Abstract:
Embodiments described herein relate to extendable sleepers for a tractor and methods of operating such a sleeper. In one embodiment, the tractor is connectable with a trailer. The trailer has a front surface. The extendable sleeper comprises a fixed portion disposed on the tractor, an extendable portion attached to the fixed portion, the extendable portion being movable between a retracted position and an extended position, and a mover operatively connected with the extendable portion for moving the extendable portion between a retracted position and an extended position. A control system is operatively connected with the mover for controlling operation of the mover. The control system operates in an extension mode where position of the extendable member is adjustable, a teach mode where a significant location of the extendable member is programmed into the control system, and an automatic mode where position of the extendable member is maintained.

Description:
BACKGROUND 
     Embodiments described herein relate generally to a sleeper for use on tractor-trailers and a method of operation of such a sleeper. More specifically, embodiments described herein relate to a sleeper for a tractor-trailer having an enclosed volume that is adjustable and a method of operating such a sleeper. 
     Air drag on a tractor-trailer reduces the fuel efficiency of the vehicle. One area where significant drag is created is at a gap located between the tractor and the trailer. This gap is typically 36 to 48 inches, depending on the vehicle and depending on the amount of loading on the trailer. The larger the gap, the more air that is trapped in the gap, and more drag is created on the vehicle. 
     To counteract the air turbulence effects on fuel efficiency, air deflectors are attached to the vehicle. The air deflectors may cause air to stream over the gap in a more controlled, less turbulent manner. Air deflectors may be heavy and costly, and may be installed in a fixed position. Changes in the air deflector configuration may be performed manually, which generally requires the use of hand tools. Fixed air deflectors offer limited improvements to air resistance because they do not close the entire gap. The fixed air deflectors may require a minimum gap measurement that exceeds the turning radius of the semi-trailer in relation to the tractor cab. 
     During travel of the vehicle, and particularly when negotiating a curved path, there is variation in the gap between the tractor cab and the trailer. To reduce air drag, the gap between the tractor and the trailer should be minimized under all travel conditions. However, if the fixed deflectors are extended too far and the gap is too small, the corners of the semi-trailer may strike and possibly encroach into a rear wall of the cab of the tractor when the vehicle is negotiating a curved path. Accordingly, fixed deflectors may not minimize air drag under all travel conditions. 
     It is known for tractor-trailers to be provided with enclosed compartments situated behind the driver&#39;s seat and accessible from the truck cab. These enclosed compartments are called sleepers. Sleepers may include one or more bunks, tables, chairs, storage closets and other furniture and amenities. The greater the length of the sleeper, the more room that is provided for the driver. 
     Length of the sleeper is dictated by the swing clearance area. However, the swing clearance area is occupied only when the tractor-trailer is in a turning configuration. When the tractor-trailer is in a substantially straight configuration, the swing clearance area may be unused and represent available free space. 
     SUMMARY 
     Embodiments disclosed herein relate to extendable sleepers for a tractor and methods of operating such a sleeper. In one embodiment, the tractor is connectable with a trailer. The trailer has a front surface. The extendable sleeper comprises a fixed portion disposed on the tractor, an extendable portion attached to the fixed portion, the extendable portion being movable between a retracted position and an extended position, and a mover operatively connected with the extendable portion for moving the extendable portion between a retracted position and an extended position. A control system is operatively connected with the mover for controlling operation of the mover. The control system operates in an extension mode where position of the extendable member is adjustable, a teach mode where a significant location of the extendable member is programmed into the control system, and an automatic mode where position of the extendable member is maintained. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a tractor-trailer, with the trailer shown in a straight position (solid lines) and in a turning position (dotted lines). 
         FIG. 2  is a side view of a tractor-trailer of  FIG. 1 . 
         FIG. 3  is a side view of the tractor-trailer of  FIG. 1  with an extendable sleeper in a retracted position. 
         FIG. 4  is a side view of the tractor-trailer, the extendable sleeper of  FIG. 3  in an extended position. 
         FIG. 5  is a top view of the tractor-trailer of  FIG. 4 . 
