WO2010084511A2

WO2010084511A2 - Cab heating system for a vehicle

Info

Publication number: WO2010084511A2
Application number: PCT/IN2009/000729
Authority: WO
Inventors: Karthik Srinivasan; Abhishek Shah; Rohan Gejji; Dhruv Kumar Jha
Original assignee: Mahindra Navistar Automotives Ltd
Current assignee: Mahindra Navistar Automotives Ltd
Priority date: 2008-12-19
Filing date: 2009-12-18
Publication date: 2010-07-29
Anticipated expiration: 2011-06-19
Also published as: WO2010084511A3

Abstract

Cab heating system for a vehicle comprises of preheated air coming from radiator (4) being routed into a liquid to air heat exchanger (6) through scoop (7) provided after the radiator (4); the scoop (7) is structured according to its position and properties of engine fan (12); the heat exchanger (6) is fitted over coolant pipe (5) connecting the coolant exit (10) at engine block (2) to coolant entry (11) at the radiator (4); the heat exchanger (6) carries the engine coolant from the engine jacket in its first passage (12); the preheated air passes through the second passage (13); the first passage (12) carrying the engine coolant has extended surfaces / fins (9) to increase the effective area through which heat exchange is achieved; while passing through the heat exchanger (6) said preheated air absorbs more heat and reaches to a temperature required for cabin heating; on passenger cabin (1) duct openings (8) are preferably positioned above the floor level at the desired elevation.

Description

Field of Invention:

The present invention relates to vehicle cabin heating system for automotive vehicles. More particularly, the present invention relates to cab heating system primarily for trucks, using heat from the internal combustion engine (particularly liquid cooled engines).

Background and Prior Art:

In the design of passenger cabins for any car or truck utmost priority is given to passenger comfort and ergonomics. This includes thermal comfort as well. In cold weather vehicle cabins are required to be heated to a temperature higher than ambient (outside) temperature. The general practice of heating the cab is to utilize heat produced in the engine or use an electrical heater to produce heat. These heater units are generally integrated with the HVAC systems (Heating, ventilation and air conditioning systems) of the vehicles or come as stand alone heater units with blowers.

Number of prior art cab heating systems has met with varying degrees of success.

Canadian patent No. CA 1155814 discloses a cab heating system for material handling equipment which maximizes energy saving by utilizing the heat generated during hydraulic operation. A heat exchanger is positioned downstream of the hydraulic control unit. Air flowing through the heat exchanger is heated by the hydraulic fluid and blown by a fan into the interior of the cab.

European patent No. EP 1145881 and American patent No. US 6254011 describes heating system for operator's cab of a vehicle powered by IC engine. Heated fluid from the engine is directed to a supply line where it is carried to a heat exchanger in communication with the interior of the operator's cab. A valve having an electrical actuator regulates the flow of heated fluid through the supply line to the heat exchanger.

American patent No. US 4136824 talks about a device for heating the operator's cab of a vehicle driven by air cooled IC engine. The lubricating oil of the IC engine is re-cooled in an oil cooler and is entirely or partially branched off from the oil cooler and is fed through valves, regulating and control devices to a heat exchanger in the operator's cab. The connecting bores for the supply and return conduits to the heating system in the operator's cab are arranged in the one-piece housing. Patent application No. US 20070366964 discloses a method and arrangement for cooling a vehicle engine while heating the vehicle cab. The system comprises cooling the engine by a liquid based cooling system in which coolant is cooled by air in a first heat exchange element which is by the vehicle radiator; heating the cab of the motor vehicle by heating air by using a coolant in a separate second cab exchange element and supplying the heated air to the cab by a fan.

In currently available cab heaters, the hot air produced by the heater is circulated in the cabin using a blower. This blower is either driven by engine power or using an alternative power source like a battery. Hence heater operation eats up into the power produced by the engine. In addition, the cost of the blower also has to be borne by the customer.

In case of an electrical heaters used for cab heating, air from blower is blown over high resistance hot wires that produce heat proportional to the electric voltage across them and the current passing through them. Here also power is utilized from the electrical battery incurring extra cost. In addition, the battery and the overall equipment in general require proper maintenance.

