Patent Publication Number: US-6699083-B2

Title: Engine cover arrangement for an outboard marine drive

Description:
TECHNICAL FIELD 
     The present invention relates to an outboard marine drive, and in particular to an engine cover arrangement for an outboard marine drive including an under cover covering a lower part of the engine and defining an upper opening, and an engine cover having a lower opening which closes upon the upper opening of the engine cover via a seal member for jointly defining an engine room. 
     BACKGROUND OF THE INVENTION 
     A relatively large outboard marine drive typically comprises an engine mount case supporting the engine, an under cover attached to the engine mount case to cover a lower part of the engine, and an engine cover having the shape of a deep bowl covering an upper part of the engine. An open upper end of the under cover and an open lower end of the engine cover are joined to each other via a seal member in a detachable manner by means of latch units provided between the under cover and engine cover. The seal member keeps moisture out of the engine room. 
     The seal member closely engages the interfaces of the under cover and engine cover by being compressed between them under a certain load. If this compressive load is too large, an unacceptably large force is required to latch the engine cover onto the under cover. If the compressive load is too small, the required sealing performance may not be achieved. To meet such a requirement, a seal member including a hollow cross section is proposed, for instance in Japanese patent laid open publication No. 2-292575. 
     The seal member based on this proposal provides a favorable resiliency which achieves a required performance with a relatively small compressive reaction. However, it still relies on the resiliency of the seal member for the compressive reaction which cooperates with the latch units, and the sealing performance tends to be lost as the seal member has been used for an extended period of time and a substantial part of its resiliency has been lost. To compensate for this problem, lip seals are additionally provided to the seal member. However, the direction of the reaction force is still the same between the hollow part and lip seals, and a sealing performance cannot be maintained once the material of the seal member loses most of its resiliency even with the addition of such lip seals. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of such problems of the prior art, a primary object of the present invention is to provide an engine cover arrangement for an outboard marine drive which can provide a favorable sealing performance for an entire service life of the outboard marine drive. 
     A second object of the present invention is to provide an engine cover arrangement for an outboard marine drive in which the seal member is not directly subjected to the pressure from the latch units or other closure elements. 
     A third object of the present invention is to provide an engine cover arrangement for an outboard marine drive which does not rely on the resiliency of the seal member for the reaction force of the latch units. 
     According to the present invention, these objects can be accomplished by providing an engine cover arrangement for an outboard marine drive, comprising: a first cover covering a part of an internal combustion engine and provided with a first opening; a second cover covering a remaining part of the engine and provide with a second opening adapted to be fit onto the first opening, the second cover being provided with a first seal surface extending substantially in parallel with a plane defined by the first and second openings along a peripheral part of the second opening and a second seal surface extending substantially perpendicularly with respect to the first seal surface from an inner periphery of the first seal surface toward the first cover; and a seal member attached along a peripheral part of the first opening of the first cover and adapted to engage both the first and second seal surfaces of the second cover. Typically, the seal member comprises a retaining portion attached to an edge of the first cover, and an engagement portion extending from the retaining portion. In particular, in a larger outboard marine drive, the engine itself is typically mounted on an engine mount case made of metallic member, and the second cover consists of an under cover fixedly attached to the engine mount case while the first cover consists of an engine cover. The under cover and engine cover are typically made of plastic material. 
     Because the seal member attached along a peripheral part of the first opening of the first cover is adapted to engage not only a first sealing surface perpendicular to the closing direction of the two covers but also a second sealing surface substantially in parallel with the closing direction of the two covers, the seal member is not required to rely on the pressure directed in the closing/opening direction of the two covers, and is prevented from being excessively compressed. Also, by providing a separate stopper arrangement for defining the closed position of the two covers, the seal member is additionally protected from excessive compression. 
     According to a preferred embodiment of the present invention, the seal member includes a first lip portion engaging the first seal surface and a second lip portion engaging the second seal surface. The lip portions provide a favorably sealing performance without much relying on the pressure acting thereof. The first lip portion is provided in the engagement portion, but the second lip portion may be provided either in the retaining portion or the engagement portion. 
     According to a particularly preferred embodiment of the present invention, the seal member comprises a first lip portion provided in the engagement portion to engage the first seal surface, a second lip portion provided in the retaining portion to engage the second seal surface, and a third lip portion which extends from the retaining portion next to the first lip portion to engage the second seal surface by being pressed by the first lip portion as the first lip portion engages the first seal surface and deforms inward as a result. The third lip portion may also additionally engage the first seal surface. 
