User Tag List

Page 1 of 3 1 2 3 LastLast
Results 1 to 15 of 34

Thread: The L4 MERC

  1. #1
    Join Date
    Feb 2015
    Location
    Ontario
    Posts
    8,091
    Thanks (Given)
    205
    Thanks (Received)
    321
    Likes (Given)
    1921
    Likes (Received)
    2005
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)

    The L4 MERC

    As mentioned earlier in the V6 History thread, the L4.

    DISCLOSURE OF INVENTION The invention provides a four cylinder, in-line, two-cycle engine having an exhaust system which is both highly efficient in operation, compactly packaged, and readily manufactured.
    The engine of the invention includes four cylinders arranged in a vertical bank. Each cylinder has an exhaust port, with all of the exhaust ports placed on the same side of the cylinder bank. An exhaust cavity is formed in the cylinder block on the same side as the exhaust ports and lies generally in a plane parallel to the plane of the cylinder block. This exhaust cavity includes a vertically extending trunk on one side of the exhaust ports, four exhaust legs, each connected to one of the exhaust ports. The two upper legs join together, as do the two lower legs, with their junctions connected by an upper and a lower exhaust branch, respectively, to the exhaust trunk. The exhaust cavity is formed to be open on the side facing away from the cylinder bank, and is closed on that side by an exhaust manifold cover to form an exhaust manifold. The engine thus formed provides an effective exhaust system which occupies a minimum of space along the side of the engine.
    Preferably an exhaust outlet is also formed by the exhaust cavity to extend downwardly from the exhaust trunk. An exhaust gas pipe can be attached to the bottom of the cylinder block to receive the exhaust gas from the exhaust outlet.
    The invention thus provides a two-cycle, four cylinder engine which has an exhaust system formed substantially by the cylinder block. The exhaust system thus can be readily water cooled and is suitable for such applications as the powerhead of an outboard motor.
    BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view, partially in section, of an outboard motor incorporating features of the invention.
    FIG. 2 is a view in elevation of the cylinder block of FIG. 1.
    FIG. 3 is a sectional view taken along line 3--3 of FIG. 2 with the exhaust cavity covers in place.
    FIG. 4 is a sectional view along line 4--4 of FIG. 2.
    FIG. 5 is a sectional view along line 5--5 of FIG. 2.
    BEST MODE FOR CARRYING OUT THE INVENTION Referring to the drawings, a two-cycle, four cylinder, in-line engine 10 supported on the drive shaft housing 11 of an outboard motor is illustrated. The engine 10 has four cylinders 12 arranged in a vertical bank with a piston, not illustrated, mounted in each cylinder 12. The pistons are connected by connecting rods to drive a crankshaft having four crank pins angularly spaced at 90° intervals. The crankshaft is connected by a drive shaft 13 to drive a propeller at the lower end of the drive shaft housing 11. The drive shaft housing 11 also includes an exhaust gas passage 14 for receiving exhaust gases from the engine 10 and discharging them below the surface of the water, preferably through the hub of the propeller, and a water passage 15 for supplying cooling water to the engine.
    The engine 10 is a crankcase compression type having a separate crankcase compartment for each cylinder 12 formed by the crankcase end of the cylinder block 16, the intake manifold casting 17, and the crankshaft. The air-fuel charge provided by the carburetors 18 is compressed in the crankcase compartments andtransferred to the cylinders 12 by a loop charging system using piston controlled ports to open and close the transfer passages, as is well known in the art. An ignition system, not illustrated, supplies appropriately timed electrical pulses to fire one of the sparkplugs 19, 20, 21, 22 at every 90° of rotation of the crankshaft. The sparkplugs are arranged to fire in the order 19-21-20-22, though for the purposes of the present invention, it would be equally satisfactory to have them fire in the order 19-22-20-21. Following each piston power stroke, an exhaust port 23 in each cylinder wall is opened by the piston to discharge the exhaust gases into the tuned exhaust system formed in the exhaust side of the engine cylinder block 16.