In cab heating process, the heaters utilizing engine coolant, the coolant is routed to a heat exchanger placed in front of the blower. The hot coolant in tubes of the heat exchanger heats the air from the blower passing across the tubes. The hot air is then circulated in the cabin. Here, the coolant is required to be routed inside the cabin near the blower. This requires additional equipment like pump and tubes and puts a strain on engine. Further it adds to the system cost, complexity and maintenance cost of the system.

Thus the cab heating systems in prior art require power from external sources viz. engine power and/or electrical power thus compromising vehicle performance. Further the prior art systems are complex, involves high cost and require regular maintenance due to moving parts like pump and blower. Objectives of the present invention:

The main object of the present invention is to provide a system that utilizes available engine heat to its maximum possible limit for heating cabin of a vehicle.

Another object of the invention is to provide cabin heating system without using any power from engine or any other external source such as electrical battery.

Still another object of the invention is to provide a low cost, simple and energy efficient cabin heating solution for automotive vehicles.

Another object of the invention is to eliminate moving and complex parts in the prior art cab heating system which add to its complexity, maintenance and cost.

Further object of the present invention is to provide a cab heating system that circulates hot air in the cabin without the use of a blower.

Still another object of the invention is to provide a cab heating system adaptable to existing trucks which have no heating provisions, as an aftermarket fitment.

Statement of present Invention:

According to the present invention 'cab heating system for a vehicle', the inbound air (to the cabin 1) is heated by capturing heat from the engine coolant. Preheated air coming from radiator being routed into a liquid to air heat exchanger through scoop provided after the radiator; the scoop is structured according to its position and the properties of engine fan; the heat exchanger is fitted over coolant pipe connecting the coolant exit at engine block to coolant entry at the radiator; the heat exchanger carries the engine coolant from the engine jacket in its first passage; the preheated air passes through the second passage; the first passage carrying the engine coolant has extended surfaces / fins to increase the effective area through which heat exchange is achieved; while passing through the heat exchanger said preheated air absorbs more heat and reaches to a temperature required for cabin heating; on passenger cabin duct openings are preferably positioned above the floor level at the desired elevation; flow rates of hot air for circulation in the passenger cabin are achieved from the ramming effect of the air as also the suction of the engine fan. Description of Figures:

The invention and further advantageous developments and arrangements of the invention will now be clear in more detail by way of description and with reference to the accompanying drawings, in which

Figure 1 shows a schematic representation of the entire system in the side view with the scoop radially positioned over the fan.

Figure 2 shows a schematic representation of the entire system in the side view with the scoop axial Iy positioned after the fan.

Figure 3 shows a schematic representation of the entire system in the front view.

Figure 4 shows a schematic representation of the liquid-air heat exchanger, scoop positioned axially at the air inlet of the heat exchanger.

Figure 5 shows a schematic representation of the liquid-air heat exchanger, scoop positioned radially at the air inlet of the heat exchanger.

Detailed description of the present invention:

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention as described below in the preferred embodiment. This invention is illustrated in the accompanying drawings, through out which like reference letters indicate corresponding parts in the various figures.

In the present invention 'cab heating system for a vehicle', vehicle cab heating is brought about by circulating hot air into the cabin (1). This system works in vehicles which have liquid cooled engines. In liquid cooled engines, the engine heat is dissipated to the coolant (usually water or ethyl glycol 50/50) which circulates around the engine block (2). The coolant then passes through the radiator (4) where it loses its heat to the air passing through the radiator (4). The coolant is again pumped into the engine block (2) and the engine cooling cycle continues. In this invention, the inbound air (to the cabin 1) is heated by capturing heat from the engine coolant. According to the present invention, rammed air (outside air ramming towards the vehicle due to the vehicle's speed) that flows through the radiator (4) collects heat dissipated by the engine coolant in the radiator (4). A scoop (7) is provided after the radiator (4) which routes this heated air into a liquid to air heat exchanger (6). The scoop (7) is structured according to its position and the properties of the engine fan (12). For an axial discharge fan, the scoop (7) is preferably located behind the fan (12) as shown in figure. For predominantly radial discharge fan, the scoop (7) is located at a radial position at the top of the fan blades as shown in figure 1. In other instances the scoop (7) may also be located just before the engine fan (12), again, either radially or axially depending on the fan configuration. In this configuration the scoop (7) will tap the preheated air from the radiator (4) utilizing the suction of the engine fan (12).

