BELT DRIVE SYSTEM

Abstract: A belt drive system (80) for counter rotating twin blades on a lawn mower is provided. The belt drive system (80) includes a belt (30), a drive pulley (10), two driven pulleys (12, 14), and an idler pulley (16). The belt (30) is preferably a single-sided V-belt, and is twisted 180 DEG at two places, one between the two driven pulleys (12, 14), and the other between the drive pulley (10) and idler pulley (16). A method of assembling a belt drive system (80) to a mower (100) is also provided. The method includes the steps of operatively connecting the belt (30) to the drive pulley (10), the first and second driven pulleys (12, 14) and the idler pulley (16) such that the belt (30) includes first and second axial twist areas (32, 34) of substantially 180 DEG each. The method may also include the step of wrapping the belt (30) at least 120 DEG around the drive pulley (10), the first and second driven pulleys (12, 14) and the idler pulley (16). Finally, the method may include the step of rotating the drive pulley (10) thereby rotating the first mower blade (108) in a first direction and the second mower blade (110) in a second direction.

Description: BELT DRIVE SYSTEM Technical Field This invention pertains to the art of belt drive systems, and more particularly, to a belt drive system using a single belt that is axially twisted 180° at two locations for use with counter rotating twin blades in a mower deck. Background Art Belt drive systems are well known in the art. It is also known for a belt drive system to utilize a belt that is twisted. However, it is generally the intent to eliminate the twisting of the belt, or at least to minimize such belt twisting. One known type of belt drive system is described in U.S. Patent No. 5,249,411 to Hake. Hake discloses a single belt drive system for a mower having a plurality of hinged mower sections. This belt system includes numerous pulleys, the pulleys not being in the same plane when any of the mower sections are pivoted. Thus, Hake's single belt is twisted when a mower section is raised or lowered relative to the rest of the mower. However, this belt twisting only occurs when a mower section is pivoted and it appears that the greatest amount of axial belt twisting is 90°. Disadvantages to the Hake belt system include the number of pulleys that are involved and the length of the belt that is needed. The numerous pulleys needed to gain the required wrap around the pulleys shorten belt life. Generally, the greater the number of pulleys in the system, the greater the weight of the mower, the greater the amount of friction the belt must endure and the greater the maintenance difficulties. Also, because of the set up of the pulley system described in the Hake patent, the belt needs to be a double-sided V-belt, or else the back side of the single-sided V-belt would be touching the pulleys. Another type of belt drive system is described in U.S. Patent No. 4,429,515 to Davis Jr., et al. Davis, et al. disclose a self-propelled lawn mower with a series of pulleys to drive the engine and wheels. As in the Hake patent, the Davis belt drive system has a complicated series of pulleys, necessitating a very lengthy belt. The pulleys are not on the same plane and thus they require a twisted belt. As is commonly found in the art, however, Davis, Jr. et. al. attempt to minimize the belt twisting from 90° to 45°. The lengthy belt and numerous pulleys of the Davis' belt drive system create the same maintenance problems as the Hake belt drive system noted above. Yet another type of belt drive system is described in U.S. Patent No. 4,925,437 to Suzuki, et al. Suzuki, et al disclose a belt tensioner device for a lawn mower. Like the previous mentioned patents, the Suzuki belt drive system contains a twisted belt on the belt drive system solely because the pulleys are not on the same plane. The extra tension placed on the belt is created by the angle of the pulleys with respect to one another. Another type of belt drive system is described in U.S. Patent No. 4,231,215 to Klas. Klas discloses a single belt drive for a three spindle rotary mower. As in the previously discussed art the Klas belt drive system has a series of pulleys that are not on the same plane. The Klas system would have the same maintenance problems as the previous described belt drive systems. The Klas system also has the problem of requiring a double-sided V-belt as opposed to a single-sided V-belt. The Klas patent also talks about avoiding a twisted belt, and how this patent tries to move away from that. The Klas patent thus teaches that a twisted belt is not desired. The present invention contemplates a new and improved single belt drive system that is especially useful with counter rotating twin blades. Thus, the invention is simple in design, effective in use, and overcomes the foregoing difficulties and others while providing better and more advantageous overall results. Disclosure of the Invention According to one aspect of this invention, a mower using an inventive belt drive system is provided. The mower includes a frame, an engine operatively mounted to the frame, and a mower deck operatively mounted to the frame. The mower deck has first and second mower blades positioned within. The belt drive system includes a drive pulley operatively connected to the engine, first and second driven pulleys operatively connected to the first and second mower blades respectively, an idler pulley, and a belt that operatively connects the drive pulley to the first and second driven pulleys and the idler pulley. The belt includes first and second axial twist areas of substantially 180° each. According to another aspect of this invention, the belt has a degree of wrap of at least 120° for the drive pulley, the first and second driven pulleys and the idler pulley. According to another aspect of this invention, the first and second driven pulleys are counter rotated by the belt drive system. According to still another aspect of this invention, a method of assembling the belt drive system to a mower is provided. The belt is connected to the drive pulley, the first and second driven pulleys and the idler pulley such that the belt includes first and second axial twist areas of substantially 180° each. This method may include the step of wrapping the belt at least 120° around the drive pulley, the first and second driven pulleys and the idler pulley. Finally, the drive pulley may be rotated thereby rotating the first mower blade in a first direction and the second mower blade in a second direction. One advantage of the present invention is the limited number of pulleys used as compared to similarly sized mowers known in the art. Another advantage of the current invention is the length of belt required is greatly reduced from the related art. A further advantage of the current invention is that the drive pulley and the first and second driven pulleys can all be aligned in the same plane, while still using a single-sided V-belt. Yet another advantage of the current invention is that the necessary degree of wrap is maintained, while using a limited number of pulleys. Still other benefits and advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed specification. Brief Description of the Drawings The invention may take physical form in certain parts and arrangement of parts. A preferred embodiment of these parts will be described in detail in the specification and illustrated in the accompanying drawings, which form a part hereof and wherein: FIGURE 1 is a side view of a mower equipped with the belt drive system of this invention. FIGURE 2 is a plan view of the belt drive system showing the belt operatively connected to the drive pulley, the first and second driven pulleys and the idler pulley. FIGURE 3 is a side view of a portion of the belt drive system showing the second driven pulley, idler pulley and belt. FIGURE 4 is a cross-sectional view of the single-sided V-belt taken along the line 4-4 of FIGURE 2. FIGURE 5 is a partial close-up view of the first axial twist area in the belt. FIGURE 6 is a partial close-up view of the second axial twist area in the belt. Description of the Preferred Embodiment Referring now to the drawings, which are for purposes of illustrating a preferred embodiment of the invention only, and not for purposes of limiting the same, FIGURE 1 shows a mower 100 equipped with an inventive belt drive system 80. Although a riding lawn mower is shown, it is to be understood that the belt drive system 80 of this invention can be used with a walk-behind mower, other mowers, other vehicles and still other drive applications as well. The mower 100 has a frame 102 and an engine 104 operatively mounted to the frame 102. A mower deck 106 is also operatively mounted to the frame 102 and includes first and second mower blades 108, 110 (shown in representative form in FIGURE 2) for use in cutting vegetation. With reference now to FIGURES 1-2, the belt drive system 80 includes a drive pulley 10 that is operatively connected to the engine 104 by any means known in the art. In this way, the engine 104 may selectively rotate the drive pulley 10. The belt drive system 80 also includes first and second driven pulleys 12, 14, an idler pulley 16, and a belt 30. In the preferred embodiment, the first and second driven pulleys 12, 14 are driven pulleys operatively connected to the first and second mower blades 108, 110 respectively. Thus, by rotating the first and second driven pulleys 12, 14, the mower blades 108, 110 can be rotated and the cutting of vegetation can be accomplished. It should be noted, however, that the first and second driven pulleys 12, 14 can be used to rotate any mower implement or other device chosen with sound engineering judgement. With reference now to FIGURE 2, the idler pulley 16 is not essential for this invention but it is preferred as it provides an easy means for removing and/or replacing the belt 30 if desired. The idler pulley 16 is rotatably connected to an idler bracket 18 that is pivotably connected to the frame 102 as shown in representative form in FIGURE 2. A spring 20 is operatively connected to the idler bracket 18 and the frame 102 for use in biasing the idler pulley toward an engaged position 24. When in the engaged position 24, the idler pulley 16 holds the belt 30 taut into operative connection with the various pulleys 10, 12, 14, 16. The idler pulley 16 can be selectively moved into a disengaged position 22 where the belt 30 is loosened or slack and can be removed if desired. With continuing reference to FIGURE 2, it is preferred that the belt 30 is a single-sided V-belt, but any belt type chosen with sound engineering judgement may be used. A V-belt gives the advantage of a closer fit with the various pulleys, and reduces slippage. FIGURE 2 shows the belt 30 wrapped around the drive pulley 10, the first and second driven pulleys 12, 14 and the idler pulley 16. It should be noted that the belt 30 has sufficient wrap around each of the pulleys 10, 12, 14, 16. The degree of wrap for each pulley can be any that is used according to sound engineering judgment but is preferably at least 120°. When the degree of wrap is less than 120° the chance for belt slippage is considered to high for this application. With reference now to FIGURES 2-6 what is especially important about this invention is that the belt 30 includes first and second axial twist areas 32, 34. By axial twist it is meant that the twist is about or around the axis of the belt 30. Preferably the first and second axial twist areas 32, 34 are substantially 180° each. This permits an inner side 36 of the belt 30 to always be exposed toward the various pulleys. The use of the twist areas 32, 34 provide important advantages. For one thing, the number of pulleys can be reduced. It is well known in the art that when a single belt is used in a belt drive system, additional pulleys beyond the drive pulley, the driven pulleys and the idler pulley are required. These additional pulleys are necessary to provide the necessary degree of wrap for each of the pulleys. The belt drive system 80 of this invention provides a sufficient degree of wrap for each pulley without the use of additional pulleys. Such additional pulleys add weight and cost to the mower. Another advantage provided by the twist areas 32, 34 are related to the belt 30. For this invention, the overall length of the belt 30 can be minimized since there are no additional pulleys to wrap around. Also, this invention allows the belt 30 to be a single-sided belt. Thus, the belt cost can be significantly reduced. Still referring to FIGURES 2-6, preferably the first axial twist area 32 is positioned between the first and second driven pulleys 12, 14 and the second axial twist area 34 is positioned between the drive pulley 10 and the idler pulley 16. Of course the axial twist areas 32, 34 could be alternately positioned. It is preferred that the axial twist areas 32, 34 occur where there is a relatively long section of belt 30 between pulleys. This minimizes twisting forces in the belt 30. With continuing reference to FIGURES 2-6, a key advantage to this invention is that the driven pulleys 12, 14 can easily be counter rotated. By counter rotated it is meant that while the first driven pulley 12 is rotated in a first direction (clockwise as shown in FIGURE 2) the second driven pulley 14 is simultaneously rotated in a second direction (counter clockwise as shown in FIGURE 2). This counter rotation may be desirable, for example, for use with a lawn mower. This permits grass clippings (not shown) cut by the mower blades 108, 110 to be moved toward the center of the mower deck 106 (that is between the driven pulleys 12, 14) for subsequent discharge away from the mower deck 106. With reference now to FIGURES 1-2, it should be noted that at least one of the pulleys 10, 12, 14, 16 must not be on the same plane as the others. If this were not true the belt 30 would contact or rub itself at location 38 shown in FIGURE 2. In the preferred embodiment, the drive pulley 10 and the first and second driven pulleys 12, 14 are positioned substantially along the same plane while the idler pulley 16 is positioned slightly above the plane of the other pulleys. It may also be desirable for the pulleys to be positioned such that their axes are not parallel. In other words, one or more of the pulleys may be tilted. In this embodiment, for example, the idler pulley is tilted as shown in FIGURE 3. It should be noted that this invention works effectively with only three pulleys, the drive pulley 10, and the first and second driven pulleys 12, 14. The idler pulley 16 is preferred for the reasons discussed above. Of course in place of the idler pulley a third driven pulley (not shown) could also be used. In fact any number of pulleys chosen with sound engineering judgement can be used with this invention. The invention has been described with reference to the preferred embodiment. Obviously, modifications and alterations will occur to others upon a reading and understanding of the specification. It is intended by applicant to include all such modifications and alterations in so far as they come within the scope of the appended claims or the equivalents thereof. Having thus described the invention, it is now claimed:

Claims: CLAIMS 1. A mower (100) including a frame (102), an engine (104) operatively mounted to the frame (102), a mower deck (106) operatively mounted to the frame (102), first and second mower blades (108, 110) positioned within the mower deck (106), and a belt drive system (80), the belt drive system (80) including a drive pulley (10) operatively connected to the engine (104), first and second driven pulleys (12, 14) operatively connected to the first and second mower blades (108, 110) respectively, an idler pulley (16), and a belt (30) that operatively connects the drive pulley (10) to the first and second driven pulleys (12, 14) and the idler pulley (16), the mower being characterized by: the belt including first and second axial twist areas (32, 34) of substantially 180° each. 2. The mower (100) of claim 1 wherein the belt has a degree of wrap of at least 120° for the drive pulley (10), the first and second driven pulleys (12, 14) and the idler pulley (16). 3. The mower (100) of claim 1 wherein the drive pulley (10), the first driven pulley (12) and the second driven pulley (14) are positioned substantially on the same plane. 4. The mower (100) of claim 1 wherein at least one of the drive pulley (10), the first driven pulley (12), the second driven pulley (14), and the idler pulley (16) is tilted. 5. The mower (100) of claim 1 wherein the first axial twist area (32) is positioned between the first and second driven pulleys (12, 14) and the second axial twist area (34) is positioned between the drive pulley (10) and the idler pulley (16). 6. The mower (100) of claim 1 wherein the first and second driven pulleys (12, 14) are counter rotated. 7. The mower (100) of claim 1 wherein the belt (30) is a single sided V-belt. 8. The mower (100) of claim 1 wherein an inner side (36) of the belt (30) is always exposed toward the drive pulley (10), the first driven pulley (12), the second driven pulley (14), and the idler pulley (16). 9. A method of assembling a belt drive system (80) to a mower (100), the method including the steps of, providing a mower (100) with a frame (102), an engine (104) operatively mounted to the frame (102), and a mower deck (106) including first and second mower blades (108, 110) operatively mounted to the frame (102), providing a belt drive system (80) that includes a drive pulley (10) operatively connected to the engine (104), and first and second driven pulleys (12, 14) operatively connected to the first and second mower blades (108, 110) respectively, the method being characterized by the step of: operatively connecting a belt to the drive pulley (10), the first and second driven pulleys (12, 14) and the idler pulley (16) such that the belt (30) includes first and second axial twist areas (32, 34) of substantially 180° each. 10. The method of claim 9 wherein, the step of operatively connecting a belt (30) to the drive pulley (10), the first and second driven pulleys (12, 14) and the idler pulley (16) such that the belt (30) includes first and second axial twist areas (32, 34) of substantially 180° each, comprises the step of: wrapping the belt (30) at least 120° around the drive pulley (10), the first and second driven pulleys (12, 14) and the idler pulley (16). 11. The method of claim 9 further comprising the step of: rotating the drive pulley (10) thereby rotating the first mower blade (108) in a first direction and the second mower blade (110) in a second direction. 12. A belt drive system (80) including a drive pulley (10), first and second driven pulleys (12, 14), and a belt (30) that operatively connects the drive pulley (10) to the first and second driven pulleys (12, 14), the belt drive system being characterized by: the belt (30) including first and second axial twist areas (32, 34) of substantially 180° each. 13. The belt drive system (80) of claim 12 wherein the belt (30) has a degree of wrap of at least 120° for the drive pulley (10) and the first and second driven pulleys (12, 14). 14. The belt drive system (80) of claim 13 wherein the first and second driven pulleys (12, 14) are counter rotated. 15. The belt drive system (80) of claim 14 further comprising: an idler pulley (16), the drive pulley (10) and the first and second driven pulleys (12, 14) being positioned substantially on the same plane. 16. The belt drive system (80) of claim 15 wherein an inner side (36) of the belt (30) is always exposed toward the drive pulley (10), the first driven pulley (12), the second driven pulley (14), and the idler pulley (16). 17. A method of attaching a belt (30) to a belt drive system (80), the method including the step of providing a belt drive system (80) that includes a drive pulley (10) and first and second driven pulleys (12, 14), the method being characterized by the step of: operatively connecting a belt (30) to the drive pulley (10) and the first and second driven pulleys (12, 14) such that the belt (30) includes first and second axial twist areas (32, 34) of substantially 180° each. 18. The method of claim 17 wherein, the step of operatively connecting a belt to the drive pulley (10) and the first and second driven pulleys (12), (14) such that the belt (30) includes first and second axial twist areas (32, 34) of substantially 180° each, comprises the step of: wrapping the belt (30) at least 120° around the drive pulley (10) and the first and second driven pulleys (12, 14). 19. The method of claim 18 further comprising the step of: rotating the drive pulley (10) thereby rotating the first driven pulley (12) in a first direction and the second driven pulley (14) in a second direction.

Inventors: BLENERT BERHARD, BLENERT, BERHARD
Applicants: BLENERT BERHARD, MTD PRODUCTS INC, BLENERT, BERHARD, MTD PRODUCTS INC.
Application year: 1999
Main classification: F16H7
IPC codes: A01D34, F16H7