . toward the lower side of the engine body51, and a substantially triangular-shaped space (space triangular in shape), when viewed in side view, is formed between the exhaust pipes59. . . and the front surface of the engine body51. The front fluid pressure-generating unit17F is laid out in the substantially triangular-shaped space.

Therefore, since a comparatively large space can be secured between the exhaust pipes59. . . and the front surface of the engine body51, the running airflow can easily flow in the surroundings of the front fluid pressure-generating unit17F disposed in the space, and the temperature of the front fluid pressure-generating unit17F can be effectively prevented from rising excessively.

Further, both the left and right end portions of the first support frame94in the support member93are supported on the engine hangers50. . . of the left-right pair of main frames46. . . through the rubber bushings100. . . , and the intermediate portion in the left-right direction of the first support frame94is supported on the engine body51through the rubber bushings107,112, so that the front fluid pressure-generating unit17F can be flexibly supported while enhancing the rigidity of the support member93.

In addition, since both the left and right end portions of the support member93are fastened to the engine hangers50. . . of the main frames46. . . by co-fastening thereof together with the brackets53a. . . of the crankcase53of the engine body51, a reduction in the number of component parts and a reduction in the number of working steps can be contrived.

Further, the support member93is composed in a frame form by use of the first support frame94which is attached to the engine hangers50. . . of the main frames46. . . and which extends in the left-right direction on the rear side of the front fluid pressure-generating unit17F, and the second support frame95which is attached to the first support frame94in such a manner as to surround the front fluid pressure-generating unit17F from the front side. Therefore, the front fluid pressure-generating unit17F can be supported in such a manner that the front fluid pressure-generating unit17F can easily receive the running airflow.

Furthermore, since the front fluid pressure-generating unit17F is laid out on the rear lower side of the radiator61supported by the body frame F on the front side of the engine body51, the front fluid pressure-generating unit17F can be protected by the radiator61and the exhaust pipes59. . . from foreign matters, such as flying stones coming from the front side.

An arrangement structure of the rear pressure-regulating unit18R is described referring toFIGS. 2 and 14to16.

First, as shown inFIG. 2, the rear pressure-regulating unit18R is arranged on the rear side of the engine body51and between an upper end portion of the cushion unit65and the engine body51. The rear pressure-regulating unit18R is supported by a support member130, as shown inFIGS. 14 and 15.

The support member130includes a support member main part130awhich is arranged between both the center frames47,47while having a portion thereof opposed from above to the rear pressure-regulating unit18R disposed on the lower side of a cross member131with a base portion77located on the rear side and with a cover78located on the front side; attaching arm portions130b,130c,130dextended from the support member main part130aso as to be opposed to both the center frames47,47and the back surface of the cross member131; and a pair of support arm portions130e,130fdrooping from the support member main part130aso as to be located on both the left and right sides of the rear pressure-regulating unit18R.

Rubber bushings132,133, and134are mounted to tip parts of the attaching arm portions130b,130c, and130d. Collars135,136, and137provided at their one-side ends with flange portions135a,136a, and137aprojecting outwards are passed through the rubber bushings132to134so that the flange portions135ato137amake contact with the center frames47,47and the back surface of the cross member131.

In addition, washers138,139, and140are put in contact with the other-side ends of the collars135to137so that the collars135to137are clamped between them and the center frames47,47and the cross member131. Bolts141,142, and143passed through the washers138to140and the collars135to137are screw engaged with the center frames47,47and the cross member131.

A frame member145is attached to an upper portion of the base77of the rear pressure-regulating unit18R by three bolts146,146, and146, for example. The frame member145is disposed between the support member main part130aand both the support arm portions130e,130fof the support member130, and the rear pressure-regulating unit18R. Three portions of the frame member147are supported respectively on the support member main part130aand both the support arm portions130e,130fthrough rubber bushings147. . . .

Specifically, the upper portion of the rear pressure-regulating unit18R is attached to the support member130through the rubber bushings147. . . so as to be supported suspendedly from the support member130.

