Abstract:
A split-frame, heavy truck, suspension system for trucks that haul trailers made of three moveable interlocked rigid frames referred to as the front frame, rear frame, and interconnecting frame. The front frame supports the cab, engine, and transmission. The rear primary frame supports the drive axle and fifth wheel. The rear end of the interconnecting frame is pivotally mounted to the rear frame whereby the rear frame may rotate about a transverse axis. The front end of the interconnecting frame is mounted to the front frame in a manner that permits the interconnecting frame to rotate and pivot along its longitudinal axis relative to the front frame. Hydraulic cylinders are used to dampen vibrations and oscillations within this split-frame structure. An alternative embodiment allows the front frame to connect directly to the rear frame.

Description:
This a continuation in part of application Ser. No. 09/240,087, filed Jan. 29, 1999, now U.S. Pat. No. 6,250,663. 

   FIELD OF THE INVENTION 
   The present invention relates to the field of frames for heavy trucks or tractors and more particularly to split-frame structures for heavy trucks designed to reduce the transmission of road vibrations from the trailer to the truck cab. 
   BACKGROUND 
   The trucking industry is one of the primary means of transporting goods and equipment in the United States. In 1994, the trucking industry hauled 5.5 billion tons of freight accounting for 55 percent of the total domestic freight volume. To handle this volume of freight, the trucking industry estimates that it will require 300,000 to 500,000 new truck drivers each year. To attract this workforce, and retain the present workforce, the trucking industry is constantly seeking new ways to improve the working conditions and living quality of heavy trucks for its drivers. 
   Rough roads, railroad crossing, and the like, cause vibrations that are felt by the occupants of the truck&#39;s cab. Road vibration is one of the greatest causes for driver fatigue experienced. Vibrations can be transmitted directly from the road surface to the occupants through the suspension of the truck. However, these same vibrations are also transmitted indirectly through the trailer linkages coupling the trailer to the truck. 
   Heavy truck drivers commonly operate in two person teams. Frequently, while one person is driving the truck, the other person will sleep in a sleeping compartment at the rear of the cab. It is therefore desirable, both for the on-duty driver, and the off-duty driver sleeping, to stabilize the movement of the truck cab and minimize the vibrations and oscillations caused by rough surfaces. One primary method of achieving this goal is through minimizing the transmission of the trailer&#39;s vibrations and oscillations to the truck cab. Therefore, there is a current and continuing need for structures and mechanisms that will reduce the amount of road vibration felt by occupants of a truck. 
   In the current state of heavy truck technology, the truck is comprised of a cab attached to the front end of a single rigid frame. The heavy truck attaches and holds a trailer through a fifth wheel coupler mounted at the rear of the truck frame. The fifth wheel couples the truck frame to the kingpin of the trailer. 
   When travelling across a road, a truck and trailer will frequently drive over minor road imperfections such as concrete seams and potholes. A road imperfection that is symmetrically impacted by the trailer, such as a concrete seam, will cause the trailer to vibrate vertically, or to rock about a transverse axis. A road imperfection that is asymmetrically impacted by the trailer, such as a single pothole, will cause the trailer to have both a transverse and a longitudinal axis of motion. Due to the trailer&#39;s mechanical engagement with the truck, these mechanical vibrations and oscillations of the trailer are transmitted to the truck and the passenger cab. This transmission of vibrations and oscillations to the cab disturbs the smooth ride for the driver and passengers. 
   There have been truck designs that attempt to minimize the transmission of trailer vibrations and oscillations through pivotally mounting the fifth wheel with ball joints. The motion of the pivotally mounted fifth wheel is then dampened with hydraulic cylinders. In contrast, the present invention utilizes a split-frame system to minimize the transmission of trailer vibrations. This split-frame system reduces the transmission of road vibrations by mounting the front and rear axles of the truck on two separate moveably interlocked frames. 
