CONCRETE SAW HAVING MULTIPLE MOTORS

Abstract

A device comprises an implement configured to be driven and a first motor and a second motor. Each motor includes a rotational output shaft and a transmission assembly connected to the output shaft. The output shafts of the first and second motors are coupled together by the transmission assemblies such that the output shafts turn at the same rate. The first and second motors contribute equally to the driving of the implement.

Description

BACKGROUND

Exemplary embodiments herein generally relate to a device including an implement driven by at least two motors, and more particularly, to a self-propelled operator-guided or steerable concrete saw having parallel motors.

In the concrete industry, when building bridges, buildings, roads and the like, it is often necessary to pour large horizontal slabs of concrete. Once poured, it is usually necessary to machine the slab. Such machining may include cutting seams completely through the slab (to form expansion joints and to allow for foundation shifting), cutting notches partially into the slab (to create stress cracks along which the slab will split), cutting multiple grooves into the slab to create a high friction surface such as for bridges, grinding the surface of the slab and the like. Concrete saws are also used in the demolition or removal of concrete, such as during the sawing and replacement of bridge decks. Various types of concrete saws may be utilized to carry out these machining and demolition tasks. In larger industrial applications, large self-propelled saws are used that are powered in a variety of manners, such as by gasoline, diesel, electric, propane and natural gas engines mounted on the saw. While performing a cut, the operator controls the direction, cutting speed, cutting depth and the like.

Conventional concrete saws include a gasoline, diesel, propane (internal combustion), hydraulic and air or electric engine aligned along an axis transverse to the longitudinal axis of the saw frame. This transverse arrangement aligns the engine crankshaft parallel to the rotational axis of the saw blade, to afford an easy design for interconnecting pulleys upon the crankshaft and the saw blade. Recently designed concrete saws include an engine that is mounted with its longitudinal axis in line with the longitudinal axis of the saw. This is in contrast to traditional transverse mounting arrangements. This new arrangement allows the saw to be easily moved through doorways and other passages that were previously not passable. However, because concrete saws require large values of torque and power (for example, at least 70 hp), the single engine for both layouts is a large engine, and hence a more powerful engine. One drawback to the use of a single large engine for the concrete saw is the high cost of such an engine. Another drawback of the single large engine for the concrete saw is an increase in the overall weight of the concrete saw which can make the saw more cumbersome to maneuver.

BRIEF DESCRIPTION

In accordance with one aspect, a device comprises an implement configured to be driven and a first motor and a second motor. Each motor includes a rotational output shaft and a transmission assembly connected to the output shaft. The output shafts of the first and second motors are coupled together by the transmission assemblies such that the output shafts turn at the same rate. The first and second motors contribute equally to the driving of the implement.

In accordance with another aspect, a concrete saw comprises a generally rectangular frame having a front end, a read end and a longitudinal length. A first motor and a second motor are supported by the frame. Each motor includes a rotational output shaft aligned generally transverse to the longitudinal length of the frame and a sprocket assembly connected to the output shaft. The output shafts of the first and second motors are coupled together by the sprocket assemblies such that the output shafts turn at approximately the same rate. The first and second motors contribute equally to the driving of a saw blade. The saw blade is rotatably connected to the frame via a saw blade shaft oriented parallel to the outputs shafts of the first and second motors. The saw blade shaft has at least one sheave pulley. A rotatable jack shaft is oriented parallel to the outputs shafts of the first and second motors. The jack shaft has a sprocket and at least one sheave pulley. The sprocket is operably connected to one of the sprocket assemblies of the first and second motors. The at least one sheave pulley is operably connected to the at least one sheave pulley of the saw blade shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a left side perspective view of an exemplary device, such as a concrete saw, having multiple motors according to one aspect of the present invention.

FIG. 2 is a right side perspective view of the concrete saw of FIG. 1.

FIG. 3 is an enlarged perspective view of the parallel motors of the concrete saw of FIG. 1.