     Preferably, to enhance such an action of the first lip portion on the third lip portion, the third lip portion may be provided with a cross section having the shape of a laterally facing letter-V or chevron with a concave side facing the first lip portion, and the first lip portion may be provided with an arcuate cross section with a concave surface facing the third lip portion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Now the present invention is described in the following with reference to the appended drawings, in which: 
     FIG. 1 is an external side view of an outboard marine drive embodying the present invention; 
     FIG. 2 is a simplified top view of the engine mount case revealing the mounting surface for the engine cover; 
     FIG. 3 is a simplified left side view of the mounting portions of the under cover and engine cover; 
     FIG. 4 is a top view of the rear latch unit; 
     FIG. 5 is a vertical sectional view of the rear latch unit; 
     FIG. 6 is a top view of the front latch unit; 
     FIG. 7 is a vertical sectional view of the front latch unit; and 
     FIG. 8 is a vertical sectional view of the latch release mechanism; and 
     FIG. 9 is a vertical sectional view of the front latch unit when the engine cover is lifted away from the under cover. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a side view showing the entire outboard marine drive embodying the present invention. This outboard marine drive  1  is adapted to be attached to the stern board P of a boat via a stern bracket  2 . 
     To the stern bracket  2  is connected a swivel case  4  so as to be rotatable around a laterally extending tilt shaft  3 . The swivel case  4  has an upper end which pivotally supports a front end of an engine mount case  5  and a lower end which pivotally supports an extension case  6  accommodating a part of a power transmission unit such as a drive shaft, so as to be rotatable around a vertically extending swivel shaft  7  in each case. 
     The upper end of the extension case  6  is connected to the engine mount case  5 , and the lower end of the extension case  6  is connected to a gear case  9  supporting a propeller  8 . The engine mount case  5  is covered by an under cover  10 , and the upper end of the under cover  10  is fitted with an engine cover  11  defining a deep bowl shape having a lower open end in a detachable manner so as to cover, primarily, the upper part of the engine E which is mounted on the engine mount case  5 . The engine E in this embodiment consists of a four-stroke V-type vertical engine. 
     A seal member  12  made of rubber or other elastomer material is interposed between the open ends of the under cover  10  and engine cover  11  to seal off water at the interface between the under cover  10  and engine cover  11 , and the two parts are retained to each other by a latching arrangement (which is described hereinafter) provided adjacent to the interface between the two parts. 
     FIG. 2 is a top view of the outboard marine drive  1  of the present invention revealing the end surface for mounting the engine cover, and FIG. 3 is a left side view of the same. The orientation of the outboard marine drive is defined such that the lower end of FIG. 2 corresponds to the front. Referring to FIGS. 2 and 3, the engine mount case  5  made of die cast aluminum alloy is provided with six bosses  13  in an outer periphery of a rear part thereof, and the lower ends  14   ab  to  14   fb  of six upright stay members  14   a  to  14   f  made of metallic material such as steel are attached to the corresponding bosses  13  by using threaded bolts B each extending in a horizontal direction. The upper ends  14   at  to  14   ft  of these stay members  14   a  to  14   f  fixedly support under cover support rails  15   a  to  15   c.    
     The under cover support rails  15   a  to  15   c  consist of three parts which are made of metallic material such as stamp formed steel members. The side parts  15   a  and  15   c  located on either side of the engine cover are integrally formed with side stay members  14   a  and  14   b ; and  14   e  and  14   f  in such a manner as to join the upper ends  14   at  and  14   bt ; and  14   et  and  14   ft  of the two side stay members  14   a  and  14   b ; and  14   e  and  14   f  to each other which are fixedly attached to either side of the engine mount case  5 . The arch shaped rear part  15   b  is fixedly attached to the upper ends  14   ct  and  14   dt  of the two rear stay members  14   c  and  14   d  with threaded bolts B. The front part of the engine mount case  5  is provided with a front bracket  16  for supporting the under cover  10 . The front bracket  16  is cast separately from the engine mount case  5  and fixedly attached to the front end of the engine mount case  5  with threaded bolts B. The right and left under cover support rails  15   a  and  15   c  are provided with an adequate mechanical strength to support the weight of the outboard marine drive  1  when it is placed on its side. 
     The under cover  10  whose upper open end is supported by these under cover support rails  15   a  to  15   c  is made of plastic material, and surrounds the lower part of the engine E and the part of the extension case  6  connected to the engine mount case  5 . In the illustrated embodiments, the support rails  15   a  to  15   c  as well as the stay members  14   a  to  14   f  are made of metallic material, but may be made of plastic or other reinforced or non-reinforced materials that are provided with an adequate mechanical strength. 