As shown inFIG. 16, the rubber bushings147. . . are mounted respectively to the support member main part130aand both the support arm portions130e,130fof the support member130, and weld nut148are securely attached to the frame member145in the manner of corresponding to the rubber bushings147. . . . In addition, collars149. . . provided at their one-side ends with flange portions149aprojecting outwards are passed through the rubber bushings147. . . so that the flange portions149a. . . are clamped between them and the support member main part130aand both the support arm portions130e,130f.

Also, washers150. . . are put in contact with the other-side ends of the collars149. . . so that the collars14. . . are clamped between them and the support member main part130aand both the support arm portions130e,130f, and bolts151. . . passed through the washer15. . . and the collars149. . . , are screw engaged with the weld nuts148. . . .

According to the arrangement structure of the rear pressure-regulating unit18R as above, the support member130for supporting the rear pressure-regulating unit18R is flexibly supported by the pair of center frames47. . . disposed on both the left and right sides of the engine body51and by the cross member131for connecting the center frame47. . . to each other on the rear side of the engine body51in such a manner as to constitute a part of the body frame F together with the center frames47. . . , through the rubber bushings132,133, and134.

Therefore, vibrations transmitted from the engine E can be prevented from reaching the rear wheel pressure-regulating unit18R. Moreover, the rigidity of the support member130can be set to a level sufficient to hold the rear wheel pressure-regulating unit18R, without being affected by the rigidity on the side of the body frame F, which makes it unnecessary to enhance the strength of the support member130more than required. Thus, reductions in weight and cost can be contrived.

In addition, since the upper portion of the rear wheel pressure-regulating unit18R is so attached as to be supported suspendedly from the support member130, the position of the rear wheel pressure-regulating unit18R in the width direction of the body frame F can easily be conditioned so as not to interfere with other component parts.

Further, the rear wheel pressure-regulating unit18R is arranged between the engine body51and the upper end portion of the cushion unit95provided between the swing arm62and the link member64, which constitutes a part of the link mechanism63provided between the swing arm62and the body frame F.

Therefore, the rear wheel pressure-regulating unit18R can be effectively laid out in the space between the engine body51and the upper end portion of the cushion unit65. Moreover, the rear wheel pressure-regulating unit18R can be protected by surrounding the left and right sides and the front and rear sides of the rear wheel pressure-regulating unit18R with the body frame F, the engine body51and the cushion unit65.

An arrangement structure of the rear fluid pressure-generating unit17R is described referring toFIGS. 17 to 21.

First, as shown inFIGS. 17 and 18, the rear fluid pressure-generating unit17R is supported on the left-right pair of seat rails49. . . constituting a part of the body frame F; in plan view, it is arranged between both the seat rails49,49at a position nearer to the left-side seat rail49of both the seat rails49. . . .

Referring toFIGS. 19 and 20, a first support member154is attached to the left-side seat rail49of both the seat rails49. . . , and the rear fluid pressure-generating unit17R is flexibly supported by the first support member154and a cross member155for connection between both the seat rails49. . . , through rubber bushings156. . . .

Both end portions of the cross member155are connected to the seat rails49. . . by pairs of bolts157,157. . . . Besides, the first support member154is fastened to the left-side seat rail49by a pair of bolts158,158.

A second support member159is secured to the cross member155, and an attaching member160fixed to the rear fluid pressure-generating unit17R is supported on the second support member159through a rubber bushing156.

Referring toFIG. 21, the attaching member160is firmly attached to the cylinder body20of the rear fluid pressure-generating unit17R by a pair of screw members161,161, and the rubber bushing156is mounted to the attaching member160. In addition, a weld nut162is securely attached to the second support member159at a position corresponding to the rubber bushing156. A collar163provided at its one end with a flange portion163aprojecting outwards is passed through the rubber bushing156so as to put the flange portion163ain contact with the second support member159.

Further, a washer164is put in contact with the other end of the collar163so as to clamp the collar163between itself and the second support member159, and a bolt165passed through the washer164and the collar163is screw engaged with the weld nut162.