         FIG. 6  is a top view of the tractor-trailer of  FIG. 4  with the turning position shown in dotted lines. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1  and  FIG. 2 , an extendable sleeper  10  is installed on a tractor  12  that is connected to a trailer  14  to form a tractor-trailer, designated generally at  16 . The tractor-trailer  16  has a tractor frame  18  with front axle wheels  20 , and rear axle wheels  24 . The front of the trailer  14  sits on a fifth wheel  44 , which transfers the front half of the trailer&#39;s weight to the tractor&#39;s frame  18  then to the rear axle wheels  24 . The tractor  12  and the trailer  14  are mechanically connected through the fifth wheel  44 . A cab  28  is located generally centrally on the frame rails  18 . The tractor  12  has two parallel frame rails  18  that run from the front to the back of the tractor  12 . The front axle  20  and the rear axles  24  are mechanically attached to the frame rails  18 . 
     In the top view of  FIG. 1  and the side view of  FIG. 2 , the extendable sleeper  10  is in a retracted position such that the sleeper  10  does not protrude from a rear edge  32  of the cab body  30  of the tractor  12 . The extendable sleeper has an end  66  opposite to connection between the fixed portion and the extendable portion, i.e. opposite to an end of the sleeper attached to the cab body  30 . As becomes clearer below, a gap  34  is located between the end  66  of the sleeper  10  and a front surface  36  of the semi-trailer  14 . 
     When the tractor-trailer  16  negotiates a curve, there is relative movement of the trailer  14  with respect to the tractor  12 . Front corners  38  of the trailer  14  move along an arc  40  toward the end  66  of the sleeper  10 . The area (seen in  FIG. 1  with solid line and dotted line arc) through which front corners  38  of the trailer  14  move is called the swing clearance area  42 . The swing clearance area  42  relates to the fifth wheel  44 , which receives and secures a kingpin mounted on the underside of the trailer  14  to provide pivotal connection between the tractor  12  and trailer  14 . It is contemplated that the swing clearance area  42  can have shapes other than the illustrated D-shaped area, depending on shape of the front surface  36  of the trailer  14 . Tractor  12  components are kept out of the swing clearance area  42  to reduce interference with or obstruction of movement of the trailer  14 . 
     The length of some sleepers is limited by the swing clearance area  42 . Sleepers have a length such that the rear edge  32  of the sleeper  10  is not positioned within the swing-clearance area  42  to prevent any possible contact between the sleeper and the trailer  14  when the tractor-trailer  16  is negotiating turns or curves. Thus, when the tractor-trailer  16  is in a substantially straight configuration, the space within the swing clearance area  42  is unused. The gap  34  created by this unused space is a source of aerodynamic wind drag for semi-tractor-trailers. Further, there may be overall vehicle length restrictions which prevent increasing the gap  34  between the tractor  12  and the trailer  14 . In some embodiments, extendable sleepers may be in an extended position only when the tractor trailer  16  is not in motion. 
     In some embodiments, the sleeper  10  may be extendable and retractable when the tractor trailer  16  is either parked (stationary) or in transit (moving). The sleeper  10  has a first portion  46  and a second portion  48 . The first portion  46  and the second portion  48  are capable of relative movement between a retracted position and an extended position. Relative movement of the first portion  46  and the second portion  48  correspondingly varies size of the gap  34  such that the gap  34  is larger when the first portion  46  and the second portion  48  are in the retracted position than the size of the gap  34  when the first portion  46  and the second portion  48  are in the expanded position. In one embodiment, the first portion  46  is disposed on and fixed to the cab body  30  of the tractor  12  and is attached to the cab  28  to provide the driver with access to the sleeper  10 . In other embodiments, the second portion  48  can be fixed and the first portion  46  can be movable. The second portion  48  is attached to the first portion  46 , and together, they form an enclosed variable volume having a substantially continuous seal to protect the driver/other occupants from environmental conditions such as temperature extremes, dust, dirt and noise. For the sake of clarity of understanding, the first portion  46  is referred to as the fixed portion  46  and the second portion  48  is referred to as the extended portion  48 . 
       FIG. 3  and  FIG. 4 , the extendable portion  48  moves with respect to the fixed portion  46  towards the trailer  14  between the retracted position and the extended position. Movement of the extendable portion  48  of the sleeper  10  is effected by a mover or actuating means  50  operatively connected with the extendable portion  48 . The means  50 , such as a low pressure pneumatic actuator  52  having an actuator rod  54 , moves or horizontally displaces the extendable portion  48  between the extended position and the retracted position. In one embodiment, low force precision linear bearings can be used to provide reduced friction, longitudinally sliding movement between the extended position and the retracted position. This construction provides pinch protection to reduce a likelihood of injury or product damage. 
