Abstract:
An object of the present invention is to provide an outdrive unit that allows space to be saved in the positioning of a hydraulic circuit for trolling, and enables easy maintenance of the hydraulic circuit for trolling. The invention provides an outdrive unit mounted outside of a boat, including: a propeller for propulsion; a hydraulic clutch that controls driving of the propeller; a transmission mechanism that transmits drive power from the hydraulic clutch to the propeller; a hydraulic circuit that operates the hydraulic clutch, the hydraulic circuit comprising a switching valve that switches a rotational direction of the propeller, a pressure-reducing valve for trolling that reduces a pressure of a pressurized oil supplied to the hydraulic clutch, a filter for the pressurized oil introduced to the pressure-reducing valve, and a hydraulic pump that supplies the pressurized oil to the hydraulic clutch; a housing that houses at least one of the hydraulic clutch, transmission mechanism, and hydraulic circuit; a base on which the switching valve, pressure-reducing valve, and filter are mounted, the base being detachably mounted in the housing.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an outdrive unit mounted outside of a boat. 
       BACKGROUND 
       [0002]    A sterndrive, which is one type of an inboard-outboard drive, is a main device comprising an engine and an outdrive unit. The engine is mounted inside the hull, and transmits driving power to the outdrive unit, which is mounted outside the hull. Recently, sterndrive units that allow trolling have also been developed as per user demands. Among such sterndrive units are, for example, those disclosed in Patent Literatures 1 and 2. 
         [0003]    In the sterndrive unit disclosed in Patent Literature 1, a hydraulic clutch and a hydraulic circuit for operating the hydraulic clutch are located inboard. The hydraulic circuit also includes a switching valve for switching between forward and reverse propulsion, and a pressure-reducing valve for trolling. However, the hydraulic clutch and hydraulic circuit located inboard reduce the space available inside the boat. For this reason, Patent Literature 2 discloses locating a hydraulic clutch for trolling in an outdrive unit mounted outboard. 
       [PTL 1] Japanese Unexamined Patent Publication No. 1999-182582 
     [PTL 2] Japanese Examined Utility Model Publication No. 1984-4879 
       [0004]    Because there is not a large amount of space that can be used inside an outdrive unit, it is necessary to save space in the positioning of a hydraulic circuit. Easy maintenance is also desired for an outdrive unit. However, in the device of Patent Literature 2, although the hydraulic clutch is located outboard, there is no specific disclosure of a hydraulic circuit for trolling control. 
         [0005]    The present invention has been made in order to solve the above-described problem. An object of the invention is to provide an outdrive unit that allows space to be saved in the positioning of a hydraulic circuit for trolling, and that enables easy maintenance of the hydraulic circuit for trolling. 
       SUMMARY OF INVENTION 
       [0006]    The invention provides an outdrive unit mounted outside of a boat, including a propeller for propulsion; a hydraulic clutch that controls driving of the propeller; a transmission mechanism that transmits drive power from the hydraulic clutch to the propeller; a hydraulic circuit that operates the hydraulic clutch; and a housing that houses at least one of the hydraulic clutch, transmission mechanism, and hydraulic circuit. The hydraulic circuit includes a switching valve that switches a rotational direction of the propeller; a pressure-reducing valve for trolling that reduces a pressure of a pressurized oil supplied to the hydraulic clutch; a filter for the pressurized oil introduced to the pressure-reducing valve; and a hydraulic pump that supplies the pressurized oil to the hydraulic clutch. The outdrive unit further includes a base on which the switching valve, pressure-reducing valve, and filter are mounted, the base being detachably mounted in the housing. 
         [0007]    In this structure, the switching valve, pressure-reducing valve, and filter that constitute the hydraulic circuit are mounted all together on the base, thereby saving space. Moreover, because the hydraulic circuit for trolling control is located on the base, maintenance on trolling can be easily performed by detaching the base. Furthermore, cables necessary for controlling the switching valve and pressure-reducing valve can be drawn together from the base into the boat, enabling easy maintenance of the cables as well. Note that the shape of the base is not limited; the base may have a box shape that can house the switching valve and the like, or it may be made of a plate-like substrate. 
         [0008]    The outdrive unit may further include a sensor that detects rotation of the transmission mechanism or hydraulic clutch. This enables detection of the trolling speed, such that trolling at a desired speed can be realized by controlling the pressure-reducing valve according to the detected rotation. The sensor can also be located on the base, further facilitating maintenance. 