   Inventors have developed many other devices that reduce the transmission of road vibrations to the trailer and the truck cab to enhance the ride quality for both the drivers and the freight. Halvorsen et al., U.S. Pat. No. 5,330,222, discloses a frame isolation system which enhances the ride quality of a terminal tractor. This patent discloses a single tractor frame assembly that includes an axle saddle provided with leading and trailing anti-torque links which permit the axle to move through a limited displacement to compensate for rough and uneven road surfaces. In contrast to the present invention, this patent does not teach the mounting of the front and rear axles on separate frames to reduce the transmission of trailer vibrations to the passenger cab. 
   A flexible joint assembly used in tandem wheel and axle suspensions for suspending a vehicle chassis is disclosed in Jable et al., U.S. Pat. No. 5,078,420. This patent discloses the pivotal mounting of equalizer leaf springs to a chassis side rail. The dual wheels of this device are separately mounted and separately flexible. 
   A frame/subframe assembly for mounting an engine and rear wheels to a race car chassis is disclosed in Huszr, U.S. Pat. No. 3,806,149. This patent discloses that the racecar engine and rear wheels are mounted to a subframe made of two side rails. The subframe is spring-mounted in the front and pivotally mounted at the rear to the main frame. The subframe is pivotally mounted with bolts to the mainframe at a point below and forward of the rear axle. The stated object of this subframe system is to provide a structure that allows for engine and chassis torque. A further object of this suspension is to provide a wheeled subframe for the engine to facilitate the repair and maintenance on the engine. This patent does not teach the use of a split-frame system, as in the present invention, to reduce the transmission of vibrations between a trailer and a heavy truck cab. 
   The present state of the art for motor vehicle frame systems fails to teach a heavy truck that includes a split-frame system mounting the front and rear axles on separate frames that reduces the transmission of transverse vibrations from the trailer to the truck cab. In addition, the present state of the art fails to disclose a split-frame system that also reduces the transmission of rotational vibrations from the trailer to the truck cab. 
   SUMMARY OF THE INVENTION 
   In accordance with the invention claimed, a novel heavy truck frame system is disclosed that reduces the transmission of the vibrations and oscillations of the trailer along its longitudinal and transverse axes to the truck cab. This heavy truck frame system is comprised of three rigid frames, referred to as the front frame, the rear frame, and the interconnecting frame. The front frame supports the truck cab, front axle, engine, and transmission. The rear frame supports the two rear drive axles and fifth wheel. The fifth wheel couples to the kingpin of the trailer. The interconnecting frame interlocks the front frame to the rear frame in such a manner to permit the rear frame to move relative to the front frame. The interconnecting frame is secured to the front frame in such a manner as to allow the interconnecting frame to pivot or rotate about its longitudinal axis relative to the front frame. A preferred means of securing the interconnecting frame to the front frame that permits this freedom of movement is a bearing guided pivot. The interconnecting frame is rigidly secured to the front frame with respect to all other degrees of freedom. The interconnecting frame is connected with the rear frame through a pair of self-centering bearings. This structure enables the rear frame to pivot or rotate about its transverse axis relative to the front frame. Therefore, the interconnecting frame enables the rear frame to pivot or rotate about is longitudinal axis and rotate about its transverse axis relative to the front frame. 
   When the rear wheels of a trailer impact a minor road imperfection such as a road seam or pot hole, the trailer will vibrate or oscillate about a transverse axis. Due to the fact that rear frame, having the fifth wheel rigidly mounted thereon, is free to rotate or pivot about its transverse axis relative to the front frame, the transmission of these transverse vibrations or oscillations to the trailer is reduced. When a trailer impacts a minor road obstruction on only one side, the trailer will vibrate or oscillate along its longitudinal axis. Due to the fact that the interconnecting frame enables the rear frame that is coupled to the trailer to rotate about its longitudinal axis relative to the front frame, these longitudinal vibrations are not transferred to the front frame. 
   In order to control the vibrations and oscillations of the rear frame relative to the front frame, a vibrational dampening system is included. Two hydraulic cylinders are connected to the front and rear frames to dampen the relative vibrations and oscillations between these two frames. These hydraulic cylinders do introduce a small amount of virbational coupling between the front and rear frames. 