     As components of the latching arrangement R for attaching the engine cover  11  made of plastic material to the upper open end of the under cover  10  which is also made of plastic material, four latch units  17   a  to  17   d  are provided, one on each of the side under cover support rails  15   a  and  15   c  connecting the side stay members  14   a  and  14   b ; and  14   e  and  14   f  of the corresponding side to each other, and two on the front bracket  16 . By thus providing the latch units  17   a  to  17   d  forming components of the latching arrangement R on members that are made of metallic material, the reliance on the under cover  10  made of plastic material in ensuring the overall mechanical strength can be avoided. 
     The four latch units  17   a  to  17   d  are arranged in such a manner that the distance between the one  17   d  on the left side of the front bracket  16  and the one  17   a  on the left under cover support rail  15   a  is substantially equal to the distance between the one  17   c  on the right side of the front bracket  16  and the one  17   b  on the right under cover support rail  15   c , and is also substantially equal to the distance between the ones  17   a  and  17   b  on the right and left under cover support rails  15   a  and  15   c , respectively. By thus arranging the latching positions in an equilateral or isosceles triangular arrangement, two in the front as a single group and two on either side, the retaining force acting between the under cover  10  and the engine cover  11  can be made substantially uniform over the entire circumference. 
     As shown in FIGS. 4 and 5, of these four latch units  17   a  to  17   d , the ones  17   a  and  17   b  on either side each consist of a vertical hole  18   a  and  18   b  passed in a cylindrical collar  23   a  and  23   b  integrally formed in the corresponding under cover support rail  15   a  and  15   c , and a latch plate  20   a  and  20   b  which is pivotally supported adjacent to the corresponding hole  18   a  and  18   b  by a vertical shaft  19  so as to be rotatable in a horizontal plane between a position interfering with the corresponding hole  18   a  and  18   b  and a position not interfering with the corresponding hole  18   a  and  18   b . FIGS. 4 and 5 show only the right latch unit  17   b , and the left latch unit  17   a  is identical to the right latch unit  17   b  except that they are mirror images of each other. 
     As shown in FIGS. 6 and 7, the two front latch units  17   d  and  17   c  comprise a pair of holder members  21   d  and  21   c  each fixedly attached to the upper surface of the front bracket  16  with a pair of threaded bolts B, right and left latch plates  20   d  and  20   c  which are each pivotally supported by the corresponding holder member  21   d  and  21   c  with a vertical shaft  22 , and a link member  24  made of steel plate punched out into a shape of a rod bent in the middle as seen from above and joining the right and left latch plates  20   d  and  20   c  with each other. Thus, the two latch units  17   d  and  17   c  form a single sub assembly by being connected to each other by the rigid link member  24 . 
     A vertical hole  18   d  and  18   c  is formed a collar  23   d  and  23   c  integrally formed in each of the holder members  21   d  and  21   c  between the two fastening bolts B, and each latch plate  20   d  and  20   c  is pivotally supported adjacent to the corresponding hole  18   d  and  18   c  so as to be rotatable in a horizontal plane between a position interfering with the corresponding hole  18   d  and  18   c  and a position not interfering with the corresponding hole  18   d  and  18   c.    
     Each of the four latch plates  20   a  to  20   d  mentioned above is resiliently urged by a torsion coil spring  27  so as to retain corresponding latch plate  20   a  to  20   d  in the position interfering with the corresponding hole  18   a  to  18   d  as long as no external force is applied thereto. Each of the latch plates  20   a  to  20   d  is provided with a notch N at a position corresponding to the center of the corresponding hole  18   a  to  18   d.    
     The right front latch plate  20   c  on the front bracket  16  is provided with a connecting end for the inner cable  29   a  of a first Bowden cable  28   a  at one end thereof, and a pin  30  for engaging a push rod (which is described hereinafter) at the other end thereof, on either side of the vertical shaft  22 . 
     As also shown in FIG. 8, the front end of the front bracket  16  is provided with a latch release lever  32  pivotally supported by a horizontal shaft  31 , and a push rod  33  that can slide in the fore-and-aft direction. The latch release lever  32  has an upper end that can engage the front end of the push rod  33 , and is normally urged by a torsion coil spring  34  in the direction to prevent the upper end of the latch release lever  32  from engaging the front end of the push rod  33  or away from the front end of the push rod  33 . 