In addition, a support plate part154aopposed to the rear fluid pressure-generating unit17R from the outer side is provided at a front part of the first support member154, and a support plate part154bopposed to the rear fluid pressure-generating unit17R from the rear side is provided at a rear part of the first support member154. The rubber bushings156,156mounted respectively to these support plate parts154a,154bare attached to the rear fluid pressure-generating unit17R with bolts166,167, by the same attaching structure as that described referring toFIG. 21above.

A sub-tank168for adjusting the damping force of the cushion unit65provided between the swing arm62and the link member64of the link mechanism63is arranged on the rear side of the rear fluid pressure-generating unit17R. The sub-tank168is supported by the left-side seat rail49of both the seat rails49. . . .

Specifically, a sub-tank support member169for supporting the sub-tank168is fixed to the left-side seat rail49. The sub-tank support member169is fixed to the left-side seat rail49with a pair of bolts170,170by co-fastening thereof together with the pillion step71.

According to the arrangement structure of the rear fluid pressure-generating unit17R as above, the rear fluid pressure-generating unit17R is supported by the left-right pair of seat rails49. . . in such a manner as to be laid out between both the seat rails49. . . in plan view. Therefore, the rear fluid pressure-generating unit17R can be laid out in the vicinity of the rear pressure-regulating unit18R, which is disposed on the rear side of the engine body51, and in a place where it is easy to secure the space necessary for disposing the rear fluid pressure-generating unit17R.

In addition, the rear fluid pressure-generating unit17R is flexibly supported by the first support member154which is attached to the left-side seat rail49of both the seat rails49. . . and by the cross member155for connection between both the seat rails49. . . , through the rubber bushings156. Therefore, vibrations on the side of the body frame F can be restrained from reaching the rear fluid pressure-generating unit17R.

Further, the sub-tank168for adjusting the damping force of the cushion unit65is disposed on the rear side of the rear fluid pressure-generating unit17R and is supported by the left-side seat rail49. Therefore, it is possible to lay out the rear fluid pressure-generating unit17R between the sub-tank168and the engine body51, and thereby to protect the rear fluid pressure-generating unit17R from external forces.

Furthermore, since the sub-tank support member169for supporting the sub-tank168is fixed to the left-side seat rail49by co-fastening thereof together with the pillion step71, the number of component parts can be reduced.

An arrangement structure of the control unit39is described referring toFIGS. 22 to 25.

The control unit39is arranged on the left side of the engine body51mounted on the body frame F. Moreover, in order to enhance the property for “knee gripping” by the driver, the control unit39is disposed on the inner side relative to the vehicle body side ends of that portion of the motorcycle at which the vehicle width is the largest.

The control unit39is contained in and supported by a synthetic resin-made control unit support case171interposed between the control unit39and the engine body51, and is covered with the side cover part74constituting a part of the front cowl72.

The control unit support case171is formed in a box-like shape opened on the side opposite to the engine body51so as to contain the control unit39on the side opposite to the engine body51. The front pressure-regulating unit18F supported on the body frame F through the support member83is arranged on the inner side relative to the control unit support case171, and an upper portion of the control unit support case171is attached to the support arm portions84e,84fpossessed by the lower frame body84constituting a part of the support member83, by bolts172,173.

Specifically, as clearly shown inFIG. 25, weld nuts178. . . are secured to the support arm portions84e,84f, and the bolts172,173passed through the control unit support case171and the support arm portions84e,84fare screw engaged with the weld nuts178. . . .

A crankcase cover174such as a generator cover is fastened to a left side surface of the crankcase53constituting a part of the engine body51, by a plurality of bolts175,175. . . . A lower portion of the above-mentioned control unit support case171is attached, by a pair of bolts177,177, with a lower support member176which is co-fastened to the crankcase53together with the crankcase cover174by use of one of the bolts175,175. Specifically, as clearly shown inFIG. 25, a pair of weld nuts179. . . are firmly attached to the lower support member176, and the bolts177. . . passed through the control unit support case171and the lower support member176are screw engaged with the weld nuts179. . . .

