US 3209534 A
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Description (OCR text may contain errors)
Oct. 5, 1965 R. c. STALLMAN OUTBOARD MOTOR EXHAUST SYSTEM 4 Sheets-Sheet 1 Filed May 9, 1963 INVENTOR. RICHARD C. STALLMAN ATTORNEYS Oct. 5, 1965 R. c. STALLMAN OUTBOARD MOTOR EXHAUST SYSTEM 4 Sheets-Sheet 2 Filed May 9, 1963 V IY/IIIIIIIIIIZI I I 1 4 n v I i F/G. 7 RICHARD g ffmm ATTORNEYS Oct. 5, 1965 R. c. STALLMAN OUTBOARD MOTOR EXHAUST SYSTEM 4 Sheets-Sheet 3 Filed May 9, 1965 INVENTOR. RICHARD C. STALLMAN ATTORNEYS Oct. 5, 1965 R. c. STALLMAN OUTBOARD MOTOR EXHAUST SYSTEM 4 Sheets-Sheet 4 Filed May 9, 1963 F/G /Z Ill III) INVENTOR RICHARD C. STALLMAN United States Patent 3,209,534 OUTBOARD MOTOR EXHAUST SYSTEM Richard C. Stallman, 392 De Anza Ave, San Carlos, Calif. Filed May 9, 1963, Ser. No. 279,206 4 Claims. (Cl. 60-3554) This invention relates generally to an exhaust system for outboard motors and more particularly to an exhaust system for outboard jet motors.
In my United States Patent No. 3,082,732, there is described a water jet pump adapted to be attached to outboard motors to form outboard jet motors.
Early exhaust silencers for outboard motors exhausted to the atmosphere and utilized a series of baflles which served to break up the sound waves. In so doing, however, they caused gas flow restriction and gave rise to back pressure. The more efficient the silencing of the system, the higher the back pressure. In high speed two-cycle engines as compared to four-cycle engines, sound suppresion becomes more diflicult and called for higher gas restrictions with its attendant higher back pressures. High increased back pressure lowered the engine efliciency and output power. Recently, outboard motor exhaust gases have been directed under water into the slip stream behind the propeller. The exhaust gases are mixed with the water so that the water absorbs the sound waves to silence the exhaust system.
It is a general object of the present invention to provide an improved engine exhaust system.
It is another object of the present invention to provide an improved engine exhaust system for use with outboard water jet motors.
It is a further object of the present invention to provide an exhaust system in which the water jet stream from the motor aspirates the exhaust gases and absorbs the sound waves as the exhaust gases are mixed in the jet stream.
It is still a further object of the present invention to provide an engine exhaust system in which the exhaust manifold outlet cooperates with the water jet stream from a Water jet motor to aspirate and silence the exhaust noises.
It is a further object of the present invention to provide an outboard jet motor including a reversing gate which cooperates with the manifold for silencing during reverse operation.
It is a further object of the invention to provide an outboard jet motor in which the exhaust manifold not only cooperates with the jet stream to be aspirated thereby but also serves as a vane to direct the jet stream.
These and other objects of the invention will become more clearly apparent from the following description when taken in conjunction with the accompanying drawmgs.
Referring to the drawing:
FIGURE 1 shows a portion of a boat and outboard water jet motor;
FIGURE 2 is a side elevational view, partly in section, of a water jet motor incorporating the exhaust system of the present invention;
FIGURE 3 is a top view of the water jet motor of FIG- URES 1 and 2;
FIGURE 4 is a partial sectional view taken along the line 4-4 of FIGURE 3;
FIGURE 5 is a partial sectional view taken along the line 5-5 of FIGURE 3;
FIGURE 6 is a partial sectional view taken along the line 6-6 of FIGURE 3;
FIGURE 7 is a sectional view taken along the line 7-7 of FIGURE 3;
3,209,534 Patented Get. 5, 1965 FIGURE 8 is the rear portion of the outboard jet motor of FIGURES 1-7 with the reverse gate disposed in the reverse position;
FIGURE 9 is a view showing the rear of the outboard jet motor shown in FIGURE 8;
FIGURE 10 shows a view of the rear portion of a jet motor having a modified exhaust manifold;
FIGURE 11 is a sectional View taken along the line 11-11 of FIGURE 10;
FIGURE 12 is a top view, partly broken away, to show the internal portions of the outboard jet motor shown in FIGURE 10; and
FIGURE 13 is a rear view of the outboard jet motor as shown in FIGURE 12 and rotated to the vertical.
