Patent Application
20130299268
The present invention relates to the drive system for a large single engine sweeper.
Powered mechanical sweepers typically come in three sizes. The smallest size is used for sweeping sidewalks and factory floors. Operators of small sweepers may either walk behind the sweeper or ride on a small seat positioned behind the sweeping mechanism. Medium size sweepers are used for cleaning parking lots and small roads such as private roads or long driveways. Large sweepers are typically found on large public roads or on vast expanses of concrete surfaces such as found in commercial airports.
A medium size sweeper is where the sweeper is either pulled behind a tractor or where the sweeping equipment is mounted on the chassis of a small truck. The operator of a medium size sweeper will travel at road speeds to the location to be swept. Once at the location to be swept, the operator of the sweeper engages the sweeping mechanism. With the sweeping mechanism engaged, the operator of the sweeper uses the engine and transmission portion of the small truck to pass back and forth over the area to be swept. Speed control of the medium size sweeper over the surface being swept is typically accomplished by applying foot pressure on the accelerator pedal or the foot brake.
A large size powered sweeper typically includes a dedicated or modified truck chassis. However, the size of the areas to be swept, along with the type and quantity of debris expected to be encountered necessitate the use of large brooms, large fans and the capacity for picking up large pieces of debris along with a debris body for transporting a large amount of swept-up debris. One example of such a large sweeper is the VacAII™ Legacy model sweeper which is manufactured and marketed by the Gradall Division of the Alamo Group, the assignee of this U.S. patent application.
Because of the size of a large sweeper and the power needed to operate the sweeping equipment on large sweepers, prior art large sweepers have typically included two internal combustion engines. One internal combustion engine is the truck chassis engine. The truck chassis engine is connected to the chassis drive train. Attached to the chassis engine is a chassis transmission; typically, an automatic transmission. The chassis automatic transmission is connected by a chassis driveshaft to the chassis differential and real wheel drive assembly. The chassis differential and real wheel assembly provide the power necessary to turn the rear wheels. The rear wheels propel the large sweeper to travel both at road speed to the location to be swept and then at sweeping speed over the surface being swept.
The second internal combustion engine in a large sweeper is usually mounted on the vehicle chassis behind the driver's compartment. This second internal combustion engine provides power to the sweeping equipment. When the large sweeper arrives at the large area, runway or road to be swept, the second internal combustion engine is put into operation. The vehicle chassis with the sweeping equipment mounted thereon is then driven at a slow speed over the area to be swept. The driver guides the vehicle over the surface to be swept with the vehicle's steering wheel. The speed of the vehicle is controlled by the driver using both the accelerator pedal and the brake pedal. The accelerator pedal governs the speed of the chassis engine and the brake pedal is used to reduce the speed of the vehicle when sweeping or when there is a need to bring the large sweeper to a stop.
The chassis internal combustion engine that comes with the vehicle chassis assembly is used to propel the large sweeper. The chassis internal combustion engine is maintained at a low idle speed when sweeping. When the sweeper moves too fast over the surface being swept, the operator of the sweeper controls the speed of the sweeper by maintaining continuous variable pressure on the brake pedal. In recent years, it has been required that the chassis engine bear an EPA rating for over the road use and that the chassis engine be certified by the model year for each particular truck chassis manufacturer.
The second internal combustion engine is used to provide the power needed to operate all of the sweeping mechanisms. Unlike the chassis internal combustion engine, the second internal combustion engine typically bears an EPA rating as an off road engine. The second internal combustion engine typically has its own cooling and air intake systems. The fuel tank and batteries for the second internal combustion engine are typically shared with the chassis internal combustion engine. Controls available to the operator provide for operating the variable speed broom motors and some of the sweeping functions; however, most everything regarding the sweeping operation runs at a speed directly proportional to the speed of the second internal combustion engine.
The disadvantages of operating a large sweeper having two internal combustion engines are the large amount of fuel consumed from the operation of two internal combustion engines, the wear and associated maintenance required to keep two internal combustion engines in operating condition as opposed to one internal combustion engine, and the noise and vibration from two internal combustion engines. Such noise and vibration has been shown to result in driver fatigue. In addition, since the brakes which are part of the vehicle chassis assembly are used to control the speed of the large sweeper in sweep mode, more frequent replacement of the brake pads, brake drums or brake rotors on the wheel brakes is required.