   Enabling the rear frame to pivot and rotate about its transverse and longitudinal axis independent of the front frame reduces the transmission of the trailer&#39;s vibrations and oscillations the truck cab. This design therefore provides a smoother ride for those persons riding in the cab. 
   An alternative embodiment of the present invention would include a direct connection between the front frame and the rear frame without the need for an inner-connecting frame. 
   It is a primary object of the present invention to provide a heavy truck frame system that stabilizes the movement of the truck cab to provide a smooth ride for the driver and passengers. 
   It is a further object of the invention to provide a split-frame system that minimizes the transmission of the trailer&#39;s vertical vibrations to the truck cab. 
   A still further object of the invention is to provide a split-frame system that minimizes the transmission of the trailer&#39;s rotational vibrations to the truck cab. 
   Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize this invention are pointed out with particularity in the claims annexed to and forming a part of this specification. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its structure and its operation together with the additional object and advantages thereof will best be understood from the following description of the preferred embodiment of the present invention when read in conjunction with the accompanying drawings wherein: 
       FIG. 1  is a perspective view of the split-frame system illustrating the front frame, rear frame, interconnecting frame, and hydraulic dampening system; 
       FIG. 2  is a side view of the split-frame system; 
       FIG. 3  is a perspective view of the interconnecting frame in engagement with the front and rear frames; 
       FIG. 4  is a perspective view of the left side of the split-frame system illustrating the hydraulic dampening system; 
       FIG. 5  is a top view of the split frame system; 
       FIG. 6  is a perspective view of the left mechanical joint between the interconnecting frame and the rear frame; 
       FIG. 7  is a perspective view of the rear frame; 
       FIG. 8  is a side view of the split-frame system mechanically engaged to a trailer; and 
       FIG. 9  is a perspective view of an alternative embodiment for the configuration of the split frame system whereby the front frame is connected directly to the rear frame. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring more particularly to the drawings by characters of reference,  FIG. 1  discloses a perspective view of the split-frame system  1 . The split-frame system  1  is useful for reducing the transmission of vibrations and oscillations from a trailer to a truck cab  11 . The split-frame system  1  is comprised of three interconnected frames, a front frame  100 , a rear frame  200 , and an interconnecting frame  300 . These three frames are preferably made of hard alloy steel. The front frame  100  supports a front axle  10 , a truck cab  11 , an engine  12 , and a transmission  13 . The front axle  10 , having a pair of tires  14  mounted thereon, is positioned on front frame  100  such that the weight of front frame  100  and the components mounted thereon is evenly balanced over the front axle  10 . 
   The rear frame  200  supports a pair of rear axles  20  and a fifth wheel  40 . Each rear axle  20  has four tires  14  mounted thereon. Trailers are coupled to the rear frame  200 , typically through a coupler such as the fifth wheel  40 . The fifth wheel  40  couples to a kingpin of the trailer. In this embodiment, fifth wheel  40  is rigidly mounted to the rear frame  200 . Front axle  10  and rear axles  20  are supported by leaf springs  30  that are mounted on leaf spring joints  31 . 
   The interconnecting frame  300  interlocks the front frame  100  to the rear frame  200  in such a manner that permits the rear frame  200  to rotate about a transverse axis relative to the interconnecting frame  300 . In addition, the interconnecting frame  300  interlocks the front frame  100  to the rear frame  200  in such a manner that permits the rear frame  200  to rotate or pivot about its longitudinal axis relative to the front frame  100 . In this embodiment, the interconnecting frame  300  is positioned in the interior of the rear frame  200 . In an alternative embodiment, disclosed in  FIG. 9 , the rear frame  200  is mounted on the interior of the interconnecting frame  300 . 