In FIGURE 1, an outboard jet motor 11 is shown attached to a boat 12 in the normal manner with suitable clamps 13. The motor 11 includes an internal combustion engine portion 14 which drives a jet water pump 16 which may be of the type described in US. Patent No. 3,082,732. It is observed that the jet pump replaces the standard outboard motor gear box and propeller section. Water enters the jet pump through the intake section 17, flows through the casing 18, is collected by the recuperator 19 and expelled to the rear through jet nozzle 20.
The intake section 17 includes an upper portion 21, FIGURE 2, which is connected to the recuperator section and which serves to house a mixed flow impeller 22. The impeller is driven by a shaft 23 which may be splined or the like at its upper end (not shown) to engage the power head of the internal combustion engine in a normal manner.
The impeller 22 is provided with helically arranged blades or vanes 10 formed integral with a hub 15. The outer edges of the vanes define a surface of revolution which matches the taper of the cooperating portion 21 of the intake section. When the impeller is driven by the engine, water is pulled into the pump casing and forced into the recuperator section 19. The centrifugal forces due to the spinning of the impeller serve to drive the water into the spiral-shaped recuperator section, shown more clearly in FIGURE 3. The water then flows through the jet nozzle designated generally by the numeral 27 in FIGURE 3. The recuperator, in the form of an ever increasing spiral, gathers the spinning water from the impeller in an orderly fashion and directs it into the nozzle 20. The jet nozzle is provided with one or more vales 41, FIGURE 2, which serve to guide the jet stream in the nozzle so that it is expelled from the small end 42 of the nozzle in an hydraulically el'ficient manner.
The shaft 23 is supported in a bearing 32 carried in the bearing housing. The bearing housing is suitably attached to the recuperator.
Referring more particularly to FIGURE 2, there is shown the lower portion of the exhaust chamber of manifold 36 of the internal combustion engine.
There is formed about the recuperator 19 and nozzle 20 an exhaust manifold. Referring to the figures, the manifold is formed by an integral casting which, together with the recuperator and nozzle, form the chamber.
The exhaust gases in the outboard motor chamber travel downwardly into the manifold in the recuperator casting, as indicated by the arrows 44, into the exhaust manifold. The exhaust manifold continues in a rearward direction along one side of the nozzle to a point near its end. The manifold is then wrapped around the nozzle, in the form of a shroud, to encircle approximately the upper half of the nozzle. The shape and extent of the exhaust manifold can best be seen by an examination of the sectional views of FIGURES 4 through 7.
manifold as described above.
The exhaust gases are then directed outwardly, as shown more clearly in FIGURE 2 by the arrow 49, Where they meet the water jet stream, represented by the plurality of arrows 51. It is observed that the water jet completely covers the open end of the manifold. The high velocity water jet stream flowing past the exhaust manifold opening will serve to aspirate the exhaust gases to lower the pressure in the exhaust manifold. The back pressure in the engine is below normal back pressure which would be obtained if the engine were opened directly to the surrounding atmosphere. This increases the efiiciency of the motor. Furthermore, the sound or shock waves of the engine exhausts are absorbed in the water stream and the engine is efficiently silenced.
A reverse gate may be suitably pivoted at the nozzle of the integral bosses 61, FIGURE 8, formed on either side thereof. The gate is pivoted about the point 62 whereby it may be moved to the position shown in FIG- URE 1 for forward travel with the jet stream cooperating with the exhaust manifold as previously described. To reverse the direction of the thrust, the gate is raised whereby it covers the jet nozzle as shown in FIGURE 8. The water jet stream then engages the reversing gate to reverse its direction, and consequently the thrust direction. The reversing gate is so formed as to have an annular ring 72 at the upper portion thereof which cooperates with the shroud of the exhaust manifold to reduce the exhaust passage to form a restricted passage 73. This serves to silence the engine in operation of the motor in reverse. The restricted exhaust passage also results in increased back pressure; however, in general, maximum efficiency is not required when operating a boat in reverse.
It is further observed that the reverse gate is pivoted about a point which is above its geometric center 78, whereby the water jet stream provides a component of force which acts to rotate the gate upwardly to maintain the gate in its reverse position.
In order to shift out of reverse, the engine is brought down to a slow speed or to idle, thus reducing the water pressure, and the gate is then shifted to the disengaged position. A small spring detent (not shown) is suflicient to maintain the hand lever 77 in its forward position. This is due to the fact that in the forward position, the control rod 74 center line coincides with the lever pivot 77 center line. This essentially locks the gate in its forward position whereby a small detent may be employed.
