Abstract:
A system for providing heat to the dump body of a dump truck is disclosed. The disclosed system is suitable for use with truck equipped with a diesel particulate filter. When enabled, the system controls the exit path of exhaust gas such that it is routed to the dump body during normal operating conditions. In one embodiment, when the diesel particulate filter enters a regeneration cycle, high heat is produced. The system then routes the exhaust gas as to bypass the dump body to avoid heat damage from the higher temperature exhaust gas.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to improved apparatus for selectively diverting a flow of exhaust to the dump body of the truck to provide heat to a dump truck body. 
   BACKGROUND 
   A dump truck includes a dump body (or bed) for receiving material therein. Typically, the body can be raised by a hydraulic system so as eject the material from the bed at an appropriate time. Thereafter, the body can be lowered so that additional material may be loaded therein. 
   During certain weather conditions, the material in the body has a tendency to adhere to the contact surfaces of the body (e.g. during cold weather conditions) thereby resisting ejection of the material from the bed. To overcome this problem, it is known to provide a duct system within the body for receiving a flow of exhaust generated by the truck engine so that the flow of exhaust may be passed through the body, thereby heating the contact surfaces. Examples of such heated-body systems are disclosed in U.S. Pat. No. 2,974,997 by Parsely et al, and U.S. Pat. No. 5,797,656 by Kauk et al, the disclosures of both of which are incorporated herein by reference, to the extent not inconsistent herewith. By providing heat to the body in the aforesaid manner, the tendency of the material to adhere to the contact surfaces of the body during freezing weather is reduced. 
   Recently, stricter environmental regulations have been passed. The new regulations will require enhanced filtering of particulates via a Diesel Particulate Filter (DPF). The DPF traps particulates with a filter. When the filter becomes full, an additional burner activates to burn off the particulates at a higher temperature than that of the exhaust under normal operating conditions. 
   When the DPF activates (known as the “regeneration” cycle, or “regen” for short), then the exhaust gas increases from the normal 500-900 degrees Fahrenheit to as high as 1100 degrees Fahrenheit. This temperature can weaken or damage an aluminum dump body. It can also damage the paint on a steel dump body. 
   Attempts to address this problem have included a plastic liner to line the dump body. In practice, this has limited effectiveness, since material may undesirably adhere to the plastic liner under certain conditions. An alternative attempt to address this issue includes a separate fuel-powered heater to heat the dump body. This has the disadvantage of extra weight and complexity for an additional heat-generating system, as well requiring additional fuel for supplying the additional heat-generating system. Therefore, what is needed is the ability to heat the dump body of a truck having a diesel particulate filter, without the aforementioned disadvantages. 
   SUMMARY OF THE INVENTION 
   The present invention provides a system for providing heat to the dump body of a dump truck. The system of the present invention is suitable for use with truck equipped with a diesel particulate filter. When enabled, the system controls the exit path of exhaust gas such that it is routed to the body dump body during normal operating conditions. In one embodiment, when the diesel particulate filter enters a regeneration cycle, high heat is produced. The system then routes the exhaust gas as to bypass the dump body to avoid heat damage from the higher temperature exhaust gas. In another embodiment, the system partially diverts the exhaust gas, such that a portion of the exhaust gas enters the dump body during the regeneration cycle of the diesel particulate filter, providing heat to the dump body during the regeneration cycle, yet restricting the flow of exhaust gas, thereby preventing damage to the dump body. 
   The present invention further provides a system for providing heat to the dump body of a dump truck using exhaust, comprising a diesel engine, an exhaust stack having a venting end, and a diesel particulate filter, the exhaust gas of said diesel engine routed to the input of the diesel particulate filter, the exhaust output from the diesel particulate filter routed to an exhaust temperature control module, the exhaust temperature control module having temperature sensing means, and exhaust diverting means, whereby the exhaust gas is diverted to the dump body when the exhaust gas is at or below a predetermined threshold, and the exhaust gas bypasses the dump body when the exhaust gas exceeds a predetermined threshold. 