     When the latch release lever  32  is turned around the horizontal shaft  31  by pulling the lower end of the lock release lever  32  outward, the upper end thereof pushes the push rod  33  rearward. As a result, the pin  30  extending upright from the left end of the front right latch plate  20   c  is pushed rearward, causing the latch plate  20   c  to rotate around the vertical shaft pin  22 . This in turn causes the left end of the latch plate  20   c  provided with the pin  30  to be moved rearward, and the right end thereof to be moved forward. Thus, the inner cable  29   a  of the first Bowden cable  28   a  is pulled outward. 
     Meanwhile, the rotation of the front right latch plate  20   c  is transmitted to the front left latch plate  20   d  via the link member  24 . As a result, the right and left latch plates  20   c  and  20   d  rotate by a same angle. This rotational movement causes the notch N of each latch plate which has been aligned with the center of the corresponding vertical hole  18   d  and  18   c  to be moved away from the corresponding hole  18   d  and  18   c.    
     The front right latch plate  20   c  is connected to the rear right latch plate  20   b  of the rear right latch unit  17   b  via the first Bowden cable  28   a . The rear right latch plate  20   b  is connected to the rear left latch plate  20   a  of the rear left latch unit  17   a  via a second Bowden cable  28   b . The outer tubes of the first and second Bowden cables  28   a  and  28   b  extending between the three latch plates are attached to a part  16   a  of the front bracket  16 , a middle part of the right under cover support rail  15   c , an upper end  14   et  of the rear right stay member  14   e , and an upper end  14   bt  of the rear left stay member  14   b  so that the tension of the inner cables  29   a  and  29   b  of the first and second Bowden cables  28   a  and  28   b  may be adjusted independently. Thus, the error in the synchronization between the two latch plates can be minimized. Because the outer tube of a Bowden cable is highly flexible as well known in the art, the latch plates can be arranged at will. 
     The parts of the inner surface of the engine cover  11  corresponding to the holes  18   a  to  18   d  are provided with striker pins  35  as shown in FIGS. 5 and 7. Each striker pin  35  is attached, by threading, to a horizontal portion H of an L-shaped bracket  38  which is fixedly attached to the inner surface of the circumferential wall of the engine cover  11  at its vertical portion V, and is oriented vertically. 
     A damper bush  39  consisting of a tubular member made of elastomer and provided with an outer diameter which allows it to be fitted into the corresponding hole  18  is slidably fitted on a stern portion of each striker pin  35  via a washer  43 . The free end of each striker pin  35  is integrally provided with a tapered enlarged diameter portion  40 . A compression coil spring  41  is interposed between the lower surface of the horizontal portion H of each bracket  38  adjacent to the base end of the corresponding striker pin  35  and the upper surface of the damper bush  39  via the washer  43  to urge them away from each other. 
     Referring to FIG. 9, the seal member  12  comprises a retaining portion  12   a  attached to the lower edge of the engine cover  11 , and an engagement portion  12   b  depending from the retaining portion  12   a . The engagement portion  12   b  includes an outer lip portion  51  and an inner lip portion  53  both depending from the retaining portion  12   a  one next to the other in a parallel relationship. The inner lip portion  53  essentially consists of a linear segment bent in the middle (or in the shape of a laterally directed letter-V or chevron) so as to present a concave surface outward or toward the outer lip portion  51 . The outer lip portion  51  has a semicircular cross section with a concave surface thereof facing inward or toward the inner lip portion  53 . One of the tip of these two lip portion  51  and  53  preferably abuts a side of the other so that the two lip portions  51  and  53  jointly define a hollow tube-like configuration (the internal hollow space is denoted with numeral  55 ) over the entire circumference of the interface between the engine cover  11  and under cover  10 . 
     The retaining portion  12   a  has a substantially U-shaped cross section so as to fit onto the lower edge of the engine cover  11  which depends vertically downward. The inner peripheral part of the retaining portion  12   a  is provided with an extension at an upper end thereof in the form of an upper lip portion  52  which is slightly bent inward. 
     The outer lip portion  51  extends obliquely downwardly and inwardly across a center line of the seal member (indicated by the chain-dot line arrow), and a free end of the outer lip portion  51  abuts an outer side of the inner lip portion  53  which is somewhat offset inwardly with respect to the center line. The under cover is provided with a horizontal seal surface  42  which extends along the outer periphery of the under cover  10  opposite the lower edge of the engine cover  11 . A substantially vertical seal surface  43  extends vertically from an inner periphery of the horizontal seat surface  42 . In this embodiment, the vertical seal surface  43  is slightly inwardly curved toward its upper part, and therefore presents a convex outer peripheral surface. 