Accordingly, there is a need for a large sweeper that reduces fuel consumption, reduces wear and maintenance, reduces noise and vibration and does not require frequent replacement of parts of the wheel brake assemblies.
Attempts have been made to create a street cleaning vehicle with a single engine. One such example is shown in U.S. Pat. No. 6,073,720 to Vanderlinden. Therein, a power take-off from the chassis transmission is connected to a hydraulic pump. The hydraulic pump is connected to a hydraulic motor which is mounted on and mechanically connected to the rear chassis differential. Power from the single chassis engine is also used to drive the sweeping equipment mounted on the chassis of the vehicle. Those of ordinary skill in the art will understand that the system disclosed in U.S. Pat. No. 6,073,720 to Vanderlinden requires modifying the chassis transmission and the rear chassis differential. Such modification of chassis components by a sweeper manufacturer is both expensive and typically voids the warranty on the chassis drive system components by the manufacturer of the vehicle chassis assembly. Because of these problems, the single engine sweeper proposed in U.S. Pat. No. 6,073,720 by Vanderlinden has not been generally accepted by the sweeper industry in the United States.
Thus, the need still remains for a large sweeper having a single internal combustion engine. Those of ordinary skill in the art will understand that as more demands are put on a single internal combustion engine in a large sweeper, more is required of the vehicle driver to manage both the distribution of power between the vehicle and sweeping equipment while guiding the large sweeper over the large area to be swept. Accordingly, there is an additional need to simplify the operation of a large sweeper with a single internal combustion engine for operation by the vehicle driver.
The system and method for operating a large single engine sweeper of the present invention includes a transfer case inserted into the chassis drive train of the vehicle on which sweeping equipment is mounted. A front drive shaft extends from the chassis automatic transmission to the transfer case. A rear drive shaft extends from the transfer case to the chassis differential and real wheel drive assembly.
In road mode, power from the chassis engine passes through the chassis automatic transmission, through the transfer case and to the chassis differential and rear wheel drive assembly.
In sweep mode, power passes from the chassis engine through the chassis automatic transmission to the transfer case. Mechanical power inputs from the transfer case provide the necessary torque to operate the hydraulic pumps which provide hydraulic fluid to the hydraulic motors and hydraulic cylinders used with the sweeping equipment.
The transfer case also provides mechanical power to a propel pump. The propel pump provides hydraulic fluid to a propel hydraulic motor. The propel hydraulic motor provides a power input to the transfer case when the large single engine sweeper is in sweep mode.
Thus, when the large single engine sweeper is placed in sweep mode, the flow of mechanical power through the transfer case from the chassis automatic transmission is interrupted so that mechanical power from the chassis automatic transmission no longer flows to the chassis differential and rear wheel drive assembly. Instead the mechanical power to the chassis differential and rear wheel drive assembly originates at the hydraulic propel pump and motor and then passes into the transfer case. From the transfer case, the mechanical power provided from the propel hydraulic pump and motor turns the chassis differential and rear wheel drive assembly to move the sweeper across the surface to be swept when in sweep mode.
When in sweep mode the position of the throttle pedal no longer controls the speed of operation of the chassis engine. In sweep mode, the chassis engine is set at a predetermined speed and the movement of the throttle pedal controls the flow of hydraulic fluid from the propel hydraulic pump. The flow of fluid from the propel hydraulic pump to the propel hydraulic motor then controls the speed of the large single engine sweeper.