   The present invention further provides an exhaust diverting means that comprises:
         an air cylinder, said air cylinder connected to an extension member;   an air supply conduit connected to the air cylinder;   an air flow controller disposed inline with said air supply conduit;   a temperature sensor, the temperature sensor disposed to provide a temperature signal to the air flow controller;   a diverter control arm having a first and second end;   the first end of the diverter control arm connected to the extension member; and   the second end of the diverter control arm connected to a diverter; whereby the temperature signal causes activation of the air cylinder, moving the extension member, thereby moving the diverter control arm, and establishing the position of the diverter.       

   The present invention further provides an operator control, whereby the operator control is disposed to disable and enable the air flow controller, thereby providing the truck operator with the capability to disable the system. 
   The present invention further provides an operator control comprising a temperature selection control, whereby a predetermined threshold temperature of the air flow controller is adjustable by the operator. 
   The present invention further provides an operator control comprising a temperature selection control having a lower selectable limit of about 650 degrees Fahrenheit, and an upper selectable limit of about 800 degrees Fahrenheit. 
   The present invention further provides a system comprising:
         a second air flow controller disposed inline with said air supply conduit; and   a second temperature sensor, the temperature sensor disposed to provide a temperature signal to the second air flow controller. This provides an additional margin of safety.       

   The present invention further provides a system comprising an exhaust diverting means comprising:
         an electrically actuated magnetic control cylinder, the cylinder connected to an extension member;   an electric supply conduit connected to the cylinder;   a switch disposed inline with the electric supply conduit;   a temperature sensor, the temperature sensor disposed to provide a temperature signal to the switch;   a diverter control arm having a first and second end;   the first end of the diverter control arm connected to the extension member; and   the second end of the diverter control arm connected to a diverter; whereby the temperature signal causes activation of the electrically actuated magnetic control cylinder, moving the extension member, thereby moving the diverter control arm, and establishing the position of the diverter.       

   The present invention further provides a system comprising an exhaust diverting means that comprises a heat sensitive coil spring actuator disposed to control the position of a diverter, whereby the heat sensitive coil spring actuator is configured to actuate at a predetermined temperature, thereby establishing the exit path of the exhaust gas. 
   The present invention further provides a system wherein the exhaust temperature control module is mounted to the venting end of the exhaust stack. 
   The present invention further provides a system for providing heat to the dump body of a dump truck using exhaust, comprising a diesel engine, an exhaust stack having a venting end, and a diesel particulate filter, the exhaust gas of the diesel engine routed to the input of the diesel particulate filter, the exhaust output from the diesel particulate filter routed to an exhaust temperature control module, the exhaust temperature control module having temperature sensing means, and exhaust diverting means, whereby the exhaust gas is diverted to the dump body when the exhaust gas is at or below a predetermined threshold, and the exhaust gas bypasses the dump body when the exhaust gas exceeds a predetermined threshold, wherein the exhaust diverting means comprises:
         an air cylinder, the air cylinder connected to an extension member;   an air supply conduit connected to the air cylinder;   at least one air flow controller disposed inline with the air supply conduit;   at least one temperature sensor, each of the temperature sensors disposed to provide a temperature signal to a corresponding air flow controller;   a diverter control arm having a first and second end;   the first end of said diverter control arm connected to the extension member; and   the second end of the diverter control arm connected to a diverter; whereby the temperature signals cause activation of the air cylinder, moving the extension member, thereby moving the diverter control arm, and establishing the position of the diverter. If any one of the temperature signals indicates that the temperature exceeds a predetermined threshold, then the air cylinder is deactivated, and exhaust gas bypasses the dump body. This provides an additional margin of safety.       

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a prior art dump truck, identifying the dump body and exhaust stack. 
       FIG. 2  shows a block diagram of an exhaust system that utilizes the present invention. 
       FIGS. 3A and 3B  show additional details of an embodiment of the exhaust temperature control module of the present invention. 
       FIGS. 3C and 3D  show additional details of alternative embodiments of the exhaust temperature control module of the present invention. 
       FIG. 4  shows another alternative embodiment of the exhaust temperature control module of the present invention. 
