Patent Application
20170073927
Trenching is a process often used when burying lengths of an item or system, such as cables or pipes, in a soil substrate. With the advent of power tools, the laborious process of manual trenching has been simplified. However, often the trenching machines are large, vehicle mounted systems. Many cases, such as sprinkler installation and the laying of buried cables, require only a narrow trench to be dug. The use of large trenching machines to form these small trenches is often inefficient. Further, the large trenching machines can be destructive in their own right just by moving, often destroying existing landscaping and compacting adjacent soil. Also, due to their size, traditional trenching machines can be difficult to maneuver in tight quarters and around existing structures.
There exists a need for a compact, portable trenching device that is suitable for use in forming narrow trenches.
The disclosed invention provides a portable, single-user trenching device. The trenching device contains an engine that drives a trenching chain that can be rotated through a substrate to form a trench. The trenching device is further configured for ease of use, minimizing kickback of the device and vibrations transmitted to a user during use. These characteristics assist in decreasing user fatigue, increasing user safety and enhancing durability of the device.
An example trenching device 100 is shown in
The trenching device 100 is a small, portable, single-user trenching tool, which allows a user to dig a trench through a substrate material. A user can hold the trenching device 100 in their hands, or alternatively, the device 100 can be placed on a wheeled cart during trenching operations.
The power unit 110 includes a top handle 114 and a rear handle 118 which can be grasped by a user to control and move the trenching device 100. The rear handle 118 includes a throttle control 119 which can be manipulated by the user hand on the rear handle 118. In the example shown, the throttle control 119 is a spring action type trigger control which is connected to an engine 121 by a throttle linkage. The rear handle 118 is ergonomically shaped for user's grip and comfort. Additional grip comfort considerations can be included, such as a foam or gel pad that can provide cushioning for the user's grip and also reduce device 100 vibrations transmitted to the user.
The top handle 114 is connected to the base of the power unit 110 and to an optional support arm 116. In the example of
In another example, the mounting system of the top handle 114 can include placing the ends of the handle 114 in spherical bearings mounted within the power unit 110. The spherical bearings allow a limited range of motion for the handle 114 in multiple planes. Allowing controlled or buffered motion in multiple planes can assist in reducing transmitted vibrations.
In a further example, the mounting system of the top handle 114 can include attaching the handle to the power unit 110 by a pliable material, such as rubber bushings in which the ends of the handle 114 are attached to the power unit 110. The pliable nature of the material will absorb and reduce the vibrations transmitted through the handle to the user. The reduction of vibration experienced by the user can reduce user fatigue which can increase user efficiency and safety.
The top handle 114 can also include a cushioned grip 115 about an upper portion that would be grasped by a user. The cushioned grip 115 provides user comfort and can also assist in lessening or minimizing the vibrations experienced by a user.
An optional support arm 116 further connects and braces the top handle 114 to the power unit 110. Due to its positioning on the machine, through the top handle 114 is where the user will support the bulk of the trenching device 100. Also, the top handle 114, serves as a pivot, at approximately the center of gravity, about which the device can balance. The support arm 116 further braces and supports the top handle 114 due to the loading that the handle 114 can experience.
In an example embodiment, the support arm 116 can be connected to the power unit 110 and the top handle 114 using a pin-type connection. A pin-type connection allows rotation of the elements relative to each other in a plane orthogonal to the pin-type connection. This degree of freedom allowed by the pin-type connection can help reduce transmitted forces to the user, reducing user fatigue. The combined use of this connection type with a pliant material used to construct support arm 116, can further reduce the vibration and/or kickback transmitted through the handle 114.
The power unit 110 also includes an air filter 112 through which air is drawn into the engine 121. During trenching operations, dust and substrate material can be released into the air. The air filter 112 prevents particulates from the surrounding air from entering the engine 121 during the combustion process. The prevention of particulate entry can reduce wear and maintenance requirements and also increase the efficiency of the engine 121. The air filter 112 should have sufficient surface area and porosity to allow adequate air flow into the engine 121 while still screening out particles of the size that may be encountered during trenching of the substrate. The filter is preferably a multi-stage type filter system as typically found in use with internal combustion engine intakes. The multi-stage type filter system can include a cyclonic action, a foam filter and a paper and/or felt filter element(s). Alternatively, the filter system can be a singular type element, such as a foam, felt or paper-type filter element.
The air filter 112 is removable and replaceable, allowing the user to quickly and easily replace and/or clean the air filter 112 as necessary. Additionally, if a substrate has very fine particles, the standard air filter 112 can be replaced with one having reduced filter openings that can sufficiently remove a reduced size of particulate from the incoming airstream. The finer air filter 112 can reduce engine 121 performance due to restricted airflow through the reduced filter opening size and/or from clogging of the filter openings. The ability to interchange the air filter 112 is desirable as the finer filter can be used only in situations where necessary.