   In order to restrict the degree to which the rear frame  200  can pivot or rotate relative to the front frame  100 , a pair of bumpers  60 , a left bumper  60 A and a right bumper  60 B, are provided. Each bumper  60  is made of a solid piece of rubber that is secured to the front frame  100  above the interconnecting frame by a metal bracket  61 . The bumpers  60  restrict the degree to which the interconnecting frame  300  may rotate about its longitudinal axis relative to the front frame  100  thereby restricting the degree to which the rear frame  200  may rotate relative to the front frame  100 . While two bumpers  60  are used to restrict the degree of rotation of the interconnecting frame  300  relative to the front frame  100  in this embodiment, a total of four bumpers  60  are used in an alternative embodiment. A more detailed description of the interconnecting frame  300 , how it is mounted to the front frame  100  and the rear frame  200 , and how its motion is restricted by bumpers  60  is provided in  FIGS. 3 and 4 . 
   A hydraulic system  50  is provided to dampen the vibrations and oscillations within the split-frame system  1 . The hydraulic system  50  is comprised of two hydraulic cylinders  51  mounted to the split-frame system  1  through the use of ball joints  52  and  53 . The two hydraulic cylinders  51  are mounted on the left and right sides of the split-frame system  1 . Each hydraulic cylinder  51  is mounted at the top to a rear ball joint  53 . Both rear ball joints  53  are secured to the rear frame  200 . The base of each hydraulic cylinder  51  is mounted to a front ball joint  52 . Both front ball joints  52  are secured to the front frame  100 . Hydraulic system  50  dampens the rotational vibrations and oscillations of the rear frame  200  along its longitudinal axis relative to the front frame  100 . In addition, hydraulic system  50  dampens the rotational vibrations and oscillations of the rear frame  200  about a transverse axis along the rear axles  20 . The use of ball joints  52  and  53  to mount hydraulic cylinders  51  enables the hydraulic cylinders  51  to adjust position to account for the relative movement of the rear frame  200  with respect to the front frame  100 . It is obvious to one skilled in the art that alternative systems and configurations are capable of performing the identical function of the hydraulic system  50  used in this preferred embodiment. While the hydraulic system  50  introduces a small amount of vibrational coupling between the front and rear frames,  100  and  200 , respectively, its use introduces an amount of control in the movement between the two frames. 
     FIG. 2  discloses a side view of the split frame system  1 . When the split-frame system  1  is on a flat surface as shown in  FIG. 2 , both the front frame  100  and the rear frame  200  are horizontal relative to the ground if a trailer is coupled to the fifth wheel  40 . In the event a trailer is not coupled to the fifth wheel  40 , the rear frame  200  will not remain horizontal relative to the ground. In this embodiment, the weight of the rear frame  200  and the components mounted thereon is not evenly balanced over the rear axles  20  as the weight of the front frame  100  is evenly balanced over the front axle  10 . The center of gravity of the rear frame  200  lies between the end of the rear frame  200  adjacent to the front frame  100  and the pair of rear axles  20 . When a trailer is not coupled to the fifth wheel  40 , the end of the rear frame  200  adjacent to the front frame  100  will pivot down toward the ground. It is desirable to maintain the rear frame  200  in a horizontal position when a trailer is not coupled to the fifth wheel  40  in order to safely operate the truck  2 . Alternatively, the hydraulic system  50  can be used to rigidly lock the rear frame  200  to the front frame  100  by altering the hydraulic pressure within the hydraulic cylinder  51 . The rear frame  200  can only pivot with respect to the front frame  100  when the rear frame  200  can compress and extend the hydraulic cylinder  51  with respect to the front frame  100 . When sufficient hydraulic pressure is created in the hydraulic cylinders  51  such that the rear frame  200  cannot compress or extend the hydraulic cylinder  51  with respect to the front frame  100 , the rear frame  200  is rigidly locked down to the front frame  100 . 