FIG. 4 is an enlarged perspective view of a sprocket assembly of one of the motors and a sprocket and a sheave pulley of a drive shaft associated with a saw blade of the concrete saw of FIG. 1.

FIG. 5 is an enlarged front prospective view of the concrete saw of FIG. 1.

FIGS. 6 and 7 are side perspective views of the concrete saw of FIG. 1 in a tilted position.

FIG. 8 is a schematic view of another exemplary device including an implement driven by multiple motors according to another aspect of the present invention.

FIGS. 9 and 10 schematically depict exemplary manners for controlling operation of the multiple motors of FIG. 8.

DETAILED DESCRIPTION

It should, of course, be understood that the description and drawings herein are merely illustrative and that various modifications and changes can be made in the structures disclosed without departing from the present disclosure. It will also be appreciated that the various identified components of the exemplary concrete saw disclosed herein are merely terms of art that may vary from one manufacturer to another and should not be deemed to limit the present disclosure.

Referring now to the drawings, wherein like numerals refer to like parts throughout the several views, FIGS. 1-7 illustrate an exemplary device having multiple motors, such as a concrete saw 100 for cutting seams, notches and/or grooves into or through asphalt, concrete, stone or other similar surfaces concrete, asphalt, stone and other hardened surfaces according to the present disclosure. The concrete saw 100 includes an implement or blade 102, at least two engines or motors 104,106 for driving the saw blade 102, a frame 108 for supporting the at least two motors and a set of front wheels 110 and rear wheels 112. The saw 100 is preferably a self-propelled saw, and thus the rear wheels 112 are driven in a conventional manner (e.g., a hydraulic drive system or other like system). However, it will be appreciated that saw 100 could be a push-type saw. The concrete saw 100 is shown having the two motors 104,106; although, more than two motors are contemplated. It will also be appreciated that the at least two motors 104,106 may comprise a gasoline, diesel or propane (internal combustion) engine, hydraulic and air engine, or an electrical motor.

The concrete saw 100 also includes operational systems that are known or conventional in the art. These systems include a locomotion system that drives the rear wheels 112 supporting the saw frame 108 at a desired speed. A lift system 120 is also included that is able to tilt the saw frame 108. When tilted the saw blade 102 may be taken out of contact with the substrate being cut (see FIGS. 6 and 7). The concrete saw 100 can include an engine mounting system that minimizes vibration within the frame. The saw also includes at least one speed selection lever 128 for controlling the speed of advancement of the saw. Additionally, the concrete saw 100 can includes some type of dampening mechanism that interrupts direct communication between the at least two motors 104,106 and saw blade 102 when the blade encounters significant predetermined resistance.

With particular reference to FIGS. 1-3, the motors 104,106 are positioned in parallel, side by-side relationship on the frame 108 and are of a type generally known in the art. With this parallel relationship, each motor 104,106 is oriented with its respective driven output shaft or crankshaft 140,142 generally perpendicular to an axis defined by the length of the frame 108. This transverse arrangement aligns the output shafts 140,142 parallel to the rotational axis of the saw blade 102, to afford an easy design for interconnecting pulleys upon the output shafts and the saw blade. However, unlike the prior art concrete saw having a similar transverse arrangement, the use of the smaller motors 104,106 allows the concrete saw 100 to be easily moved through doorways and other narrow passages.

As indicted previously, the known concrete saw typically requires a single seventy horsepower (70 hp) motor to drive the saw blade. In order to provide similar torque and power values as the 70 hp single motor, each motor 104,106 is at least a thirty-five horsepower (35 hp) motor, which when operating in unison provides the necessary torque and power for the concrete saw 100. One type of motor for use with the concrete saw 100 is a Briggs & Stratton Vanguard® 35 hp motor; although, alternative motors having a similar torque and power ratings are contemplated. As is known, these Briggs & Stratton motors 104,106 each includes an air cooling system 150, an air cleaner 152 and a muffler 154. Further details of the Briggs & Stratton motors 104,106 are known to one skilled in the art and, as such, are omitted for conciseness.