The drive unit 120 includes an engine 121 and drive arm 122, which generate and transmit power to the trenching unit 150. The drive unit 120 can be mounted to, or in, the power unit 110 and is preferably mounted to isolate vibration and kickback from the drive unit 120 into the power unit 110. Minimizing vibration and kickback transmitted from the drive unit 120 to the power unit 110 can assist in reducing the amount of fatigue experienced by the user. The less fatigued the user is, the longer they can operate the trenching device 100 and the more safely the device can be operated.
The drive unit 120 can be mounted to, or in, the power unit 110 using a number of vibration minimization and/or isolation techniques. An example mounting can include using cushioning blocks, such as rubber pads, arranged between the drive unit 120 and the power unit 110, with the rubber pads configured to absorb at least a portion of the vibrations and/or kickback from the drive unit 120.
Another mounting example can include using a rod and hole mounting system, whereby the power unit 110 and the drive unit 120 include aligned holes through which a rod, or rods, can be secured to attach the drive unit 120 to the power unit 110. The use of a rod system is preferable as it can be configured to allow a small or controlled degree of relative movement between the drive unit 120 and the power unit 110 in three planes. Transmission of vibration and kickback from the drive unit 120 to the power unit 110 can be further minimized through the use of rubber washers and spherical bearings. The holes of the rod system of the housing can include spherical bearings through which rods pass through, the spherical bearings allowing the rod limited motion relative to the power unit 110. Allowing limited motion of the drive unit 120 relative to the power unit 110 can absorb and minimize vibrations and/or kickback transmitted through the drive unit 120 to the user operating the trenching device 100.
For size and the power-to-weight ratio, the engine 121 of the example trenching device 100 of
The engine 121 has sufficient power output to pull the trenching chain 152 though a desired substrate. In certain substrates, such as a loose soil, the power requirement can be low. However, in denser substrates, such as packed dirt or clay, and/or substrates that contain debris such as rocks, the power requirement can be high as more torque can be required to pull the trenching chain 152 through the substrate material.
In an alternative example embodiment, the engine 121 can be a small, lightweight four-stroke engine. The four-stroke engine is typically quieter than a two-stroke engine and does not require the oil-gas mixture to run on. Additionally, the four-stroke motor design has a more constant, or flatter, torque curve, providing a consistent level of torque across a wide range of operating speeds or engine RPMs. In some applications, it may be advantageous to power the trenching device 100 with the alternative four-stroke engine embodiment.
Alternative engines can be used with the trenching device 100, including smaller engine units, larger engine units and different types of engines. Alternative engine types can include electric, hydraulic and pneumatic motors that may be directly connected to a power source or include device mounted power supplies, such as batteries. The selection of the engine 121 of the device 100 can be determined by the operating conditions of the device 100.
Further, the engine 121 should be rated to operate consistently for extended periods of time at the desired RPM operating range. The continuous duty cycle of the engine 121 during use of the trenching device 100 requires that the engine 121 have sufficient operational abilities to withstand such a duty cycle. A lower RPM operating range can assist in withstanding the continuous duty cycle, the lower operating speeds reduces the likelihood of engine failure from overheating. An engine not rated for such continuous use, such as an engine designed for intermittent use at a higher RPM operating range, can have premature failure when used with the device 100. When selecting an appropriate power source, or engine 121, the operating specifications of the engine must be considered in view of the demands that will be imposed on it during use within the device 100.
The drive arm 122 transmits the engine 121 output to the trenching unit 150 and includes a housing 123, a first pulley 124, a second pulley 125, a driven shaft 126, a belt 127 and eccentric tensioner 128. The output of the engine 121 rotates an output shaft causing the first pulley 124 disposed thereon to rotate. The pulley 124 is engaged with the belt 127, which is in turn engaged with the second pulley 125. As the belt 127 is rotated by the first pulley 124, the second pulley 125 is also rotated, causing the driven shaft 126 to rotate. The driven shaft 126 includes a chain sprocket disposed opposite the second pulley 125, the rotation of the driven shaft 126 causing rotation of the engaged chain sprocket, causing rotation of the trenching chain 152. The pulley and belt arrangement is preferred as it further absorbs and dampens vibrations and kickback. Additionally, the belt drive system reduces shock loading to the engine 121, thereby eliminating the need for a shock absorbing element, such as shear bolts, to prevent damage to the engine 121.