     FIG. 3  illustrates interconnecting frame  300  mechanically engaged with the front frame  100  and rear frame  200 . Interconnecting frame  300  is formed in the general shape of a wishbone with two arms  301  attached to two arm braces  302  that are attached to a coupling shaft  303 , and two pivot bearings  304 . The components of the interconnecting frame  300  are preferably made of a hard steel alloy. The preferred method of attaching arms  301 , arm braces  302 , and coupling shaft  303  together is welding. Coupling shaft  303  is pivotally attached by two bearing guided pivots  305  to the front frame  100 . Coupling shaft  303  defines a longitudinal axis about which interconnecting frame  300  rotates relative to the front frame  100 . Arms  301  are rotationally mounted to the rear frame  200  through bearing guided pivots  304 . A pivot  304  is secured to each of the two arms  301 . Each pivot  304  has a pivot shaft  306  secured to the interconnecting frame  300  that is received by a pivot aperture with a bearing race located in the rear frame  200 . Pivot shaft  306  defines a transverse axis about which the rear frame  200  rotates relative to the interconnecting frame  300 . In an alternative embodiment, ball joints are used in place of these pivots  304 . The pivot shaft  306  is secured to rear frame  200  by caps  307 . The interconnecting frame  300  attaches front frame  100  to rear frame  200  while permitting rear frame  200  to rotate longitudinally and transversely relative to the front frame  100 . 
   The split-frame system  1  is provided with a hydraulic system  50  to dampen the vibrations and oscillations of the rear frame  200  relative to the front frame  100 .  FIG. 4  illustrates a perspective view of the hydraulic cylinder  51  mounted on the left side of the split-frame system  1 . The hydraulic cylinder  51  is mounted at the top to a rear ball joint  53 . The rear ball joint  53  is rigidly secured to the rear frame  200 . The base of hydraulic cylinder  51  is mounted to front ball joint  52 . The front ball joint  52  is rigidly secured to front frame  100 . The use of ball joints permits the hydraulic cylinder  51  to alter position in relation to the relative motion between the front frame  100  and the rear frame  200 . 
   Also visible in  FIG. 4  is one of the two bumpers  60 . The bumper  60  is rigidly mounted to the front frame  100  by bracket  61 . When the interconnecting frame  300  rotates a sufficient amount in a clockwise direction about shaft  303 , the upper left end of arm brace  302  will impact against bumper  60 . In the alternative embodiment where four bumpers  60  are used, the bottom right end of arm brace  302  would impact against the bumper  60  mounted to the right side of the split-frame system  1  to front frame  100  below the interconnecting frame  300  as the upper left end of arm brace  302  impacts against the bumper  60  shown in FIG.  4 . While these bumpers  60  do partially couple the front frame  100  to the rear frame  200 , the interconnecting frame  300  has sufficient freedom to rotate relative to the front frame  100  to account for the trailer vibrations and oscillations caused by most minor road imperfections. Therefore, the vibrations and oscillations of the trailer caused by minor road imperfections are not transferred to the truck cab  11 . 
   A top view of the split-frame system  1  is disclosed in FIG.  5 . In this embodiment, the interconnecting frame  300  is configured to fit within the interior of rear frame  200 . Interconnecting frame arms  301  pivotally mount to the rear frame  200  on the interior of rear frame  200 . In an alternative embodiment, the interconnecting frame  300  is configured to attach to the rear frame  200  on the exterior of rear frame  200 . In this alternative embodiment, arms  301  are positioned on the exterior of rear frame  200 . In contrast to the pivot shaft  306  used to secure the interconnecting frame  300  to the rear frame  200  in the preferred embodiment, the alternative embodiment employs ball joints to pivotally secure arms  301  to the exterior of rear frame  200 . 
   The rear frame  200  is free to pivot only about a transverse axis relative to the interconnecting frame. The rear frame  200  is rigidly secured to the interconnecting frame  300  with respect to all other degrees of freedom. When a trailer experiences vibrations and oscillations about its longitudinal axis due to minor road imperfections, the trailer will transmit these vibrations to the rear frame  200  due to its coupling with the fifth wheel  40 . The rear frame  200 , secured to the frame arms  301 , will vibrate and oscillate with the trailer about the coupling shaft  303 . Since the coupling shaft  303  is pivotally mounted to the front frame  100  by the two bearing guided pivots  305 , the longitudinal vibrations experienced by the rear frame  200  are not transmitted to the front frame  100 . The hydraulic cylinders  51  dampen this longitudinal vibrational motion of the rear frame  200  about its longitudinal axis relative to the front frame  100 . The two bumpers  60  limit the degree to which the interconnecting frame  300  can pivot or rotate relative to the front frame  100 . The bumpers  60  permit the interconnecting frame  300  to freely pivot for the small angular vibrations and oscillations caused by most minor road imperfections. However, the interconnecting frame  300  will impact bumpers  60  and transmit vibrations to the front frame  100  when large road obstructions cause the rear frame  200  to experience large rotational vibrations. 
