Patent Application
20130026244
The invention relates generally to the field of work vehicles, and more particularly to vehicles having catalytic converters utilizing selective reduction agents, and to heating arrangements in such vehicles.
Many work vehicles are known for various applications that demand considerable power output and high reliability. Construction and agricultural applications, for example, make use of trucks, tractors, combines, and specialized vehicles of numerous configurations, many utilizing powerful diesel engines as their primary power plant. Historically, these vehicles have emphasized power and reliability first and foremost, with issues such as fuel consumption and emissions being important, but somewhat secondary. Increasingly, however, ever more stringent requirements are being placed on these vehicles to reduce fuel consumption and emissions, while still providing the power output needed for their particular applications.
One standard currently requiring significant redesign in such vehicles is the Tier 4 emission regulations being implemented by the U.S. Environmental Protection Agency. These regulations provide guidance for off-road diesel engines, and affect certain higher horsepower engine ratings. They call for significant reductions in particulate matter (smoke), as well as in oxides of nitrogen. Some adaptations contemplated to address these standards include selective catalytic reduction, in which engine exhaust passes through a catalytic chamber where it is sprayed with a non-toxic mixture of chemical urea (also known as carbamide) and purified water, the urea acting as a selective nitrous oxide (NOx) reduction agent. Other reduction agents may also be used. When the mixture combines with hot exhaust in the catalytic chamber, it is broken down into water vapor and nitrogen. Advantages of such systems include longer service intervals, lower fuel consumption, and wider fuel compatibility.
Problems with such systems can stem from use of the reduction agents at temperatures at which the agents freeze or solidify. For example, aqueous urea solutions containing 32.5% urea, common in such systems, may freeze at or below temperatures of approximately 12° F. For proper operation of the exhaust system, therefore, any vessel containing the urea and/or urea solution must be heated when the vehicle is operated at such temperatures so that the product may be pumped into the exhaust stream. Such heat demands displace heat needed for other purposes, and improvements to such vehicles are needed that balance the use of available heat.
The present invention provides novel techniques for vehicle heating designed to respond to such needs. The techniques may be used for many types of vehicles, such as tractors, combines, off-road and other work vehicles, particularly those employing diesel engines with selective reduction agents and catalytic converters. The techniques seek to utilize available heat in judicious ways to service both the defrosting (and heating) of the reduction agents for reduced emissions, and cabin heating needs.
In accordance with certain aspects of the present disclosure, a vehicle heating system comprises an internal combustion engine that generates heat when operating, and a cooling system configured to circulate a coolant to extract heat from the engine during operation. A catalytic converter is coupled to an exhaust of the engine, and a reduction agent system is configured to hold a reduction agent and to inject the reduction agent into the exhaust upstream of the catalytic converter. A first valve coupled to the cooling system and upstream of the reduction agent system, and is configured to open and close to control flow of the coolant to the reduction agent system to heat the reduction agent. A cabin heating system configured to heat an operator cabin, and a second valve is coupled to the cooling system and upstream of the cabin heating system, and is configured to open and close to control flow of the coolant to the cabin heating system to heat a vehicle cabin. Control circuitry is coupled to the first and second valves, and is configured to control flow of coolant to the reduction agent system and to the cabin heating system.
In accordance with other aspects, a method is provided for heating a vehicle. The method comprises circulating a coolant through an internal combustion engine that generates heat when operating to extract heat from the engine, and directing exhaust from the engine to a catalytic converter. The coolant is preferentially directed through a cabin heating system configured to heat a vehicle cabin rather than through a reduction agent system configured to hold a reduction agent for injection upstream of the catalytic converter. Subsequently, the coolant is preferentially directed through the reduction agent system rather than the cabin heating system based upon at least one of a cabin-related temperature and a predetermined time.
In accordance with further aspects, a method is provided for making a vehicle heating system. The method comprises coupling an internal combustion engine that generates heat when operating to a cooling system configured to circulate a coolant to extract heat from the engine during operation, and coupling a catalytic converter to an exhaust of the engine. A reduction agent system configured to hold a reduction agent and to inject the reduction agent into the exhaust upstream of the catalytic converter is coupled to the exhaust of the engine upstream of the catalytic converter. A first valve is coupled to the cooling system and upstream of the reduction agent system, while a second valve is coupled to the cooling system and upstream of a cabin heating system configured to heat an operator cabin. Control circuitry is coupled to the first and second valves. The control circuitry is configured to control the first and second valves to control flow of coolant to the reduction agent system and to the cabin heating system.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Turning now to the drawings, and referring first to
A transmission 20 is coupled to the engine 16 and allows for transfer of mechanical effort to a drive train 22 under the manual or automated control of the vehicle. The drive train, in turn, drives any driven wheels in a conventional manner. The engine exhaust is routed through a catalytic converter 24 that performs conventional chemical processes to reduce certain emissions, such as emissions of oxides of nitrogen (NOx).
Because the engine 16 may operate at lower temperatures that would be otherwise preferred for optimal performance of the catalytic converter 24, a reducing agent system 26 is provided. The reducing agent system will typically include a tank and associated components and plumbing for drawing a reducing agent from the tank for injection, such as in aqueous solution, into the exhaust from engine 16. Such injection is typically reformed upstream of the catalytic converter 24. Although a number of reduction agents may be employed, in a presently contemplated embodiment, urea is used in an aqueous solution as the reduction agent.
The engine 16 is temperature regulated by a cooling system. The cooling system may be, in many respects, conventional insomuch as it circulates a cooling fluid, such as water mixed with an antifreeze or other additive. In a typical application, the cooling fluid is pumped through one or more engine components and out of the engine system as indicated by reference numeral 28. Within the engine or engine system, the fluid may be routed through various heat exchangers, and so forth to extract heat energy produced by the engine. The cooling system will also typically include a thermostat, a radiator, and further components for regulating the flow and temperature of the coolant and thereby of the engine (not separately represented).
In the illustrated embodiment, the cooling system fluid 28 is routed to a first valve 30 that is coupled between the cooling system outlet from the engine and the reduction agent system 26. As described more fully below, the valving 30 may be a two-way (open/closed) valve or may allow for certain modulation (e.g., metering) of coolant flow to the reduction agent system. A second valve 32 is coupled to the cooling system and receives coolant flow from the same or a different outlet from the engine and delivers flow to a cabin heating system 34. The cabin heating system 34 serves to extract heat from the cooling fluid for use by a heat exchanger or heater 36 positioned in the cabin. In certain applications, the cabin heating system 34 may comprise a motor-driven blower (not shown), and the heater 36 may comprise a heat exchanger that transfers heat from the coolant to air in the cabin. Thus, although represented serially in
As discussed more fully below, the first and second valves 30 and 32 are controlled to balance or share available heat from the engine for both heating the cabin 12 and for heating the reduction agent system 26. Various schemes may be envisaged for utilization of this available heat as discussed below. In the embodiment illustrated in
These sensors and valves 30 and 32 are coupled to control circuitry 42. This control circuitry may be part of one or more comprehensive control circuits (e.g., electronic control units) that control operation of temperatures in cabin 12, operation of the vehicle, operation of the engine, or any other functions of the vehicle. Although not separately represented, the control circuitry 42 will typically include one or more processors, such as a microprocessor, digital signal processor, or the like, along with associated memory circuitry. The memory circuitry may serve to store settings, configuration parameters, calibration parameters, and so forth, as well as routines executed by the processing circuitry for regulation of any vehicle systems, and in the present context particularly the control of heat extraction by the reduction agent system 26 and the cab heating system 34. Where such control is performed by separate controllers, these may communicate with one another, such as over a vehicle data bus, to coordinate utilization of the engine-generated heat. Accordingly, the control circuitry may also include analog-to-digital converters, valve drive circuitry, and any other necessary support circuitry for receiving signals, processing the signals to carry out the desired functions described in the present disclosure, and driving any actuators, such as valves 30 and 32 for performing these functions. In practice, valves 30 and 32 may comprise solenoid-operated, two-way valves capable of opening and closing to regulate the flow of cooling system fluid to their associated heating systems.
Several possible approaches are presently contemplated for balancing the use of this available heat for cabin heating and for reduction agent heating. For example, in one presently contemplated embodiment, following startup of the engine, fluid is directed through the cabin heating system for a pre-determined time period, such as 20 minutes, during which time no coolant is directed through the reduction agent heating system. Similarly, during a pre-determined time, fluid may be circulated through both the cabin heating system and through the reduction agent heating system, and in certain implementations the relative flow through these two systems may be adjusted so that the reduction agent is heated, while some portion of the heat is diverted for heating the cabin. Still further, a closed-loop approach may be employed in which the temperature of the cabin (or another related temperature) is sensed, and some or all of the engine coolant is directed through the cabin heating system until a set or desired cabin temperature is reached, or until a temperature within a predetermined tolerance range of the set temperature.
Thus, at step 54, the system determines whether the period set for heating the cabin, a temperature set-point (ts) is reached, or a combination of these. If the desired time or temperature has not been reached, the diversion of the coolant for cabin heating continues as indicated at step 52. Once the time and/or temperature are reached, the valving directing coolant through the cabin heating system may be closed or regulated to reduce heat extraction, with more heat being extracted by the reduction agent system, as indicated by reference numeral 56. Thereafter, the reduction agent is heated with all or more of the available heat as indicated at reference numeral 58. It should be noted that the system may also, or instead, use sensed coolant temperatures as a basis for regulating relative flows of coolant to one or both of the cabin heating system and the reduction agent heating system.
It should be noted that other components of the vehicle may also utilize some of the available heat at various phases of operation of the vehicle. Similarly, it should be recognized that the cabin heating system 34 may include other means for heating the cabin, such as electric heaters. Nevertheless, it is presently contemplated that at least some of the heat that would otherwise be used for heating the reduction agent will be diverted for punctual heating of the cabin, particularly when cabin temperatures fall below certain points and/or at certain times, such as upon startup of the vehicle. Thereafter, cabin heating may switch to alternate mechanisms, such as electric heaters, although a similar balance of the use of available engine heat may also be performed periodically as needed after initial cabin heating.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
This application claims priority from and the benefit of U.S. Provisional Patent Application No. 61/512,828, entitled, “Work Vehicle Heating System and Method,” filed Jul. 28, 2011, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61512828 | Jul 2011 | US |