The ratio of the diameter of the first pulley 124 to the diameter of the second pulley 125 is used to determine a “gear ratio” or “drive ratio” of the pulley system. The “drive ratio” determines the speed and torque at the driven shaft 126 based on the rotational speed and torque of the first pulley 124. The pulleys, 124 and 125, can be selected based on the desired power and speed transmission to the driven shaft 126. The pulleys, 124 and 125, can be interchangeable, allowing a user to effectively change the “gear ratio” as necessary or desired.
In an embodiment, the gear ratio can be 2 to 1, drive pulley to driven pulley. In the embodiment shown in
Proper chain speed is an important consideration when performing a trenching operation using the trenching device 100. The chain speed must be sufficient to allow for a continuous trenching operation, i.e. preventing the chain from bogging down or getting stuck in the substrate. Chain speed can also influence the amount of vibration experienced by the user. At higher speeds, the chain can skip or kickback when hitting obstructions rather than digging through or engaging the obstruction to move it. Also, at high chain speeds, imbalances within the chain can be magnified, further increasing overall vibration of the device 100 which can lead to increased user fatigue.
In the example trenching device 100 of
To maintain proper tensioning on the belt 127, the second pulley 125, includes an eccentric tensioner 128. Rotating the eccentric tensioner 128 about the driven shaft 126 causes the second pulley 125 to move, loosening or tightening the pulley 125 against the belt 127. Proper tension of the belt 127 is important for the overall efficiency of the power transfer from the belt 127 to the pulley 125. Alternative belt tensioning systems can be used, including a spring tensioning system or a sliding/telescoping drive arm 122 that can be adjusted by a set screw(s). The tensioning system can be arranged to further absorb and dampen vibration and kickback.
A drive arm housing 123 encloses the drive arm 122. In the example of
The first pulley 124 preferably includes a clutch disposed between the pulley 124 and the output of the engine 121. The use of a slip clutch can prevent damage to the engine and increase user safety. Additionally, a clutch can be included within the driven pulley 125 or connected to the driven shaft 126.
In an alternative embodiment, the belt drive system of the example of
A mounting attachment 130 is directly affixed to the drive arm 122. The mounting attachment 130 includes the necessary hardware to affix the trenching unit 150 and trenching bar 140 to the drive unit 120. The mounting attachment 130 includes a mounting plate 132, a guard 134 and a trenching bar mounting block 136, as shown in
The mounting plate 132, shown in more detail in
A guard 134 can be affixed to the mounting plate 132 at mounting points 135a and 135b, shown in
A trenching bar mounting block 136 (shown in
A trenching bar 140 supports the trenching chain 152 and can provide the necessary chain 152 tensioning system. The trenching bar 140 is preferably constructed of metal, for the strength and weight considerations. The trenching bar 140 can be treated and/or coated to increase its strength, hardness and/or durability. However, plastic or other suitable material can be used. A low friction material can also be disposed about the periphery of the trenching bar 140, to provide a low friction surface over which the chain 152 can be pulled. Such material can include a block, or blocks, of PTFE, disposed about the perimeter of the trenching bar 140. The width of the bar 140 is less than the width of the chain, but is suitably wide to adequately support the chain 152 and prevent it from twisting along a plane of travel.
A nose sprocket 142 guides the trenching chain 152 about the nose of the trenching device 100. The nose sprocket 142 is connected to the trenching bar 140 by a connector 144. The connector 144 spaces the nose sprocket 142 a distance from the end of the bar 140 to provide sufficient clearance for the teeth of the nose sprocket 142 as it rotates. In the embodiment shown in
A tensioning system or mechanism 146 can be included in the connector 144. The tensioning system 146 can tension the trenching chain 152. A tensioning system 146 can include a spring and set screw type tensioning system or other suitable chain 152 tensioning system or mechanism.
The excavation of substrate material to form a trench is performed by the trenching chain 152 and the attached trenching teeth 154. As the chain 152 is pulled, the teeth 154 engage the substrate material, separating and removing the substrate material to form a trench. The trench formed by the trenching device 100 will be approximately the width of the chain 152. The chain 152 can be interchanged to achieve a desired trench width.
The trenching teeth 154 are affixed to the trenching chain 152, in a pattern that alternates to each side of the chain. Additionally, the teeth 154 are spaced a number of chain elements apart from each other (e.g. three), as shown in
The trenching teeth 154 can have a profile that can direct the excavated substrate material to a selected side of the trenching device 100 during a trenching operation. The profile of the teeth 154 can be optimized to place the excavated substrate material in a desired manner.