The heat exchanger (6) is fitted over the coolant pipe (5) connecting the coolant exit (10) at the engine block (2) to the coolant entry (11) at the radiator (4). In this exchanger (6), the coolant loses heat to the inbound heated air. The heat exchanger (6) carries the engine coolant from the engine jacket in its first passage (12). The preheated air passes through the second passage (13). While passing through the heat exchanger (6) the air absorbs more heat and reaches a temperature required for cabin heating. The flow rates of hot air for circulation in the passenger cabin (1) are achieved from the ramming effect of the air as also the suction of the engine fan (12).

In the present embodiment of the invention a parallel flow, liquid to air heat exchanger is used as shown in figures 4 and 5. The first passage carrying the engine coolant has extended surfaces/ fins (9) to increase the effective area through which heat exchange is achieved. In other configurations, we may install heat exchangers with improved effectiveness using counter flow, extended surfaces or any other similar improvements in heat exchanger design.

On the passenger cabin (1), the duct openings (8) are positioned at areas so as to improve cabin ergonomics with respect to thermal needs of the occupants. The duct openings (8) can also be fitted with louvers to regulate amount of heated air entering the cabin (1). The system can be designed incorporating a blower through which the circulation patterns maybe improved in other configurations. The system is made adaptable to tilting cabins widely found on trucks by making use of flexible ducts/ bellows-connecting the exit of the heat exchanger (6) to the cabin inlet (8) to account for cabin tilting.

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment.

Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or matter.

The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention; which is defined by the scope of the following claims.

Advantages of the present Invention a. No power taken from engine to operate the vehicle cab heating system. b. High utilization of engine heat for cabin heating is achieved. c. No use of external power device - electrical battery. d. The system has no moving parts. e. It is simple in construction and easy for serviceability. f. It is economic (low cost) cab heating system for vehicles.

Claims

We Claim:

1. Cab heating system for a vehicle comprises of preheated air coming from radiator (4) being routed into a liquid to air heat exchanger (6) through scoop (7) provided after the radiator (4); the scoop (7) is structured according to its position and the properties of engine fan (12); the heat exchanger (6) is fitted over coolant pipe (5) connecting the coolant exit (10) at engine block (2) to coolant entry (11) at the radiator (4); the heat exchanger (6) carries the engine coolant from the engine jacket in its first passage (12); the preheated air passes through the second passage (13); the first passage (12) carrying the engine coolant has extended surfaces / fins (9) to increase the effective area through which heat exchange is achieved; while passing through the heat exchanger (6) said preheated air absorbs more heat and reaches to a temperature required for cabin heating; on passenger cabin (1) duct openings (8) are preferably positioned above the floor level at the desired elevation; flow rates of hot air for circulation in the passenger cabin (1) are achieved from the ramming effect of the air as also the suction of the engine fan (12).

2. Cab heating system for a vehicle as claimed in claim 1 wherein heat exchanger with improved effectiveness using counter flow, extended surfaces or any other similar improvements in heat exchanger design is used.

3. Cab heating system for a vehicle as claimed in claim 1 wherein duct openings (8) are fitted with louvers to regulate amount of heated air entering the cabin (1).

4. Cab heating system for a vehicle as claimed in claim 1 wherein a blower is used to improve circulation of air through system.

5. Cab heating system for a vehicle system as claimed in claim 1 wherein the system is made adaptable to tilting cabins widely found on trucks by making use of flexible ducts / bellows connecting the exit of the heat exchanger (6) to the cabin inlet (8) to account for cabin tilting.

6. Cab heating system for a vehicle as claimed in claim 1 wherein for an axial discharge fan (12) the scoop (7) is preferably located behind the fan (12); for predominantly radial discharge fan, the scoop (7) is located at a radial position at the top of the fan blades; in other instances the scoop (7) located just before the engine fan (12); again, either radially for axially depending on the fan configuration.