     In some embodiments, the means  50  for moving the extendable portion  48  include powered actuators, such as high pressure pneumatic actuators, hydraulic actuators, electric motors, or any other suitable actuator or power assisted device known in the art. Further, the means  50  can be activated by the driver or occupant of the tractor-trailer  16  using a switch or button  58  located at an instrument panel in the cab, or at an exterior of the tractor-trailer (shown at both locations on  FIG. 3  and  FIG. 4 ). 
     Pressure of the pneumatic actuator  52  can be limited to a minimum force required to horizontally move the extendable portion  48  between the retracted poison and the extended position. It is contemplated that, in some embodiments, as little as about 10 lbs of force may be required to move the extendable portion  48 . 
     In one embodiment, at least one of the fixed portion  46  and the extendable portion  48  has at least one of rigid side walls  60 A,  60 B, a rigid roof  62 A,  62 B and a rigid floor  64 A,  64 B. Other embodiments having different constructions are possible. It is contemplated that the extendable portion  48  may have exterior features such as a window, a skylight, a moon roof, and other features. In their interiors, the fixed portion  46  and/or the extendable portion  48  may have various features, such as furniture, appliances, fixtures and amenities. In one embodiment, a deflector  68  is located on the roof  62 B of the extendable portion  48  to reduce air drag. 
     The extendable portion  48  has a height and width that are substantially equivalent to like dimensions of the front surface  36  of the trailer  14 , such that when the extendable portion  48  is in the extended position, a large portion or substantially all of the gap  34  is occupied by the extendable portion  48  to reduce air drag. However it is contemplated that the extendable portion  48  may have various shapes and sizes and thus can occupy any desired portion of the gap  34 . 
     A control system  70  is operatively connected with the mover  50  for controlling operation of the mover  50 . The control system includes a computer  71  having memory that contains a program, adjusts, controls, and maintains position of extendable portion  48 . Position of the extendable portion  48  can be chosen to reduce the gap  34  to both provide reduced air resistance and increased sleeper length. 
     With structure of embodiments being disclosed, some methods of operation of the embodiments will be discussed. Steps of the methods can be performed in any suitable manner. Steps of one method may be combined, in any appropriate manner, with steps of another method to arrive at yet additional methods. In one method, initially, the control system  70  is in a extension mode and position of the extendable portion  48  can be adjusted by the driver for any reason, e.g. different position of the extendable portion  48  for each trailer  14 . It is contemplated that all variation in gaps  34  between any tractor  12  and any trailer  14  can be accommodated. When the tractor  12  is backed up and all hook-ups between the trailer  14  and the tractor  12  have been secured, the extendable portion  48  is placed in the retracted position. With the air brakes of the tractor  12  engaged, the control system  70  can be switched to a teach mode for programming the computer  71 . 
     The driver or other operator triggers a switch or button  72  to move the extendable portion  48  towards the extended position until the extendable portion  48  is just shy, such as less than 2-3 inches, of the trailer  14 , viz. a significant location of the extendable portion  48 . This can be done with a person controlling movement of the extendable portion  48 , or alternatively, with a gap sensor  74  operatively associated with the extendable portion  48  that can detect a distance between the extendable portion  48  and the trailer  14 . Either way, movement of the extendable portion  48  is stopped at a pre-determined distance from the trailer  14 . The selected position of the extendable portion  48  is locked by the control system  70 , for example by releasing the switch or button  72 . Releasing the switch or button  72  teaches the computer  71  where a maximum extension of the extendable portion  48  is located, representing the smallest attainable gap  34 . In one embodiment, the smallest gap  34  is less than about 2-3 inches. However, other gap  34  measurements are possible. 
     Initial programming of the computer  71  and the control system  70  can be accomplished quickly without the need of tools. Once programmed, the maximum extension of the extendable portion  48  (and the minimum gap  34  measurement) is set, and the control system  70  is switched to an automatic extension mode. 