As best depicted in FIGS. 3-5, the concrete saw 100 includes a drive system for transmitting rotational energy from the motors 104,106 to the saw blade 102. The drive system includes a first drive or jack shaft 160, which is oriented substantially parallel with the output shafts 140,142, is supported at each end by bearings 162,162 for transmitting power across the front of the concrete saw 100 and to the saw blade 102. The first jack shaft 160 includes at one end a first multi-sheave pulley 170 for driving one or more V-belts 172 and at the other end a second multi-sheave pulley 174 for driving one or more V-belts 176. A second drive or jack shaft 180 (i.e., saw blade shaft), which is oriented parallel to the first jack shaft 160, is connected to the saw blade 102, and is supported by bearing (not shown) mounted to the frame 108. The second jack shaft 180 includes at one end a third multi-sheave pulley 190 and at the other end a fourth multi-sheave pulley 192. As shown, the one or more V-belts 172 are engaged with the first and third sheave pulleys 170 and 190 and the one or more V-belts 176 are engaged with the second and fourth sheave pulleys 174 and 192. Located at the fore end of the first jack shaft 160 and inside of the first sheave pulley 170 is a sprocket 200. In the depicted embodiment, the sprocket 200 and the first sheave pulley 170 are of different diameters; although, this is not required. As shown, sprocket 200 can have a diameter which is about twice the diameter of first sheave pulley 170.

The drive system further includes a sprocket assembly 210 provided on the output shaft 140 of motor 104 and comprises a pair of sprockets 212 and 214. Extending between sprocket 200 and sprocket 212 is a flexible belt 220. The belt 220 includes a plurality of teeth extending along the inside surface or diameter 222 of the belt 220. The teeth of belt 220 engage teeth formed along the outer diameter of the sprockets 200 and 212. Similarly, provided on the output shaft 142 of motor 106 is a sprocket assembly 230 including a pair of sprockets 232 and 234. Extending between sprocket 214 and sprocket 234 is a flexible belt 240 which includes a plurality of teeth extending along the inside surface or diameter 242 the belt 240. The teeth of belt 240 engage the teeth formed along the outer diameter of the sprockets 214 and 234. By coupling the motors 104,106 together such that their respective output shafts 140,142 turn at the same rate, the motors can contribute equally to the driving of the saw blade 102 and together provide twice the power as a single 35 hp motor. This, in turn, provides the necessary 70 hp to drive the saw blade 102. As shown, the sprockets 212,214,234 have approximately equal diameters; though it should be appreciated that the sprockets can be of different diameters. Also, the sprocket 200 has a diameter larger than the diameters of the sprockets 212,214,234; although, this is not required. Similarly, it will be appreciated that motors of different horsepower may be coupled together in order to provide a desired combined horsepower. For example, a 50 hp motor and a 30 hp motor could be combined to provide a total of 80 hp to drive the saw blade 102.

With continued reference to FIGS. 1 and 3, operably connected to the sprocket 232 is a flexible belt assembly 250 that powers a conventional hydrostatic motor that is used to propel the saw. The assembly 250 includes a first idler roller or sprocket 252 and a second idler roller or sprocket 254. Both the first idler roller 252 and the second idler roller 254 are positioned forward of the sprocket assembly 230, the first idler roller being located below the second idler roller. The assembly 250 further includes an idler arm 260 and a biasing means 262 for biasing the arm toward the frame 108. Extending to the hydrostatic transmission is a power belt 256. The arm 260 includes a first end 264 pivotally connected to the frame 108 and a second end 266 connected to the first idler roller 252. The biasing means 262 is operably coupled to the second end 266 and the frame 108. A bolt 268 that can be loosened with a conventional tool, such as a wrench, to allow the arm 260 to pivot freely, or tightened to lock the arm 260 into position.