The control unit39is contained in the control unit support case171with, for example, three elastic members181. . . interposed between itself and the control unit support case171. The control unit39is supported on the control unit support case171through a fixing member182which is put in elastic contact with an outside surface of the control unit39along the front-rear direction of the body frame F and which is detachably attached to the control unit support case171.

The fixing member182may be, for example, an endlessly continuous rubber string, which is selectively engaged with lock parts182,182provided at the control unit support case171at positions on the front and rear sides of the control unit39.

The control unit support case171is provided with a running airflow leading-in part184for permitting the running airflow to pass to the side of the control unit39, the running airflow inlet port184being located on the lower front side of the control unit39, and also with a running airflow leading-out part185for leading out the running airflow having passed through the lateral sides of the control unit39, the running airflow leading-out part185being located on the upper rear side of the control unit39.

The side cover part74of the front cowl72covers the control unit39, with a cushion member186between itself and a lower portion of the control unit support case171. The side cover part74is provided with a running airflow intake port187at its portion corresponding to the running airflow leading-in part184, and with running airflow exhaust ports188,189, and190at its portions corresponding to the running airflow leading-out part185.

According to the arrangement structure of the control unit39, as discussed above, the control unit39arranged on a lateral side of the engine body51is contained in and supported by the control unit support case171interposed between the control unit39and the engine body51. Therefore, direct reach of the heat from the engine body51to the control unit39can be avoided by the control unit support case171interposed between the control unit39and the engine body51, while permitting the control unit39to be disposed in the vicinity of the engine body51.

Moreover, the running airflow leading-in part184for permitting the running airflow to pass to the side of the control unit39is formed at a front part of the control unit support case171, and the running airflow leading-out part185for leading out the running airflow having passed through the lateral sides of the control unit39is formed at a rear part of the control unit support case171. Therefore, during running of the motorcycle, the running airflow can be caused to pass through the lateral sides of the control unit39, thereby cooling the control unit39.

In addition, an upper portion of the control unit support case171is attached to the support arm portions84e,84fpossessed by the support member39for supporting the front pressure-regulating unit18F on the body frame F. Therefore, the components and members for supporting the front pressure-regulating unit18F and the control unit support case171onto the body frame F can be made to be suited to common use, which contributes to a reduction in the number of component parts.

Further, a lower portion of the control unit support case171is attached to the lower support member176which is co-fastened to the crankcase53together with the crankcase cover174fastened to one side of the crankcase. Therefore, the bolts175for fastening the lower support member176to the side of the crankcase53can be used in common to the fastening of the crankcase cover174, which contributes to a reduction in the number of component parts.

In addition, the control unit39accompanied by the plurality of elastic members181. . . interposed between itself and the control unit support case171is supported on the control unit support case171by the fixing member182which is put in elastic contact with the outside surface of the control unit39along the front-rear direction of the body frame F and which is detachably attached to the control unit support case171. Therefore, the fixing member182can be attached and detached easily, whereby maintainability of the control unit39can be enhanced.

Furthermore, the control unit39is covered with the side cover part74constituting a part of the front cowl72, and the running airflow intake port187and the running airflow exhaust ports188,189, and190are provided at portions corresponding to the running airflow leading-in part184and the running airflow leading-out part185of the side cover part74.

Therefore, the running airflow can be introduced from the exterior into the running airflow leading-in part184and can be exhausted from the running airflow leading-out part185, whereby performance of cooling the control unit39is maintained, and, at the same time, the control unit39is covered with the side cover part74, whereby the control unit39can be protected from externally coming foreign matter, rainwater, etc.

While the embodiment of the present invention has been described above, the invention is not limited to the embodiment, and various design modifications are possible without departure from the invention as described in claims.

In other words, although the present invention has been described herein with respect to a number of specific illustrative embodiments, the foregoing description is intended to illustrate, rather than to limit the invention. Those skilled in the art will realize that many modifications of the illustrative embodiment could be made which would be operable. All such modifications, which are within the scope of the claims, are intended to be within the scope and spirit of the present invention.