Abstract:
In one aspect, the invention is directed to a conduit laying system for laying conduit, including a vehicle, a trench former, a conduit feed system and a base material handling system. The trench former is configured for forming a trench. The conduit feed system includes a conduit feed passage having a conduit feed passage inlet for receiving at least one conduit and a conduit feed passage outlet positioned to deposit the at least one conduit in the trench. The base material handling system includes a base material hopper and at least one base material passage. The at least one base material passage is positioned to receive base material from the base material hopper and to discharge base material in the trench around the at least one conduit. The base material handling system, the conduit feed system and the trench former are driven by the vehicle.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to conduit laying machines and more particularly to conduit laying machines that lay conduits, such as high-voltage electrical cables, and that discharge base material around the conduits. 
       BACKGROUND OF THE INVENTION 
       [0002]    Laying electrical cables underground is typically accomplished by digging a trench and laying the cable in the trench. The trench may be dug using a backhoe loader or the like and the cable may be laid in the trench manually, while being fed from a reel that is mounted on a truck. Typically, such work is slow, and relatively labour intensive. 
         [0003]    Systems have been proposed to lay cable in an open trench, however, such systems suffer from a variety of shortcomings. For example, in some instances, no means for protecting the cable in the trench is provided. Accordingly, the cable is at risk of puncture or other damage from exposed rocks and the like in the trench. 
         [0004]    It would be advantageous to provide a system that lays cable or other types of conduit while protecting it from damage. 
       SUMMARY OF THE INVENTION 
       [0005]    In a first aspect, the invention is directed to an assembly for laying conduit, including a trench former, a conduit feed system and a base material handling system. The trench former is configured for forming a trench. The conduit feed system includes a conduit feed passage having a conduit feed passage inlet for receiving at least one conduit and a conduit feed passage outlet positioned to deposit the at least one conduit in the trench. The base material handling system includes a base material hopper and at least one base material passage. The at least one base material passage is positioned to receive base material from the base material hopper and to discharge base material in the trench around the at least one conduit. Optionally, the invention is directed to a conduit laying system that is made up of the aforementioned assembly and a vehicle for driving the assembly. Optionally, depending on the type of conduit that is to be laid, the conduit laying system may further include a conduit reel holder mounted to the vehicle for holding one or more reels of conduit. The at least one base material passage may be configured in a way to inhibit the base material from bridging therein. For example, the at least one base material passage may have a cross-sectional area that increases in a downward direction. Additionally or alternatively, the base material passage may extend in a downward direction (not necessarily a strictly downward direction) and may have a lateral spacing and a longitudinal spacing, whereby the lateral and longitudinal directions are relative to the direction of travel of the base material handling system. One of the lateral and longitudinal spacings may be shorter than the other. The shorter of the spacings may increase in a downward direction. 
         [0006]    In a second aspect, the invention is directed to a conduit laying system including a trench former, a conduit feed system and a base material handling system. The trench former is configured for forming a trench and includes a vibration mechanism. The conduit feed system includes a conduit feed passage having a conduit feed passage inlet for receiving at least one conduit and a conduit feed passage outlet positioned to deposit the at least one conduit in the trench. The base material handling system includes a base material hopper and at least one base material passage. The at least one base material passage is positioned to receive base material from the base material hopper and to discharge base material in the trench around the at least one conduit. The base material in the hopper and/or in the at least one base material passage may be subject to vibration from the vibration mechanism. The at least one base material passage may be configured to inhibit bridging of base material therein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention will now be described by way of example only with reference to the attached drawings, in which: 
           [0008]      FIG. 1  is a perspective view of a system for creating a trench and for laying one or more conduits in the trench in accordance with an embodiment of the present invention; 
           [0009]      FIG. 2  is another perspective view of the system shown in  FIG. 1  showing the front of the system; 
           [0010]      FIG. 3  is a side view of a portion of the system shown in  FIG. 1  ; 
           [0011]      FIG. 4  is a sectional side view of a portion of the system shown in  FIG. 1 ; 
           [0012]      FIG. 5  is a another perspective view of the system shown in  FIG. 1  showing the rear of the system; 
           [0013]      FIG. 6  is a plan view of the portion of the system shown in  FIG. 4 ; 
           [0014]      FIG. 7  is a cutaway perspective view of selected components from the portion of the system shown in  FIG. 4 ; 
           [0015]      FIG. 8  is a sectional perspective view along section line  8 - 8  shown in  FIG. 4 ; and 
           [0016]      FIG. 9  is a perspective end view of the portion of the system shown in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Reference is made to  FIG. 1 , which shows a system  10  for creating a trench  11  and for laying one or more conduits  12  in the trench  11  in accordance with an embodiment of the present invention. The system  10  shown in  FIG. 1  lays three conduits  12 . It is however, possible for a system in accordance with an embodiment of the invention to lay some other number of conduits  12 , such as one conduit  12 , two conduits  12  or more. The conduits  12  may be any suitable type of conduits. For example, the conduits  12  may be high voltage, electrical conduits (which may also be referred to as electrical cables), wherein each conduit  12  carries one phase of a three-phase electrical supply. 