The toothed belts 220,240 may be any number of conventionally available toothed flexible rubber belts. However, a preferred belt is a POLYCHAIN® synchronous belt available from the Gates Rubber Company. Such synchronous belts resist slipping and they normally do not require continual retensioning. This type of belt does an excellent job of transferring energy. One synchronous belt can do the job of many V-belts thereby saving valuable space. The use of a synchronous belt affords several advantages over conventional V-belts. For example, synchronous belts operate at zero slip and they do not require near the load that V-belts require for proper tensioning. Lower tension levels reduce load levels on shafts, thereby helping to extend bearing life. Engine crankshafts are especially sensitive to high tension loads. High belt tension loads create a bending effect upon the crankshaft which reduces engine life. Generally, engines are designed with light shell type bearing to support the crankshaft. These shell type bearings are not capable of withstanding major side loads over a substantial period of time. The use of a synchronous belt, that requires minimal tensioning, avoids all of the excessive loading issues presented by V-belts.

Also, in the present design the one or more V-belts 172,176 are at the end of the respective first and second jack shafts 160,180 thereby facilitating the replacement of such belts. The configuration also allows one to use small pulleys to drive the V-belts 172,176, thereby facilitating good cutting depths. Use of the jack shafts 160,180 that extends across the width of the concrete saw 100, along with V-belts 172,176 and toothed belts 220,240 also provides an advantage. Specifically, such arrangement minimizes the width of the saw 100, reduces loads on the engine bearings, and because it employs V-belts 172,176, it allows for slip in the event that the blade 102 becomes trapped or stalled.

With reference now to FIG. 5, a pair of V-belt tensioner assemblies 280,282 can be provided at a forward end of the frame 108. The tensioner assemblies 280,282 provide for positional adjustment, and preferably vertical adjustment, between the output shaft 140 of motor 104, the first jack shaft 160 and the second jack shaft 180. This enables positional adjustment, i.e. the spacing between the sprocket 200 located on the jack shaft and the sprocket 212 located on the output shaft 140, and between the first and second sheave pulleys 170,174 and the third and fourth sheave pulleys 190,192. Adjustment of the spacing between sheave pulleys 170,174 provides for tension adjustment of the one or more V-belts 172,176 extending between the sheave pulleys.

Each V-belt tensioner assembly 280,282 may be in a variety of different forms and configurations. In the depicted embodiment, each tensioner assembly 280,282 includes a bolt shaft 290,292 which threadingly engages an opening of a flange 294,296 extending from a second frame or motor mount 300 positioned on the frame 108. Each motor 104,106 and the bearings 162,162 for supporting the first jack shaft 160 are located on the motor mount 300. Provided along an uppermost end of each bolt shaft 290,292 is a bolt head 310,312 configured for engagement by a conventional tool, such as a socket or wrench. A lowermost end 314,316 of the each bolt shaft rests upon and is supported by the frame 108. A corresponding rear set of pivotable engine mounts (not shown) can be provided along an opposite end of the motors 104,106. Adjustment of the tensioner assemblies provides for vertical adjustment between the frame 108 and the motor mount 300.

FIG. 8 schematically illustrates another device 350 according to the present disclosure. A shown, the device 350 comprises an implement 352 configured to be driven by multiple motors, such as the depicted first and second motors 354 and 356. Although, more than two motors are contemplated. The implement 352 can be a cutting implement, a drilling implement, a hammering implement, a power pack or any other motor driven implement. It will also be appreciated that the at least two motors may comprise a gasoline, diesel or propane (internal combustion) engine, hydraulic and air engine, or an electrical motor.

The device 350 includes a supporting frame 358, a set of front wheels 360 and a set of rear wheels 362. The device 350 is preferably a self-propelled device, and thus at least one of the sets of wheels 360,362 can be driven in a conventional manner (e.g., a hydraulic drive system). However, it will be appreciated that device 350 could be a push-type device. A controller 366 is provided for controlling operation of the device 350, particularly the first and second motors. The controller can be one of mechanically and electrically connected to one of the first and second motors 354,356. For a self-propelled device 350, the controller 350 can also be connected to the driving means associated with the driven set of wheels for controlling operation of the driving means.