       FIG. 5  shows a dump truck equipped with the exhaust temperature control module of the present invention. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows a prior art dump truck  100 , having a dump body  104 , and an exhaust stack  108 . In this prior art dump truck, exhaust gas will either exit via exhaust stack  108 , or pass through the dump body  104 , depending on whether the dump body is in a horizontal or tilted orientation. This system works satisfactorily when no DPF is present. However, with a DPF, the exhaust gas is too hot to safely enter the truck body  104  during the DPF regen cycle. The present invention addresses this problem. 
     FIG. 2  shows a block diagram of an exhaust system  200  that utilizes the present invention. In this case, a diesel engine  204  outputs exhaust gas via conduit  206  to a DPF  208 . The exhaust gas of the DPF  208  is output via conduit  210  to the exhaust temperature control module (ETC)  212  of the present invention. Exhaust gas is output from the ETC  212  via conduit  222 , which leads to the exhaust stack of the dump truck (in which case the exhaust gas bypasses the dump body), or via conduit  226 , which leads to the dump body of the dump truck. Hence, ETC  212  establishes the exit path of the exhaust gas. In some operating modes, the exhaust gas may be output via both conduit  222  and conduit  226  simultaneously, in varying amounts, to maintain a desired temperature range of exhaust gas output to conduit  226 . Other elements that are not depicted in this block diagram, but may be present, include muffler devices, and other pollution control devices, such as catalytic converters, as is well known in the art. 
     FIG. 3A  shows additional detail of an embodiment of the exhaust temperature control module  212  of the present invention. In this embodiment, exhaust gas travels from the engine  204  via conduit  206 , and enters DPF  208 . The exhaust gas exits DPF  208  via conduit  210 , and enters ETC module  212 . Within ETC module  212 , exhaust may be routed to conduit  322 , which leads to the exhaust stack (e.g.  108  of  FIG. 1 ), or routed to conduit  326 , which leads to the dump body (e.g.  104  of  FIG. 1 ) to provide heat to the dump body. An air cylinder  304  moves extension member  312  when supplied with air. Extension member  312  is connected to diverter control arm  316 . Diverter control arm  316  is attached to pivot joint  320 . Inside the exhaust pipe  323 , diverter  336  is connected to diverter control arm  316 . As shown in  FIG. 3A , the air cylinder is biased such that when no compressed air source is fed into air cylinder  304 , all exhaust gas is routed via conduit  322 , and is sent to the exhaust stack. Compressed air is supplied to air cylinder  304  via air supply conduit  309 . The flow of compressed air to air supply conduit  309  is controlled by air flow controller  308 , which is disposed inline with air supply conduit  309 . Air flow controller  308  provides compressed air to air cylinder  304  upon detecting a safe temperature from temperature sensor  328 . Temperature sensor  328  provides a temperature signal via signal path  332 . The temperature sensing means may be implemented by a variety of technologies, including, but not limited to, thermocouples, thermistors, RTD (resistance temperature detectors), and thermal imaging devices. In one embodiment of the present invention, the temperature signal provided by temperature sensor  328  is a binary signal that indicates if a predetermined temperature threshold is exceeded. In another embodiment of the present invention, the temperature signal is an analog signal whose voltage varies in a predetermined relationship to temperature. In yet another embodiment of the present invention, the temperature signal is a digital communication signal, providing temperature values in packets or a data stream that is received by air flow controller  308 . Air flow controller may also be configured to restrict compressed air flow via operator control  343 . Operator control  343  is preferably located within the cab of the truck. In this way, an operator can disable the dump body heat when the conditions do not require it. This may be the case when the ambient temperature is above freezing, when the dump body is raised, or when the dump body is empty. Operator control  343  may optionally provide a temperature selection control for adjustment of the predetermined threshold temperature for diverting the exhaust gas to the dump body. For example, the control may provide for adjusting the threshold temperature in a range from 650 degrees Fahrenheit to 800 degrees Fahrenheit. 
