US3599594A

US3599594A - Sound and vibration isolating mount for an outboard motor

Info

Publication number: US3599594A
Application number: US856990A
Authority: US
Inventors: Dale L Taipale
Original assignee: Outboard Marine Corp
Current assignee: Outboard Marine Corp
Priority date: 1969-09-11
Filing date: 1969-09-11
Publication date: 1971-08-17
Anticipated expiration: 1988-08-17
Also published as: CA920000A

Abstract

Disclosed herein is a sound and vibration isolating arrangement for an outboard motor having a marine propulsion unit mounted rearwardly of the steering axis of the outboard motor. The mounting arrangement includes a pair of mounts secured to the propulsion unit in a vertically spaced relation approximately in alignment with the neutral or roll axis of the propulsion unit and rearwardly of or behind the drive shaft. Each mount includes a crossbar which is supported by a resilient bushing within a casing and which has ends extending outwardly from the casing transversely to the direction of motion of the propulsion unit.

Description

United States Patent [72] Inventor Dale L. Taipale Waukegan, Ill.

[21 Appl. No. 856,990 [22] Filed Sept. 11,1969 [45] Patented Aug. 17, 1971 I73 I Assignee Outboard Marine Corporation Waukegan, lll.

[54] SOUND AND VIBRATION ISOLATING MOUNT FOR AN OUTBOARD MOTOR 15 Claims, 7 Drawing Figs.

[52] US. Cl... 115/17 [51] Int. Cl ....B63h 21/26 [50] Field ot'Search 115/18, 17;

[56] References Cited UNITED STATES PATENTS 2,630,991 3/l 953 Long 248/4 ll5/l8 248/15 2,740,368 4/1956 lrgensetal.... 3,432,127 3/1969 Philipp Primary Examiner-Andrew H. Farrell Attorneyslohn W. Michael, Gerrit D. Foster, Bayard H.

Michael, Paul R. Puerner, Joseph A. Gemignani, Andrew 0. Riteris, Spencer B. Michael and Robert E. Clemency ABSTRACT: Disclosed herein is a sound and vibration isolating arrangement for an outboard motor having a marine propulsion unit mounted rearwardly of the steering axis of the outboard motor. The mounting arrangement includes a pair of mounts secured to the propulsion unit in a vertically spaced relation approximately in alignment with the neutral or roll axis of the propulsion unit and rearwardly of or behind the drive shaft. Each mount includes a crossbar which is supported by a resilient bushing within a casing and which has ends extending outwardly from the casing transversely to the direction of motion of the propulsion unit.

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ATTORNI1$ SOUND AND VIBRATION ISOLATING MOUNT FOR AN OUTBOARD MOTOR BACKGROUND OF THE INVENTION The isolation from a boat hull ofv sound and vibration emanating from a propulsion unit of an outboard motor has conventionally been accomplished by using a plurality of mounts as shown in U.S. Pat. Nos. 2,740,368, 2,910,007, 2,91 1,963 and 3,002,489.

SUMMARY OF THE INVENTION The sound and vibration isolation mounting arrangement of this invention utilizes one pair of resilient mounts to isolate the I v vibrations due to violent motions of the outboard motor.

Other objects and advantages of the invention will become apparent from the following description when read in connection with the accompanying drawings, in which:

FIG. I is a side view in elevation of an outboard motor with portions broken away to show the sound and vibration mounting arrangement.

FIG. 2 is a top view of a portion of the outboard motor partly broken away to show the upper mount.

FIG 3 is a side view in section of the upper mount in the propulsion unit.

FIG. 4 is an exploded view in perspective of the upper mount and upper yoke.

FIG. 5 is a top view in section of the lower mount positioned within the drive shaft housing of the propulsion unit.

FIG. 6 is a side view in section of the lower mount.

FIG. 7 is an exploded view in perspective of the lower mount, supporting bracket and lower resilient snubber.

DESCRIPTION OF THE INVENTION drive shaft housing 30 having a drive shaft indicated at 32 and a lower unit gearcase 34. As will be explained in greater detail hereinafter, the drive shaft housing 30 also includes a mounting opening which is shown at 36 in FIG. I and which is located somewhat above the gearcase 34.

The propulsion unit 24 is supported for pivotal steering movement on the swivel bracket 16 by means of a kingpin assembly 38 which includes a pivot shaft 40 journaled in the bushings 22 provided in the swivel bracket aperture 20. Secured to the upper end of the pivot shaft 40 is an upper yoke 42 having a forwardly extending steering bracket 44 and rearwardly extending arms 46. Secured to the lower end of the pivot shaft 40 is a lower support yoke 48 having a splined aperture 50 mounted on a splined portion 52 on the pivot shaft 40 and retained thereon by a nut 54.