         [0018]    The system  10  also discharges a base material  14  around the conduits  12  in the trench  11 , which supports the conduits  12  and assists in protecting the conduits against damage from sharp rocks and the like that may be exposed when the trench  11  is formed. 
         [0019]    The base material  14  may be any suitable base material, such as, for example, a granular particulate material, or a slurry that hardens after a period of time. Some examples of base materials  14  that may be used include sand, concrete, cement, and particulate material that absorbs moisture from the ground around it to harden into a solid. 
         [0020]    The system  10  includes a conduit reel support  16 , a trench former  18 , a base material handling system  20 , a conduit feed system  22  and a vehicle  24 . In the embodiment shown in  FIG. 1 , the conduit reel support  16  is positioned at the front of the vehicle  24  and is configured to hold three reels  26  (best seen in  FIG. 2 ) of conduit  12 . The front of the vehicle is shown at  27 . The conduit reel support  16  may include a plurality of arms  28  having ends  30  that include cradles  32  for holding the shafts, shown at  34  (see  FIG. 2 ) of the conduit reels  26 . The arms  28  may be movable between a loading/unloading position in which new reels  26  may be rolled into position in the cradles  32  or in which spent reels  26  may be rolled out of the cradles  32 , and a use position (shown in  FIGS. 1 and 2 ) in which the reels  26  are held above the ground and are rotatable. Optionally, when the reels  26  are held in the use position they are freely rotatable in the cradles  32 . Alternatively, a tensioning means is provided to maintain some selected tension in the conduit  12  and to inhibit the reels  26  from releasing more than a selected amount of conduit  12 . In embodiments configured for laying high-voltage electrical conduit  12 , it may be advantageous to omit a tensioning means so that the tensile stress on the electrical conduit  12  is reduced. 
         [0021]    The trench former  18  is configured to form the trench  11  as the vehicle  24  moves forward. The trench former  18  may have any suitable structure for forming the trench  11 . For example, referring to  FIG. 3 , the trench former  18  may be configured as a plow and may include a body  36  having a front face  38  covered with a plurality of plowing elements  40 . The plowing elements  40  may be generally C-shaped, having generally front faces shown at  42 , which are flat in a lateral direction, and generally planar side faces  44 , and having relatively sharp lateral corner edges  46  at the junctions of the front faces  42  and the side faces  44  respectively. During operation, as the vehicle  24  moves forward, the plowing elements  40  continuously raise earth upwards out of the trench  11 . The plowing elements  40  may be removably mounted to the trench former body  36 , and may thus be made from a material that is different from that of the trench former body  36  and that is selected for reduced wear during use. Additionally, by making the plowing elements  40  removable from the trench former body  36 , the plowing elements  40  may be easily replaced when they are excessively worn. The trench former body  36  may be slidably mounted on a trench former base  52  and may be vertically adjustable with respect to the trench former base  52  by any suitable means, such as by a trench former height adjustment hydraulic cylinder  54 . The trench former height adjustment hydraulic cylinder  54  may be used to control the depth of the trench  11  that is formed. 
         [0022]    A separate vibratory mechanism  55  ( FIG. 3 ) may be provided with the trench former  18  to assist in loosening earth in front of the trench former  18 . The vibratory mechanism  55  may have any suitable structure. Alternatively, depending on the type of trench former that is used, vibration may inherently be produced. For example, certain types of trench former inherently produce some vibration during use and as such can be considered to include a vibratory mechanism. Some effects of such vibration are discussed further below. 
         [0023]    The trench former  18  may be connected to the vehicle  24  in any suitable way. For example, a connecting arm  56  may have a first pivot connection  58  to the rear of the vehicle  24  about a vertical axis, and a second pivot connection  60  to the trench former base  52  about a vertical axis. The pivot connections  58  and  60  facilitate the vehicle  24  turning while the trench former  18  is in the ground. It is alternatively possible to eliminate the connection arm  56  and to provide a single pivot connection between the vehicle  24  and the trench former  18 , however. By providing the connecting arm  56  with pivot connections  58  and  60  to the vehicle  24  and trench former  18 , a greater degree of flexibility is provided for the movement of the vehicle  24  with respect to the trench former  18 , relative to an embodiment with a single pivot connection and no connecting arm. First and second pivot angle adjustment hydraulic cylinders  62  and  64  may be provided at the first and second pivot connections  58  and  60  for actively controlling the angles of the pivot connections  58  and  60 . 