     The mode of operation of this embodiment is described in the following. When placing the engine cover  11  over the under cover  10 , the striker pins  35  are fitted into the corresponding holes  18   a  to  18   d  provided in the under cover  10  while the engine cover  11  is placed over the engine E. When the damper bushes  39  are fitted into the holes  18   a  to  18   d  and the engine cover  11  is pushed further down, the striker pins  35  are lowered against the spring force of the compression coil springs  41 . As the enlarged diameter portions  40  of the striker pins  35  reach the notches N of the corresponding latch plates  20   a  to  20   d , the tapered enlarged diameter portions  40  push away the corresponding latch plates  20   a  to  20   d . As the enlarged diameter portions  40  pass the corresponding notches N, the latch plates  20   a  to  20   d  are forced back to their original positions by the spring force of the torsion coil springs  27 , and the notches N of the latch plates  20   a  to  20   d  engage the enlarged diameter portions  40  of the corresponding striker pins  35  with the result that the engine cover  11  is locked in place. 
     Meanwhile, the outer lip portion  51  of the engagement portion  12   b  of the seal member  12  engages the first seal surface  42  defined by a horizontal surface in the upper end of the under cover  10 . Because the free end of the outer lip portion  51  is offset inward or toward the engine room with respect to the center (indicated by the chain-dot line arrow in FIG. 9) of the load from the engine cover  11 , the outer lip portion  51  deforms inward as it is pushed against the horizontal first seal surface  42 . The inner lip portion  53  likewise abuts the horizontal seal surface  42  as the engine cover  11  is fully closed, but by being pushed inward by the outer lip portion  51 , additionally abuts the vertical seal surface  43  at an intermediate part of the inner lip portion  53 . Thus, the outer and inner lip portions  51  and  53  engage the seal surfaces  42  and  43  at three places, and this provides a highly reliable sealing performance. At the same time, the upper lip portion  52  engages the vertical seal surface  43 , and this provides an additional assurance for the reliable performance. 
     In this latched state, because the compression coil springs  41  disposed coaxially with respect to the corresponding striker pins  35  apply a force which urges the under cover  10  and engine cover  11  away from each other, the reaction force acting against the engagement force between the latch plates  20   a  to  20   b  and the striker pins  35  is not required to rely on the restoring force of the seal rubber  12 . 
     During this latching process, when the engine cover  11  is pushed downward onto the under cover  10 , the downward movement of the engine cover  11  is limited by the abutment between the horizontal portions H of the brackets  38  and the upper end of the collars  23   a  to  23   b  with the washers  43  and the rubber bushes  39  interposed between them. The rubber bushes  39 , in cooperation with the compression coil springs  41 , accommodate positional errors that may be present in the latch units, and provide a cushioning effect. Also, this prevents the seal member  12  from being excessively compressed when closing the engine cover  11  onto the under cover  10 , and contributes to the elongation of the effective service life of the seal member  12 . 
     When the latch release lever  32  is pulled outward, all of the latch plates  20   a  to  20   d  connected to the link member  24  and the Bowden cables  28   a  and  28   b  rotate in the direction to release the latch plates  20   a  to  20   d . This causes the enlarged diameter portions  40  of the striker pins  35  to be disengaged from the corresponding notches N, and the engine cover  11  to be pushed upward by virtue of the spring force of the compression coil springs  41  provided on the striker pins  35  which is possibly assisted by the restoring force of the seal member  12 . This in turn causes the striker pins  35  to be moved upward, and the enlarged diameter portions  40  to be moved to such positions as to disable the notches N of the corresponding latch plates  20   a  to  20   d  from engaging the striker pins  35 . Under this condition, because the latching arrangement R is entirely released, the engine cover  11  can be lifted while the damper bushes  39  are pushed away from the corresponding holes  18   a  to  18   d.    
     Thus, according to the present invention described above, because the seal member attached along a peripheral part of the first opening of the first cover is adapted to engage not only a first sealing surface perpendicular to the closing direction of the two covers but also a second sealing surface substantially in parallel with the closing direction of the two covers, the seal member is not required to rely on the pressure directed in the closing/opening direction of the two covers, and is prevented from being excessively compressed. This contributes to the improvement in the reliability of the seal member. Also, by providing a separate stopper arrangement for defining the closed position of the two covers, the seal member is additionally protected from excessive compression. 
     Although the present invention has been described in terms of a preferred embodiment thereof, it is obvious to a person skilled in the art that various alterations and modifications are possible without departing from the scope of the present invention which is set forth in the appended claims.