     Referring now to  FIGS. 4-6 , in the automatic extension mode, the computer  71  automatically maintains the minimum gap  34  measurement while the tractor-trailer  16  is either parked (stationary) or in transit (moving) by appropriately moving the extendable portion  48  between the retracted position and the extended position. The control system  70  automatically maintains the minimum gap  34  measurement. When the tractor-trailer  16  turns, and the tractor  12  and the trailer  14  are not substantially aligned, and, if necessary to maintain the minimum gap  34  measurement, the computer  71  automatically moves the extendable portion  48  between the extended position and the retracted position to substantially preserve the minimum gap  34  measurement. For instance, air pressure is reversed in the pneumatic actuator  52 , moving the extendable portion  48  towards the fixed portion  46  of the sleeper  10  and out of the swing-clearance area  42 . It is contemplated that the extendable portion  48  can be retracted either fully or partially. When the tractor  12  and the trailer  14  are substantially aligned, the extendable portion  48  may be extended to the maximum extension limit/smallest gap distance that was set by the control system  70  during the teach mode. 
     In one embodiment, in the automatic extension mode, a gap sensor  74  is used to sense the amount of gap  34  between the extendable portion  48  and the trailer  14 . It is contemplated that the gap sensor  74  could be any appropriate sensing means, including a light screen, a magnetic proximity sensor, an ultrasonic sensor, or any other physical contact or non-contact gap sensing technology. In one embodiment, the gap sensor  74  measures and maintains a gap of about 2-3 inches or less. Non-contact gap sensors can be used to reduce road noise and physical contact wear and tear on the trailer  14 . A grommet limit switch  73  can be used as well. The grommet limit switch  73 , in one embodiment, could allow up to about 2-inches of tolerance between the trailer  14  and the extendable portion  48  prior to triggering a minimum gap fault or deviation during travel. 
     The gap sensor  74  and/or the grommet limit switch  73  substantially continuously monitors dimensions of the gap for any deviations from the minimum gap measurement. In the automatic extension mode, when the gap sensor  74  or the grommet limit switch  73  senses a deviation from the minimum gap measurement, the computer  71  causes automatic movement of the extendable portion  48  between the extended position and the retracted position to achieve the minimum gap measurement, and an alarm operatively associated with the fixed portion  46  is triggered to alert the driver of the deviation from the minimum gap  34  measurement and subsequent movement of the extendable portion  48 . The computer  71  causes automatic movement of the extendable portion  48  by an incremental distance, such as about one inch in one embodiment, to reduce a likelihood of future minimum gap measurement deviations. It is contemplated that other distances of movement of the extendable portion  48  can be used. The program repeats and updates the computer  71  of the control system  70  each time the gap sensor  74  and/or the grommet limit switch  73  detects a minimum gap measurement deviation. 
     When the computer  71  receives information that the tractor-trailer is turning, the computer  71  causes automatic movement of the extendable portion  48  as appropriate. However, in the event that the trailer  14  comes in contact with the extendable portion  48 , in one embodiment, a minimal force, for example about 10-lbs, could initiate movement of the extendable portion  48  towards the retracted position. The low friction linear bearings enable the extendable portion  48  to be moved relatively quickly. The extendable portion  48  laterally “floats” relative to the trailer, thereby avoiding possible pinch points. 
     In some embodiments, location of the swing clearance area  42  of the tractor-trailer  16  may be made available to the control system  70 , such as when the control system  70  is in the teach mode. When in the teach mode, the extended position of the extendable portion  48  and a position of the extendable portion  48  that reaches a boundary of the swing clearance area  42  are entered into the computer  71  of the control system  70 . When the control system  70  is in the extension mode, and the tractor-trailer  16  negotiates a curve, the extendable portion  48  is automatically moved to the position where the extendable portion  48  reaches a boundary of the swing clearance area  42 . Thus, the extendable portion  48  is just outside of the swing clearance area  42 . When the tractor-trailer  16  is straightened out, the extendable portion  48  is moved to the extended position. 
     Changes in relative positioning of the fixed portion  46  and the extendable portion  48  change volume enclosed within the sleeper  10 , thereby corresponding adjusting room for the driver/other operator. Relative positioning of the fixed portion  46  and the extendable portion  48 , i.e. moving the extendable portion  48  between the extended position and the retracted position, reduces air resistance of the tractor-trailer  16  by automatically maintaining dimensions of the gap  34  during operation of the tractor-trailer  16 .