         [0024]    The base material handling system  20  is positioned rearwardly of the trench former  18  and may be pivotally connected to the rear of the trench former  18  at a third pivotal connection  66  about a vertical axis. Referring to  FIG. 4 , the base material handling system  20  includes a base material hopper  67 , a first base material passage  68  and a second base material passage  69 . The base material hopper  67  has an inlet  70  at the top. The base material  14  may be fed into the base material hopper  67  by any suitable means. For example, in the embodiment shown in  FIG. 1 , wherein the base material  14  is sand, a sand storage and feed vehicle  72  ( FIG. 5 ) may travel behind the base material hopper  67  and may feed sand into the base material hopper inlet  70  via a belt conveyor or the like. A coarse grating  73  may be provided at the base material hopper inlet  70 , which assists in breaking up large agglomerations of base material, and which also braces and strengthens the base material hopper  67  in the region of the hopper inlet  70 . 
         [0025]    Referring to  FIG. 6 , the base material hopper  67  has a first hopper outlet  74  that feeds base material  14  into the first base material passage  68  ( FIG. 4 ), which discharges base material into the trench  11  at a first base material passage outlet  78 . The base material hopper  67  also has a second hopper outlet  80  that feeds base material  14  into the second base material passage  69  which discharges base material into the trench  11  at a second base material passage outlet  82 . 
         [0026]    The conduit feed system  22  includes a conduit feed passage  84  that extends from a conduit feed passage inlet  86  to a conduit feed passage outlet  88 . The conduit feed passage outlet  88  is positioned between the first base material passage outlet  78  and the second base material passage outlet  82  in the sense that the conduits  12  are deposited in the trench  11  above the base material  14  discharged from the first base material passage outlet  78  and base material  14  is discharged from the second base material passage outlet  82  above the conduits  12  in the trench  11 . 
         [0027]    The conduit feed passage  84  may extend down through the base material hopper  67  and between the first and second base material passages  68  and  69 . Alternatively the conduit feed passage  84  may have another routing whereby it extends downwards outside of the base material hopper  67  such that the conduit feed passage outlet  88  still terminates between the first and second base material passages  68  and  69 . 
         [0028]    A plurality of rollers  90  are positioned in the conduit feed passage  84  to facilitate transport of the conduits  12  through the conduit feed passage  84 . For the specific embodiment shown in the figures to be laying three phase electrical conduits  12 , the rollers  90  may be provided with a peripheral profile, shown at  92  ( FIG. 7 ), that is configured to hold the conduits  12  in a triangular arrangement. 
         [0029]    The conduit feed passage inlet  86  is positioned to receive the conduits  12  from the conduit reels  26 . The conduit feed system  22  may further include a conduit guide  94  ( FIG. 5 ) provided above the conduit feed passage inlet  86  to guide the conduits  12  from the conduit reels  26  over the vehicle cab, shown at  96  ( FIG. 1 ), and downwardly into the conduit feed passage inlet  86 . 
         [0030]    The first base material passage  68  may extend generally downwards (not necessarily strictly vertically downwards) from the first hopper outlet  74  to the first base material passage outlet  78 . An air passage  97  may be provided in the wall  99  of the base material hopper  67  in the vicinity of the first hopper outlet  74 . The air passage  97  inhibits bridging of the base material  14  as it passes through the first hopper outlet  74 . The air passage  97  may be configured in any suitable way. In the embodiment shown in  FIG. 9 , the air passage  97  is configured as a vertical slit  978   a  that extends above and below the first hopper outlet  74  in combination with a horizontal passage  978   b  along a cross-sectional edge of the first hopper outlet  74 . 