In the embodiment just described, it is seen that in reverse, the exhaust gases are not mixed in the jet stream but rather flow through a restricted opening which suppresses the sound waves. In the embodiment shown in FIGURES -13, there is provided an exhaust manifold 82 which is continuously in the water jet stream whether the boat is operated in the forward or reverse direction. This exhaust manifold serves also the function of guiding the water flow in the nozzle.
Referring more particularly to the figures, FIGURE 10 is a side elevational view showing a modified nozzle; FIGURE 11 is a view taken along the line 11-11 of FIGURE 10; FIGURE 12 is a top view, partly broken away to show the exhaust outlet; and in FIGURE 13, there is shown a rear view.
The exhaust manifold includes a portion 81 which cooperates to receive the gases from the engine exhaust The exhaust manifold 82 projects downwardly into the nozzle and provides an opening such that the exhaust gases travel down into the exhaust manifold to the outlet which is in the jet stream.
If desired, a splash guard 86 may be provided for preventing splashing of water when the boat is shifted from manifold outlet. This provides mixing and aspiration of the exhaust gases while operating the boat in either forward or reverse.
Thus, there has been provided an improved exhaust system for outboard water jet motors. The sound waves are so directed as to be absorbed by the jet stream which cooperates with the exhaust manifold to provide aspiration of the exhaust gases to lower the back pressure.
1. In an outboard jet motor of the type including an internal combustion engine connected to drive a water pump which jets the water through a jet nozzle comprising a pump having an intake, a mixed flow impeller serving to pump the water within the same, a spiral recuperator serving to recuperate the water being pumped by the mixed flow impeller and terminating in a nozzle which forms the jet stream, a means forming an exhaust manifold enveloping a portion of said nozzle, one end of said exhaust manifold serving to receive exhaust gases from the engine, and the other end of said exhaust manifold opening toward the jet stream and positioned to be closed by the jet stream whereby the exhaust gases are aspirated from the manifold and entirely mixed with the jet stream.
2. In an outboard motor of the type including an internal combustion engine connected to drive a water pump which jets the Water through a jet nozzle comprising a pump having an intake, a mixed flow impeller serving to pump the water into said intake, a spiral recuperator serving to recuperate the Water being pumped by the mixed flow impeller and terminating in a nozzle which forms a jet stream, means forming an exhaust manifold enveloping a portion of said nozzle, one end of said exhaust manifold serving to receive exhaust gases from the engine, the other end of said exhaust manifold being positioned to engage and be closed by the jet stream whereby the exhaust gases are aspirated from the manifold and mixed with the jet stream, a cup-shaped reversing gate pivotally mounted on said nozzle and adapted to have a first position in which the jet stream is free to flow past the same, and a second position in which the reversing gate engages the jet stream and restricts said other end of the exhaust, said reversing gate being mounted off center whereby the Water pressure in the reversed position serves to lock the gate in said position.
- 3. An outboard jet of the type adapted to be attached to an internal combustion engine comprising a jet nozzle, a water pump for pumping water into said nozzle to form a water jet stream, an exhaust manifold having one end arranged to receive the engine exhaust gases and another end disposed to exhaust the same, said other end being formed by a shroud which surrounds a portion of said nozzle to form an opening which opens towards the jet stream and which is positioned to be closed by the jet stream, said jet stream serving to aspirate the exhaust gases from said other end of said manifold and mix the same entirely in the jet stream.
4. An outboard jet of the type adapted to be attached to an internal combustion engine comprising a jet nozzle, a water pump for pumping water into said nozzle to form a water jet stream, an exhaust manifold having one end arranged to receive the engine exhaust gases and another end disposed to exhaust the same, said other end being formed by a shroud which surrounds a portion of said nozzle to form an opening which opens towards the jet stream and which is positioned to be closed by the jet stream whereby the jet stream aspirates the exhaust gases from said other end of the manifold and mixes the same in the jet stream, a cup-shaped reversing gate having a first position in which it does not engage the jet stream and a second position in which it engages the jet stream to reverse the direction of the same and at the same time cooperates with said other end of the exhaust manifold to provide a restricted passage, said cup-shaped reversing gate including an annular ring portion which cooperates with said other end of the exhaust manifold to form the restricted passage.
References Cited by the Examiner UNITED STATES PATENTS 6 3,090,346 5/63 Burgin 60-3555 3,105,353 10/63 Schulz 60-3555 3,111,108 11/63 Trotter 60-3554 FOREIGN PATENTS 932,548 11/ 47 France.
877,982 9/61 GreatBritain.
SAMUEL LEVINE, Primary Examiner.