   As shown in  FIG. 3B , when air cylinder  304  is supplied with compressed air, it causes extension member  312  to extend. This causes diverter  336  to move to a position that directs the majority of the exhaust gas to conduit  326 , which supplies the exhaust gas to the dump body, thereby providing heat to the dump body. When the DPF  208  initiates a regen cycle, the exhaust gas will rise from approximately 500-900 degrees Fahrenheit to approximately 1,100 degrees Fahrenheit. The air flow controller  308  is preferably configured to stop the flow of compressed air when the exhaust gas temperature at the temperature sensor  328  exceeds about 700 degrees Fahrenheit, thereby diverting exhaust gas via conduit  322  to the exhaust stack (as shown in  FIG. 3A ). This ensures that the dump body, which is usually aluminum or steel, is not subject to excessive heat. 
   In one embodiment, it is contemplated that the flow controller will either route exhaust gas to the exhaust stack (via conduit  322 ), or route exhaust gas to the dump body (via conduit  326 ). However, it is also contemplated that an embodiment may provide more precise temperature control via a variable positioning of the diverter  336 , such that a portion of the exhaust gas is allowed to flow through conduit  322 , and a portion is simultaneously allowed to flow through conduit  326 , thereby allowing for more precise control of the exhaust gas entering the dump body. 
     FIG. 3C  shows an alternative embodiment of the exhaust temperature control module  212  of the present invention. In this embodiment, an electrically actuated magnetic control cylinder  404  is used in place of an air cylinder. In this embodiment, the electric supply to cylinder  404  is delivered via electric conduit  409 , and is controlled by switch  408 . Switch  408  provides electric current to cylinder  404  upon detecting a safe temperature from temperature sensor  328 . 
     FIG. 3D  shows an alternative embodiment of the exhaust temperature control module  212  of the present invention. In this embodiment, heat sensitive coil spring actuator  446  controls the diverter  336 . When the temperature of actuator  446  exceeds a predetermined level, the diverter  336  moves to block conduit  326 , and allows exhaust to vent to the exhaust stack via conduit  322 . 
     FIG. 4  shows an alternative embodiment of the exhaust temperature control module  212  of the present invention. In this embodiment, two temperature sensors ( 328 A,  328 B) are used. Temperature sensor  328 A provides a temperature signal via signal path  322 A to air flow controller  308 A. Temperature sensor  328 B provides a temperature signal via signal path  332 B to air flow controller  308 B. In this arrangement, an extra margin of safety is provided by having air flow controllers  308 A and  308 B in series, each controlled with independent temperature sensors ( 328 A and  328 B) and signal paths ( 332 A and  332 B). If either one of the air flow controllers ( 308 A,  308 B) stops the flow of compressed air to air cylinders  304 , the exhaust gas will be diverted to the exhaust stack via conduit  332 . In this way, if one temperature sensor or signal path fails, the redundancy of multiple temperature sensors and signal paths allows for the exhaust gas to be diverted via conduit  332  to the exhaust stack, thereby preventing excessively hot exhaust gas from entering the dump body. 
     FIG. 5  shows a dump truck  500  equipped with the exhaust temperature control module  512  of the present invention, and a DPF (not shown). In this embodiment, an exhaust temperature control module (ETC)  512  (similar to the ETC  212  described previously) is adapted to mount to the venting end of exhaust stack  108 . Electrical and compressed air supplies (not shown) are also provided to ETC  512 . When the ETC is operating in a mode to provide heat to the dump body  104 , it routes exhaust gas via conduit  526 . When the ETC is operating in a mode to prevent exhaust gas from entering the dump body  104 , it routes exhaust gas to the atmosphere via conduit  522 . In this way, the present invention can be adapted to a dump truck with no modification to the exhaust system prior to the point where the exhaust would be output to the atmosphere. 
   Although the descriptions above contain many specific details, these should not be construed as limiting the scope of the invention, but merely as providing illustrations of some of the presently preferred embodiments of this invention. For example, exhaust gas diverting mechanisms may be used, such as an electrically actuated magnetic control cylinder, or a heat sensitive coil spring actuating the diverter. Various types of signaling arrangements can be used in addition to, or instead of monitoring the temperature, such as monitoring a DPF activation signal directly from the DPF device or the engine. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.