         [0031]    Referring to  FIG. 8 , the first base material passage  68  may be generally rectangular in cross-section, and may be defined by a first side wall  98 , a second side wall  100 , a front wall  102  and a rear wall  104 . The spacing between the first and second side walls  98  and  100  is shown at D 1  and may be defined as the spacing of the first base material passage  68  in a lateral direction, i.e. a direction that is perpendicular to the direction of travel of the base material handling system  20 . The spacing D 1  increases progressively in a downward direction. Additionally, the spacing D 1  between the first and second side walls  98  and  100  may increase progressively in the rearward direction. The spacing between the front and rear walls  102  and  104  is shown at D 2  and may be defined as the spacing of the first base material passage in a longitudinal direction, i.e. a direction that is parallel to the direction of travel of the base material handling system  20 . The spacing D 2  may increase in the downward direction. By configuring the first base material passage  68  such that the spacing D 1  increases in the downward and rearward directions and such that the spacing D 2  increases in the downward direction, the first base material passage  68  is configured to inhibit bridging of the base material  14  therein. The rates of increase of the spacings D 1  and D 2  may be selected based on the particular properties of the base material  14 . For some base materials, for example, such as certain types of sand, the spacing D 1  may increase from about 5 inches at the top of the first base material passage  68 , shown at  106  ( FIG. 4 ), which is also the first hopper outlet  74 , to about 5¼ inches at the bottom of the first base material passage  68 , shown at  108 , which is at the first base material passage outlet  78 . Additionally, the spacing D 1  ( FIG. 8 ) may increase from about 5 inches at the front of the first base material passage  68 , shown at  110 , to about 5¼ inches at the rear of the first base material passage  68 , which is shown at  112 . 
         [0032]    To achieve satisfactory flow of base material  14  in the first base material passage  68  it is particularly preferable for the first base material passage  68  to be provided with all three of the aforementioned features, namely that the spacing D 1  increases in the downward direction; that the spacing D 1  increases in the rearward direction; and that the spacing D 2  increases in the downward direction. It is, however, alternatively possible that satisfactory flow of base material  14  can be achieved with only one or two of the aforementioned features being provided. 
         [0033]    It will be noted that increasing one of the aforementioned spacings D 1  and D 2  as noted above does not necessarily mean that the cross-sectional area of the first base material passage  68  increases in the downward direction. It will also be noted that the first base material passage  68  need not be generally rectangular and may instead have any other suitable cross-sectional shape for transporting base material  14 . For example, the first base material passage  68  may have one or more chamfered corners (as shown in  FIG. 6 ). As another example, the first base material passage  68  may have a generally rounded cross-sectional shape, such as a circular cross-sectional shape, an elliptical cross-sectional shape, or an oval cross-sectional shape or an irregular cross-sectional shape. It is further possible for the first base material passage  68  to have a cross-sectional shape that changes along the length of the passage  68 . 
         [0034]    Without specific reference to any spacings (eg. D 1  or D 2 ), it is possible to achieve satisfactory flow of base material  14  by configuring the first base material passage  68  to have a cross-sectional area that increases progressively in a downward direction (see  FIG. 4 ). 
         [0035]    The second base material passage  69  may be similar to the first base material passage  68 . For example, referring to  FIG. 4 , the second base material passage  69  may extend generally downwards (not necessarily strictly vertically downwards) from the second hopper outlet  80  to the second base material passage outlet  82 . Referring to  FIG. 8 , the second base material passage  69  may be defined by a first side wall  114 , a second side wall  116 , with a lateral spacing D 3  therebetween, and a front wall  118  and a rear wall  120 , with a longitudinal spacing D 4  therebetween. The second base material passage  69  may be configured such that the spacings D 3  and D 4  increase progressively in a downward direction from the top of the second base material passage  69 , shown at  122  ( FIG. 4 ), to the bottom of the second base material passage  69 , shown at  124 , and additionally such that the spacing D 3  increases progressively in a rearward direction from the front of the second base material passage  69 , shown at  126 , to the rear of the second base material passage  69 , shown at  128 . By configuring the second base material passage  69  such that the spacing D 3  ( FIG. 6 ) increases in the downward and rearward directions and such that the spacing D 4  increases in the downward direction, the second base material passage  69  is configured to inhibit bridging of the base material  14  therein. As with the spacings D 1  and D 2 , the rates of increase of the spacings D 3  and D 4  may be selected based on the particular properties of the base material  14 . Also as with the spacings D 1  and D 2 , it is possible that satisfactory flow of base material  14  can be achieved by providing one or two of the three aforementioned features, though it is particularly preferable for the second base material passage  69  to be provided with all three of the aforementioned features. 
         [0036]    It will be noted that increasing one of the aforementioned spacings D 3  and D 4  in the downward direction does not necessarily mean that the cross-sectional area of the second base material passage  69  increases in the downward direction. It will also be noted that decreasing one of the aforementioned spacings D 3  or D 4  does not imply that the overall cross-sectional area of the second base material passage  69  is decreasing. In particular, it can be observed in  FIG. 4  that along a lower portion of the second base material passage  69 , the longitudinal spacing D 4  decreases, while the lateral spacing D 3  increases. The cross-sectional area of the second base material passage  69  may or may not increase in this region, depending on specific values for the spacings D 3  and D 4 . 