    The tuned exhaust system, formed by the cylinder block 16 and the exhaust manifold cover 24, includes four equal length legs 25, one extending from each of the exhaust ports 23. The upper and lower pair of legs 25 each join to form two exhaust branches 26, also of equal length. The two branches 26 are joined by an exhaust trunk 27. Since the engine fires in an order alternating between one of the upper pair of cylinders and one of the lower pair of cylinders, the exhaust pressure pulses arising when an exhaust port 23 is opened will always have the same distance to travel to reach the exhaust port 23 of the cylinder next to be charged. With the engine operating in the design high speed range, the positive pressure pulse arrives at the cylinder being charged just prior to closure of the exhaust port to provide a supercharging effect.
    The tuned exhaust system also includes an exhaust outlet passage 28 connected to the lower end of the exhaust trunk 27 and an exhaust pipe 29 extending down from the lower end of the exhaust outlet passage 28 into the drive shaft housing 11. When a positive pressure or compression wave from one of the exhaust ports 23 arrives at the end of the exhaust pipe 29, a negative pressure or rarefaction wave is reflected back up the exhaust pipe 29. The length of the exhaust pipe 29 is designed to cause the rarefaction wave to reach the originating exhaust port when the piston in the corresponding cylinder is approximately at bottom dead center with the engine operating in the design high speed range. The rarefaction wave thus aids in scavenging the cylinder of exhaust gases. Because the exhaust outlet passage 28 connects to the bottom of the exhaust trunk 27, the effective length of the exhaust pipe is greater for the upper pair of cylinders than for the lower pair. Thus the lower cylinders will be optimally tuned at an engine speed somewhat higher than that for the upper cylinders.
    The exhaust system is arranged to be substantially defined by a cavity formed in the exhaust side of the die-cast cylinder block 16 with the manifold cover 24 completing the passageways. The cavity includes the upper and lower pair of legs 25, one leg connecting to the exhaust port 23 of each cylinder 12. Each pair of exhaust legs extend out from the exhaust ports 23, merging together and turning toward the forward or crankcase end of the cylinder block to partially form the pair of exhaust branches 26. The exhaust branches 26 turn upward and toward the rear or head end of the cylinder block and are joined by the exhaust 27 trunk extending vertically at the rear of the cylinder block 16. The exhaust outlet 28 connects to the bottom end of the trunk 27 and provides a passage exiting through the bottom of the cylinder block 16. The exhaust branches 26, the exhaust trunk 27, and the exhaust outlet 28 are all substantially the same depth. All of the corners in the system are smoothly rounded to provide an efficient flow path for the exhaust gases. The exhaust cavity is formed by the exhaust side die which is withdrawn in a direction perpendicular to the plane of the cylinders and by the bottom die which is withdrawn downward. Cooling cavities 30, also formed by the exhaust side die, surround the exhaust cavity and fill the loops formed by the exhaust passage to provide water cooling and prevent overheating of any portion of the cylinder block 16.
    The exhaust cavity is closed by the exhaust manifold cover 24 attached by bolts to the flat, machined surface on the exhaust side of the cylinder block 16. The manifold cover 24 includes a shallow channel mating with the exhaust cavity in the cylinder block 16 to form the exhaust manifold. Projections 31 and 32 formed on the manifold cover extend into the portions of the cavity forming the four legs 25 of the manifold to smoothly turn the exhaust flow from the exhaust ports 23.
    The manifold cover 24 also serves to close the water cooling cavities 30 formed in the cylinder block 16. A water jacket cover 33 is attached on the outside of the manifold cover 24 by the same bolts attaching the manifold cover to the cylinder block 16. A series of holes 34 through the manifold cover provides flow paths for the cooling water to assure water flow over essentially all of the external surfaces of the exhaust manifold.