A better understanding of the system and method for operating a large single engine sweeper may be had by reference to the drawing figures, wherein:
An exploded view of the large single engine sweeper 100 of the present invention appears at
Mounted on the frame rails 122 which extend behind the driver's cab 110 is the sweeping equipment package 130. The sweeping equipment package 130 may include a large rotating broom and/or one or more gutter brooms 132. Located near the centerline of the vehicle chassis assembly 120 is a suction or vacuum head assembly 134 for picking up debris such as rocks, stone, bottles, pieces of asphalt, along with wet and dry leaves. A negative pressure at the suction or vacuum head assembly 134 results from the air flow created by a large fan (not shown). The material picked up by the suction or vacuum head assembly 134 passes into a large tiltable debris body 136. A hingedly mounted, hydraulically operated tailgate 137 enables emptying the debris body 136. In some sweepers, an intake or pick up tube 138 is mounted on the back of the debris body 136 and is used for manually picking up leaves or other types of debris. Many sweepers also include a water tank 140. Water from the water tank 140 passes through a hydraulically powered water pump to a wand or sprayer to loosen debris dried on the surface being swept, as well as dust control.
All of the equipment in the sweeping equipment package 130, to include the brooms, the fan creating the air flow which results in a negative pressure at the suction or vacuum head, and the water pump is operated by hydraulic motors. The operating parts within the sweeping equipment package 130 are positioned by the use of hydraulic cylinders. The hydraulic fluid which enables the hydraulic motors to produce the needed rotational torque and the hydraulic cylinders to provide the needed linear force comes from one or more hydraulic pumps.
Located about halfway between the driver's cab 110 and the rear drive wheels 124 in
As shown in the schematic of
Additionally, rotational power output from the transfer case provides rotational power to an implement hydraulic pump 28. The implement hydraulic pump 28 provides hydraulic fluid to the hydraulic motors which turn the brushes, pump the water, as well as the other hydraulic motors and/or hydraulic cylinders which are used to move and position the various operating parts of the sweeper equipment.
Shown on the right rear of the transfer case in
When the large single engine sweeper 100 is in sweep mode, no rotational power from the chassis engine 127 passes through the transfer case assembly 20 to turn the rear drive wheels 124. Instead, the rotational power from the chassis automatic transmission 128 goes to the transfer case assembly 20 to operate the propel hydraulic pump 32 along with the other hydraulic pumps. Hydraulic fluid from the propel hydraulic pump 32 goes to the propel hydraulic motor 34. Rotational power from the propel hydraulic motor 34 goes back into the transfer case assembly 20. The rotational power from the propel hydraulic motor 34 that goes back into the transfer case assembly 20 and is used to turn the rear drive shaft 24 which connects the transfer case assembly 20 to the chassis differential and rear axle assembly 129. When in sweep mode, all of the power used to propel the sweeper 100 forward is received from the propel hydraulic motor 34.
The single engine sweeper 100, according to the present invention, is driven in road mode to a location where sweeping is to take place. Power from the chassis engine 127 passes through the chassis automatic transmission 128 to the transfer case assembly 20. From the transfer case assembly 20, the rotational power passes to the chassis differential and rear axle assembly 129 to power the rear drive wheels 124.
When the large single engine sweeper 100 arrives at the location to be swept, the single engine large sweeper 100 is ready to be placed in sweep mode.
Placing the large single engine sweeper 100 in sweep mode requires that the operator of the sweeper 100 bring the vehicle to a full stop, shift the chassis automatic transmission 128 into Neutral, and set the parking brake (not shown) 144 located within the driver's cab 110. The sweep mode is now engaged by the operator of the sweeper 100. With the sweep mode engaged, the chassis automatic transmission 128 is placed in Drive. Shifting the chassis automatic transmission 128 out of Drive disengages the sweep mode. In sweep mode, the transfer case assembly 20 provides rotational power to all of the hydraulic pumps which supply hydraulic fluid to the hydraulic motors and to the hydraulic cylinders found in the sweeping equipment package 30. In addition, the flow of rotational power from the chassis automatic transmission 128 through the transfer case assembly 20 to the chassis differential and rear axle assembly 129 is interrupted at the transfer case assembly 20. Instead, the transfer case assembly 20 receives power from the propel hydraulic motor 34. This power from the propel hydraulic motor 34 passes through the rear drive shaft 24 between the transfer case assembly 20 and the chassis differential and rear axle assembly 129.