         [0037]    It will further be noted that, for the second base material passage  69 , the spacing D 3  (i.e. the lateral spacing) is smaller than the spacing D 4  (the longitudinal spacing). By increasing the smaller spacing (in this particular case, the lateral spacing), satisfactory flow of base material  14  may be achieved even when the other spacing (in this case the longitudinal spacing) decreases along a portion of the length of the passage  69 . 
         [0038]    As noted for the first base material passage  68 , the second base material passage  69  need not have a generally rectangular cross-section and may instead have any suitable cross-sectional shape for transporting base material. It is further possible for the second base material passage  69  to have a cross-sectional shape that changes along the length of the passage  69 . 
         [0039]    Without specific reference to any spacings (eg. D 3  or D 4 ), it is possible to achieve satisfactory flow of base material  14  by configuring the second base material passage  69  to have a cross-sectional area that increases progressively in a downward direction. 
         [0040]    It will be noted that the vibration that occurs during use of the trench former  18  ( FIG. 1 ) may pass into the base material  14  that is held in the base material hopper  67  and in the first and second base material passages  68  and  69  ( FIG. 4 ). With certain types of base material  14 , the induced vibration may urge the base material  14  to pack, which would encourage bridging. Because of the induced vibration, it is particularly advantageous to increase the cross-sectional areas of the first and second base material passages  68  and  69  in the downward direction and/or to increase the spacings D 1  and/or D 2  and D 3  and/or D 4  in the downward direction as described above. 
         [0041]    As the vehicle  24  moves forward, base material  14  is discharged from the first base material passage  68  onto the floor of the trench  11 . The thickness of the layer of base material  14  that is discharged from the first base material passage  68  is determined by the height of the bottom edge, shown at  130 , of the rear wall  104 . The conduits  12  are laid on top of the layer of base material  14  discharged from the first base material passage  68 . Base material  14  is discharged from the second base material passage  69  on top of and around the conduits  12 , preferably such that the base material  14  surrounds the conduits  12  in the trench  11 . The thickness of the layer of base material  14  that is discharged from the second base material passage outlet  82  is controlled by the height of the bottom edge, shown at  132 , of an outlet panel  134  that makes up a bottom portion of the rear wall  128  of the second base material passage  69 . The outlet panel  134  may be vertically movable so that the height of the bottom edge  132  can be selected, so that the thickness of the layer of base material  14  discharged from the second base material passage  69  may be selected. 
         [0042]    To assist in protecting the conduits  12  from inadvertent damage from work being carried out by workers afterwards, a cover layer  136  may be provided from a cover layer reel (not shown) and may be fed through a cover layer passage  138  and discharged on top of the conduits  12 . The cover layer passage  138  may extend adjacent the conduit feed passage  84 . The cover layer  136  may be made from a relatively tough material that is resistant to puncture from construction equipment such as the bucket from a backhoe loader. Thus, in the event that a worker inadvertently encounters the cover layer  136  later on while digging, the cover layer  136  will resist puncture and will thus provide some protection to the conduits  12  lying underneath, inhibiting damage to them from the worker&#39;s construction equipment. 
         [0043]    Additionally, or alternatively, the system  10  may further include a marker tape reel support  140  that holds a reel  141  of marker tape  142  and a marker tape passage  144  that carries the marker tape  142  to a marker tape passage outlet  146 . The marker tape passage  144  may be connected to the outlet panel  134  so that the marker tape passage outlet  146  is always a selected distance above the bottom edge  132  of the outlet panel  134 . In this way, the marker tape  146  is always laid down in a consistent manner on top of the base material  14  that is discharged from the second base material passage  69 . As an alternative however, it is possible for the marker tape passage  144  to be connected to a non-moving member, such as a non-moving portion of the rear wall  128 . It will be understood that in such an alternative embodiment, the distance between the marker tape passage outlet  146  and the top of the base material  14  would vary depending on the particular position of the outlet panel  134 . 
         [0044]    It is conceivable that a customer may wish to use an existing vehicle  24  and conduit reel support  16  (if one is required for the particular application) instead of purchasing those components as part of the system  10 . Accordingly, it is possible that a supplier may supply an assembly that is made up of only the trench former  18 , the base material handling system  20  and the conduit feed system  22  instead of supplying the entire system  10 . 
         [0045]    While the above description constitutes a plurality of embodiments of the present invention, it will be appreciated that the present invention is susceptible to further modification and change without departing from the fair meaning of the accompanying claims.