    Then later with diverter,

    BACKGROUND AND SUMMARY This invention relates to a marine engine exhaust system.
    It is common to employ a vertical drive shaft in-line two-stroke cycle engine in the power head of an outboard marine propulsion system. With this type of engine, it is known to provide an exhaust flow path in which exhaust from the upper cylinders is collected and routed through an exhaust passage to a substantially vertical branch. Exhaust from the lower cylinders is collected and routed in a similar manner to a substantially vertical branch, which is in line with the branch from the upper cylinders and which receives exhaust therefrom. The lower branch thus forms a common exhaust passage which receives exhaust from all cylinders, which exhaust is then routed downwardly into an exhaust collection cavity provided in the upper end of the drive shaft housing.
    By design, this arrangement provides effective exhaust tuning at high engine speeds to increase horsepower. However, operation at low speed is not satisfactory because certain exhaust ports effectively are supplied with a negative pulse, which detracts greatly from performance under low speed and idle conditions. Most notably, this design provides a rough idle and a decrease in low-end horsepower.
    One solution to this problem has been to cut off the supply of fuel to certain cylinders at low engine speed. In a four cylinder engine, for example, the number three and four cylinders continue to receive fuel, while the fuel supply to the number one and two cylinders is cut off. This eliminates negative pulses at the exhaust ports of the number three and four cylinders, which provides smoother idle operation. The result, of course, is a substantial decrease in available horsepower at low speed operation.
    It is an object of the present invention to solve the above problems, and to provide an engine having satisfactory operation at both high and low engine speeds by providing proper exhaust tuning. The invention is utilized in connection with an internal combustion engine including two or more cylinders, first and second exhaust passages and an exhaust discharge. Each exhaust passage receives exhaust from at least one of the cylinders, and the exhaust passages are arranged so as to be in communication with each other. In accordance with the invention, the improvement to such a structure comprises a third exhaust passage having an inlet in communication with one of the first or second exhaust passages, and valve means actuable between an open position and a closed position for selectively controlling the flow of exhaust through the third exhaust passage. The valve means in its open position allows flow of exhaust through the third exhaust passage and cuts off exhaust flow through the second passage. In its closed position, the valve means allows no flow of exhaust through the third passage and restores communication between the first and second passages, so that exhaust flowing through the first passage merges with exhaust flowing through the second passage prior to discharge. The third passage preferably has an outlet in communication with the exhaust discharge. The valve means is preferably disposed at or adjacent to the inlet to the third exhaust passage, and when open directs substantially all exhaust upstream thereof into the third passage and cuts off flow of such exhaust into the downstream passage. Actuator means is provided for moving the valve means between its open and closed positions. In one embodiment, the actuator means comprises a solenoid having a retractable and extendable plunger, which is operatively connected to a valve actuating arm for moving the valve between its open and closed positions. The solenoid is preferably interconnected with means outputting a signal proportional to engine speed. In this manner, the valve is opened at low engine speeds to provide proper exhaust tuning and improved operation of the engine, and closed at higher rpms.
    BRIEF DESCRIPTION OF THE DRAWINGS The drawings illustrate the best mode presently contemplated of carrying out the invention.
    In the drawings:
    FIG. 1 is an elevation view of a four cylinder two-stroke cycle outboard marine engine with its outer cover plate assembly removed, showing the exhaust path thereof and the diverter valve of the invention disposed therein;
    FIG. 2 is a partial elevation view somewhat similar to FIG. 1, showing a portion of the engine of FIG. 1 with its outer cover plate assembly in place and showing the third exhaust passage in section;
    FIG. 3 is a sectional view taken generally along line 3--3 of FIG. 2, with the diverter valve of the invention in its open position; and
    FIG. 4 is a view similar to FIG. 3, showing the diverter valve of the invention in its closed position.
    DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 partially illustrates the block, shown at 10, of a vertical drive shaft two-stroke cycle four cylinder internal combustion engine. As shown in FIG. 1, a cover assembly is removed so as to expose the exhaust discharge system of the engine.
    A pair of upper exhaust ports 12, 14, are formed in block 10 to receive exhaust gases from a pair of upper cylinders, as is known. A branch passage 16 routes exhaust from port 12, and a branch passage 18 routes exhaust from port 14. Branch passages 16 and 18 merge into an exhaust passage which includes a substantially vertical portion 22 and a horizontal portion 24, which routes exhaust to an upper vertical passage 26 to direct the exhaust downwardly.
    In a similar manner, block 10 includes a pair of lower exhaust ports 28, 30 in communication with a pair of lower cylinders. Branch passages 32, 34 merge into a passage including a vertical portion 38 and a horizontal portion 40, which leads to a lower vertical passage 42 for discharging exhaust downwardly. As shown, upper vertical passage 26 and lower vertical passage 42 are in communication with each other.