The propulsion unit 24 is subject to various vibrations including torsional or oscillatory vibrations set up by the power impulses of the'engine in the power head 26. These torsional vibrations occur about a neutral or roll axis which is generally indicated at 56 and which extends approximately vertically through the center of mass of the propulsion unit 24 and is generally spaced from the drive shaft 32 on the same side as the pistons 28 in the cylinder block. Forward and reverse thrust forces are also set up in the propulsion unit 24 by the motion of a propeller 58 mounted on a stub shaft 60 in the lower unit gearcase 34. The stub shaft 60 is driven off of the drive shaft 32 by means of a forward and reversing gear assembly generally indicated at 62.

In accordance with the invention, the vibrations set up in the propulsion unit 24 are isolated from the boat hull and the propulsion thrust is simultaneously transmitted from the propulsion unit 24 to the swivel bracket 16 and then to the boat hull by means including vertically spaced upper and lower

resilient mounts

64 and 66 connected between the propulsion unit 24 and the kingpin assembly 38 rearwardly of the drive shaft indicated at 32. The upper mount 64 and the lower mount 66 also provide the principal support for the weight of the propulsion unit 24 and transmit the thrust force of the propeller 58 to the boat hull. When a forward thrust force is produced by the propeller 58, the principal force acting on the upper mount 64 will occur on the forward side and on the lower mount 66 on the aft side.

More particularly, the upper mount 64, as seen in FIGS. 2, 3 and 4, includes a bushing 68'formed from a resilient material such as natural rubber and an insert or crossbar 70 having at each end a threaded mounting hole 72. The crossbar 70 is encircled or embedded in the bushing 68 and extends outwardly from each end of the bushing 68. Means are provided for connecting the upper mount 64 to the propulsion unit 24 in the form of a casing 74 having mounting holes 76 which encloses and is secured to the outer surface of the bushing 68. Bolts 78 are inserted through the mounting holes 76 in the casing 74 and are screwed into the threaded holes 79 provided in the drive shaft housing 30. The mount 64 is also connected to the yoke 42 by means of mounting screws 80 inserted through holes 82 provided at the ends of arms 46 and screwed into holes 72 in the crossbar 70. The crossbar 70 extends transversely to the direction of thrust of the propulsion unit and approximately transversely to the neutral axis 56.

It is desirable that the bushing 68 in the upper mount 64 be soft in order to damp vibrations emanating from the propulsion unit. This is accomplished by means of a number of holes 84 and L-shaped slots 85 provided in the bushing 68 in a generally parallel relation to the crossbar 70. The holes 84 are provided on the forward side of the bushing 68 and the L- shaped slots 85 are provided only on the upper and lower sides of the aft side of the bushing 68 since the principal thrust force on the upper mount 64 occurs on the forward side of the bushing 68.

The transmission of local vibrations from the power head 26 to the yoke 42 is prevented by means of a snubber sleeve 86 provided on the end ofeach of the arms 46. The sleeves 86 are formed from a resilient material such as Neoprene and act to prevent metal-to-metal contact between the power head 26 and the arms 46 of the yoke 42.

The lower mount 66, as seen in FIGS. 5,6 and 7, includes a resilient bushing 88 formed from a resilient material such as natural rubber and an insert or crossbar 90 having at each end mounting holes 92. The crossbar 90 is encircled or embedded in the bushing 88 and extends outwardly from each end of the bushing 88. A casing or sheel 94 encloses and is secured to the outer surface of the bushing 88 and is covered with a resilient shield or coating 96. The lower mount 66 is connected to the lower end of the drive shaft housing by being positioned in the opening 36 provided in the drive shaft housing 30. The crossbar 90 extends transversely to the direction of thrust of the propulsion unit and approximately transversely to the neutral axis 56.

Means are provided to limit transverse movement of the lower mount 66 in the opening 36 in the form of a flange 98 provided at one end of the opening 36 and a retainer plate 100 provided at the other end of the opening 36. The lower mount 66 is connected to the lower support yoke 48 by means of bolts 102 which are inserted through the mounting holes 92 in the crossbar 90 and nuts 104 which are screwed onto the bolts 102.

A snug fit is provided between the mount 66 and the housing 36 by means of a resilient shield 96 molded on the outersion unit. This is accomplished by means of a number of holes 106 and L-shaped slots 107 located in a generally parallel relation to the crossbar 90. The holes 106 are provided on the aft side of the bushing 88 and the slots 107 are provided only on the upper and lower portion of the forward side of the bushing 88 since the principal thrust occurs on the aft side of the bushing 88.

In a preferred embodiment the lower mount 66 has twice the spring rate as the upper mount 64. If the mounts are used to'isolate vibrations in a 85 or 1 l5-hp. motor, the lower mount 66 can have a spring rate of approximately 20,000 lbs./in. and the upper mount 64 can have a spring rate of 10,000 lbs./in.