         [0009]    The outdrive unit may further include a power-generating device that is mounted on the base and that generates electrical power by the rotation of the transmission mechanism or hydraulic clutch; and a control device that is mounted on the base and that controls the switching valve and pressure-reducing valve. The control device can be operated with the electrical power generated by the power-generating device. Thus, power can be saved. 
         [0010]    The control device can be operated wirelessly from inside the boat. This reduces the number of cables to be drawn from inside the boat. Of course, the control device can also be operated via cables from inside the boat. 
         [0011]    In the outdrive unit, the base may be mounted on a stern side of the hydraulic clutch, and the hydraulic pump may also be mounted in the base. In this case, the hydraulic pump is connected to the clutch shaft of the hydraulic clutch, and is driven by the rotation of the clutch shaft. 
         [0012]    In this structure, the hydraulic circuit that includes the hydraulic pump is mounted on the base, allowing the maintenance of the hydraulic circuit to be easily performed by detaching the base. Particularly because the base is mounted on the stern side of the hydraulic clutch, it can be easily detached. The base may be directly mounted to the hydraulic clutch, or may be mounted thereto via a fixing member. In the base, the switching valve and pressure-reducing valve may be located below the hydraulic pump. The hydraulic pump is located on the stern side of the hydraulic clutch, thereby saving space. The base may also be directly mounted on the stern side of the hydraulic clutch, or may be mounted to the hydraulic clutch via a partition or the like. When a partition or the like is used, the sensor may be secured to the partition. 
         [0013]    Furthermore, a detachable cover may be provided on a stern side of the housing, allowing the base to be accessed by opening the cover. This provides quick access to the base by opening the cover, further facilitating maintenance. A plurality of such covers may also be provided. For example, a dual cover may be provided in order to prevent water ingress. 
         [0014]    The outdrive unit according to the invention allows space to be saved in the positioning of a hydraulic circuit for trolling, and enables easy maintenance of the hydraulic circuit for trolling. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0015]      FIG. 1  is a cross section of a portion of an inboard-outboard drive according to an embodiment of the invention. 
           [0016]      FIG. 2  is a cross section showing principal parts of the inboard-outboard drive of  FIG. 1 . 
           [0017]      FIG. 3  is a cross section taken along line A-A in  FIG. 2 . 
           [0018]      FIG. 4  is a perspective view showing the interior of an aft end of the outdrive unit of  FIG. 2 . 
           [0019]      FIG. 5  is a hydraulic circuit diagram of the outdrive unit according to an embodiment of the invention. 
           [0020]      FIG. 6  is a cross section showing another embodiment of the outdrive unit of  FIG. 2 . 
           [0021]      FIG. 7  is a cross section taken along line B-B in  FIG. 6 . 
         Reference Signs List 
         [0000]    
         
             1 : engine 
             3 : outdrive unit 
             4 : propeller 
             53 : controller (control device) 
             54 : power-generating device 
             8 : hydraulic multiplate clutch (hydraulic clutch) 
             10 : casing (base) 
             101 : forward/reverse electromagnetic switching valve 
             102 : electromagnetic proportional pressure-reducing valve 
             103 : filter 
         
       
       
    
    
     DETAILED DESCRIPTION 
       [0032]    One embodiment of the outdrive unit according to the invention will be described below, referring to the drawings. A portion of a boat equipped with the outdrive unit is also described herein.  FIG. 1  is a cross section of a portion of a sterndrive unit.  FIG. 2  is a cross section showing principal parts of the inboard-outboard drive of  FIG. 1 .  FIG. 3  is a cross section taken along line A-A in  FIG. 2 .  FIG. 4  is a perspective view showing the interior of an aft end of the outdrive unit. In the specification, the bow side of the hull is referred to as “fore”, and the stern side of the hull is referred to as “aft”. The term “horizontal direction” means the direction from the starboard side to the port side, or vice versa. 
         [0033]    As shown in  FIGS. 1 and 2 , the inboard-outboard drive installed in a boat includes an engine  1  and an outdrive unit. The engine  1  is mounted inside a hull  2 , and the outdrive unit  3  is mounted outside the hull  2 . The outdrive unit  3  is a propulsion device incorporating propeller blades  4 , a clutch, and the like, and is connected to a transom portion  21  at the stern. Further, as will be described below, power from the engine  1  is transmitted to the outdrive unit  3  via an input shaft  11  that extends outboard, thereby driving the propeller blades  4 . 