    Exhaust passing through passage 42 is discharged through an exhaust discharge outlet 44 into a cavity 46 formed in the upper portion of a drive shaft housing 48. As is known, the resonation of exhaust pulses within cavity 46 provides exhaust tuning to the engine by assisting in scavenging exhaust gases from the cylinders. This type of system is described and discussed in detail in Hale U.S. Pat. No. 4,484,442, hereby incorporated by reference.
    The exhaust discharge construction as described above is generally designed to provide satisfactory exhaust tuning at high speed operation. However, it has been found that, at low speed operation, this construction does not provide satisfactory exhaust tuning, resulting in rough operation during idle and inadequate acceleration at low speeds.
    With reference to FIG. 2, a cover assembly 50 is shown in place on block 10. Cover assembly 50 includes an exhaust passage 52 for providing an alternate route of discharge of exhaust from upper vertical exhaust passage 26. An inlet 54 is formed in cover assembly 50 for providing communication between exhaust passage 52 and upper vertical exhaust passage 26. This construction is clearly illustrated in FIGS. 3 and 4. Exhaust passage 52 is oriented so as to extend along a longitudinal axis substantially parallel to that of lower vertical exhaust passage 42. Exhaust passage 52 is provided with an outlet 56 for discharging exhaust flowing therethrough into cavity 46 of drive shaft housing 48.
    A valve mechanism is provided for selectively controlling passage of exhaust into exhaust passage 52. The valve mechanism includes a valve flap 58 mounted to a pivotable rod 60. As best shown in FIGS. 1 and 2, rod 60 is pivotably mounted at its ends so as to extend through upper vertical exhaust passage 26 and leftwardly therefrom. Flap 58 is disposed adjacent inlet 54 to passage 52, and adjacent upper vertical passage 26.
    Flap 58 is movable between an open position, as shown in FIG. 3, and a closed position as shown in FIG. 4. In its open position, flap 58 directs exhaust from upper vertical exhaust passage 26 into exhaust passage 52, cutting off the flow of exhaust from upper vertical exhaust passage 26 into lower vertical exhaust passage 42. In this manner, all exhaust from the upper two cylinders is routed from upper vertical exhaust passage 26 into exhaust passage 52 through inlet 54. When flap 58 is in its closed position, all flow of exhaust through inlet 54 into passage 52 is prevented, allowing exhaust flowing through upper vertical exhaust passage 26 to merge with exhaust flowing through lower horizontal exhaust passage 40 for discharge through lower vertical exhaust passage 42.
    An actuator mechanism, shown generally at 62, is provided for controlling the position of flap 58. Actuator mechanism 62 includes an actuator arm 64 mounted to pivotable rod 60, and a solenoid 66 including an extendable and retractable plunger 68 which acts on actuator arm 64. When solenoid plunger 68 is in its retracted position, as shown in FIG. 3, flap 58 is in its open position for routing exhaust into passage 52. A torsion spring or other such biasing means may be associated with pivotable rod 60 for biasing flap 58 toward its open position. When solenoid plunger 68 is in its extended position, as shown in FIG. 4, actuator arm 64 is forced downwardly so as to move flap 58 to its closed position, thus cutting off flow of exhaust into exhaust passage 52.
    Solenoid 66 is mounted to the exterior of cover assembly 50, and is actuated in response to a signal indicative of engine speed. For example, solenoid 66 may satisfactorily be interconnected with a sensing device linked to the ignition system, which outputs a signal responsive to engine speed.
    At low speed operation, solenoid plunger 68 is in its retracted position so as to allow flap 58 to attain its open position, thus routing exhaust into passage 52. With this operation, proper exhaust tuning at low speed is provided by preventing exhaust from the upper two cylinders from merging with exhaust from the lower two cylinders prior to discharge into exhaust cavity 46. This operation in effect provides two separate engines operating independently of each other, eliminating the effect of exhaust pulses from the upper cylinders on the lower cylinders, and vice versa. This results in smoother operation at idle, and increased horsepower at low engine speeds. At high speed operation, solenoid plunger 68 is extended so as to move flap 58 to its closed position. Exhaust from the upper two cylinders is then merged with exhaust from the lower two cylinders for discharge into exhaust cavity 46, providing satisfactory exhaust tuning at high speed operation.
    A wall 70 formed in drive shaft housing cavity 46 separates exhaust outlets 44 and 56 and effectively extends the length of passages 42 and 52. It is to be appreciated that, when valve flap 58 is open so that exhaust passes through both passages 42 and 52, exhaust pulses from exhaust discharged from exhaust passage 52 must travel downwardly through drive shaft housing cavity 46 and then back upwardly before such pulses can have any possible effect on the lower cylinders. By this time, the strength of such pulses has been weakened sufficiently so as to have little, if any, effect on operation of the lower cylinders. The same holds true for any effect which exhaust discharged through passage 42 may have on operation of the upper cylinders.
    While the invention has been described with reference to an in-line four cylinder vertical drive shaft two-stroke cycle engine, it is to be appreciated that the invention is not limited to such an application, and may be utilized in connection with any orientation of a two- or four-stroke cycle engine having any number of cylinders. For example, in a three cylinder two-stroke cycle engine with a vertical drive shaft, each of the upper two cylinders could be provided with its own diverter valve and its own separate exhaust passage, such as shown at 52, for providing an alternate discharge of exhaust from such cylinders at low engine speeds.
    Various alternatives and modifications are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.