In the depicted exemplary embodiment, the first and second motors 354,356 are positioned in parallel, side by-side relationship on the frame 358 and are of a type generally known in the art. With this parallel relationship, each motor 354,356 is oriented with its respective driven output shaft or crankshaft 370,372 generally perpendicular to an axis defined by the length of the frame 358. This transverse arrangement provides for a device having a smaller footprint which can allow the device 350 to be easily moved through doorways and other narrow passages.

A first transmission assembly 380 is provided on the output shaft 370 of the first motor 354. A second transmission assembly 382 is provided on the output shaft 372 of the second motor 356 and is operably coupled to the first transmission assembly 370. Similar to the concrete saw 100 described above, to connect the first and second motors 354,356 together, each of the first and second transmission assemblies 380,382 can include at least one sprocket and at least one flexible belt extending between the sprockets. Although, alternative manners for coupling the motors 354,356 together are contemplated. At least one of the first and second transmission assemblies is operably coupled the implement 325.

By coupling the first and second motors 354,356 together such that their respective output shafts 370,372 turn at the same rate, the motors can contribute equally to the driving of the implement 352 and together provide twice the power as a single motor. It will be appreciated that motors of the same or different horsepower may be coupled together in order to provide a desired combined horsepower. To ensure that the output shafts 370,372 turn at the same rate a timing assembly 390 can be operably coupled to at least one of the first and second transmission assemblies 380,382. The timing assembly can be part of a central control of the ignition system of the motors 354,356. As schematically depicted in FIG. 9, and according to one aspect, the timing assembly can be part of an electronic engine control. The electronic engine control can be configured to determine the amount of fuel, ignition timing and other parameters that each motor 354,356 needs to keep running. This can be accomplished by using input values (e.g. engine speed) calculated from signals coming from sensors, such as a crankshaft position sensor, which monitor each motor 354,356. The electronic engine control can compare the input values and adjust operation of the motors 354,356 (e.g., adjust spark timing of each motor) to ensure that the output shafts 370,372 are turning at the same rate. As schematically depicted in FIG. 10, and according to another aspect, the timing assembly can be a load sensor control. The load sensor control can convert the amount of air drawn into each motor 354,356 into a voltage signal, which can then be used to calculate engine load. The engine loads of the motors 354,356 can be compared and operation of the motors can be controlled to again ensure that the output shafts 370,372 are turning at the same rate.

It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

Claims

1. A device comprising: an implement configured to be driven; anda first motor and a second motor, each motor including a rotational output shaft and a transmission assembly connected to the output shaft, the output shafts of the first and second motor being coupled together by the transmission assemblies such that the output shafts turn at the same rate, the first and second motors contributing equally to the driving of the implement.

2. The device of claim 1, further including a frame for supporting the first and second motors in a front-to-back relationship, the rotational output shaft of each motor being aligned generally transverse to a longitudinal length of the at least one frame.

3. The device of claim 1, wherein the implement is rotatably connected to the frame via an implement shaft oriented parallel to the outputs shafts of the first and second motors, the implement shaft having at least one sheave pulley, and the transmission assembly of the first motor nearest the implement shaft includes a first sprocket assembly having a first sprocket and a second sprocket, the at least one sheave pulley of the implement shaft being operably coupled to one of the sprockets of the first sprocket assembly.

4. The device of claim 3, further including a rotatable jack shaft oriented parallel to the outputs shafts of the first and second motors and to the implement shaft, the jack shaft having a sprocket and at least one sheave pulley, the sprocket being operably connected to the first sprocket of the first sprocket assembly of the first motor, the at least one sheave pulley being operably being connected to the at least one sheave pulley of the implement shaft.

5. The device of claim 4, wherein the sprocket of the jack shaft has a diameter approximately twice a diameter of the at least one sheave pulley of the jack shaft.

6. The device of claim 4, further including a first flexible belt having teeth formed along an inner surface thereof, the teeth of the first flexible belt engaging the first sprocket of the first sprocket assembly and the sprocket of the jack shaft.

7. The device of claim 4, wherein the jack shaft includes a first end portion and a second end portion, the first end portion including the sprocket and a first sheave pulley and the second end portion including a second sheave pulley, and the implement shaft includes a first end portion and a second end portion, the first end portion including a first sheave pulley and the second end portion including a second sheave pulley,wherein the first sheave pulley of the jack shaft is operably connected to the first sheave pulley of the implement shaft and the second sheave pulley of the jack shaft is operably connected to the second sheave pulley of the implement shaft.

8. The device of claim 7, further comprising a second flexible belt engaging the first sheave pulley of the jack shaft and the first sheave pulley of the implement shaft, and a third flexible belt engaging the second sheave pulley of the jack shaft and the second sheave pulley of the implement shaft.

9. The device of claim 4, further including a tensioner assembly connected to the frame, the tensioner assembly configured to provide positional adjustment between the output shaft of the first motor, the jack shaft and the implement shaft.

10. The device of claim 9, further including a second frame positioned on the frame, the implement shaft being located on the frame, each of the first and second motors and the jack shaft being located on the second frame, the tensioner assembly configured to provide vertical adjustment between the frame and the second frame.

11. The device of claim 3, wherein the transmission assembly of the second motor includes a second sprocket assembly having a first sprocket and a second sprocket, one of the sprockets of the second motor being operably connected to the second sprocket of the first motor, and further comprising a belt assembly operably connected to the other sprocket of the second motor, the belt assembly adapted to power an associated hydrostatic motor for propelling the device.

12. The device of claim 11, further including a fourth flexible belt having teeth formed along an inner surface thereof, the teeth of the fourth flexible belt engaging the second sprocket of the first sprocket assembly of the first motor and the one sprocket of the second sprocket assembly of the second motor.

13. The device of claim 11, wherein each of the first and second sprockets of the first sprocket assembly of the first motor and the one sprocket of the second sprocket of the second motor have approximately equal diameters.

14. The device of claim 1, further comprising a timing assembly configured to ensure that the output shafts of the first and second motors turn at approximately the same rate, the timing assembly being part of an ignition system of each of the first and second motors.

15. The device of claim 1, wherein the device is a concrete saw and the implement is a saw blade.

16. A concrete saw comprising: a generally rectangular frame having a front end, a read end and a longitudinal length;a first motor and a second motor supported by the frame, each motor including a rotational output shaft aligned generally transverse to the longitudinal length of the frame and a sprocket assembly connected to the output shaft, the output shafts of the first and second motors being coupled together by the sprocket assemblies such that the output shafts turn at approximately the same rate, the first and second motors contributing equally to the driving of a saw bladethe saw blade rotatably connected to the frame via a saw blade shaft oriented parallel to the outputs shafts of the first and second motors, the saw blade shaft having at least one sheave pulley; anda rotatable jack shaft oriented parallel to the outputs shafts of the first and second motors, the jack shaft having a sprocket and at least one sheave pulley, the sprocket being operably connected to one of the sprocket assemblies of the first and second motors, the at least one sheave pulley being operably connected to the at least one sheave pulley of the saw blade shaft.

17. The concrete saw of claim 16, wherein the first and second motors are positioned in a front-to-back relationship on the frame.

18. The concrete saw of claim 16, further including a second frame positioned on the frame and a tensioner assembly connected to the frame and second frame, the saw blade shaft being located on the frame, each of the first and second motors and the jack shaft being located on the second frame, the tensioner assembly being configured to provide vertical adjustment between the frame and the second frame.

19. The concrete saw of claim 16, further comprising a timing assembly operably configured to ensure that the output shafts of the first and second motors turn at approximately the same rate, the timing assembly being part of an ignition system of each of the first and second motors.

20. The concrete saw of claim 16, further comprising a plurality of flexible belts for interconnecting the sprocket assemblies of the first and second motors, the at least one sheave pulley of the saw blade shaft, and the sprocket and at least one sheave pulley of the jack shaft.