When the driver places the single engine sweeper 100 in sweep mode, the chassis engine 127 is set to operate at a predetermined fixed rpm by the driver. Once this predetermined fixed chassis engine rpm is set, it cannot be changed by the driver. Control over the forward speed of the vehicle now depends on the flow of hydraulic fluid from the propel hydraulic pump 32 to the propel hydraulic motor 34. In sweep mode, control of the flow of hydraulic fluid from the propel hydraulic pump 32 is controlled by a swash plate in the propel hydraulic pump. The swash plate is electronically connected to the foot throttle control pedal normally used to govern the speed of the chassis engine 127 when in road mode. When the driver pushes down on the foot throttle control pedal, the output of hydraulic fluid from the propel hydraulic pump 32 increases thereby causing the power output of the propel hydraulic motor 34 to increase and the single engine sweeper 100 will move across the surface being swept at a faster speed. Typically, this system enables a vehicle speed in sweep mode of from 0 mph to about 12 mph. The maximum speed is set by the operator of the sweeper 100 by a speed limiter control located on the control panel 140.
The operator turns the speed limiter on and sets the maximum travel speed desired for the sweeper 100. With the speed limiter on and set, fully depressing the foot throttle control pedal will achieve the pre-set maximum speed. If the operator of the sweeper 100 removes pressure from the foot throttle control pedal, the sweeper 100 will slow down. If the operator removes all pressure from the foot throttle control pedal, the sweeper 100 will come to a stop. With the speed limiter on, the foot throttle control pedal is proportional to the speed of the sweeper 100 and the sweeper 100 will move from zero (operator's foot off the foot throttle control pedal) to the pre-set maximum speed on the speed limiter (foot throttle control pedal fully depressed). If something were to happen to the operator, the sweeper 100 will come to a stop assuming that the foot of the operator falls away from the foot throttle control pedal. This system acts like a dead man switch. The maximum speed of the sweeper 100 while the speed limiter is engaged can be changed or shut off regardless of whether the sweeper 100 is moving and whether or not the foot throttle control pedal is depressed.
Because of the increased ability of the operator to control the speed of the sweeper 100 in sweep mode, there is little reason to use the brakes to control the speed of the sweeper 100 except for emergency stops or holding the single engine sweeper 100 in position on a grade. In addition, the continuous input of foot pressure on the throttle control pedal protects the driver in the case of an event where the driver is no longer able to operate the sweeper 100. When pressure is taken off the foot throttle control pedal, the sweeper 100 will come to a stop.
When the sweeping job has been completed, the sweeper 100 is brought to a stop. Everything that was running in the sweeper equipment package 130 is shut off and the sweeper equipment package 130 put in the storage location by pressing the auto store button on the control panel 140. The parking brake 144 (not shown) is set and the chassis automatic transmission 128 is shifted into Neutral. A toggle switch on the control panel 140 is labeled road mode on the top and sweep mode on the bottom. The operator presses the road mode button and the transfer case assembly 20 shifts after the parking brake 144 (not shown) is set and the chassis automatic transmission 128 is placed in Neutral.
When the sweeping job has been completed, the sweeping equipment is positioned in its storage location for transport to another area to be swept. The single engine sweeper 100 is then taken out of sweep mode and placed back into road mode. Rotational power from the chassis engine 127 and chassis automatic transmission 128 now passes through the transfer case assembly 20 directly to the chassis differential and rear axle assembly 129.
Those of ordinary skill in the art will understand the disclosed invention provides several advantages over large sweepers having two internal combustion engines, as follows.
1. Lowered exhaustion emissions and lower fuel consumption.
2. Quieter operation and less vibration because of lower engine speed.
3. Less maintenance and replacement of components subject to wear and less adjustment of engine components.
4. Less operating cost.
5. Accurate vehicle speed control and dynamic hydraulic braking from simply changing the position of the foot control throttle pedal in the driver's cab.
Those of ordinary skill in the art will also understand that while the present invention has been explained with regard to its use on a large sweeper, the disclosed invention may be adapted for use on smaller sweepers.
The invention described in this patent application was not the subject of federally sponsored research or development.