Due to the desirable softness of the

bushings

68 and 88 on the reverse thrust side, means are provided to mechanically connect the drive shaft housing 30 to the swivel bracket 16 to minimize deflection of the propulsion unit 24 with respect to the swivel bracket 16 when reverse thrust is produced by the propeller 58. Such means, as shown in FIG. his in the form of strap 108 which encircles the swivel bracket 16 is secured to the drive shaft housing 30 by pin 1 10.

Means are also provided for preventing transmission of mechanical vibration between the lower support bracket or yoke 48 and the lower portion of the drive shaft housing 30 in the form of a resilient snubber 112 positioned between the yoke 48 and the outer surface of the drive shaft housing 30. The lower snubber 112 is formed from a resilient material such as Neoprene and has a pair of enlarged sections 1 l4 positioned to engage the drive shaft housing 30. The snubber 112 is secured to the yoke 48 by means of brackets 116 embedded in each end of the snubber and have apertures 118. The brackets 116 are positioned on the bolts 102 between the end of the crossbar 90 and the yoke 48 to locate the snubber between the yoke 42 and the drive shaft housing 30.

Various of the features of the invention are set forth in the following claims.

What I claim ls:

1. The combination in an outboard motor of a transom bracket, a swivel bracket mounted on said transom bracket for vertical tilting movement, a propulsion unit, a crossbar disposed transversely to the direction of motion of said propulsion unit and connected to one of said swivel bracket and said propulsion unit, and a resilient bushing encircling said crossbar and connected to the other of said swivel bracket and propulsion unit.

2. A combination according to claim I wherein said crossbar is connected to said swivel bracket and said bushing is connected to said propulsion unit.

3. A combination according to claim 1 wherein said propulsion unit includes a drive shaft housing having'a vertically disposed drive shaft, said crossbar being disposed rearwardly of said drive shaft.

4. A combination according to claim 1 including a casing enclosing said bushing, said casing being connected to said propulsion unit.

5. A combination according to claim 1 including a second crossbar disposed transversely to the direction of motion of said propulsion unit and connected to one of said swivel bracket and said propulsion unit, and a second resilient bushing encircling said second crossbar and connected to the other of said swivel bracket and said propulsion unit.

6. A combination according to claim 5 wherein said crossbars are connected to said swivel bracket and said bushings are connected to said propulsion unit.

7. A combination according to claim 5 including a casingenclosing each of said bushings, said casings being connected to said propulsion unit.

8. A combination according to claim 5 wherein said propulsion unit includes a drive shaft housing having a drive shaft, said crossbars being disposed rearwardly of said drive shaft.

9. A combination according to claim 8 wherein one of said casings is connected to one end of said drive shaft housing and the other of said casings is connected to the other end of said drive shaft housing.

10. A combination according to claim 5 wherein each of said bushings includes a number of holes located parallel to said crossbar.

11. A combination according to claim 5 wherein one of said bushings has twice the spring rate of the other of said bushings.

12. A combination according to claim 8 including means for preventing transmission of mechanical vibrations from said drive shaft housing to said swivel bracket.

13. The combination in an outboard motor of a transom bracket, a swivel bracket mounted on said transom bracket for vertical tilting movement, a propulsion unit including a power head, a drive shaft housing including a drive shaft, and a lower unit gearcase, means for pivotally mounting said propulsion unit on said swivel bracket for steering movement rearwardly of said swivel bracket and including an upper and a lower yoke, an upper resilient mount connecting said propulsion unit to said upper yoke and a lower resilient mount connecting said propulsion unit to said lower yoke, each of said mounts including a bushing and a crossbar embedded in said bushing and disposed transversely to the direction of motion of said propulsion unit.

14. A combination according to claim 13 wherein said propulsion unit includes a neutral axis extending through said power head, drive shaft housing and lower unit gearcase in a spaced relation to said drive shaft, said mounts being positioned substantially transversely to said neutral axis.

15. A combination according to claim 13 including means for mechanically connecting said drive shaft housing to said swivel bracket to minimize deflection onreverse thrust of said propulsion unit.

Claims

2. A combination according to claim 1 wherein said crossbar is connected to said swivel bracket and said bushing is connected to said propulsion unit.

3. A combination according to claim 1 wherein said propulsion unit includes a drive shaft housing having a vertically disposed drive shaft, said crossbar being disposed rearwardly of said drive shaft.

7. A combination according to claim 5 including a casing enclosing each of said bushings, said casings being connected to said propulsion unit.

15. A combination according to claim 13 including means for mechanically connecting said drive shaft housing to said swivel bracket to minimize deflection on reverse thrust of said propulsion unit.