         [0034]    The outdrive unit is now described in further detail. The outdrive unit  3  includes a body portion  31  connected to the transom portion  21 , and a housing  32  pivotally connected to an aft end of the body portion  31 . As shown in  FIG. 2 , the body portion  31  includes a gimbal housing  311  secured to the transom portion  21 ; and a gimbal ring  312  supported by pivot shafts  3111  and  3112  at lower and upper portions, respectively, of the gimbal housing  311 . The gimbal housing  311  houses the input shaft  11  of the outdrive unit  3 . The gimbal ring  312  is capable of pivoting in the horizontal direction via the pivot shafts  3111 ,  3112 . A steering lever  3113  that extends inside the hull is connected to the upper pivot shaft  3111 . 
         [0035]    The housing  32  includes an upper housing  321  and a lower housing  322  that are arranged in the vertical direction. Further, a bell housing  323 , which is inserted through an opening in the gimbal ring  312 , is connected to a fore end of the upper housing  321 . Both side surfaces of the gimbal ring  312  are connected to trim-shaft members (illustration omitted) disposed on both sides of the bell housing  323 , whereby the bell housing  323  can pivot about the gimbal ring  312  in the vertical direction. The pivoting is performed by a pair of hydraulic cylinders  5  disposed on both sides of the housing  32 . Each hydraulic cylinder  5  has a fore end attached to the gimbal ring  312 , and an aft end attached to the upper housing  321 . Thus, during travel, extending the hydraulic cylinders  5  causes the housing  32  to pivot upward, i.e., trimming out, and retracting the hydraulic cylinders  5  causes the housing  32  to pivot downward, i.e., trimming in. 
         [0036]    As shown in  FIG. 2 , the upper housing  321  has an upper housing body  321   a  that houses a forward gear  71 , a reverse gear  72 , a hydraulic multiplate clutch  8 , and the like; and a cosmetic cover  321   b  that covers side surfaces and a portion of an upper surface of the upper housing body  321   a . The input shaft  11  of the outdrive unit is connected to a clutch shaft  61  via a universal joint  12  (see  FIG. 1 ). The input shaft  11 , universal joint  12  and clutch shaft  61  in turn extend into the upper housing  321  via the interiors of the gimbal housing  311  and bell housing  323 . The clutch shaft  61  is then connected to the clutch  8  in the upper housing  321 . The forward gear  71  and reverse gear  72  are pivotally fitted into fore and aft sides, respectively, of the clutch shaft  61 , with the clutch  8  disposed between the fore and aft sides of the clutch shaft  61 . By actuating the clutch  8 , either of the gears  71 ,  72  is connected to the clutch shaft  61 . 
         [0037]    As shown in  FIG. 2 , the forward gear  71  and reverse gear  72  are engaged with a bevel gear  731 , which is secured to the upper end of a drive shaft  73  that extends vertically. A bevel gear (illustration omitted) is also secured to a lower end of the drive shaft  73 . A propeller shaft  74  that extends in the fore-aft direction can be rotated via this bevel gear. As shown in  FIG. 1 , the propeller blades  4  are attached around an outer peripheral surface of the propeller shaft  74 . The gears  71 ,  72 , drive shaft  73 , bevel gear  731 , and the like that transmit power to the propeller blades  4  from the clutch constitute the transmission mechanism of the invention. 
         [0038]    A hydraulic control unit  9  incorporating a hydraulic pump  91 , a hydraulic circuit for controlling a clutch hydraulic oil, and the like is mounted to a stern-side end of the clutch shaft  61 . The hydraulic control unit  9  has a casing  10 , in which the hydraulic pump  91  is located. The hydraulic pump  91  is a gear pump with a pair of gears. A gear  91   a , which is one of the gears constituting the gear pump, is engaged with the end of the clutch shaft  61  and rotates with the clutch shaft  61 , whereby oil is pumped from an oil sump described below so that the hydraulic oil is supplied to the clutch  8 . A trochoid pump, for example, may be used as the hydraulic pump  91 . Furthermore, as shown in  FIG. 4 , an aft end of the casing (base)  10  is provided with a forward/reverse electromagnetic switching valve  101 , electromagnetic proportional pressure-reducing valve  102 , a pressure-reducing valve filter  103 , and a relief valve  104  (see  FIG. 5 ), which constitute a hydraulic circuit. More specifically, the pressure-reducing valve filter  103 , forward/reverse electromagnetic switching valve  101 , and electromagnetic proportional pressure-reducing valve  102  are arranged in order from top to bottom. An oil passage that connects these components is also located in the casing  10 . As shown in  FIGS. 2 and 3 , the hydraulic control unit  9  is further covered with an interior cover  99  located inside the cosmetic cover  321   b . This prevents water ingress. The interior cover  99  also prevents oil from leaking outside from the hydraulic control unit  9 . Further, a partition  20  is located on a fore end of the casing  10 . The partition  20  is provided with a sensor  201  that detects rotation of the forward gear  71  or reverse gear  72 . 