   Similarly, when a pair of rear axles of the trailer encounters minor a road imperfection, the front end of the trailer will rotationally oscillate about a transverse axis. The trailer, coupled to the fifth wheel  40 , will cause the rear frame  200  to also rotationally oscillate about a transverse axis. Due to the fact that the rear frame  200  is free to transversely pivot about pivot shaft  306 , these transverse rotational vibrations are not transmitted from the rear frame  200  to the front frame  100 . Hydraulic cylinders  51 , secured to the front and rear frames  100  and  200  as previously described, dampen this rotational transverse vibration between the rear frame  200  and the front frame  100 . 
   A perspective view of one of the two identical pivotal joints between the interconnecting frame  300  and the rear frame  200  is shown in  FIG. 6. A  bearing guided pivot  304  is bolted to arm  301 . A person skilled in the art may secure the pivot  304  to arm  301  by other conventional means such as welding. Pivot shaft  306  is rotationally coupled to the bearing guided pivot  304 . The pivot shaft  306 , as previously noted, is secured to rear frame  200 . 
     FIG. 7  discloses a perspective view of the rear frame  200 . This figure discloses the preferred embodiment of the invention where the interconnecting frame  300  is positioned within the interior of rear frame  200 . The arms  301  of interconnecting frame  300  having bearing guided pivots  304  mounted thereon are visible within the interior of rear frame  200  below the fifth wheel  40 . As described earlier, the fifth wheel  40  is rigidly secured to the rear frame  200 . The pivot shaft  306  that rotationally mounts the interconnecting frame  300  to the rear frame  200  is fixed to the rear frame  200  in this embodiment through the use of threaded nuts  307 . Other conventional means such as welding may be used to secure the pivot shaft  306  to the rear frame  200 . 
   A side view of the split-frame system  1  illustrating a trailer  80  coupled to the fifth wheel  40  is disclosed in FIG.  8 . When the rear wheels of the trailer  80  impact a minor road obstruction, the rear portion of the trailer will vertically oscillate causing the front portion of the trailer  80  to rotationally oscillate about the rear axle  20  as shown by the arrows in this figure. In addition, the trailer  80  will cause the rear frame  200  to rotationally oscillate in a similar manner due to its coupling with the fifth wheel  40 . The pivotal mounting between the rear frame  200  and the interconnecting frame  300  prevents the transmission of the rotational oscillations from the rear frame  200  to the front frame  100 . These oscillations experienced by the rear frame  200  are dampened by the hydraulic cylinder  51 . 
   An alternative embodiment for the structure of the rear frame  200  and the front frame  100  is disclosed in FIG.  9 . The front frame  100  directly to the rear frame  200  in such a manner that permits the rear frame  200  to rotate about a transverse axis relative to the front frame  100 . In addition, the front frame  100  interlocks to the rear frame  200  in such a manner that permits the rear frame  200  to rotate or pivot about its longitudinal axis relative to the front frame  100 . In this embodiment, the front frame  100  is positioned on the exterior of the rear frame  200 . Ball joints  308  are used to pivotally mount the front frame  100  to the rear frame  200 . 
   While these descriptions directly describe the above embodiments, it is understood that those skilled in the art may conceive modifications and/or variations to the specific embodiments shown and described herein. Any such modifications or variations that fall within the purview of this description are intended to be included therein as well. It is understood that the description herein is intended to be illustrative only and is not intended to be limitative. Rather, the scope of the invention described herein is limited only by the claims appended hereto.