  2. #2
    Join Date
    Feb 2015
    Location
    Ontario
    Posts
    8,091
    Thanks (Given)
    205
    Thanks (Received)
    321
    Likes (Given)
    1921
    Likes (Received)
    2005
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    diagram from first design
    Attached Thumbnails Attached Thumbnails screenshot.png  

  3. #3
    Join Date
    Dec 2001
    Posts
    9,503
    Thanks (Given)
    23
    Thanks (Received)
    270
    Likes (Given)
    191
    Likes (Received)
    1975
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    yack yack.......yes....... it works...... thank you....

  4. #4
    Join Date
    Dec 2001
    Posts
    9,503
    Thanks (Given)
    23
    Thanks (Received)
    270
    Likes (Given)
    191
    Likes (Received)
    1975
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    kinda when I saw my first LOOOPER.....went home .... looking ..... how can I mod my 44 cid merc...Thanks

  5. #5
    Join Date
    Feb 2015
    Location
    Ontario
    Posts
    8,091
    Thanks (Given)
    205
    Thanks (Received)
    321
    Likes (Given)
    1921
    Likes (Received)
    2005
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    ... back to sleep then

  6. #6
    Join Date
    Dec 2001
    Posts
    9,503
    Thanks (Given)
    23
    Thanks (Received)
    270
    Likes (Given)
    191
    Likes (Received)
    1975
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    What I call goose neck....

  7. #7
    Join Date
    May 2001
    Location
    Ga
    Posts
    1,788
    Thanks (Given)
    1
    Thanks (Received)
    28
    Likes (Given)
    22
    Likes (Received)
    216
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    With all that technology you’d think they could have figured out how to run it on all cylinders at idle . The idle on two and run on four was just an ugly band aid in my opinion . That engine definitely makes the mercury list of most undesirable engines they ever built . Hf...

  8. #8
    Join Date
    Jun 2007
    Location
    Singapore/Melbourne/Italy
    Posts
    9,097
    Thanks (Given)
    1008
    Thanks (Received)
    354
    Likes (Given)
    4297
    Likes (Received)
    1953
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(s)
    if they just had cheap efi back then....