         [0039]    As shown in  FIG. 3 , a single bundle of cables  105 , which are connected to the forward/reverse electromagnetic switching valve  101 , electromagnetic proportional pressure-reducing valve  102 , sensor  201 , and the like, passes along an interior side surface of the housing  32 , and is connected to an inboard controller  51 . Midway along this wiring is formed a portion  105   a  that extends in the form of a spiral. When the cables  105  are pulled during trimming in or out of the housing  32 , the spiral portion  105   a  is unwound and extended. The cables  105  include, for example, leads for supplying electrical power, in addition to signal cables for transmitting signals to the switching valve and the like. 
         [0040]    As shown in  FIG. 2 , the hydraulic multiplate clutch  8  includes an outer drum  81  that is secured to the clutch shaft  61 ; and inner drums  82   a ,  82   b  that are disposed radially inward of the outer drum  81 , and extend from the forward gear  71  and reverse gear  72 , respectively. A plurality of forward annular pressure plates and reverse annular pressure plates are attached to an inner surface of the outer drum  81  so that they can move in the fore-aft direction. A plurality of forward annular clutch plates and reverse annular clutch plates are also attached to the inner drums  82   a ,  82   b , respectively, so that they can move in the fore-aft direction. The clutch  8  is also provided with a forward piston  83   a  and reverse piston  83   b  that press the forward and reverse pressure plates, respectively, via the hydraulic oil from the hydraulic pump. 
         [0041]    Further, an oil sump is formed fore of the propeller shaft  74  in the lower housing  322 . The oil contained in the oil sump is pumped through the hydraulic pump  91 , and used as a hydraulic oil and lubricating oil for the clutch  8 . The oil supplied to the clutch  8  as a lubricating oil drops down through gaps in the periphery of the bevel gear  731  located on the upper end of the drive shaft, and through the oil passage located around the periphery of the drive shaft  73 , and then returns to the oil sump. 
         [0042]    The hydraulic circuit of the outdrive unit is described next.  FIG. 5  is a hydraulic circuit diagram. Pressurized oil pumped by the hydraulic pump  91  from the oil sump via a filter  97  passes through a hydraulic oil supply passage  94  and is supplied to the clutch  8 . The filter  103 , electromagnetic proportional pressure-reducing valve  102 , and forward/reverse electromagnetic switching valve  101  are disposed in order from the hydraulic pump  91  along the hydraulic oil supply passage  94 . The controller  51  shown in  FIG. 1  is provided with a shift lever  52 . By operating the shift lever  52 , the forward/reverse electromagnetic switching valve  101  is actuated, causing the oil passage for supplying the hydraulic oil from the oil sump to be switched to a forward oil passage  94   b  or reverse oil passage  94   a , which is connected to the forward piston  83   a  or reverse piston  83   b , respectively, of the clutch  8 . The controller  51  is also provided with a trolling control unit not shown in  FIG. 1 . The trolling control unit opens/closes the electromagnetic proportional pressure-reducing valve  102 . Specifically, by adjusting the opening/closing of the electromagnetic proportional pressure-reducing valve  102 , the pressure plates and clutch plates in the clutch  8  are caused to slip against one another to attain a so-called half-clutch position, thereby enabling trolling. Moreover, by instantaneously attaining a half-clutch position by adjusting the opening/closing of the electromagnetic proportional pressure-reducing valve  102 , shock caused by sudden engagement of the clutch  8  can be reduced. The hydraulic circuit is also provided with a relief valve  104 . The relief valve  104  is disposed along a branch oil passage  95 , which branches from the hydraulic oil supply passage  94  between the hydraulic pump  91  and filter  103 . The branch oil passage  95 , which branches off partway from the hydraulic oil supply passage  94 , is connected to the clutch  8 . When the relief valve  104  is opened by a pressure exceeding a prescribed pressure, the pressurized oil is supplied to the clutch  8  as a lubricating oil. 
         [0043]    When electrical current is not applied to the forward/reverse electromagnetic switching valve  101 , return springs  101   a ,  101   b  cause the forward/reverse electromagnetic switching valve  101  to shift to a position for stopping the oil supply to the clutch  8 . In the event that electrical current cannot be applied to the forward/reverse electromagnetic switching valve  101  because of electrical problems such as a disconnection, the return springs  101   a ,  101   b  cause the hydraulic oil supply to be discharged via a drain, so that the clutch  8  is disengaged, and the boat stops. 
         [0044]    The operation of the outdrive unit with the above-described structure is described next. As stated above, when the shift lever  52  is placed in a forward position F, hydraulic oil is supplied to the forward piston  83   a  of the clutch  8  via the forward/reverse electromagnetic switching valve  101 , causing the clutch shaft  61  and forward gear  71  to be connected. This causes power from the input shaft  11  to be transmitted to the drive shaft  73  via the forward gear  71 , causing the propeller blades  4  to rotate in the forward direction. Conversely, when the shift lever  52  is placed in a reverse position R, hydraulic oil is supplied to the reverse piston  83   b  of the clutch  8  via the forward/reverse electromagnetic switching valve  101 , causing the clutch shaft  61  and reverse gear  72  to be connected. This causes the reverse gear  72  to be rotated, causing the propeller blades  4  to rotate in the reverse direction. Furthermore, a half-clutch position can be attained by adjusting the electromagnetic proportional pressure-reducing valve  102  using the controller  51 , thereby enabling trolling. During trolling, the number of revolutions of the propeller blades  4  is detected by a sensor  201  provided in the casing. The degree of opening/closing of the electromagnetic proportional pressure-reducing valve  102  is then adjusted to a number of revolutions that is suitable for trolling. 
         [0045]    As described above, according to this embodiment, the forward/reverse electromagnetic switching valve  101 , electromagnetic proportional pressure-reducing valve  102 , and filter  103  are mounted on the casing  10 . This allows maintenance to be easily performed by detaching the casing  10 . Particularly because the casing  10  is located at the aftermost position of the housing  32 , it is readily accessible by detaching the cosmetic cover  321   b  and interior cover  99 . This further facilitates maintenance. Moreover, because the hydraulic circuit for trolling control is located on the casing  10 , maintenance on trolling can be performed all together by detaching the casing  10 . 
         [0046]    While one embodiment of the present invention has been described above, the invention is by no means limited to the foregoing embodiment, and various modifications are possible without departing from the gist of the invention. For example, although the controller  51  is located inboard in the foregoing embodiment, it may also be located in the outdrive unit. 
         [0047]      FIG. 6  is a cross section of an outdrive unit, and  FIG. 7  is a cross section taken along line B-B in  FIG. 6 . In the embodiment shown in  FIGS. 6 and 7 , a casing  10  for a hydraulic control unit  9  further houses a controller  53  and a power-generating device  54 . The power-generating device  54  is connected to an aft end of a clutch shaft  61 , and generates electrical power by rotation of the clutch shaft  61 . An electromagnetic switching valve  101  and the like are operated with the generated electrical power, under the control of the controller  53 . Moreover, in this embodiment, the controller  53  is equipped with a wireless device, allowing the controller  53  to be operated based on a radio signal transmitted from inside the boat. A single cable  106 , which extends inboard from the controller  53 , is used to allow communication between the controller  53  and inboard devices such as the engine. The use of such a wireless device is not limited to the use in an outdrive unit that allows trolling. Note that when the controller  53  is operated via cables, cables for transmitting signals are further required. 
         [0048]    Furthermore, in the foregoing embodiment, the number of revolutions of the propeller blades  4  is controlled by detecting the rotation of the forward or reverse gear using the sensor  201 ; however, for example, as shown in  FIG. 1 , a pressure sensor  45  may be located on a lower end of the upper housing  321  in a position opposite the propeller blades  4 , thereby detecting the number of revolutions of the propeller blades  4 . The sensor may also be located in a desired position on either the clutch  8  or on the transmission mechanism. 
         [0049]    Furthermore, because the hydraulic circuit associated with trolling, which contains the pressure-reducing valve  102  and the like, is located all together in the casing  10 , an outdrive unit that does not have a trolling function can be easily made capable of trolling by mounting the casing  10  thereto.