The trenching teeth 154 are constructed of a durable material, such as a high strength and durable metal. The teeth 154 are profiled and constructed such that they self-sharpen as the trenching chain 152 and the attached teeth 154 are pulled through the soil substrate. Should the teeth 154 dull, a user can run the trenching device 100 in an abrasive substrate in order to resharpen the teeth 154. Alternatively, the teeth 154 can be sharpened by hand or using a sharpening device.
Preferably, the selected tooth material can be sharpened and annealed or strengthened to hold a cutting edge 155. The use of such a material can allow the user to sharpen and/or hone the trenching teeth 154 regularly, as needed, to increase the overall efficiency of the trenching device 100 during a trenching operation. The trenching chain 152 and the trenching teeth 154 can be composed of the same or different materials that can be strengthened or hardened using various treatments and/or processes.
Additionally, the chain elements can undergo a coating process to further increase the strength, sharpness and/or durability of the cutting edge 155, teeth 154 and/or trenching chain 152. Example coatings can include coating to reduce the friction between elements and/or the substrate and deposition of durable coating material on wearing surfaces, such as those that engage the substrate, along with other types of desirable coating processes and materials.
In a further example, the teeth 154 may be removable from the chain 152, allowing the user to replace broken or worn teeth 154.
Inserts can be included on the trenching teeth 154, the inserts forming the cutting edge 155 of each tooth 154. The inserts can be made of a more durable material, such as carbide. The use of an insert made of a durable material means that rather than replacing a tooth or the whole chain 152, just the insert is required to be replaced as necessary. This can extend the life of the chain 152 as the inserts bear the brunt of the mechanical wear during a trenching operation.
The trenching bar 140 and trenching chain 152 form a trenching unit 150 that can be removed and mounted to the drive unit 120. The trenching bar 140 and trenching chain 152 can be changed to correspond to the desired depth of the formed trench, with a longer bar 140 and chain 152 combination used to form deeper trenches. This interchangeability allows the drive unit 120 and trenching assembly to be swapped as needed to achieve the desired trenching ability. Further, this modularity allows for the easy breakdown and transport of the device, and easy replacement of parts as a module or assembly. The modularity can also increase the efficiency of the production of the trenching device 100.
In the example shown in
Preferably, the trenching chain 152 is run under-tensioned by an amount. Operating the trenching chain 152 in an under-tensioned state assists with clearing debris from the chain 152 and nose sprocket 142 without adversely affecting the efficiency and safety of the operation of the trenching device 100.
The nose sprocket 142 is attached to the trenching chain bar by a connector 144, which is composed of two halves 144a and 144b. Disposed between the two halves, 144a and 144b, is a nose sprocket bearing 141 with the nose sprocket 142 mounted thereon. The connector 144 is mounted to the trenching bar 140 such that the nose sprocket 142 is forward of the trenching bar 140 with clearance for the nose sprocket teeth 143 as the nose sprocket 142 is rotated.
The distance separating the nose sprocket 142 from an end of the trenching bar 140 is set by the geometry of the pattern of holes 145a disposed on the two halves, 144a and 144b, of the connector 144. Screws 145b are inserted through holes 145c of the trenching chain bar 140 and the holes 145a of the connector 144. The screws 145b are secured, preferably by locknuts, thereby joining the two halves, 144a and 144b, of the connector 144 to the trenching chain bar 140. Alternative fasteners and fastening methods can be used to affix the connector 144 to the trenching bar 140, such as rivets or threading of the holes 145a.
The nose sprocket 142, on the bearing 141, is connected to the connector 144 by a screw, or other fastener, 147a that is inserted through holes 147b of the two halves, 144a and 144b, and secured. The two halves, 144a and 144b, of the connector 144 include protrusions 146 that interface with an inner race of the bearing 141, securing the bearing 141 to the connector 144.
To form a trench, the trenching chain 152 of the trenching device 100 is placed in motion by a user, using the throttle control 119. The nose of the device 100 is placed against the substrate and guided to a desired trenching depth. Once the user has achieved the desired depth, the device 100 is guided along a pathway to form the desired trench.
As the trenching chain 152 and trenching teeth 154 are pulled through the substrate, the excavated substrate material is drawn to the surface and guided to a side of the forming trench by the profile of the trenching teeth 154 and the guard 134.
In an alternative example, the trenching device 100 can be mounted to a wheeled cart for the trenching operation. Attaching the device to a cart relieves the user from having to support the device 100. The cart can allow the user to guide the nose of the trenching device 100 to a desired trench depth. The user can then move the cart, with the attached device 100, along a desired pathway to form the trench.
It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. 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.
This application claims the benefit of U.S. Provisional Application No. 62/219,024 filed Sep. 15, 2015, the contents of which are herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62219024 | Sep 2015 | US |