  9. #9
    Join Date
    Feb 2004
    Location
    Palm City Fla
    Posts
    7,197
    Thanks (Given)
    0
    Thanks (Received)
    831
    Likes (Given)
    0
    Likes (Received)
    6491
    Mentioned
    13 Post(s)
    Tagged
    1 Thread(s)
    FuMPulse , Well .. that didn't go where you expected ...

    The Invention .. Patent lawyer-speak for can't copy this POS ..

  10. #10
    Join Date
    Apr 2001
    Location
    Gothenburg, Sweden
    Posts
    7,057
    Thanks (Given)
    143
    Thanks (Received)
    60
    Likes (Given)
    76
    Likes (Received)
    334
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by half fast View Post
    With all that technology you’d think they could have figured out how to run it on all cylinders at idle . The idle on two and run on four was just an ugly band aid in my opinion .
    Or how to run it above 5300 rpm without killing itself due to resonance...

    Quote Originally Posted by half fast View Post
    That engine definitely makes the mercury list of most undesirable engines they ever built . Hf...
    I think it did quite well in the walleye market.

    I would take a Yamaha V4 over it in a heartbeat, though.
    Markus' Performance Boating Links:
    www.toastedmarshmallow.com/performance

  11. #11
    Join Date
    Jun 2007
    Location
    Singapore/Melbourne/Italy
    Posts
    9,097
    Thanks (Given)
    1008
    Thanks (Received)
    354
    Likes (Given)
    4297
    Likes (Received)
    1953
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Markus View Post
    Or how to run it above 5300 rpm without killing itself due to resonance...



    I think it did quite well in the walleye market.

    I would take a Yamaha V4 over it in a heartbeat, though.
    yamaha smarter, copy evinrude and improve it...

  12. #12
    Join Date
    Feb 2015
    Location
    Ontario
    Posts
    8,091
    Thanks (Given)
    205
    Thanks (Received)
    321
    Likes (Given)
    1921
    Likes (Received)
    2005
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    rckid74 ,

    Something's wrong here , still a couple in this area and they do run well.

    They'll out muscle a Yamaha low and mid from what I've seen of them.

  13. #13
    Join Date
    Apr 2001
    Location
    Michigan
    Posts
    15,422
    Thanks (Given)
    214
    Thanks (Received)
    475
    Likes (Given)
    7697
    Likes (Received)
    4259
    Mentioned
    1 Post(s)
    Tagged
    1 Thread(s)
    I loved mine. It was great for skiing and fishing. Still see manyof them on the water.

  14. #14
    Join Date
    Feb 2015
    Location
    Ontario
    Posts
    8,091
    Thanks (Given)
    205
    Thanks (Received)
    321
    Likes (Given)
    1921
    Likes (Received)
    2005
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Yup , pull stumps all day long and never blow a head gasket.

    Someone else mentioned over 6000 they have a resonance.

  15. #15
    Join Date
    Dec 2001
    Posts
    9,503
    Thanks (Given)
    23
    Thanks (Received)
    270
    Likes (Given)
    191
    Likes (Received)
    1975
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    No head gasket is a good thing..... but bad too..... harder to bore.....and the sleaves move to the crank for company.......If you have them set Right....low idle.... they don't chuck pinions....

Page 1 of 3 1 2 3 LastLast

Similar Threads

  1. merc water pressure gauge part# to match older merc gauges??
    By syclone01 in forum General Boating Discussion
    Replies: 3
    Last Post: 09-09-2016, 10:48 PM
  2. Lifeline jacket, merc manual, merc lifting ring, LU flush adapter
    By John S in forum Misc. Parts and Accessories
    Replies: 5
    Last Post: 07-13-2016, 02:21 PM
  3. Mercury Tech: 50hp 4cyl Merc vs. 70hp 3cyl Merc vs. ??? - Weight vs HP - Opinions??
    By Steve2ManyBoats in forum Technical Discussion
    Replies: 6
    Last Post: 02-22-2016, 07:25 AM
  4. Replies: 17
    Last Post: 01-30-2016, 12:35 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •